RTBR 2A - Assemble and Troubleshoot Devices
Which of the following would cause the FIO2 delivered by an air entrainment mask to be different than that specified by the manufacturer? Select one: A.an increase in resistance downstream from the jet B.a decrease in the patient's peak inspiratory flow C.an increase in the flow of oxygen into the jet D.obstruction of the patient's nasal passages
A 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
Mechanical ventilation in the home setting can be provided by which of the following methods? Select one: A.positive pressure via an intact upper airway B.nasal continuous positive airway pressure C.positive pressure via an oral endotracheal tube D.negative pressure via an oral endotracheal tube
A 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
A bubble humidifier is not bubbling during oxygen therapy, despite the flowmeter set and running at 6 L/min. You should check which of the following? Select one: A.flowmeter-humidifier connection for leaks B.humidifier outlet for obstruction C.patient delivery tubing for leaks D.50 psi wall outlet for obstruction
A Failure of a bubble humidifier to bubble during therapy indicates either an obstruction to flow or leak occurring at or before the bubble/diffusion element. Because the flowmeter is running at 6 L/min, there is no obstruction. Therefore among the conditions listed, only a leaky connection between the flowmeter and the humidifier would cause this problem. A leak distal to the humidifier (e.g., in the delivery tubing) would not prevent bubbling. The correct answer is: flowmeter-humidifier connection for leaks
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? Select one: A.a missing lead B.motion artifact C.improper filtering D.a corroded connector
A 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
Which of the following indicate that a three- chamber pleural drainage system is working properly? Select one: A.the water seal chamber level rises and falls with breathing B.there is no bubbling in the suction control chamber C.there is continuous bubbling in the water seal chamber D.the suction control chamber level rises and falls with breathing
A If a standard three-chamber pleural drainage system is functioning normally, the suction control chamber should be bubbling continuously, and the water level in the water seal chamber should rise and fall with the patient's breathing or the ventilator cycle. Continuous bubbling in the water seal chamber indicates either a patient OR drainage system leak. The correct answer is: the water seal chamber level rises and falls with breathing
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 Select one: A.recheck the handle/blade connection B.replace the blade C.replace the batteries D.check/replace the bulb
A 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
The airway clearance technique that uses a pneumatic device to deliver compressed gas minibursts to the airway at rates above 100/min Hz best describes: Select one: A.intrapulmonary percussive ventilation B.active cycle of breathing C.high frequency chest wall compression D.intermittent positive pressure breathing
A Intrapulmonary percussive ventilation (IPV) is the airway clearance technique that uses a pneumatic device to deliver a series of pressurized gas minibursts at rates of 100 to 225 cycle per minute (1.6 to 3.75 Hz) to the respiratory tract, usually via a mouthpiece. The duration of each percussive cycle is manually controlled by the patient or clinician using a thumb button. During the percussive cycle, constant positive airway is maintained at the airway. The device also incorporates a pneumatic nebulizer for deliver of bland or medicated aerosol. The manufacturer recommends a total treatment time of about 20 minutes. The correct answer is: intrapulmonary percussive ventilation
Which of the following devices would you select to condition inspired gas to 100% body humidity? Select one: A.heated wick humidifier B.bubble humidifier C.pneumatic nebulizer D.small volume nebulizer
A 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
The oxygen concentration delivered by an air entrainment nebulizer to a patient's airway is usually higher that set. What is the reason for this discrepancy? Select one: A.downstream resistance in the delivery tubing B.inaccuracy of the air entrainment system C.air leaks in the patient delivery tubing D.excessive forward velocity of the source gas
A The O2 concentration delivered by some air entrainment nebulizers is often higher than that set due to the added downstream resistance created by the tubing used to deliver the gas. This effect is greatest at high mixing ratios (low O2 concentrations), and when the tubing becomes blocked with water. In the latter case, the tube lumen must be decreased by more than 70% before the FIO2 changes. The correct answer is: downstream resistance in the delivery tubing
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? Select one: A.nasal cannula B.nasal catheter C.simple oxygen mask D.air entrainment mask
A 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
The oxygen and air supply lines of an ICU ventilator are accidentally switched at set-up. When attached to a patient, the oxygen percentage is set to 100%. Which of the following is correct about this situation? Select one: A.the O2 and air supply alarms will not sound B.the patient will receive about 50% oxygen C.the ventilator will go inoperative and shut down D.the low inspiratory pressure alarm will sound
A The oxygen and air supply alarms on most ventilators are activated by low inlet pressures, not gas concentrations. As long as both inlet pressures are adequate (usually > 35 psi), neither the O2 nor air alarms will sound, nor will the ventilator go inoperative. In this case the patient will receive 100% of the gas attached to the O2 inlet, i.e., air only. Only if the ventilator incorporates an O2 analyzer would any alarm sound. The correct answer is: the O2 and air supply alarms will not sound
Which of the following devices would be used in the home for administering small volume nebulizer (SVN) bronchodilator therapy? Select one: A.air compressor B.oxygen blender C.oxygen concentrator D.portable liquid oxygen system
A 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 create CPAP in a continuous flow "Wye" circuit requires: Select one: A.an expiratory threshold resistor B.an inspiratory flow restrictor C.an adjustable demand flow valve D.an inspiratory threshold resistor
A To create CPAP in a continuous flow system requires a threshold resistor on the expiratory limb of the "Wye" circuit. Examples of expiratory threshold resistors include spring-loaded or electromechanical exhalation valves and underwater "bubbler" columns. Also required in these systems are built-in FIO2 control, humidification, and safety and alarm features (including a disconnect/ low-pressure alarm). The correct answer is: an expiratory threshold resistor
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? Select one: A.place a water trap in delivery tubing B.heat the nebulizer reservoir to 37° C C.place the nebulizer above the patient D.use smooth bore, not corrugated tubing
A 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
Which of the following conditions will cause a DECREASE in the FIO2 delivered to a patient receiving oxygen at 4 L/min via a nasal cannula? Select one: A.increase in patient inspiratory flow B.increase in patient inspiratory time C.decrease in patient minute ventilation D.decrease in patient tidal volume
A With a low-flow device like a nasal cannula, the larger the tidal volume, the higher the inspiratory flow, the less the inspiratory time, or the greater the minute ventilation, the greater will be the amount of air diluting the O2 and the lower the FIO2. Conversely, with all else constant, the greater the input O2 flow during inhalation, the less air dilution occurs, and the higher the FIO2. The correct answer is: increase in patient inspiratory flow
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? Select one: A.the flow of gas to the patient system is insufficient B.there is a leak in the patient system C.the patient's endotracheal tube is too small D.the CPAP pressure is set too high for the patient
A 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
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? Select one: A.obstruction of the expiratory line B.loose humidifier/circuit connection C.a mucous plug in the patient's ET tube D.a decrease in patient compliance
B 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: loose humidifier/circuit connection
At the higher end of its flow range, a high flow nasal cannula provides performance comparable to what other O2 delivery device? Select one: A.28% air-entrainment mask B.nonrebreathing mask C.transtracheal catheter D.simple mask
B 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
In working with an electrically powered apparatus, you notice a slight tingling sensation when the metal parts of the equipment are touched. In this case, you should: Select one: A.use this device only with non-electrically sensitive patients B.immediately take the piece of equipment out of service C.use an extension cord to increase electrical resistance D.use a 'cheater' adapter to bypass the ground connection
B A tingling sensation which occurs when the metal parts of a piece of equipment are touched usually indicates improper grounding and the possibility of a serious leakage current. In these cases, you must ensure that the faulty equipment is immediately taken out of service. The correct answer is: immediately take the piece of equipment out of service
If you increase the oxygen input flow to a 35% air-entrainment mask from 7 to 10 L/min, what is the resulting O2 concentration? Select one: A.30% B.35% C.40% D.45%
B Air-entrainment masks mix air and oxygen at a fixed ratio (e.g., 3:1, 5:1, 10:1), which is based on the port and jet size of the selected adapter. Because the mixing ratio is fixed, changes in oxygen input flow do not affect the delivered O2 concentration. The delivered O2 concentration will only vary if either the air-entrainment ports are blocked or significant resistance to flow develops downstream from the jet. Note that the FIO2 received by the patient may or may not be the same as that delivered by the device. It will only be the same if the total device flow (air + O2) equals or exceed the patient's inspiratory flow. The correct answer is: 35%
Increasing the amount of tubing between the "wye" connector of a dual limb ventilator breathing circuit and the patient's airway will have which of the following effects? Select one: A.increase in delivered volume B.increase in rebreathed volume C.decrease in circuit compliance D.decrease in inspired PCO2
B Any extra tubing between the "wye" connector of a dual limb ventilator breathing circuit and the patient's airway will increase mechanical deadspace and rebreathed volume, thereby increasing the inspired PCO2, and potentially raising the PaCO2 (the purpose of adding deadspace).The extra tubing will also increase the overall volume of the circuit. The larger the circuit volume, the greater the circuit compliance and volume lost to gas compression/tubing expansion. The greater this volume loss to the circuit, the less the actual volume delivered into the lungs. The correct answer is: increase in rebreathed volume
Which of the following should be done before filling a portable liquid O2 system from its stationary reservoir? Select one: A.open the reservoir vent valve to atmosphere B.remove any moisture from the connectors C.turn the portable unit's flow control knob on D.empty the portable unit by opening its vent valve
B Before refilling a portable liquid O2 unit from a stationary reservoir, you should prevent icing by using a clean, lint-free, dry cloth to remove any moisture from the reservoir and the portable unit connectors . One should also check the reservoir contents indicator to make sure enough liquid O2 is available and that it is operating at the specified pressure (usually about 24 psi). After the portable unit flow control knob is set to zero/off, its connector should be aligned and pressed onto the reservoir connector and the reservoir vent valve opened to initiate filling. You do not need to empty the portable before transfilling it. The correct answer is: remove any moisture from the connectors
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: Select one: A.check the bedside AC outlet to make sure it is properly grounded B.make sure the source gas connection is not flow-restricted C.check for/replace burned-out fuse or reset a the circuit breaker D.remove and replace the device's disposable pad with a new one
B 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 attempting to ventilate an intubated patient during CPR using a nondisposable, self-inflating bag-valve resuscitator, you note that a patient's chest does not rise and that there is minimal resistance when you squeeze the bag. Which of the following would you do to correct the problem? Select one: A.reconnect the oxygen line B.reseat the inlet valve C.increase the oxygen flow D.open the pressure relief valve
B Failure of a self-inflating bag-valve resuscitator to inflate the lungs is usually due to either (1) airway obstruction (in which case resistance to bagging is high) or (2) valve leakage (in which case resistance to bagging is minimal). Since resistance to bagging is minimal, the likely problem is valve leakage, particularly at the bag inlet valve. During bag compression, the bag inlet valve normally closes and prevents gas escape out to the atmosphere, instead of forcing gas into the patient. The correct answer is: reseat the inlet valve
Which of the following indicate that a three-chamber pleural drainage system is working properly? Select one: A.the water seal chamber level remains constant during breathing B.there is continuous bubbling in the suction control chamber C.there is continuous bubbling in the water seal chamber D.the suction control chamber level rises and falls with breathing
B If a standard three-chamber pleural drainage system is functioning normally, the suction control chamber should be bubbling continuously, and the water level in the water seal chamber should rise and fall with the patient's breathing or the ventilator cycle. Continuous bubbling in the water seal chamber indicates either a patient OR drainage system leak. The correct answer is: there is continuous bubbling in the suction control chamber
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: Select one: A.airway pressure release ventilation B.pressure support with adjustable off-cycling C.mandatory minute ventilation D.high frequency oscillation ventilation
B 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
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? Select one: A.aerosol particle size (MMD) would increase B.total aerosol output (mL/min) would increase C.aerosol weight density (mg/L) would increase D.total output flow (L/min) would remain constant
B 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
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? Select one: A.excessive flow through the humidifier B.a leak in the humidifier/delivery system C.diameter of the delivery tubing is too small D.the flowmeter is not pressure compensated
B The pressure pop-off on a bubble humidifier normally sounds when the pressure in the system exceeds a preset limit (e.g., 2 psi). The 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
When making routine equipment checks you hear the relief valve of a patient's bubble humidifier sounding. Which of the following is the most likely cause of this problem? Select one: A.clogged bubble/diffuser B.delivery tube obstruction C.high wall outlet pressure D.rise in patient ventilation
B The relief valve of a humidifier sounds when the pressure in the reservoir container 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 bubble humidifiers that use a diffuser plate to break up the gas stream, clogging of this element would prevent gas from entering and pressurizing the system. Flowmeter restriction prevents high wall outlet pressures (> 50 psig) from affecting pressure in the humidifier. And changes in patient ventilation would have no effect on pressure in the humidifier. The correct answer is: delivery tube obstruction
Which of the following humidifiers would be most effective in overcoming a humidity deficit? Select one: A.unheated bubble humidifier B.heated wick humidifier C.unheated cascade humidifier D.heat and moisture exchanger
B The single most important factor determining a humidifier's overall performance is temperature. In all humidifiers, heat is lost due to evaporative cooling. This cooling lowers a humidifier's humidity output to somewhat less than of saturated air at ambient temperature. The simple solution is to heat the humidifier. In fact, heating is the only way to ensure high humidity at the high flows required with some O2 delivery systems and mechanical ventilators. The correct answer is: heated wick humidifier
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? Select one: A.simple O2 mask, unheated bubble humidifier B.oxyhood, air+O2 flowmeters, heated humidifier C.50% air-entrainment mask with humidity adapter D.oxyhood, O2 flowmeter, unheated humidifier
B 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
To continually monitor the FIO2 being delivered by a mechanical ventilator, the oxygen analyzer probe should ideally be placed: Select one: A.at or near the patient's Y connector B.proximal to the humidifier and bacteria filter C.at or near the circuit's expiratory valve D.distal to the humidifier and bacteria filter
B 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
Which of the following could be done to help assure delivery of 70% O2 via a standard air-entrainment nebulizer to an intubated patient? Select one: A.heating the water reservoir to 40° C B.adding an open reservoir to the T-tube C.increasing nebulizer input flow to 25-30 L/min D.powering the nebulizer with an O2 blender
B 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: adding an open reservoir to the T-tube
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? Select one: A.ultrasonic nebulizer B.large air-entrainment nebulizer C.simple bubble humidifier D.heat and moisture exchanger
B 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
You would use a Lukens trap to: Select one: A.collect sputum from a patient with a productive cough B.prevent condensate from blocking ventilator circuit tubing C.gather sputum samples during suctioning or bronchoscopy D.prevent aspirated material from getting into a suction regulator
C A Luken's trap is used to collect sputum samples during suctioning or bronchoscopy. To use the trap, you place it between the suction catheter (or bronchoscope suction port) and the suction system's connecting tubing/vacuum source, while maintaining its internal sterility and position (upright). For patients who have productive coughs, sputum can be gathered using a simple sputum collection cup. The correct answer is: gather sputum samples during suctioning or bronchoscopy
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?
C 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. The correct answer is: C
A 12-lead ECG has: Select one: A.8 chest leads and 4 limb leads B.6 chest leads and 6 limb leads C.6 chest leads and 4 limb leads D.4 chest leads and 6 limb leads
C A standard 12-lead ECG has only 10 actual leads to place, not 12 (4 limb leads and 6 chest leads). The right leg doesn't really count, since it is just a ground lead. The additional three leads are the augmented limb leads (aVR, aVL and aVF), which use the right arm, left arm and left leg electrodes to obtain their data. The correct answer is: 6 chest leads and 4 limb leads
A large volume jet nebulizer is operating on 70% O2 at 12 L/min. You observe that the aerosol being delivered in short rapid puffs and note a gurgling sound in the system. Which of the following actions would be most appropriate? Select one: A.reduce the water volume in the nebulizer reservoir B.switch the nebulizer entrainment port to 40% O2 C.drain any accumulated water from the delivery tubing D.increase the nebulizer input flow to 15 L/min
C Aerosols produced by large volume jet nebulizers contain a wide range of particle sizes. Many of the larger unstable particles will impact or deposit by sedimentation in the tubing, causing water to accumulate at low points in the circuit, and intermittently blocking flow (as evidence by the gurgling sound). To ensure proper flow and the set FIO2, this water should be regularly drained AWAY from the patient and discarded (never returned to the reservoir). The correct answer is: drain any accumulated water from the delivery tubing
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? Select one: A.turn the nursing unit's oxygen zone valve off then back on B.increase the cannula flow rate to 6 L/min C.occlude the cannula to see if the humidifier pop-off sounds D.measure the patient's O2 saturation (SpO2)
C 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
During time-cycled, pressure-controlled ventilation, if the pressure limit is reached before the inspiratory time cycle is completed, which of the following will occur? Select one: A.the ventilator will cycle to end-inspiration B.the delivered volume will decrease C.the pressure will remain at the preset limit D.gas will continue to enter the patient's lungs
C During time-cycled, pressure-controlled ventilation, if the pressure limit is reached before the inspiratory time cycle is completed, the pressure will be maintained at the preset limit. No additional gas enters the patient's lungs, but the ventilator remains in the inspiratory phase until the inspiratory time interval is complete. The correct answer is: the pressure will remain at the preset limit
When selecting an endotracheal tube, you should consider which of the following to minimize airflow resistance? Select one: A.outside diameter (OD) B.cuff compliance C.inside diameter (ID) D.component materials
C 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? Select one: A.NPPV via an oronasal mask B.tracheotomy and invasive ventilation C.negative pressure ventilation D.oral intubation and invasive ventilation
C 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
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? Select one: A.obtain a new E cylinder B.turn the flowmeter/gauge on C.replace the regulator washer D.replace the pressure regulator
C 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
Which of the following would deliver the most particulate water to a patient's airway? Select one: A.a bubble humidifier B.a wick humidifier C.an ultrasonic nebulizer D.a jet nebulizer
C In general, only nebulizers can deliver particulate water to the airway. Among nebulizers, large-volume ultrasonics produce the highest density aerosols, with some capable of adding 500 mg of water to each liter of carrier gas (10 x BTPS conditions!) The correct answer is: an ultrasonic nebulizer
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? Select one: A.Decrease the input flow to the nebulizer B.Ask the patient to breath slower and deeper C.Check the entrainment setting on the nebulizer D.Obtain an arterial blood gas sample for analysis
C 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
In order to achieve FIO2s greater than 0.21, the typical home ventilator: Select one: A.uses a venturi or air entrainment system B.attaches directly to a 50 psi O2 source C.'bleeds' in O2 via a flow metering device D.attaches directly to a liquid O2 reservoir
C In order to achieve FIO2s > 0.21, the typical home ventilator bleeds O2 into the system via a flow metering device. Because these devices are electrically powered, a 50 psi O2 source is not needed. Instead, the flow metering device may be attached to either a concentrator or LOX system. The correct answer is: 'bleeds' in O2 via a flow metering device
To maximize the duration of flow/runtime outside the home, liquid portable O2 systems: Select one: A.hold about three liters of liquid oxygen B.can be refilled from a liquid O2 base unit C.incorporate a pulse-dose delivery system D.include a battery-powered contents indicator
C 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 types of breathing circuits would you select when assembling a noninvasive positive pressure/BiPAP ventilator? Select one: A.dual-limb "Y" circuit B.single-limb circuit with expiratory balloon valve C.single-limb circuit with leakage-type exhaust valve D.single-limb circuit without any valve
C 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
While checking a crash cart for adult intubation equipment, you find: suction equipment, O2 flowmeter/tubing, bag-valve resuscitator, 2 laryngoscopes/assorted blades, 4 ET tubes (6 - 9 mm), tube stylet, Magill forceps, tape, and lubricating jel. What is missing? Select one: A.scapel set B.tube obturator C.syringes D.suture kit
C Needed equipment includes: O2 flowmeter/tubing, suction apparatus, bag-valve resuscitator, pharyngeal airway(s), laryngoscopes/assorted blades, assorted tube sizes, tongue depressor, stylet, tape, syringes, lubricating jel, Magill forceps, local anesthetic spray, and towels (for positioning). A scapel set, tube obturator and suture kit are required for tracheotomy, not ET intubation.
Which of the following would most affect the accuracy of a capnometer's end-tidal CO2 (PetCO2) measurements? Select one: A.water vapor B.O2 concentration C.system leaks D.patient fever
C 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
You are checking a battery-powered laryngoscope and its separate blades/light bulbs in the drawer of a code cart. When you attach the Miller blade the bulb shines bright white. When you attach the MacIntosh blade the bulb fails to shine You should initially Select one: A.replace the laryngoscope batteries B.remove the MacIntosh blade from the code cart C.tighten the bulb on the MacIntosh blade D.take the MacIntosh blade to the department for repair
C Since the Miller blade bulb worked fine, the problem cannot be the laryngoscope's batteries. The first step should be to tighten the bulb on the MacIntosh blade. If this doesn't work, the bulb should be replaced. If a new bulb fails to light, the problem must be the blade's electrical connections. In the latter case, the blade itself should be replaced (this pertains only to blades with replaceable bulbs) The correct answer is: tighten the bulb on the MacIntosh blade
The major hazard associated with the use of bag-valve resuscitator is: Select one: A.decreased cardiac output B.nosocomial infection C.pulmonary barotrauma D.fractured ribs
C The major hazard with bag-valve resuscitator is pulmonary barotrauma. With the full volume of adult devices being no more than 2000 ml, the likelihood of barotrauma in adults is small. However, use of an adult resuscitator on a small child or infant is contraindicated. Moreover, some pediatric resuscitators have bag capacities greater than 500 ml, enough to cause barotrauma if applied to small children or infants. To minimize the possibility of barotrauma when ventilating infants and small children, a pressure manometer should be used with the manual resuscitator. The correct answer is: pulmonary barotrauma
Which of the following is the most common indication for adult high flow nasal cannula therapy? Select one: A.as an alternative to nasal CPAP therapy B.to provide precise low O2 concentrations C.as an alternative to a nonrebreather mask D.to forestall the need for mechanical ventilation
C 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? Select one: A.check and correct the patient's technique B.switch to a universal MDI boot adapter C.clean the boot and canister outlet D.recommend the patient use a spacer
C 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
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? Select one: A.addition of deadspace to circuit B.increased patient minute ventilation C.addition of cool water to humidifier D.decreased patient minute ventilation
C 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: addition of cool water to humidifier
Which of the following occurs when gas leaves a simple unheated bubble humidifier and is delivered to a patient? Select one: A.the absolute humidity of the gas decreases B.condensation occurs in the delivery tubing C.the relative humidity of the gas decreases D.the temperature of the gas increases
C 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
Which of the following is TRUE regarding the FIO2 provided by an IPPB device that uses air-entrainment to enhance flow? Select one: A.the shorter the inspiratory time, the higher the FIO2 B.the entrainment ratio is fixed at about 3:1 or 40% O2 C.the higher the inspiratory pressure, the higher the FIO2 D.air entrainment increases as inspiratory pressure increases
C 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
Which of the following are essential features for a CPR 'pocket' mask? SupplementalO2 | inlet15/22 mm connector | Jam-free one-way valve A.YesYesNo B.NoYesYes C.YesNoYes D.YesYesYes Select one: A.A B.B C.C D.D
D 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.
Which of the following is true regarding using a remote alarm unit in conjunction with a home apnea monitor? Select one: A.activating the remote should disable the monitor's alarm signals B.the remote alarm should sound only for confirmed apnea events C.use of a remote apnea monitor alarm is optional in the home setting D.the remote alarm should sound whenever it goes out of monitor range
D 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 types of nebulizers can produce the highest density aerosol suspension? Select one: A.a heated jet nebulizer B.a sidestream nebulizer C.a metered dose inhaler (MDI) D.an ultrasonic nebulizer
D Depending on the rate of carrier gas flow, ultrasonic nebulizers can produce aerosols with densities as high as 0.5 g/L (500 mg/L), some 10 times the absolute humidity of saturated gas at 37 °C. The MMD of these ultrasonic aerosol suspensions is approximately 6 µm, with an effective particle size range between 1 and 10 µm. The correct answer is: an ultrasonic nebulizer
Which of the following oxygen administration devices is capable of providing a stable FIO2 to patients with changing rates and depths of breathing? Select one: A.standard nasal cannula B.simple oxygen mask C.face tent D.air-entrainment mask
D 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: Select one: A.the reservoir jar is loose B.the pop-off valve is open C.a diffuser plate is missing D.the down tube is plugged
D 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
Fluid column manometers are best used to measure: Select one: A.pressures greater than atmospheric B.rapidly changing pressures C.negative (vacuum) pressures D.static/slowly changing pressures
D Fluid column pressure manometers are used to (1) measure atmospheric pressure (barometer); (2) measure static or slowing changing pressures, e.g., CVP; and (3) calibrate other pressure measuring devices (U-tube manometer). In the past, mercury column manometers were used to measure blood pressure, however, the toxicity of this chemical now prohibits this use. Fluid column manometers are not suited for measuring rapidly changing pressures, and their accuracy depends on proper upright positioning. The correct answer is: static/slowly changing pressures
In a dual-limb ventilatory breathing circuit, the proper position for placing a heat and moisture exchanger (HME) is: Select one: A.in the inspiratory limb, between the ventilator outlet and the 'Y' connector B.distal to the ventilator's expiratory flow and pressure sensors C.in the expiratory limb, between the 'Y' connector and ventilator inlet D.between the 'Y' connector and the patient's airway
D 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
You note a sudden increase in PO2 measurement and decrease in the PCO2 measurement on a transcutaneous monitor. The most likely cause is: Select one: A.a decrease in blood flow in the area of the probe B.electrode temperature is too low C.electrode temperature is too high D.an air leak at the transducer site
D 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: Select one: A.greater than saturated air at ambient temperature B.equal to saturated air at ambient temperature C.greater than saturated air at body temperature D.less than saturated air at ambient temperature
D 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
While using a Yankauer device to orally suction an adult patient, you are unable to remove thick secretions. The regulator attached to the oropharyngeal suctioning device displays a reading of -70 mm Hg. Which of the following should you do at this time? Select one: A.perform nasotracheal suctioning B.replace the wall suction regulator C.change to a flexible catheter D.increase the suction pressure to -120 mm Hg
D In general, you should set the suction pressure as low as possible, yet high enough to effectively clear secretions. For adults, a pressure of -100 to -120 mm Hg is usually adequate. For children, you should limit the suction pressure to -80 to -100 mm Hg. With infants, -60 to -80 mm Hg is the limit. The correct answer is: increase the suction pressure to -120 mm Hg
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%)? Select one: A.increase total output flow and decrease O2% B.increase both total output flow and O2% C.decrease both total flow output and O2% D.decrease total output flow and increase O2%
D 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 analyzers would you select if your objective were to continuously measure changes in the FIO2 in a ventilator circuit with the fastest possible response time? Select one: A.physical (paramagnetic) analyzer B.thermal conductivity analyzer C.galvanic fuel cell analyzer D.polarographic (Clark) analyzer
D Only the polarographic and galvanic fuel cell analyzers can provide continuous sampling and measurement under dynamic conditions (as in ventilator circuits). However, with its current flow maintained solely by the chemical reaction itself, the galvanic fuel cell has a comparatively slow response time. The correct answer is: polarographic (Clark) analyzer
The aerosol output (in mg/L) of an ultrasonic nebulizer depends mainly on the which of the following? Select one: A.chamber baffling B.source current C.signal frequency D.signal amplitude
D 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
The aerosol is "puffing" out the end of the tubing on a patient who is receiving 40% heated aerosol. This could be caused by Select one: A.an empty reservoir jar B.a low flow rate C.poor oxygen entrainment D.water in the large bore tubing
D The most likely cause for intermittently "puffing" of mist out the end of the delivery tubing on a patient who is receiving heated aerosol is partial tubing occlusion with condensed water. This partial tubing occlusion will decrease air-entrainment, increase the delivered oxygen concentration and lowers the total output flow of the nebulizer. To correct this problem, you should drain the tubing (away from the nebulizer!) The correct answer is: water in the large bore tubing
The pressure pop-off is alarming on the humidifier attached to an oxygen cannula. Which of the following would correct this problem? Select one: A.reposition the cannula on the patient B.add water to the humidifier C.check and adjust liter flow D.check for obstruction in the cannula
D 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
To assure delivery of an FIO2 of at least 0.70 to a nonintubated adult patient, you would select which of the following? Select one: A.nasal cannula B.simple mask C.air-entrainment mask D.nonrebreathing mask
D To 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
Which of the following occurs when an unheated bubble humidifier is used to delivered oxygen to a patient? Select one: A.the absolute humidity of the gas decreases B.condensation occurs in the delivery tubing C.the relative humidity of the gas increases D.the temperature of the gas decreases
D 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 temperature of the gas decreases
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? Select one: A.pressure B.inspiratory time C.volume D.expiratory time
D 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
