TMC Practice Week 3

After changing the circuit on a patient receiving volume control ventilation, you note that the exhaled volume is 250 mL less than before and the peak inspiratory pressure is 8 cm H2O lower. Which of the following is the most likely source of the problem?

A 250 mL drop in exhaled volume and drop in PIP during volume control ventilation signals the presence of a leak. Common sites for leaks in a ventilator circuit are (1) the humidifier connection, and (2) open sensor ports (if incorporated into the circuit). Leaks may also occur at the patient airway, especially with a blown ET tube cuff. If the expiratory tubing were somehow obstructed, system pressure would rise not fall. Likewise, a decrease in patient compliance or mucous plug in the airway would cause the PIP to increase, not decrease. The correct answer is: a sensor port open to atmosphere

Which of the following must be included in the delivery circuit of an in-exsufflation (cough assist) device?

A basic in-exsufflation circuit includes the delivery tubing and a patient interface (face mask, mouthpiece, or 15 mm ET/trach tube adapter. A HEPA bacteria filter must be connected to the device outlet. The filter provides not only protects the patient from inhaled microbes but also prevents backflow of secretions into the device. Filters (and circuitry) must be changed between patients. The correct answer is: HEPA bacterial filter

At the higher end of its flow range, a high flow nasal cannula provides performance comparable to what other O2 delivery device?

A high flow nasal cannula overcomes the limitations of a standard cannula by providing oxygen (or other medical gases) at BTPS conditions (37º C and 100% relative humidity). Gas so conditioned can then be provided at flows exceeding patient needs, thus assuring a stable/fixed FIO2 or medical gas mixture. In this manner, a high flow nasal cannula provide performance comparable to a nonrebreathing mask, but with better patient comfort and tolerance. The correct answer is: nonrebreathing mask

What gas source is required when using a pneumatic demand valve for resuscitation?

A pneumatic demand valve resuscitator requires a 50 PSI unrestricted gas source to function properly. Because all flowmeters restrict flow, you should never attach a demand valve to this type device. Although a demand valve will run on 50 PSI air, for resuscitation we need 100% oxygen. An O2 concentrator provides neither the needed pressure, flow nor O2%. The correct answer is: 50 PSI oxygen

Which of the following devices would you select to meter the flow of medical gas to a patient if accuracy under changing downstream pressure conditions were a primary consideration?

A pressure-compensated Thorpe tube is a variable orifice, constant pressure flow metering device. With its flow control valve distal to the flow tube, the entire meter is calibrated at a constant pressure of 50 psig. This ensures that the position of the float accurately reflects actual outlet flow, regardless of the pressure generated by downstream resistance. Thus, the pressure-compensated Thorpe tube is the preferred flow metering instrument when accuracy under changing downstream pressure conditions is a requirement. The correct answer is: compensated Thorpe tube

A patient is receiving volume control A/C ventilation with 10 cm H2O PEEP via a transport ventilator with a single limb circuit. A disconnected exhalation valve line will cause which of the following conditions?

A single limb circuit typically employs an external balloon valve that controls exhalation. Disconnection of the valve line will cause valve failure. Since the exhalation valve normally closes the system during inspiration and controls PEEP during expiration, its failure will result in a loss of delivered volume AND a loss of PEEP. If so equipped, a low volume, low pressure or disconnect alarm should also activate. Depending on the device's sensitivity function, failure of the exhalation valve might also cause auto-triggering.

You observe that a pressure-cycled ventilator fails to cycle off when the patient exhales. The most likely cause of this problem is

A true pressure-cycled ventilator will cycle to exhalation (cycle off) only when the preset peak inspiratory pressure (PIP) is reached. The most common cause for failing to cycle to exhalation is a leak, either in the patient circuit or at the airway (e.g., blown cuff). Patient-ventilator dysynchrony or an obstructed ET tube are more likely to cause inspiration to end prematurely, and an improper sensitivity setting affects on-triggering, not off-cycling. The correct answer is: an airway or patient circuit leak

After setting up an intubated patient for ventilatory support, which of the following supplementary equipment would you require be available at the bedside?

After beginning invasive ventilatory support, one must assure that all supplementary equipment is available, including: 1) a backup artificial airway (in case of accidental extubation or cuff rupture); a manual resuscitator connected to O2 and ready for immediate use (in case of mechanical/electrical failure); and 3) a suction source, catheters and sterile water/saline (as all patients are at risk of airway occlusion by secretions at any time).

While using a galvanic fuel cell to analyze the O2 concentration on a mechanically ventilated patient, you notice that the O2 percentage fluctuates during the mechanical breath. This could be caused by

All electrochemical O2 analyzers (Clark electrodes and galvanic fuel cells) measure the partial pressure of oxygen in a mixture. If the total gas pressure fluctuates (as during positive pressure ventilation), so too will the analyzer reading. This is a normal response. The correct answer is: changes in pressure

A patient receiving humidified oxygen at 2 L/min via nasal cannula complains that she cannot 'feel' any gas flow at her nose. Which of the following actions would help determine the nature of this problem?

Although an O2 flow of 2 L/min can be hard to 'feel,' the patient may be correct. First, check the wall outlet and flowmeter. If these are OK, the problem must be a leak in the system. In set-ups using a bubble humidifier (as here), you can confirm a leak by occluding the O2 tubing--if the humidifier pop-off fails to function, there is a leak. If no humidifier is being used, you could immerse the cannula tips in a container of clean water and observe for bubbling. Measuring the SpO2 would not necessarily help determine if there were flow through the cannula, and operating the O2 zone valve might only endanger patients on the unit. The correct answer is: occlude the cannula to see if the humidifier pop-off sounds

Which of the following is a potential problem when using an air-entrainment nebulizer to deliver gas to an infant in an oxyhood?

An air entrainment nebulizer generates high noise levels, which are transmitted through the delivery tubing into the oxyhood. High noise levels can damage an infant's hearing. To avoid this problem, use a blender with heated humidifier to deliver O2 to the hood, and keep the flows at the minimum needed to maintain the FIO2, usually 5 to 7 L/min. The correct answer is: production of harmful noise levels

Which of the following are essential features for a CPR 'pocket' mask?

An ideal CPR pocket mask should be transparent, capable of tightly sealing against the face, provide an inlet for supplemental O2, and employ a standard 15/22 mm connection. One-way valves should be simple, dependable, and jam-free. Moreover, the mask should be available in various sizes to accommodate adults, children and infants.

After fitting a patient with a CPAP nasal mask, you set the prescribed pressure and turn the flow generator on. At this point the mask pressure reading is 0 cm H2O. You should:

An inability to generate any pressure in a CPAP system indicates that a large leak is present. In this circumstance, you should identify the source of the leak and correct it. The correct answer is: check for/correct any major leaks

Which of the following would cause the FIO2 delivered by an air entrainment mask to be different than that specified by the manufacturer?

An increase in flow resistance downstream from the jet (such as would occur were bedding to cover the mask's outlet ports) decreases the amount of air entrained, thereby decreasing total output flow. A similar effect is produced by obstruction of the air entrainment ports. Under these conditions, the delivered O2 concentration rises, but the actual FIO2 may decrease as room air is inhaled around the mask parts. Changes in O2 input flow do not affect the delivered O2 concentration because for a given size jet and entrainment ports, the mixing ratio is fixed. Patient changes also do not affect the O2 concentration delivered by these devices, but (as described above) may alter the actual FIO2. This occurs most commonly when the patient's peak inspiratory flow exceeds that provided by the device, a problem often seen with systems delivering over 35 to 40% O2. Mouth vs. nose breathing has no impact on full face mask systems. The correct answer is: an increase in resistance downstream from the jet

A conscious patient with an intact gag reflex requires an artificial airway solely to prevent obstruction of the upper airway by the tongue. Which of the following types of airways is most suitable in this situation?

An oropharyngeal airway can readily illicit a gag reflex and possible vomiting and should therefore generally not be used in conscious patients. In this instance, a nasopharyngeal airway should be used to maintain a patent airway. The correct answer is: nasopharyngeal airway

You are refilling a nondisposable nebulizer supplying O2 to a postoperative patient via aerosol face mask. The capillary tube dislodges and falls on the floor. The most appropriate action would be to

Any piece of respiratory equipment that falls on the floor should be considered contaminated and be replaced with a clean or sterile unit. The correct answer is: replace the entire nebulizer with a clean unit

Which of the following is true regarding using a remote alarm unit in conjunction with a home apnea monitor?

Apnea monitors that are intended for home use should include a remote alarm unit. The remote alarm unit should sound when (1) the monitor alarm signal has been actuated and (2) whenever the remote loses the monitor signal, e.g. goes out of range. Use of the remote alarm unit should not disable the alarm signals on the apnea monitor. The correct answer is: the remote alarm should sound whenever it goes out of monitor range

Which of the following would cause a nondisposable bubble humidifier to not bubble?

Assuming the flowmeter is turned on, if a humidifier does not bubble either the diffuser or something proximal to it is obstructing flow. In this instance, a clogged down tube (located proximal to the diffuser) is the only good explanation among the options provided. A tight lid would have no effect on bubbling. Were the pop-off valve open, bubbling would still occur, but gas would escape out the valve. And if the diffuser were missing, the unit would still bubble--only with larger bubbles. The correct answer is: the down tube is obstructed

A home care patient needs 8 L/min oxygen bled into an air nebulizer system. Which of the following would you recommend as the most efficient and cost-effective way to provide the oxygen?

At the desired flow (8 L/min), large gas cylinders and liquid oxygen systems would be very inefficient and costly, due to the need for frequent deliveries. Because most concentrators cannot deliver more than 5 to 6 L/min, higher flows can only be achieved by running two systems together in parallel. The correct answer is: dual O2 concentrators

Mechanical ventilation in the home setting can be provided by which of the following methods?

Based on individual evaluation of patient need, one of two major support approaches may be considered for home mechanical ventilation: invasive or noninvasive support. Invasive ventilatory support in the home always involves application of positive pressure ventilation via tracheotomy (NOT via oral or nasal endotracheal tubes). Noninvasive approaches include both positive and negative pressure ventilation via an intact upper airway, diaphragmatic pacing and abdominal displacement methods. Standard nasal CPAP does not augment ventilation and is thus not considered a mode of ventilatory support. The correct answer is: positive pressure via an intact upper airway

The upper limit of INPUT flow for most jet nebulizers driven by 50 psig source gas ranges from:

Because gas-powered nebulizer jets create such high resistance, the upper limit of input flow through these devices (at 50 psig) ranges between 12 to 15 L/min. With source pressures less than 50 psig (as with some air compressors), the maximum flow through the jet will be less still. Since total flow through an entrainment nebulizer is partly influenced by its input jet flow, therapists must know the maximum flow limit through the nebulizers they use. The correct answer is: 12-15 L/min

In a dual-limb or 'Y' ventilatory breathing circuit with heated humidifier, you should place the inspiratory HEPA filter between:

Because its performance can be affected by condensation, the HEPA filter must be positioned proximal to any active humidification system, i.e., between the ventilator outlet and heated humidifier. In order to prevent airborne cross-contamination, some ventilators also place a HEPA filter at or near the expiratory valve, which must be heated to prevent condensation. The correct answer is: the ventilator outlet and heated humidifier

You are preparing to conduct a complex transport of a patient receiving oxygen, and expect to have to alter O2 flows during the transport. Which of the following devices would best meet your needs?

Because upright positioning of the O2 cylinder is seldom possible and because movement of both the cylinder and patient is common, Thorpe tubes are not useful during patient transport. Instead either a flow restrictor or Bourdon gauge should be used. However a fixed or preset flow restrictor does not provide adjustable flows, as required in this scenario. Of the choices available only a Bourdon gauge (with adjustable regulator) would provide a range of flows. Note that a fixed 50 psi regulator with an adjustable flow restrictor (e.g., Grab 'n Go system) would also be a good choice if available. Just be sure when using these systems that you set the flow at the desired click stop and confirm that gas is flowing. Typically an "in between" setting on an adjustable flow restrictor provides no O2 flow whatsoever. The correct answer is: Bourdon-type gauge

Which of the following must be handled as infectious medical wastes?

Biohazardous wastes can be categorized as noninfectious or infectious. Infectious wastes include isolation wastes, cultures and stocks of infectious agents and associated biologicals, blood and blood products, pathological wastes, used/contaminated sharps, and miscellaneous contaminated wastes, i.e., those from surgery and autopsies, contaminated laboratory wastes, and contaminated disposable equipment. Noninfectious wastes include toxic chemicals, cytotoxic drugs, and radioactive, flammable, and explosive wastes. The correct answer is: used isolation supplies

Which type of disinfection inactivates all microorganisms except bacterial spores?

By definition, only high-level disinfection inactivates all microorganisms except bacterial spores. Some high-level disinfectants may also destroy spores if the exposure time is sufficient. The correct answer is: high-level

What is the primary purpose of using chemical indicators in equipment sterilization processing?

Chemical indicators are usually impregnated on packaging tape. These indicators change color when exposed to specific conditions, telling the user that the package has been processed via an appropriate sterilizer cycle. Chemical indicators cannot assure that the contents are actually sterile. Only biological indicators can provide that information. The correct answer is: to show that a package has been through a sterilizing process

Which of the following is a common cause for contamination of large reservoir jet nebulizers?

Common causes for contamination of large reservoir jet nebulizers include the following: use of non-sterile water, entrainment of contaminated air, handling of internal nebulizer components, and drainage or back-flow of contaminated condensate (from the delivery tubing) into the reservoir. Daily replacement of the nebulizer would help prevent contamination and neither obstruction of the air-entrainment port nor delivery of high O2 concentrations would necessarily cause bacterial contamination. The correct answer is: handling of the nebulizer components

A patient is receiving volume-controlled ventilation through a circuit containing a heated wick humidifier. The patient is comfortable only when a fan is blowing on him. The fan causes significant rain out of water in the breathing circuit. Which of the following should you do?

Condensation ("rain out") in a breathing circuit occurs when the gas leaving a heated humidifier cools on its way to the patient. Increasing the humidifier temperature will only increase circuit condensation. The only sure way to eliminate condensation and still provide gas at BTPS (100% RH at 37 °C) to the patient's airway is to use a heated wire circuit. If slightly lower humidity levels are acceptable, one could use an HME. Covering or wrapping a heated wire circuit can cause overheating and increase the risk of malfunction (due to melting of the plastic) or fire. And of course, the fan should not be removed. The correct answer is: Change to a heated wire circuit

While performing equipment rounds, you observe continuous bubbling in the humidifier of a standby oxygen setup. You also note that the flowmeter needle valve is completely closed. Which of the following should be done initially?

Continuous bubbling in a standby oxygen humidifier indicates that gas is flowing when there should be no flow. Since the needle valve is closed, the problem can't be a valve left open by mistake. Were there a leak in the wall outlet valve seat, gas would escape there and not go through the humidifier (there would be no bubbling). The problem must be a faulty flowmeter ('leaky faucet'). You should replace the faulty device with a properly working unit and send the malfunctioning flowmeter for repair. The correct answer is: replace the flowmeter

Instructions for an electrically-powered respirometer clearly specify that it cannot be immersed in water. What procedure would you recommend to decontaminate this piece of equipment before further processing?

Decontamination procedures remove infectious materials, particularly organic residues, from equipment that has been in-use. Normally, this is accomplished by complete disassembly and washing in a disinfectant detergent. Objects that cannot be immersed in liquid should at least be surfaced disinfected with a 70% alcohol solution or the equivalent. Thereafter, if sterilization is needed either a low temperature gas (e.g. ehtylene oxide) or steam autoclave process (if not heat sensitive) should be performed. The correct answer is: surface disinfection with 70% alcohol

All else being equal, which of the following statements is correct regarding a device that mixes air and oxygen using air-entrainment (Venturi principle)?

Design factors that determine the FIO2 delivered by an air-entrainment device include the size of the jet (and the resultant velocity of gas through it) and the size of the air-entrainment ports. In general, the smaller the jet and the larger the air-entrainment ports, the more air dilution occurs, the lower the delivered FIO2, and the higher the total output flow. The delivered FIO2 generally is independent of input flow, i.e., for a given jet and port size, the mixing ratio is fixed. The correct answer is: the smaller the jet orifice, the lower the delivered FIO2

Factors that affect the concentration of oxygen delivered by an air-entrainment (Venturi) mask include

Design factors that determine the concentration of oxygen delivered by an air-entrainment mask include: 1) the size of the jet (and the resultant velocity of gas through it), and 2) the size of the air-entrainment port(s). In general, the smaller the jet and the larger the air-entrainment ports, the more air dilution occurs and the lower the delivered FIO2. The key operational factor affecting these relationships is downstream resistance. An increase in downstream resistance always decreases air-entrainment, increases the delivered O2 concentration, and lowers total output flow.

Which of the following is characteristic of volume controlled ventilation?

During volume control, a ventilator will cycle to end inspiration after a preset volume is delivered out of the system. The patient never receives this full volume, due to normal compressed volume loss through the ventilator circuit and the presence of any circuit or airway leakage. The correct answer is: it ends inspiration after a preset volume is delivered by the ventilator

A 1 year-old child is apneic and cyanotic and will likely require mechanical ventilation. The physician asks you to prepare for oral intubation. Which of the following size ET tubes would you recommend in this situation?

ET tube sizes (and insertion lengths) vary according to the patient age and size. In general, a 4.0 mm tube would be appropriate for a 1 year-old (always have available at least one size larger and one size smaller). Note that uncuffed tubes are recommended for premature infants or those weighing less than 3 kg. Otherwise both cuffed and uncuffed ET tubes are acceptable for intubating infants and children. As with adults, if cuffed ET tubes are used on infants and children, cuff pressure must be monitored and limited according to manufacturer's specifications (usually 20 to 30 cmH2O). The correct answer is: 4.0 mm

Which of the following oxygen administration devices is capable of providing a stable FIO2 to patients with changing rates and depths of breathing?

Either a high-flow or leak-free reservoir system is needed to deliver a stable FIO2 to patients with changing rates and depths of breathing. An air-entrainment mask (set to deliver < 40% O2) is a good example of a high-flow system with such capability. When set so that its flow exceeds the patient's peak flow, a high-flow nasal cannula also can provide a stable FIO2 under changing demand. Last, a leak-free nonrebreathing mask with a reservoir volume that exceeds the patient's tidal volume also can ensure a stable FIO2. Of course, the typical disposable nonrebreathing mask is prone to leakage and thus may or may not provide a stable FIO2, and a simple mask lacks the reservoir volume needed to do so. The correct answer is: air-entrainment mask

A nondisposable humidifier will not bubble if

Failure of a humidifier to bubble indicates a problem at or before the diffusing head. This eliminates a loose reservoir jar and open pop-off as possible problems. A missing diffuser plate/head would simple cause large (as opposed to small) bubbles. The most likely problem is a clogged or plugged downtube. The correct answer is: the down tube is plugged

When setting up a 12-lead ECG on a patient, you cannot obtain any electrical signal. The batteries are fully charged and the device passed its power-on self-test. Which of the following is the most likely cause of this problem?

Failure to obtain a signal is usually due to a loose, missing or defective lead. In the presence of a poor electrical connection, patient motion, or improper filtering of extraneous electrical activity a signal may still be obtained, but will be characterized by unwanted interference or 'noise.' The correct answer is: a missing lead

When selecting an endotracheal tube, you should consider which of the following to minimize airflow resistance?

Flow resistance through an endotracheal tube depends on both the tube's inside diameter (ID) and its length, with the ID being the most important factor. The larger the tube's ID (and the shorter the tube length), the lower its resistance to flow. Neither the outside diameter, component materials of the tube (e.g., PVC vs. rubber) nor the compliance of the cuff affect flow resistance. The correct answer is: inside diameter (ID)

Plans are being made for a patient with a chronic neuromuscular condition requiring ventilatory support to be discharged to home. Swallow testing indicates that he is able to protect his upper airway and adequately clear secretions. However, he did not tolerate an in-hospital trial of nasal noninvasive positive-pressure ventilation (NPPV). Which of the following support options would you recommend?

For home care patients with an intact upper airway requiring ventilatory support, NPPV is the most common option. However, some patients cannot tolerate this approach or cannot accommodate any available NPPV interface (if a nasal mask is not accepted, it is unlikely that a full face mask will be tolerated). In these cases you should consider recommending negative-pressure ventilation, using either a chest cuirass or pneumosuit. The correct answer is: negative pressure ventilation

An adult patient requires frequent suctioning of oral secretions. Which of the following should be made available at the patient's bedside?

For suctioning of oral or oropharyngeal secretions at the bedside, you need 1) a vacuum system with collection bottle/canister, 2) connecting tubing, and 3) a Yankauer suction tip. A Lukens trap is used to collect sputum samples from the lower respiratory tract, with the Coude (curved) catheter designed to help enter the left bronchus during tracheobronchial suctioning. A bulb suction device is used to clear secretions from an infant's nose and mouth. The correct answer is: Yankauer tip

When turning on an H cylinder valve, gas leaks around the regulator connection to the cylinder. Your most appropriate action to correct the problem would be to:

Gas leaks between regulators and large cylinders are usually due to loose or misthreaded connections. You should first tighten the cylinder connection with a wrench. If this does not work, the connection is likely misthreaded. In this case, the regulator should be removed and reseated and the nut retightened. The correct answer is: tighten the cylinder connection

You open the valve on an E cylinder which has a regulator attached and hear a hissing noise. The flowmeter/gauge is turned off. Which of the following corrective actions would you take first?

Given that the flowmeter/gauge is off, the hissing noise must be coming from the cylinder/regulator, probably from a leaky connection. On E cylinders, a leaky connection usually is due to either 1) loose fitting of the cylinder valve outlet to the regulator (corrected by tightening the connection with the handscrew) or 2) a missing or damaged washer (corrected by replacing the washer). Until you take these simple actions to find/correct the leak, replacing the cylinder or regulator would be premature. The correct answer is: tighten the regulator connection

Which of the following methods could be used to sterilize a pressure transducer that is heat-sensitive and cannot be immersed in liquid?

Heat-sensitive items requiring sterilization require low-temperature sterilization, which rules out steam autoclaving. Also, because the item cannot be immersed in a liquid sterilant, such as glutaraldehyde or peracetic acid. That leave the two low-temperature gas sterilization methods, ethylene oxide and hydrogen peroxide plasma. The correct answer is: hydrogen peroxide plasma

CPAP systems used to treat obstructive sleep apnea in the home generates flow via:

Home CPAP (and BiPAP) systems generate flow via a blower or turbine powered by an electrical motor and standard house AC current. Modern home CPAP/BiPAP systems incorporate various sensors and computer control to vary flow and pressure according to patient need and can even automatically titrate pressure levels to minimize apnea episodes and thus optimize therapy. The correct answer is: an electrically-powered blower/turbine

In a dual-limb ventilatory breathing circuit, the proper position for placing a heat and moisture exchanger (HME) is:

If a heat and moisture exchanger (HME) is used for humidification, it must be placed to assure bidirectional flow, i.e., distal to the patient connector/ swivel adaptor in a dual-limb circuit and between the expiratory valve and patient airway in a single-limb circuit. The correct answer is: between the 'Y' connector and the patient's airway

When checking a nondisposable steel laryngoscope blade prior to intubation, you note that the bulb does not light when connected to the handle. Your first step should be to

If the bulb does not light when checking a laryngoscope blade prior to intubation, the first thing you should do is to recheck the handle/blade connection. If this does not work then replace the blade, check/replace the bulb, or replace the batteries The correct answer is: recheck the handle/blade connection

You note a sudden increase in PO2 measurement and decrease in the PCO2 measurement on a transcutaneous monitor. The most likely cause is:

If the electrode is not prepared and positioned correctly, or detaches during use, air (PO2 ~ 150 torr and PCO2 = 0 torr) may leak into the area around the electrode. For a patient with a low to normal PaO2, this will mean an erroneously high PtcO2 and low PtcCO2. The correct answer is: an air leak at the transducer site

The humidity output of a simple unheated humidifier is always:

In all humidifiers, heat is lost due to evaporative cooling. This cooling lowers the temperature of the gas, and thus its ability to carry water vapor. If a humidifier is not heated, as water vaporizes into the gas, heat is lost and both the gas and the water are cooled. Since the gas leaving the humidifier is cooler than room air, the humidity output will always be less than of saturated air at ambient temperature. The correct answer is: less than saturated air at ambient temperature

A patient requires a portable oxygen source capable of delivering the equivalent of 3 L/min O2. Which of the following systems can meet this requirement?

In general only portable liquid O2 units or portable O2 concentrators that can operate in the continuous-flow mode are appropriate for patients requiring more that 30% O2 or flows greater than 2 L/min

Shortly after you replace a jet nebulizer and tubing on a patient who has a tracheostomy, the SpO2 drops from 98% to 90%. Aerosol is visible throughout inspiration and expiration in the tracheostomy collar. Which of the following should you do first to resolve the situation?

In general, when troubleshooting oxygenation issues the first step always should be to check the O2 source and confirm that the proper FIO2 is being delivered. Because aerosol is visible throughout inspiration and expiration, the flow is adequate to meet patient needs and thus assure a stable FIO2. Given adequate flow, the only good explanation is that the FIO2 setting on the new nebulizer was not checked and is providing a lower O2 concentration than the prior setup. To correct the problem, readjust the entrainment setting to match the prescribed value. The correct answer is: Check the entrainment setting on the nebulizer

A patient with a normal ventilatory drive develops an acute restrictive disorder which causes a reduction in lung compliance and hypercapnic respiratory failure. Which of the following ventilatory support devices would you select for this patient?

In patients with an acute restrictive disorders causing reduced lung compliance, controlled ventilation is poorly tolerated. Moreover, use of the assist/control mode in these patients can result in respiratory alkalosis. For these reasons, IMV/SIMV is the preferred approach. With low lung compliance, a ventilator that can deliver high pressures will be required. In addition, if changes in impedance to ventilation are expected, a volume control ventilator will be needed. The correct answer is: a volume control ventilator capable of SIMV and high pressures

During manual bag-valve ventilation of an adult patient via endotracheal tube, you note poor chest expansion. Which of the following is the most likely cause of this problem?

Inadequate ventilation during manual bag-valve ventilation via ET tube would be due to either 1) airway problems (e.g., deflated or blown tube cuff, improper tube placement) or 2) failure of the bag-valve system (misassembly, missing or torn valves, etc). To quickly differentiate between these two categories of problems, secure a new bag and continue manual ventilation. If the problem persists after applying a new bag, the problem is likely the airway. Bag refill time, O2 flow rates and O2 reservoir issues would affect the FIO2, but not the adequacy of lung inflation. The correct answer is: ET tube cuff deflated

In a patient with a brachial artery catheter in place, you note loss of a palpable radial pulse. Which of the following is the most likely cause of this problem?

Indwelling catheters give ready access for blood sampling and allow continuous monitoring of vascular pressures, all without the traumatic risks associated with repetitive percutaneous punctures. However, infection and thrombosis are more likely with indwelling catheters than with intermittent punctures. Thrombosis is indicated by loss of a palpable pulse distal to (downstream from) the catheter site. The correct answer is: arterial thrombosis distal to the cannula

An intubated patient with COPD who is in acute respiratory failure requires a ventilator. To optimize support of this patient you would recommend a ventilator capable of:

Intubated patients typically require pressure support (PSV) to help overcome the extra work imposed by the artificial airway during spontaneous breaths. Unfortunately, during PSV many COPD patients experience a slower rise and decrease in inspiratory flow which can delay off-cycling and increase auto-PEEP. The ability to adjust the PSV off-cycle (to a higher % of peak inspiratory flow) in patients with COPD can improve patient-ventilator synchrony and reduce inspiratory muscle effort. The correct answer is: pressure support with adjustable off-cycling

When checking on a patient receiving aerosol therapy via large volume jet nebulizer, you notice that the device is delivering 'puffs' of aerosol instead of a continuous aerosol stream. What is the likely cause of this problem?

It is common for water to collect at low-points in the delivery tubing during bland aerosol therapy. This can cause intermittent aerosol delivery and can be resolved by draining the tubing and/or adding a water trap. The correct answer is: Water has collected in the delivery tubing

A patient receiving oxygen by nasal cannula at 8 L/min complains of discomfort. Which the following is the most likely explanation for problem?

Nasal O2 flows in excess of 6-8 L/min are uncomfortable for most patients, due to the low humidity and temperature of the inspired gas. Since these flows are used to achieve moderate O2 concentrations (> 35-40%), short-term therapy with this same goal is best achieved via a high flow cannula (with blender). High flow cannula systems warm and humidify the gas to BTPS conditions, providing better patient comfort and tolerance of the therapy. High flow cannulas also avoid the common problems with O2 masks, including heat retention and claustrophobia. The correct answer is: nasal drying

Which of the following is an acceptable way to dispose of liquid biohazardous/infectious waste, such as blood or body fluids?

Liquid biohazardous/infectious waste can be disposed of either 1) via the sanitary sewer system (pouring down the drain or toilet) or 2) via steam autoclaving (liquid cycle). If disposing into the sewer, state or local regulations may require pretreatment with a disinfectant like sodium hypochlorite (typically 1 part bleach to 9 parts liquid waste). If autoclaving, be sure to open the collecting vessel before initiating the cycle. After autoclaving the treated liquid can be poured down the drain. Appropriate PPE (e.g., gloves, gown, mask, and protective eyewear) should be worn when handling liquid waste, which must be transported in sealed leak-free containers, not bags. Only treated solid wastes are placed in sanitary landfills. The correct answer is: pour into sanitary sewer (drain or toilet)

To maximize the duration of flow/runtime outside the home, liquid portable O2 systems

Liquid portable O2 systems are used in conjunction with a home-based stationary unit, from which they are refilled. Because refilling requires a return to the base unit, it does not extend runtime outside the home. When full the typical unit holds 1-liter of liquid O2 and provides 3-4 hours continuous flow at a typical low flow setting of '2.' A 3 liter unit would triple this duration of flow but would weigh over 12 lbs and not be readily transportable. Thus the best way to maximize portable unit runtime is to incorporate a pulse dosing system that delivers small boluses of O2 only during inspiration. The correct answer is: incorporate a pulse-dose delivery system

Which of the following methods is appropriate for treatment of solid infectious waste before disposal?

Methods used to treatment solid infectious waste before disposal include sterilization by steam (autoclaving), gas or irradiation; incineration; thermal inactivation; and high-level chemical disinfection. The correct answer is: incineration/thermal inactivation

Which of the following types of breathing circuits would you select when assembling a noninvasive positive pressure/BiPAP ventilator?

Most noninvasive positive pressure (NPPV) ventilators/BiPAP devices use single-limb circuit with a leakage-type exhaust valve. These circuits consist of a single section of large-bore tubing and an open exhaust port, usually either a small orifice or a set of slotted vent holes. The continuous flow that noninvasive positive pressure ventilators provide through the circuit forces expired gas out this exhaust port during exhalation. The correct answer is: single-limb circuit with leakage-type exhaust valve

A small apneic child is receiving pressure control SIMV with PEEP via a ventilator at a preset rate of 40/min. You note that the ventilator is triggering to inspiration as soon as exhalation ends, with the actual rate being about 76/min. Which of the following is the most likely cause of this problem?

On some ventilators, the presence of a patient-ventilator system leak causes a drop in PEEP pressure (or an increase in flow) that tricks the device into 'thinking' that the patient is making an inspiratory effort, with the respnse being to trigger on and start inspiration. As here, the ventilator will tend to trigger on soon after exhalation ends, causing an undesirably fast rate and potential hyperventilation. The solution is to find and fix the leak (circuit, airway, etc.). The correct answer is: the ventilator is auto-triggering due to a system leak

Which of the following devices would you select to condition inspired gas to 100% body humidity?

Only a heated humidifier can condition gas to BTPS conditions (100% saturation at 37 degree Celsius). Nebulizers provide particulate water in addition to water vapor. The correct answer is: heated wick humidifier

A jet nebulizer is operating at an O2 input flow of 10 L/min on the 100% setting. If the input flow remains constant when the air-entrainment port is opened to the 40% O2 setting, which of the following would occur?

Opening the entrainment port of a jet nebulizer causes room air to be entrained, and total system flow to increase. This increase in flow increases total aerosol output per minute, but actually decreases aerosol density. Aerosol density decreases because the increase in carrier gas flow exceeds the increase in aerosol production, resulting in more aerosol evaporation and smaller aerosol particles. The correct answer is: total aerosol output (mL/min) would increase

Which of the following equipment would you select in order to suction the oral cavity or pharynx of an infant?

Oral and pharyngeal suctioning in infants is best accomplished with a bulb syringe. Either a DeLee trap or a mechanical vacuum source with attached catheter may be used for nasopharyngeal and nasotracheal suctioning of the neonate. The correct answer is: a simple bulb syringe

Which of the following portable O2 systems provides the greatest overall mobility and freedom for patients receiving long-term O2 therapy?

Portable O2 concentrators are smaller and lighter versions of standard concentrators that essentially free patients from their stationary liquid O2 reservoirs or bulky AC powered in-home concentrators and allow them to go wherever they want. The correct answer is: a portable oxygen concentrator

Which of the following equipment could be powered by a portable electric diaphragm or turbine air compressor?

Portable electric compressors are available for bedside or home use. Typically, these units use a diaphragm or turbine to compress the air, and generally do not have a reservoir tank. Due to their limited flow and pressure capabilities, these compressors can only power equipment that does not require unrestricted flows at 50 psig, such as small volume drug medication nebulizers. Large volume nebulizers, Pneumatic IPPB machines and Intrapulmonary Percussive Ventilation (IPV) devices require 50 psig to operate properly. The correct answer is: small volume drug nebulizer

Which of the following represents a potential hazard associated with home oxygen therapy?

Possible physical hazards to patients and caregivers using home oxygen therapy equipment include injuries due to unsecured cylinders, shocks caused by ungrounded equipment (e.g., O2 concentrator), 'burns' caused by mishandling liquid O2, and increased risk of fire. Careful preliminary instruction, followed by ongoing assessment of the environment, can help minimize these problems. The correct answer is: ungrounded equipment

A 35 lb (16 kg) toddler requires intubation with a laryngeal mask airway (LMA). What size LMA would you select for this patient?

Proper size selection is critical to effective use of the LMA, as well as maximum cuff inflation volumes. The recommended size LMA for a 10-20 kg infant/children is a #2, with a maximum cuff inflation volume of 10 mL. Often lesser volumes are sufficient to obtain a seal and/or achieve 60 cm H2O cuff pressure. The correct answer is: 2

A 15-year-old with cystic fibrosis is receiving pressure control SIMV with pressure support due to a severe bilateral pneumonia. The pulmonologist asks you to administer aerosolized dornase alfa (Pulmozyme, DNase) in-line with the ventilator. Which of these devices would you select to administer this therapy?

Pulmozyme is available only as a liquid (ampule) preparation for single use and thus cannot be administered by either MDI or DPI. Pulmozyme normally is administered by FDA-approved jet nebulizers. However, in-line jet nebulization during mechanical ventilation can alter ventilator response (especially with spontaneous breathing) and cause inaccurate flow/volume measurement. For this reason many clinicians are using vibrating mesh nebulizers for in-line ventilator drug aerosol therapy. These devices do not add any flow to the circuit and thus do not affect ventilator function. The correct answer is: vibrating mesh nebulizer

Which of the following is a shortcoming associated with the use of simple masks for delivery of moderate O2 concentrations?

Simple masks are among the most versatile O2 delivery systems, easily applied to adults, children and infants. However, the need for a tight seal and the confinement of radiant heat from the face can make these devices uncomfortable and can cause claustrophobia in some patients. Moreover, a mask can block expulsion of vomitus, thereby increasing the risk of aspiration. As long as the flow is properly set (least 5 L/min in adults), masks do not increase mechanical deadspace. The correct answer is: increased risk of aspiration

Solid infectious wastes can be disposed of by

Solid infectious wastes can be disposed of either by incineration and burying of the ashes or by autoclaving, then treating as trash. Unlike liquid waste, soild waste cannot be disposed of by discharging into the sanitary sewer systems. Note that landfilling of infectious wastes is allowed in some states and prohibited in others. The correct answer is: autoclaving, then treating as trash

To provide a low to moderate concentration of oxygen to a patient receiving nasal BiPAP via a device that uses a turbine or blower to generated pressure, you would:

Some NPPV ventilators and CPAP devices use a simple air blower to generated pressure. In order to provide supplemental oxygen with these devices, you place a small bore tubing adapter at either the patient interface or machine outlet. After connecting this adapter to a flowmeter via O2 delivery tubing, you bleed O2 into the circuit until the desired level is confirmed by O2 analysis. Note that high supplemental O2 flows can interfere with the proper triggering or cycling of some NPPV ventilators. For this reason, you should always follow the manufacturer's recommendations when considering how best to increase the FIO2 of these devices. The correct answer is: bleed supplemental O2 from a flowmeter into the circuit

A 2-year old asthmatic child is placed on an inline small volume nebulizer while receiving volume control SIMV. Shortly after the treatment has started, an alarm on the servo-controlled humidifier is activated. Which of the following is the most likely cause for this alarm?

The 4-6 L/min of additional unheated gas flow added to the circuit when using a small volume nebulizer will lower the temperature at the patient's airway, which can trigger a humidifier alarm. Either the humidifier's low temperature alarm should be readjusted during treatment or an electronic drug nebulizer (ultrasonic or mesh) should be used to avoid adding extra flow to the ventilator circuit. The correct answer is: low gas temperature

Which of the following factors effect the oxygen concentration delivered by an air entrainment system?

The O2 concentration delivered by an air entrainment system is primarily a function of the air:O2 ratio of the device. The delivered O2 concentration will however rise if resistance to flow increases downstream from the jet (which will also lower the total output flow). Total output flow also varies with both the air:O2 ratio and the O2 input flow to the jet. Changes in O2 input flow to the jet do not affect O2 concentrations because for a given jet and entrainment port size the air:O2 mixing ratio is constant.

Which of the following devices could you use to accurately meter flow through a large volume jet nebulizer?

The accuracy of flow restrictors, Bourdon gauges, and uncompensated Thorpe tubes are all affected by high resistance equipment, such as a jet nebulizer. Only a compensated Thorpe tube flowmeter will provide accurate readings when attached to equipment that creates high downstream pressures. The correct answer is: compensated Thorpe tube

The major function of the baffle in a nebulizer is to

The major function of the baffle in a nebulizer is to remove larger particles from the suspension. This is accomplished by inertial impaction. The correct answer is: remove larger particles from the suspension

Which of the following is the most common indication for adult high flow nasal cannula therapy?

The most common indication for adult high flow nasal cannula therapy is as an alternative to a nonrebreathing mask in patients requiring precise moderate to high FIO2s. Less common is the use of these systems to administer heliox or NO therapy. High flow nasal cannulas also can serve as an alternative to CPAP therapy, but only in infants. The correct answer is: as an alternative to a nonrebreather mask

A patient complains to you that her MDI 'does not mist when squeezed.' After confirming that the canister is new and full, you hand warm it, fit it tightly in its boot, detach the protective cap and actuate it, but observe that no aerosol plume is produced at the mouthpiece. Which of the following would you do to correct this problem?

The most likely problem in this case is that the aerosol outflow is being obstructed by dirt or debris. You should remove or clean out any dirt or foreign material in the boot and clean the canister's outlet in hot water. Using a universal adapter may only worsen the problem since different MDI formulations operate at different pressures, and thus may have different sized boot nozzles. The correct answer is: clean the boot and canister outlet

A cooperative and alert post-operative patient taking food orally requires a small increment in FIO2, to be provided continuously. Precise O2 concentrations are not needed. Which of the following devices would best achieve this end?

The nasal cannula is the device of choice for the cooperative and alert patient when the goal is small to moderate increments in FIO2 and precision is not needed. The correct answer is: nasal cannula

To maximize the FIO2 delivered by a manual bag-valve resuscitator you would:

The oxygen concentration delivered by a manual resuscitator (bag-valve-mask) depends on 1) the flow of oxygen into the bag, 2) the size of the oxygen reservoir, and 3) the bag refill time/rate. The greater the input flow, the larger the reservoir, and the longer/slower the bag refill time, the higher the FIO2. The correct answer is: increase bag refill time

A bubble humidifier is connected to a flowmeter set and running at 5 L/min. When you obstruct the outlet of the small-bore delivery tubing, the pressure pop-off does NOT sound. Which of the following is the most likely cause of this observation?

The pressure pop-off on a bubble humidifier normally sounds when the pressure in system exceeds a preset limit, e.g. 2 psi. Pressure in the system rises only when there is an obstruction to flow DISTAL to the downtube or bubble-diffuser. If the pop-off does not sound when you obstruct flow, either (1) there is no inlet flow, (2) there is a leak in the humidifier/ delivery system, or (3) the pop-off is malfunctioning. The correct answer is: a leak in the humidifier/delivery system

The pressure setting during pressure control ventilation determines the

The pressure setting during pressure control ventilation determines the highest pressure that can be achieved during inhalation. During pressure control ventilation, another parameter such as time determines when machine cycles off to end inhalation. The correct answer is: highest pressure achieved during inhalation

The pressure pop-off is alarming on the humidifier attached to an oxygen cannula. Which of the following would correct this problem?

The relief valve of a humidifier sounds when the pressure in the bottle exceeds the valve's threshold pressure (usually between 1-2 psig). The most common reasons for this to occur are 1) an excessive oxygen input flow and 2) downstream obstruction to outflow. In this case, one should check for obstruction in the cannula and its delivery tubing. The correct answer is: check for obstruction in the cannula

When suctioning an adult intubated with a 8 mm endotracheal tube, you suddenly lose vacuum pressure. Which of the following is the likely cause?

The two most common conditions that would cause a sudden loss of vacuum pressure during suctioning are (1) disconnected tubing (leak; loss of vacuum) or (2) a full suction collection reservoir (ball-valve shut-off). Normal clearance of secretions would not cause loss of vacuum, nor would displacement of the ET tube or its obstruction by a mucous plug. However, a mucous plug in the catheter could cause loss of vacuum at its tip. The correct answer is: suction tubing disconnection

A patient is started on a spontaneous breathing trial via a T-tube connected to a large-volume nebulizer set at 35% O2. In order to decrease the likelihood of condensate occluding the delivery circuit, you should do which of the following?

To decrease the likelihood of condensate occluding the tubing of a large-volume nebulizer system you can place water traps at low points of the delivery circuit and inspect and drain the tubing periodically.Heating the nebulizer or using smooth-bore tubing will only increase the likelihood of condensate blocking the circuit, and placing the nebulizer above the patient increases the risk of condensate spilling into the patient's airway. The correct answer is: place a water trap in delivery tubing

To prevent foreign matter from entering an oxygen regulator that is to be attached to an oxygen cylinder, the cylinder valve must be

To prevent foreign matter from entering an oxygen regulator that is to be attached to an oxygen cylinder, the cylinder valve must be cracked. The correct answer is: cracked

You are asked to transport a mechanically ventilated a patient to the MRI center. What type of ventilator would you recommend to support the patient during this procedure?

Ventilators used in the MRI must not use any moving metal parts, such as inspiratory or expiratory valves. Pneumatically powered and controlled ventilators tend to have few metal components and are best suited for this purpose. Before use, however, check the manufacturer's specifications to ensure MRI compatibility. The correct answer is: a pneumatically powered and controlled ventilator

Which of the following types of breathing circuits would you select when assembling a home-care ventilator for use on a patient with a tracheotomy?

To provide invasive ventilation to a home care patient with a tracheotomy, select an electrically powered home-care ventilator that uses a single-limb circuit with expiratory balloon valve. Single-limb circuits have a separate pneumatic line running from the ventilator to the expiratory valve which pressurizes the expiratory valve during inspiration in order to block gas outflow during the application of positive pressure. The expiratory valve also can be used to control or retard expiratory flow or provide CPAP/PEEP. The mechanical deadspace in these circuits is that between the built-in expiratory valve and patient airway. Single-limb circuits with leakage-type exhaust valves are used for noninvasive positive pressure ventilation (NPPV). The correct answer is: single-limb circuit with expiratory balloon valve

To test that a cough assist or mechanical in-exsufflation (MI-E) device is working properly, you should:

To test that a cough assist or mechanical in-exsufflation (MI-E) device is working properly, you should turn it on, occlude the circuit and toggle between inhalation and exhalation. Pressures should correspond to those set on the device control panel. Never use the patient to test for proper equipment function The correct answer is: occlude the circuit and manually toggle the device between inhalation and exhalation

A physician has ordered administration of a steroid available only in a metered dose (MDI) preparation. In training the patient in its use, you cannot get her to coordinate MDI discharge with her breathing. Which of the following actions would be appropriate?

Two techniques can be used to aid proper application of MDI aerosols: extension devices (spacers and holding chambers) and demand systems. Extension devices minimize aerosol loss and maximize propellant evaporation, thereby increasing stability and penetration. Demand systems synchronize MDI discharge with the patient's inspiration, thereby requiring less patient coordination The correct answer is: add a spacer or holding chamber to the MDI

Which of the following is used by the ultrasonic nebulizer to produce droplets from the water reservoir

Ultrasonic nebulizers use high frequency sound vibrations to mechanically disrupt the surface of a liquid. At the right frequency and amplitude, these vibrations create a unstable geyser of liquid particles from which the aerosol is formed. The correct answer is: vibration

When performing a routine ventilator check, you note that the airway temperature indicator reads 26° C. The flowsheet indicates a prior temperature of 35° C. Which of the following best explains this discrepancy?

Unexpected changes in inspired gas temperature could be due to 1) an (unintended) change in the humidifier thermostat setting; 2) failure of the humidifier thermostat mechanism; or 3) recent addition of cool water to the humidifier. Neither changes in patient minute ventilation nor the addition of mechanical deadspace to the circuit should alter a properly monitored airway temperature. The correct answer is: failure of the thermostat mechanism

Which of the following occurs when gas leaves a simple unheated bubble humidifier and is delivered to a patient?

Unheated bubble humidifiers can saturated dry gases with water vapor, but operating temperatures are always less than ambient (due to evaporative cooling). Thus, gas leaving the device is warmed, and no tubing condensation occurs. Absolute humidity remains unchanged, but relative humidity drops to about 35-40% of the water vapor needed to saturate gas at body temperature. The correct answer is: the relative humidity of the gas decreases

To continually monitor the FIO2 being delivered by a mechanical ventilator, the oxygen analyzer probe should ideally be placed:

Variable FIO2s during ventilatory support are normally provided by an O2 blending mechanism. Accuracy of these devices cannot be assumed, and should thus be confirmed by analysis with each ventilator check. This is done by placing a calibrated analyzer probe in the inspiratory side of the circuit, proximal to the humidifier and bacteria filter (to prevent contamination of the circuit and moisture damage to the probe). The correct answer is: proximal to the humidifier and bacteria filter

Most IPPB devices are classified as pressure-cycled ventilators because:

Ventilators commonly are classified according to the how they end inspiration, i.e., the 'cycle' mechanism. Since most IPPB devices use a valve that closes when the pressure reaches a preset level (thereby ending inspiration), they are referred to as 'pressure-cycled' ventilators. In devices such as the Bird Mark 7 and Bennett AP-5, this preset pressure limit can be adjusted, and typically ranges up to 30-60 cm H2O. The correct answer is: inspiration ends when a preset pressure limit is reached

You note that the reading from a pulse oximeter equipped with a disposable finger probe has decreased from 93% to 71%, without a change in FIO2 or patient condition. The most likely cause is that the:

Were a patient's Hb saturation to really drop from 93% to 71%, severe hypoxemia would occur and there would be a dramatic change in the patient condition (an SpO2 of 71% corresponds to a PaO2 of 40 mm Hg or less). Since pulse oximeters do not require manual calibration, the most likely problem is equipment malfunction, i.e., probe or probe cable is malfunctioning and should be replaced. And unlike transcutaneous ABG monitors, pulse oximeter probes do not require warming to provide accurate data. The correct answer is: probe or probe cable is malfunctioning

If you have to deliver medical gas to a patient from a compressed gas cylinder, which of the following devices would you select?

When a high pressure gas cylinder is used to provide medical gas for patient use, both a reducing valve and a flowmeter are combined into a regulator. However, when gas is provided through a central supply system, the pressure has already been reduced to the desired working pressure (50 psig) by the time it reaches the outlet stations. This eliminates the need for pressure reducing devices at the bedside and requires only a device for regulating the gas flow. The correct answer is: a regulator

Which of the following is TRUE regarding the FIO2 provided by an IPPB device that uses air-entrainment to enhance flow?

When driven by 100% O2 and set to air-mix, the FIO2 provided by an IPPB device varies according to the amount of air entrained. Because air entrainment decreases as the system pressure increases, FIO2s are neither stable nor predictable. In general, the higher the end-inspiratory pressure and the longer the inspiratory time, the greater will be the average FIO2. The correct answer is: the higher the inspiratory pressure, the higher the FIO2

In which chamber of a three-chamber pleural drainage system would you expect to see fluctuations of the fluid level with each breath?

When properly set-up and working, the water in the suction control chamber of a three-chamber pleural drainage system should constantly be bubbling, and the water level in the water seal chamber should fluctuate with the patient's breathing or the ventilator cycle. This indicates that the system is working and the chest tube is patent and functioning without leaks. The correct answer is: water seal chamber

You note that the air intake ports surrounding the jet of a 40% air entrainment mask are partially obstructed by the patient's bedding. Which of the following would you expect?

When the air intake ports around the jet of an air entrainment mask become obstructed, both the amount of air entrained and the total output flow will decrease. Under these conditions, the delivered O2 concentration rises, but the actual FIO2 received by the patient may decrease as room air is inhaled around the mask parts. A similar effect occurs when flow resistance downstream from the jet increases. The correct answer is: an increase in the delivered O2 concentration

A large volume jet nebulizer is operating at the 100% O2 setting with an input flow of 12 L/min. What effect will changing the entrainment port setting from 100 to 70% have on the system?

When the air-entrainment port of a large volume jet nebulizer is opened, room air is entrained, and total flow through the system increases (in direct proportion to the size of the opening). This increased output flow increases total aerosol output per minute, but actually lowers aerosol density. The correct answer is: the total output liter flow will increase

Which of the following oral airways would you select for a newborn infant?

When using an oral airway in infants, a Guedel type (with a central passageway) is probably the best choice, since the infant tongue may easily occlude the lateral slots of other designs (like the Berman), thereby worsening the obstruction. The correct answer is: Guedel

You are called by an ICU nurse to check on a patient receiving volume controlled A/C ventilation. You note that both the low tidal volume and high pressure limit alarm are sounding on each inspiration. You first action should be to:

Whenever a potential problem arises during ventilatory support, the first priority is to assure that the patient is being adequately ventilated and oxygenated. If there is any doubt about the proper function of the support system, the patient should be disconnected from the device and ventilated with 100% oxygen via a manual resuscitator until the problem is resolved. The correct answer is: disconnect patient and provide manual ventilation with 100% O2

A patient is receiving continuous flow CPAP at 10 cm H2O. Each time the patient inhales, the pressure decreases to 2 cm H2O. It returns to 10 cm H2O on exhalation. Which of the following is the most likely cause of the problem?

With any continuous flow system, a drop in pressure below baseline that coincides with the patient's inspiration indicates inadequate flow. In general, a drop in pressure of 2 cm H2O is acceptable; any greater decrease in pressure means that system flow should be increased. The correct answer is: the flow of gas to the patient system is insufficient

Which of the following could be done to help assure delivery of 70% O2 via a standard air-entrainment nebulizer to an intubated patient?

With input flow limited to 12-15 L/min (due to jet restriction), air-entrainment nebulizers set above 40-50% O2 provide inadequate output flow to assure a stable FIO2, especially for patients with tachypnea and/or high minute volumes. Adding an open reservoir ('afterburner') to the T-tube can minimize air entrainment. More flow can be obtained by hooking two nebulizers together with a "Y" adapter or by adding extra O2 through a T-adapter. Alternatively, you could use a gas-injection nebulizer or GIN (e.g., Misty Ox). By combining dual input of air and O2 source gas (using high flow flowmeters) without air entrainment, GINs can provide high FIO2 at high output flows. Last, a true nonrebreathing system with one-way valves and a reservoir bag could be used. The correct answer is: hooking 2 nebulizers in parallel, both at max flow

Immediately after performing a percutaneous tracheotomy, a doctor requests that you place the patient on a trach collar at 40% O2. Which of the following would you select to provide this therapy?

With the upper airway bypassed, this patient now requires extra water vapor content in the inspired gas (at least 30 mg/L) to prevent damage to the respiratory tract mucosa. A simple unheated bubble humidifier cannot provide the needed extra water vapor, so either a heated humidifier with blended gas (40%) or a large volume air-entrainment nebulizer (set to 40%) is needed. Ultrasonic nebulizers are contraindicated for continuous delivery of bland aerosols (they provide TOO MUCH water). Also, the typical ultrasonic is driven by an air blower and would require adaptation to deliver 40% O2. The correct answer is: large air-entrainment nebulizer

After attaching a yoke connector regulator to an E cylinder and opening the cylinder valve, you notice a leak at the regulator-cylinder connection. Which of the following is the most likely cause for this leak?

Yoke connectors for cylinders A-E use a hand screw to hold the yoke on the valve stem. If not tightened properly, a leak could result. In addition, the small receiving nipple on the yoke is normally sealed to the gas outlet with a nylon or hard rubber washer. For this reason, a missing or damaged washer also cause a leak. Missing PISS pins would not cause a leak, nor would low cylinder pressure. And were the flowmeter not turned completely off, gas would escape from the regulator outlet, not from the regulator-cylinder connection. The correct answer is: missing connection washer

A Thorpe tube flowmeter is pressure compensated if:

You can tell if a Thorpe tube flowmeter is pressure compensated by connecting it -- with the needle valve CLOSED -- to a 50 psig gas source. If the float 'jumps' when making this connection, the flowmeter is pressure compensated; if the float remains in position, the flowmeter is not pressure compensated. The correct answer is: with the valve closed, the float jumps when attached to 50 psig

To assure delivery of an FIO2 of at least 0.70 to a nonintubated adult patient, you would select which of the following?

o assure delivery of an FIO2 of at least 0.70 to a nonintubated adult patient, you would select a nonrebreathing mask. The nonrebreathing mask is the only device listed capable of high oxygen concentrations (60% or more). Alternatively, you could use a high flow nasal cannula to provide the high FIO2, with flows set to 30-40 L/min. The correct answer is: nonrebreathing mask