Assemble and Troubleshoot Devices

An 80 years old patient is having a problem using the mouthpiece attached the small volume nebulizer being used to administer her bronchodilator treatment. What action should you take?

A mouthpiece can only be used by an alert and cooperative patient. Changing to a mask will benefit the patient and save you time. The correct answer is: change to an aerosol mask

The gauge on an E cylinder of oxygen reads 1800 psig. About how long would the contents of this cylinder last at a flow of 2 L/min?

A gas cylinder's duration of flow equals its gauge pressure times the appropriate cylinder factor divided by the flow. For an E cylinder of oxygen (factor=0.28) at 1800 psig with a flow of 2 L/min: duration (min) = [gauge pressure x cylinder factor]/flow duration (min) = [1800 x 0.28]/2 = 252 minutes = 4 hours, 12 minutes. The correct answer is: 4 hours, 10 minutes

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

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 fluctuation is a normal response. The correct answer is: changes in pressure

In clinical practice, positive identification of medical gas cylinder contents is made by:

Although color codes for medical gases are specified by the National Institute of Standards & Technology of the US Dept of Commerce, these codes are not yet accepted world-wide (O2 cylinders are white in many other countries). For this reason, a cylinder's color should be used only as a rough guide. As with any medicinal agent, the therapist must always positively identify the cylinder contents by carefully reading its label. The correct answer is: reading the cylinder label

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

You note that the servocontroller mechanism on a large volume heated humidifier intermittently cycles on and off vary rapidly. The most appropriate action in this situation would be to:

As described, the situation indicates potential failure of the servocontrol mechanism on the humidifier and/or the temperature sensors. Regardless of cause, any device that appears to have failed should immediately be taken out of service and replaced with a unit confirmed to be properly functioning. The correct answer is: immediately take the unit out of service and replace it

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

A toddler is receiving volume-controlled ventilation. To minimize volume loss due to compression and tubing expansion, which of the following should you select?

Compressed volume is machine-delivered volume that the patient does not receive due to gas compression (following Boyle's law) and circuit expansion. Compressed volume is most critical when delivering small volumes to infants and toddlers. The larger the volume and more compliant the full gas delivery system is (including ventilator "innards," humidifier volume, and delivery tubing), the greater the compressed volume loss will be. Therefore, to minimize compressed volume loss in infants and toddlers, you should use small-diameter, stiff delivery tubing and humidifiers and ventilators with low internal volumes. The correct answer is: low compliance tubing

When setting up a pneumatically-powered percussor at the bedside of a patient receiving postural drainage therapy, you note that regardless of the control settings the device cycles slowly and with inadequate force. To correct this problem you would:

Failure of a percussor or vibrator to function at all usually is due to lack of source power. To avoid this problem, you should always check and confirm proper connections to the pneumatic or electrical power source. If the device is electrically powered, you should also check for a burned-out fuse or tripped circuit breaker and replace or reset it. For pneumatically-powered devices, make sure the source is not flow-restricted (e.g., by a flowmeter). The correct answer is: make sure the source gas connection is not flow-restricted

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

A 65 year old patient with COPD is receiving O2 via a 28% air entrainment mask. With an O2 input of 4 L/min, what is the total output gas flow?

First, you must compute the air to oxygen ratio for 28% O2.Liters air entrained/liter O2 = (100 - O2%)/(O2% - 21)= 72/7 = 10.3:1.Next, multiply the sum of the ratio parts times the O2 input in L/min:>total flow = 11.3 x 4 = 45.2 L/min. The correct answer is: 45 L/min

If you increase the oxygen input flow to a 30% air-entrainment mask from 9 to 12 L/min, what will be the oxygen concentration?

For a given jet and port size, air-entrainment devices operate at relatively fixed ratios. This means that the air to O2 ratios remains about the same, regardless of input flow. Thus increasing the oxygen input flow to a 30% air-entrainment mask from 9 to 12 L/min will have little or no effect on the %O2 delivered (remains at 30%). It will, however, increase the total flow from about 54 L/min (6 x 9) to about 72 L/min (6 x 12). The correct answer is: 30%

A patient has a peak inspiratory flow of 48 L/min. What is the MINIMUM flowmeter setting needed to meet the patient's requirements if a 40% nebulizer is being used?

For a nebulizer to provide its set FIO2, its total output flow must equal or exceed the patient's peak inspiratory flow. Since a 40% air-entrainment device mixes at a fixed ratio of 1:3, we can simply divide the patient's peak inspiratory flow (48 L/min) by the sum of the ratio parts (4). 48/4 = 12 L/min. The correct answer is: 12 L/min

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: replace the regulator washer

Compared with other types of humidifiers, a major advantage of heated wick-type humidifiers is that

Heated wick-type humidifiers can easily saturated gas with water vapor at body temperature (BTPS), even at the high flows used with adult ventilators or high-flow O2 systems. They do not produce aerosols or incorporate baffling. However, as with any device that adds volume to a ventilator circuit, they do increase the compliance factor, via increasing the compressed volume loss. This is why small volume humidifier chambers are used in neonatal ventilator circuits. The correct answer is: BTPS conditions can be provided at any therapeutic flow

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

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: bag valve missing

In a patient with a brachial artery catheter in place, you note a 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

A resident just placed a size 4 laryngeal mask airway in a patient and asks that you inflate the cuff. What volume of air would you use?

Laryngeal mask airways come in six sizes and are selected based on patient weight. Size 4 is appropriate for adults weighing 50-70 kg (most adult women and small to average size men). The size 4 LMA requires 30 mL air to inflate its mask cuff. The correct answer is: 30 mL

Which of the following valves in a typical high frequency oscillation ventilation (HFOV) is used to regulate the mean airway pressure?

Mean airway pressure is a HFOV typically is regulated by a pneumatic valve (the Control Valve) that provides variable resistance to outflow of gas from the circuit. Unique to this circuit are two additional pneumatic valves, both designed to ensure patient safety. The Limit Valve opens when the airway pressure meets or exceeds the ventilator's maximum pressure alarm setting. The Dump Valve activates when either the airway pressure rises above 60 cm H2O or falls below 5 cm H2O. The correct answer is: Control valve

You are measuring the expired minute volume of a spontaneously breathing intubated patient in ICU using a mechanical volumeter (Wright respirometer) with a disposable one-way breathing valve and bacterial filter. After connecting this setup to the patient, you note that no volume whatsoever is recorded. Which of the following is the most likely cause of this problem?

Mechanical volumeters like the Wright measure flow only in one direction, from device inlet to outlet. To properly record a patient's expired volumes with a volumeter, you need to connect its inlet to the expiratory side of the valve assembly. There are three common causes for failing to record volumes with a mechanical volumeter. First, you may have left the ON/OFF switch set to OFF. Second, you may have incorrectly attached the respirometer's outlet connector to the expiratory side of the one-way valve. Third, by mistake you may have attached the respirometer's inlet to the inspiratory side of the valve. On the other hand, if you attach the respirometer's outlet to the inspiratory side of the valve, inspired--not expired--volume will be recorded. The bacterial filter should is placed between the expiratory side of the valve and respirometer. The correct answer is: the respirometer's outlet is attached tothe expiratory side of the valve

Which type of ventilator would you recommend for a patient with an artificial airway who is a candidate for weaning?

Most 'on-ventilator' weaning protocols include use of pressure support ventilation (PSV) to help overcome the imposed work of breathing created by artificial airways and/or to boost spontaneous tidal volumes. For this reason, having a ventilator capable of PSV would be appropriate. The correct answer is: a ventilator capable of pressure support ventilation

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

Which of the following are power sources can be used with most portable O2 concentrators? Household AC current 12 volt DC car outlet Portable battery pack A. Yes Yes No B. No Yes Yes C. Yes No Yes D. Yes Yes Yes

Most portable O2 concentrators employ the same method to separate O2 from room air as used by home concentrators, i.e., passing it through a regenerative, N2-adsorbent material or "molecular sieve." To do so requires electrical power, supplied by either household AC, 12 volt DC (available in cars, RVs, and motorhomes), or portable battery packs. The correct answer is: D

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

Obstruction of the air entrainment ports decreases the amount of air entrained, thereby decreasing total output flow. Under these conditions, the delivered O2 concentration rises, but the actual FIO2 may decrease as room air is inhaled around the mask parts. A similar effect is produced if flow resistance increases downstream from the jet, such as would occur were bedding to cover the mask's outlet ports. 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: obstruction of the air entrainment ports

You notice that the air-entrainment ports of a Venturi mask are occluded by a patient's bedding. What effect would this have on total flow and output O2 concentration (O2%)?

Occlusion of the entrainment port would decrease (or eliminate) the entrainment of air. Because the entrainment of air accounts for a significant amount of output, the total flow of the device would drop. The decrease in entrained air would also mean that less air would be available to dilute the oxygen. Hence, the device's output O2 concentration would increase. The correct answer is: decrease total output flow and increase O2%

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

When visiting a home care patient receiving nasal O2 at 2 L/min via an oxygen concentrator, you measure the O2 concentration at 80%. Which of the following best explains this finding?

Oxygen concentrator FIO2s should be checked and confirmed as part of a routine maintenance visit. Routine maintenance of these devices should include cleaning and replacing filters, checking the alarm system, and confirming the FIO2s using either the unit's oxygen sensor or a separate calibrated O2 analyzer. At 2 L/min a typical concentrator should produce at least 90 to 95% O2. In general, a concentrator that cannot supply at least 85% oxygen at its maximum flow (5-6 L/min for 'home' concentrators, 3 L/min for portable ones) is malfunctioning and should be replaced by a back-up source of O2 while undergoing repair or replacement. Were electrical power inadequate to run the unit, an alarm would have activated. And water levels in the humidifier should not affect the O2 concentration. The correct answer is: the unit is malfunctioning and needs repair

Which of the following would most affect the accuracy of a capnometer's end-tidal CO2 (PetCO2) measurements?

PetCO2 levels vary normally according to the patient's CO2 production (metabolic rate), breathing pattern, deadspace and VT. Significant errors in measurement can occur due to leakage of air into the system or the presence of liquid water on the sensor or in the sampling line. Because PetCO2 measurements are standardized to BTPS conditions, neither the presence of water vapor nor the patient's body temperature will affect instrument accuracy. Variations in O2 concentration have minimal effect on device accuracy, with most units providing automatic compensation for FIO2. The correct answer is: system leaks

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

Room air will NOT enter the ports of an aerosol face mask if the

Room air will enter ANY open O2 delivery system (like an aerosol mask) when the patient's inspiratory flow exceeds that delivered by the device. Because on average a patient's inspiratory flow is about three times the minute ventilation (VE), the minimum flow needed to prevent air dilution will be at least that high (3 x VE). Because no air is entrained, a standard jet nebulizer set to 100% source gas cannot deliver more that about 12-15 L/min flow, which is below the 3 x VE rule of thumb for most adult patients. Of course, dilution of source gas with air will lower the FIO2 received by the patient. This problem can be overcome by hooking up two standard nebulizers in parallel or using a gas injection nebulizer. The correct answer is: gas flow exceeds patient's inspiratory flow

In a single-limb transport ventilator breathing circuit with a built-in expiratory valve, what is the purpose of the small pneumatic line that accompanies the large-bore main tubing?

Single-limb circuits have a separate pneumatic line running from the ventilator to the expiratory valve. This line intermittently provides the pressure needed to close the expiratory valve during inspiration, which blocks gas outflow during the application of inspiratory positive pressure. At the beginning of expiration, this valve depressurizes and opens to allow expired gases to escape. The expiratory valve also can be used to provide CPAP/PEEP. CPAP/PEEP is provided simply by maintaining pressure in the valve's balloon or diaphragm at the desired level throughout expiration. The correct answer is: it pressurizes the expiratory valve and prevents gas outflow during inspiration

The purpose of the small refillable liquid oxygen tank that comes with many stationary home liquid oxygen reservoirs is:

Small portable liquid oxygen units are ideal for the ambulatory patient who is capable of physical activity. Portable units can be refilled directly from the large stationary reservoir, with most providing 5-8 hours of O2 at flow of 2 L/min. This in-use time can be extended (doubled or even tripled) when the patient uses an oxygen-conserving device. The correct answer is: to provide oxygen to ambulatory patients outside the home

Which of the following factors effect the oxygen concentration delivered by an air entrainment system? Oxygen input to the jet Device air to oxygen ratio Downstream flow resistance A. Yes Yes No B. Yes No Yes C. No Yes Yes D. Yes Yes Yes

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. The correct answer is: C

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 aerosol output (in mg/L) of an ultrasonic nebulizer depends mainly on the which of the following?

The amplitude of the ultrasonic signal determines the amount of energy applied to the piezoelectric transducer, and thus the magnitude of its oscillations. The magnitude of oscillations, in turn, determines the aerosol output of the device. Depending on the make and model of nebulizer, adjustment of the amplitude control provides an aerosol output ranging from 0 to 6 ml/min. The correct answer is: signal amplitude

Patients can control a flutter valve's pressure by changing:

The flutter valve combines the techniques of PEP with high frequency oscillations at the airway opening. The valve consists of a pipe-shaped device with a heavy steel ball sitting in an angled "bowl." The pipe bowl is covered by a perforated cap. When the patient exhales actively into the pipe, the ball creates a positive expiratory pressure of between 10-25 cm H2O. At the same time, the pipe angle causes the ball to flutter back and forth at about 15 Hz. When the valve is properly used, the oscillations it creates are transmitted down into the airways. Patients can control the pressure by either changing their expiratory flows (higher flows generate higher pressure) or by changing the angle of the device (raising the device above horizontal increases the pressure). The correct answer is: their expiratory flow

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 vacuum ranges would you initially select to suction a home care adult patient using a portable electric suction unit?

The recommended initial vacuum range used to suction a home care adult patient using a portable electric suction unit is 12-15 in Hg. For infants, the range is 5-7 in Hg. For children, 7-12 in Hg are used. Depending on the volume and character of secretions, higher or lower levels of negative pressure may be needed. As in the hospital, always apply the least amount of suction needed to adequately remove the secretions. The correct answer is: 12-15 in Hg

Which of the following devices would be used in the home for administering small volume nebulizer (SVN) bronchodilator therapy?

To administer small volume nebulizer (SVN) bronchodilator therapy in the home, one needs a small-volume electrically-powered air compressor. Using compressed gas to power an SVN in the home would be expensive and inconvenient, and concentrators and liquid systems do not provide sufficient pressure. The correct answer is: air compressor

To change the level of negative pressure delivered by a pleural drainage system, you would:

To change the level of negative pressure delivered by a pleural drainage system, you adjust the water level in the suction control chamber. The correct answer is: adjust the water level in the suction control chamber

A doctor orders 50% O2 for a newborn infant being cared for in a radiant warmer. No O2 blender is available and the doctor wants to avoid the infection risk associated with a using a nebulizer. Which of the following equipment would you select to fulfill the doctor's order?

To deliver 50% O2 to a newborn infant being cared for in a radiant warmer, you would select an oxyhood. When no O2 blender is available, air and O2 must be mixed together to achieve the desired FIO2. Although this can be done with an air-entrainment nebulizer, noise and infection control issues generally rule out that approach. Instead, in addition to the oxyhood itself, you will need (1) air and O2 flowmeters; (2) an O2 analyzer to help confirm FIO2; (3) a heated humidifier; (4) an O2 bleed-in adapter with small bore tubing; and (5) large bore corrugated delivery tubing. If the O2 delivery circuit does not use heated wires to prevent condensation, an H2O trap should be placed at the low point of the circuit to gather rain-out. The correct answer is: oxyhood, air+O2 flowmeters, heated humidifier

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

What is the approximate duration of flow of an oxygen D-cylinder which is half empty running at 4 L/min?

Using the duration of flow formula of: tank pressure x factor/flow in liters per minute, and a factor of 0.16 (for a D cylinder) the answer is about 44 minutes. The correct answer is: 40 minutes

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

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

In managing a patient in respiratory failure due to severe expiratory airflow obstruction, it is essential that the ventilator used provide the ability to control which of the following parameters?

Whether you use volume control of pressure control in managing a patient in respiratory failure due to severe expiratory airflow obstruction is less important than assuring that the patient has sufficient time to completely exhale (to avoid auto-PEEP). This usually is achieved by providing a longer than normal expiratory time, with I:E ratios such as 1:4 or 1:5. The correct answer is: expiratory time

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

Which of the following incentive spirometers would you select for a 180 lb adult male surgical patient with a diagnosis of atelectasis?

You should select an incentive spirometer based on its maximum volume. For adults, the devices should have a maximum volume over 2500 mL. For pediatric patients, the device should have a maximum volume less than 2500 mL and ideally incorporate colorful, child-oriented labeling to help gain compliance with the therapy. The correct answer is: a device with a maximum volume > 2500 mL

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?

nadequate 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