chapter 10. manual resuscitators
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Chapter 10
Manual ResuscitatorsIntroduction
Breathing systems that use nonrebreathing valves have largely disappeared from
anesthesia pract ice. However, these v alves are st i l l used in small portable manual
resuscitators, which are used primarily for patient transport, suct ioning, and
emergency si tuat ions. They can also be used to administer anesthesia. A manual
resuscitator may be adapted for use during magnetic resonance imaging (MRI) ( 1).
Manual resuscitators are also known as bag venti lators; bag-assist devices; bag-
type resuscitators; bag-valve devices, units, or resuscitators; bag-valve-mask units,
resuscitators, or venti lators; emergency manual venti lators; hand v enti lators; hand-
operated bag resuscitators; manual venti lators; hand-operated emergency
ventilators; hand- or operator-powered resuscitators; handbag resuscitators;
manual bag v enti lators; manually operated resuscitators; manual pulmonary
resuscitators; respiratory bags; resuscitator or resuscitat ion bags; self- inf lat ing
manual resuscitators; self- inf lat ing respirator bags or resuscitators; venti lator bags;
and self- inf lat ing bag-valve devices.
View Figure
Figure 10.1Manual resuscitators. Note the pressure-limiting mechanism near the nonrebreathing valve on the
smaller resuscitators. This can be overridden by placing afinger on top. Note also the air inlet and outflow valves
between the self-refilling bag and the reservoir. (Picturecourtesy of Hudson RCI.)
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Examples of these devices are shown in Figure 10.1 . Disposable manual
resuscitators that avoid the inconvenience and hazards associated with
reprocessing and steri l izat ion a re commonly used. International and U.S. standards
for resuscitators have been published (2,3).
Components
A typic al man ual resuscita to r is shown diagr amma tic al ly in Figure 10.2. I t has a
compressible self-expanding bag, a bag inlet valve, and a nonrebreathing valve.
The bag inlet and nonrebreathing valves are combined in some units. Optional
components include a pressure-l imit ing device, oxygen-enrichment device, p osit ive
end-expiratory pressure (PEEP) valve, mechanism for scavenging, carbon dioxide
detector, and a port for measuring airway pressure.
Se lf - e x pand i n g B ag
The self-expanding bag (venti lat ing or venti lat ion bag, self- inf lat ing bag, s elf-
ref i l l ing bag, compressible unit , compressible reservoir) is constructed so that it is
inf lated in its rest ing state. Some bags collapse l ike an accordion for storage.
During exhalat ion, the bag expands. I f the volume of oxygen from the delivery
source is i nadequate to f i l l the bag, the dif ference is made up by room air. The rate
at which the bag reinf lates wil l determine the maximum minute volume.
Non r eb r e at h i n g Va l v e
The nonrebreathing valve is sometimes called the direct ional control v alve,
exhalat ion valve, expiratory v alve, inf lat ing valve, inhalat ion-exhalat ion valve,
inf lat ing-exhalat ion valve, inspiratory-expiratory valve, nonreturn valve, patient
valve, routing valve, or one-way inf lat ing valve. I t has a number of parts that
ensure that gas flows out of the bag and into the patient port during inspiration and
from the expiratory port without mixing with fresh gas during exhalat ion.
Body
Most nonrebreathing valves are T-shaped. It is preferable that the housing be
transparent so that the internal mechanism movement can be observed.
The expiratory port is the opening through which exhaled gases pass from the
patient to atmosphere. It may have a means to deflect exhaled gas (Fig. 10.3). A
PEEP valve may be connected at this point. The expiratory port may have a tapered
19- or 30-mm connector for attachment to a scavenging system transfer tube
(Chapter 13). The American Society for Testing and Materials (ASTM) s tandard (2)
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requires that the connector for this port have a ridge (baulk) in its internal lumen so
that it cannot accept a 22-mm male connector.
The patient connector is the part that connects to a tracheal tube, face mask, or
supraglott ic device. I t has 15-mm female and 22-mm male coaxial f i t t ings. I t may be
designed to swivel.
The inspiratory port is the opening through which gas enters the valve from the
bag. It is usually permanently attached to the bag.
Unidirectional Valves
Unidirect ional valves direct the gases from the bag to the patient during inspirat ion
and exhaled gases from the patient to atmosphere. In order to accomplish this,
there are usually two valves. During inspirat ion, gas is directed from the bag to thepatient connection port. At the same t ime, the expiratory port is blocked. During
exhalat ion, the expiratory port is open, and the inspiratory port is blocked so that
the patient exhales to atmosphere. The valve may have a means to prevent air from
entering when the patient is breathing spontaneously so that the patient wil l inhale
gas only from the bag.
View Figure
Figure 10.2Components of a manual resuscitator. The
nonrebreathing valve directs the gas from the bag to the
patient during inspiration. During expiration, thenonrebreathing valve directs exhaled gases from the patientto atmosphere through the expiratory port, and the bag inletvalve opens to allow the bag to fill.
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Sp r i n g - d i s c o r S p r i n g - b a l l V a l v e
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Spring-disc valves are shown in Figures 10.4and 10.5. In Figure 10.4, a spring
holds the disc against the seat. When the pressure on the disc is great enough to
overcome the force of the spring, the v alve opens. As the pressure drops, the
spring causes the disc to close the valve. Some unidirect ional valves have a ball in
place of the disc. The ball or disc may be held in place by gravity rather than a
spring.
Figure 10.5shows a T-shaped valve with a spring disc that alternately blocks the
gas inlet or outlet. When the bag is compressed, the disc is pushed across the
valve, connecting the inspiratory port with the patient port
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while, at the same time occluding the expiratory port. When the bag is released, the
disc moves back toward the bag and allows exhaled gas pass through the
expiratory port. A guide pin keeps the disc centered. I f the patient is b reathing
spontaneously, the disc wil l not close the exhalat ion port, and room air wil l be
inhaled.
View Figure
Figure 10.3The exhalation port may have a means todeflect the exhaled gas away from the operator.
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View Figure
Figure 10.4Spring-disc unidirectional valve. In the closedposition, the spring holds the disc against the seat. When thepressure to the left of the disc increases above the pressureof the spring, the disc is forced away from the seat. Whenthe pressure to the left of the disc drops, the valve closes.
View Figure
Figure 10.5Spring-disc nonrebreathing valve. The disc isheld on the seat by the spring. When the bag is squeezed,the disc moves to the left, closing the expiratory port. At the
end of inspiration, the spring forces the disc to the right sothat the patient exhales to atmosphere and not into the bag.A guide pin keeps the disc in the center. A spontaneously
breathing patient can inhale room air unless a valve isplaced over the expiratory port to prevent air entrainment.
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View Figure
Figure 10.6Edge-mounted flap unidirectional valve.Increased pressure upstream of the flap pushes the flapaway from the seat, opening the valve. When the pressuredownstream of the flap increases above the pressureupstream, the flap is forced back against the seat, blockingthe flow of gas.
F l a p Va l v e
The f lap (leaf) valve has a rigid or f lexible f lap that moves. The f lap may be f ixed to
the housing at the edge (Fig. 10.6) or the center (Fig. 10.7).
Figure 10.8shows a nonrebreathing valve that incorporates two f lap valves. During
inspirat ion, the center-mounted
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flap valve moves to the right. The peripheral f lap v alve covers the exhalat ion port.
During exhalation, the flaps move to the left, preventing exhaled gas from re-
entering the bag, and the exhalat ion ports are uncovered. The peripheral f lap v alve
prevents inhalat ion of room air during spontaneous breathing.
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View Figure
Figure 10.7Center-mounted flap unidirectional valve. Theflap valve is secured by a tab at the center. The tab issecured by a retainer, which is attached to the valve body.
View Figure
Figure 10.8Nonrebreathing valve with two flap valves.During inspiration, the center-mounted flap valve opens,and the peripheral flap closes over the exhalation ports.During exhalation, the central flap valve closes, and the
peripheral flap falls away from the exhalation ports. Thisvalve has an oxygen inlet and two bag inlet valves, which
open if the oxygen flow is not sufficient to prevent anegative pressure from developing in the space to the left.
F is hm o u t h V a lv e
The f ishmouth (duck-bil l) valve (Fig. 10.9) opens and closes l ike a f ish's mouth. As
pressure upstream of the valve increases, it opens at the slit in the center. An
increase in pressure downstream pushes the leaf lets together, closing the valve.
D i a p h r a gm -f l a p Va lv e
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A diaph rag m-f lap valv e is shown in Figure 10.10. The diaphragm is attached at its
periphery. When the bag is squeezed, the diaphragm is pushed to the left and
occludes the expiratory port. Flap valves at the side of the diaphragm open,
allowing gas from the bag to f low to the pa tient. When inspirat ion ends, the
diaphragm returns to its rest ing posit ion and the f lap valves close, allowing the
patient to exhale through the expiratory port. A spontaneously breathing patient
may inhale room air through the exhalation port i f there is no f lap valve to block
ambient air from entering the valve.
View Figure
Figure 10.9Fishmouth unidirectional valve. As pressure tothe left increases, the leaflets open, allowing gas to flow
through the valve. An increase in pressure to the rightpushes the leaflets together, closing the valve and
preventing backflow of gas.
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View Figure
Figure 10.10Diaphragm-flap nonrebreathing valve. Duringinspiration, when the bag is squeezed, the pressure to theright increases and the diaphragm is pushed to the left,closing the exhalation channel. At the same time, the flapsat the edge of the diaphragm open, allowing gas from the
bag to flow to the patient connector. When inspiration ends,
the diaphragm moves away from the exhalation channel andthe flaps close, blocking the inspiratory port.
View Figure
Figure 10.11Mushroom-flap valve. This valve contains amushroom-style diaphragm that is inflated when the
pressure in the pressure channel increases. This occursduring inspiration. When the mushroom is inflated, it blocks
the exhalation channel, allowing the lungs to be inflated.When the pressure inside the mushroom drops at the end ofinspiration, it opens the channel and allows the exhaledgases to pass out of the exhalation channel. The flap valve
prevents backflow of exhaled gases into the bag.
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Mu s h r o o m - f l a p Va l v e
The valve i l lustrated in Figure 10.11combines one mushroom and two flap valves.
The inside of the mushroom is connected to a pressure channel. During inspirat ion,
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the mushroom is inf lated against the seat, preventing f low of gas through the
expiratory port and the inhalat ional f lap opens. During exhalat ion, the inspiratory
flap valve prevents flow back into the bag. The mushroom collapses and opens the
exhalat ion channel. A f lap v alve over the expiratory port prevents room air from
being inhaled during spontaneous breathing.
View Figure
Figure 10.12Fishmouth-flap nonrebreathing valve. Thecircular flap and fishmouth valves are attached, around the
periphery. When the bag is squeezed, the flap valve isseated against the exhalation ports, and the fishmouth
portion of the valve opens. During expiration, the fishmouthcloses and the flap falls away from the exhalation channel.
A second flap valve over the exhalation ports prevents airfrom being inspired during spontaneous respiration.
F i s hm o u t h - f l a p V a lv eThe valve diagrammed in Figure 10.12and pictured disassembled in Figure 10.13
has one f ishmouth and two f lap valves. The f ishmouth and one circular f lap valve
are combined into one piece. The f lap valv es surround the central f ishmouth.
Outside the main valve body is another circular f lap valve. During inspirat ion, the
f ishmouth opens and the circular f lap valve closes the exhalat ion port. The outside
flap valve prevents room air from entering the valve during spontaneous breathing.
During exhalat ion, the f ishmouth section closes. The circular f lap valve attached to
it is l i f ted off the expiratory apertures, allowing exhaled gas to escape to
atmosphere.
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View Figure
Figure 10.13Components of the fishmouth-flapnonrebreathing valve. Left:The patient connection with theexpiratory flap. Center:The fishmouth with its concentricflap. Right:The part of the housing closest to the bag.
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B ag In l e t Va l ve
The bag inlet (ref i l l) v alve is a one-way valve that is opened by negative pressure
inside the bag. When the bag is squeezed, the valve closes. This p revents escape
of gas through the inlet. A simple f lap (Figs. 10.2, 10.7) or spring-disc valve (Fig.
10.4) is most commonly used. This valve is usually located at the opposite end of
the bag from the nonrebreathing valve but may be at the same end and may be
combined with the nonrebreathing valve.
P re s su r e -l im i t i n g Dev i c e
The pressure-l imit ing device (pressure relief device, v alve, or system; overpressure
limit ing system; overpressure valve; pop-off valve; pressure l imit ing s ystem)
protects against barotrauma and may prevent gases from entering the stomach
during manual ventilation (4).
A varie ty of dev ices hav e be en used . One is a spri ng -load ed disc , wi th the tension
on the spring adjusted so that it opens at the desired pressure. Another is a
magnetic device, with the force of the magnet adjusted to open at the desired
pressure. Some systems provide a small hole. The maximum pressure depends on
the size of the hole and how f irmly the bag is compressed. In order to override the
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device, it is usually necessary to place a f inger over the outlet (Fig. 10.1). An
override mechanism may cause confusion (5).
For adult resuscitators, the ASTM standard requires that if there is a device that
l imits the pressure to below 60 cm H2O, there must be an ov erride mechanism (2).
I f the override mechanism can be locked, i t must be designed so that the operating
mode (ON or OFF) is readily apparent to the user. It recommends that if a
resuscitator is equipped with a pressure-l imit ing device, there should be an audible
or visible warning to the operator when the pressure l imit ing device is operat ing. I t
also requires that with a pressure l imit ing device set at a f ixed pressure, that
pressure must be marked on the resuscitator.
The ASTM standard (2) requires a pressure-l imit ing system for infant and child
resuscitators, with an opening pressure of 45 cm H2O and an option for an override.
The means that to c reate a higher inf lat ion pressure is especially important in a
resuscitator designed for infants, because the f irst few breaths may require
pressures as high as 50 to 70 cm H 2O. The pressure needed to overcome flow
resistance in a narrow tracheal tube and to expand the st if f lungs of a premature
infant may exceed 30 to 40 cm H 2O. It is recommended that a manometer be used
with neonatal resuscitat ion devices, because using these resuscitat ion devices can
be associated with extremely high inspiratory pressures (6).
Oxyg en -e n r i c hm en t Dev i c e
Mechanisms to increase the i nspired oxygen concentrat ion above that of room a ir
are present on nearly all resuscitat ion devices.
Oxygen Delivered Near the Bag Inlet Valve
Tubing from an oxygen f lowmeter attached near the bag inlet valve is a simple
means of increasing the concentrat ion of oxygen in the bag. The oxygen does not
enter the bag direct ly. The increase in oxygen concentrat ion is l imited because air
can be drawn into the bag. The delivered oxygen concentrat ion can be increased by
increasing the oxygen f low, but this is of l imited value. The higher the minute
volume and the greater the inspiratory:expiratory (I :E) rat io, the l ower the delivered
oxygen concentration.
Oxygen Delivered Directly into the Bag
Oxygen can be delivered direct ly into the resuscitat ion bag. This method wil l result
in high delivered oxygen concentrat ions without making the resuscitator
cumbersome. However, provision must be made for venting excess oxygen to
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minimize the danger of the nonrebreathing valve locking in the inspiratory posit ion.
I f the oxygen f low is less than the bag f i l l ing rate, the bag inlet valve wil l open and
admit air.
Reservoir
Most units have a reservoir (accumulator) in which oxygen is stored when the bag
is not f i l l ing. I t may be a tube or a bag. When the resuscitat ion bag inlet valve
opens, oxygen from the reservoir enters the bag. In general, resuscitators with
reservoir bags provide a higher fract ion of delivered oxygen than resuscitators with
tubing reservoirs (7). The size of the reservoir may limit the oxygen concentration
delivered. I f the volume of the reservoir is less than that of the bag, the inf lowing
oxygen may not be suff icient to make up the dif ference, and room air wil l b e drawnin. On the other hand, a large reservoir makes a resuscitator more cumbersome.
Op e n Re s e r v o i r
Open reservoirs are shown in Figures 10.14( left ) and 10.15. A piece of corrugated
tubing or other material open to atmosphere is placed l ike a sleeve around the bag
inlet valve. I f the oxygen f low is high, oxygen wil l f low into a tmosphere at the open
end of the reservoir. I f the oxygen f low is low or the reservoir is smaller than the
tidal volume, air wil l be drawn into the bag along with the oxygen. The highest
possible concentrat ion of ox ygen wil l be administered if the reservoir is large andthe oxygen f low is g reater than the minute volume.
View Figure
Figure 10.14Left:A resuscitator with an open reservoir.Right:One with a closed reservoir.
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Tidal volume wil l be increased when a two-handed technique is used. Grip strength
is the best predictor of delivered volumes and is more important when the t idal
volume is delivered by a one-hand technique (20). Tidal volume may be increased
by compressing the bag against a solid s urface such as a thigh or the operating
room table. Another method to increase the tidal volume is to compress the bag
between the open palm and body (21 ).
The respiratory rate may be l imited by how fast the bag re-expands, which depends
on the bag construct ion and the size of the bag ref i l l valve inlet. The maximum
compression rate may be reduced at low temperatures (13,22,23 ).
De li v e r ed Oxyg en Conc en t r a t i o n
The ASTM standard (2) requires that a resuscitator for adults be capable of
delivering an inspired oxygen concentrat ion of at least 40% when connected to an
oxygen
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source supplying not more than 15 L/minute and at least 85% with an oxygen-
enrichment device supplied by the manufacturer.
View Figure
Figure 10.15Open reservoir. A:The bag is filling. Oxygenfrom the delivery tubing as well as that in the reservoirflows into the bag. If the volume entering the bag exceedsthat in the reservoir and flowing through the deliverytubing, room air will make up the difference. The size of thereservoir is, therefore, important. B:The bag inlet valve isclosed. Oxygen from the delivery tubing flows into thereservoir. Because the reservoir is open to atmosphere,some oxygen will be lost if the flow is high.
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The delivered oxygen concentrat ion is l imited by reservoir size and the oxygen f low
(7). I f the volume of the reservoir is greater than the volume of the bag and the
oxygen f low is greater than the minute volume, the delivered ox ygen concentration
may approach 100%. If the t idal volume is greater than the reservoir volume plus
the volume of oxygen delivered during inspirat ion, air wil l be drawn into the unit
and reduce the delivered oxygen percentage (24).
Controlled Ventilation
The delivered oxygen concentrat ion wil l be determined by the minute volume, the
size of the reservoir ( i f present), the oxygen f low, and the technique used to
squeeze and release the bag (25 ). I f the bag is allowed to f i l l at i ts most rapid rate,
all of the oxygen in the reservoir may be exhausted and air drawn in. I f bag f i l l ing ismanually retarded, the delivered oxygen concentrat ion wil l be higher (8). This may
be useful when low oxygen flows must be used or when the reservoir is small or not
present, but it l imits the respiratory rate that can be achieved. Furthermore, it may
cause the nonrebreathing valve to jam in the inspiratory posit ion. Activat ing the
pressure-l imit ing device may cause the delive red oxygen concentrat ion to decrease
(26).
Spontaneous Ventilation
With spontaneous venti lat ion, inspired gas may come from the exhalat ion port aswell as the bag. The inspired oxygen concentration can vary f rom 25% to 100%
(24,27). Bags with f ishmouth valves are associated with low inspired oxygen
concentrat ions (24 ,28,29 ).
Reb r ea t h i n g
I f the nonrebreathing valve is competent, inhaled and exhaled gases should not
mix. I f the valve is incompetent, a back leak wil l al lo w exhaled gases to pass back
into the resuscitator.
UseA bag and mask that are the ap pro pri ate s ize fo r the pa ti en t shou ld be sele cte d.
For adults, an oxygen f low of 10 to 15 L/minute is most commonly used. For
children and infants, lower flows are recommended. Higher flows than those
recommended by the manufacturer can result in significant levels of auto-PEEP
(30).
I f anesthetic gases are to be administered, the transfer tube (Chapter 13) from a
scavenging system should be attached to the expiratory port.
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A ma nu al re susc ita tor can be adapted for ma nu al vent i lat ion duri ng MR I by
insert ing an extension tube that is long enough to cover the distance between the
patient and the person squeezing the bag between the nonrebreathing valve and
the bag (1). An extension must not be placed between the patient and the
nonrebreathing valve, as this wil l cause the dead space to be increased.
Hazards
H ig h A i r w a y P r e s s u r e
High airway pressure is a hazard mainly if the patient is intubated. A dangerously
high pressure is less l ikely when a mask or supraglott ic device is used.
View Figure
Figure 10.16Closed reservoir. Top:The reservoir is full,and the pressure increases. Oxygen flows through theoverflow valve. B:The resuscitator bag is filling. Becausethere is insufficient gas in the reservoir, air enters throughthe intake valve.
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Nonrebreathing Valve Sticking in the Inspiratory Position
I f the nonrebreathing valve st icks (locks up, jams) in the inspiratory posit ion, the
patient wil l be at tempting to exhale against a c losed outlet, and continued inf low
wil l quickly cause a continuous and dangerous increase in pressure. A variety of
other condit ions can cause this, including interrupting manual venti lat ion for
observation of spontaneous respiratory efforts, manually restrict ing bag ref i l l , the
valve becoming contaminated with foreign material, a small squeeze or bump on the
bag causing the valve to lock up, coughing, improper assembly, attaching an
oxygen inlet nipple without vent holes direct ly to the resuscitator, fai lure of the
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expiratory f lap valve to open, and a kink in the reservoir tai l
(31,32,33,34 ,35 ,36,37 ,38 ,39,40 ,41 ).
High Oxygen InflowThe ASTM resuscitator standard (2) requires that the valve not jam at an input f low
of up to 30 L/minute. Infant resuscitators are especially prone to obstruct ion with
high f lows because the bag is so small. A case has been reported in which the
pressure monitoring port was connected to an oxygen source (11). This distorted
the inspiratory valve and resulted in excessive pressure.
Asynchrony between Patient Exhalation and the Demand
Valve
Manually act ivat ing a demand valve while the patient is exhaling can cause
dangerously high pressures (8).
Pressure-limiting Device Failure
Pressure-l imiting devices often malfunction, opening well above an acceptable
pressure (26 ,42,43 ).
Excessive Resistance
Resuscitators with high resistance can expose the patient with high expiratory f lows
to acute airway pressure elevations (44 ).
Reb r ea t h i n g
Rebreathing exhaled gases can occur if the valve on the inspiratory l imb from the
bag is not competent or is improperly assembled (45 ,46 ). The f ishmouth valve can
become unseated, allowing rebreathing and/or insufficient pressure during
inspirat ion (47 ). Extension tubing should not be added between the patient and the
valve.
Hypo v e n t i l a t i o n
Studies show that it is more dif f icult to achieve satisfactory venti lation with a
resuscitat ion bag and face mask
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than with a supraglottic airway device or Combitube (48,49 ).
A def ec t ive non reb rea thing valve may hav e forward leak , so durin g ins pirat io n part
of the volume expelled from the bag escapes through the expiratory port (45,50,51 ).
Unrecognized venting through the pressure relief device may result in
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During spontaneous v enti lat ion, the patient may inhale room air from the expiratory
port as well as oxygen-enriched gas f rom the bag. The inspired oxygen
concentrat ion can vary from 25% to 100% (24,27).
H i gh Res i s t a n ce
Some nonrebreathing valves offer high resistance to f low s o that high negative
pressures must be generated during spontaneous venti lat ion (24 ,27 ,44). The work
of breathing may be quite high.
Con t am i n a t i o n
Because these devices are of ten used on patients who have respiratory infect ions,
they f requently become contaminated (72 ,73 ,74 ). Oxygen f lowing through the valve
may aerosolize bacteria and spread them into the surrounding air. For these
reasons and because these devices are dif f icult to clean, disposable units have
become popular. Bacterial/viral f i l ters (Chapter 7) may be used.
In h a la t io n o f F o r e i g n Bod i es
Part of the inside of the bag or parts of the nonrebreathing valve may break off and
be inhaled (75,76 ).
Checking Manual Resuscitators
Before use, the resuscitat ion bag should be visually inspected for signs of wear
such as c racks or tears. After the bag has been inspected, it should be checked for
leaks. The patient port should be occluded and the bag squeezed. Pressure should
build up rapidly to a point at which the bag can no longer be compressed. I f there is
a pressure l imit ing device, it c an be checked by connecting a pressure manometer
between the patient port and the bag by using a T-f it t ing. I f there is an override
mechanism on the pressure l imit ing device, this should be checked. This check also
determines that the ref i l l valve wil l close when the bag is squeezed.
To check that the bag ref i l l valve opens, the b ag should be squeezed, then thepatient port occluded and the bag released. The bag should expand rapidly.
I f the resuscitator has a closed reservoir, i ts function can be checked by performing
several compression-release cycles with no oxygen flow into the reservoir. The
reservoir should deflate, but the resuscitat ion bag should continue to expand.
A re serv oi r bag f rom a bre athing sys tem is plac ed ov er the patient po rt. Squeezin g
the resuscitat ion bag should cause the reservoir bag to inf late. After the reservoir
bag has become fully inf lated and the resuscitat ion bag has been released, the bag
should deflate easily. This
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tests the inspirat ion and exhalat ion parts of the v alve and the exhalat ion pathway
for patency. The reservoir bag should deflate easily.
Advantages
The equipment is inexpensive, compact, lightweight, and portable yet rugged.
The equipment is easy to use.
The equipment is simple with a s mall number of parts. Disassembly and
reassembly are usually easily p erformed.
Dead space and rebreathing are minimal if the nonrebreathing valve
functions properly.
With proper attention to the oxygen-enrichment device, oxygen f low, and
venti lat ion technique, it is possible to administer close to 1 00% oxygen with
most resuscitators.
During emergency situat ions in which a connection to a gas source is not
readily available, the resuscitator can be used with room air unti l a s ource of
oxygen becomes available.
The operator has some feel for pressures and v olumes delivered. Barotrauma
may be less l ikely with these devices than with gas-powered resuscitators,
which do not allow the operator to sense when the patient 's lungs are fully
inf lated.
Disadvantages
Some of the valves are noisy and st ick, part icularly when wet.
There may be considerable heat and humidity loss from the patient with
prolonged use. Considerat ion should be given to using a heat and moisture
exchanger with prolonged transport.
feel of the bag is dif ferent from that in other breathing systems. The user's
hand must be re-educated.
The valve must be l ocated at the patient 's head. I ts bulk may be
troublesome, and its weight may cause the tracheal tube to kink or be
displaced downward.
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During infant resuscitat ion, manual resuscitators are unreliable as free-
f lowing oxygen delivery devices (77)
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P.295
QuestionsFor the following question, select the correct answer.
1. What determines the maximum minute volume delivered from a resuscitation
device?
The rate of oxygen f low into the bag
The rate at which the bag reinf lates
The size of the oxygen reservoir
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The rate at which the bag is squeezed
View AnswerFor the following questions, answer
i f A, B, and C are correct
i f A and C a re correct
i f B and D a re correct
is D is correct
i f A, B, C, and D are correct.
2. Measures that can increase the concentration of oxygen delivered from a
resuscitation bag include
Increasing the oxygen flow
Low minute volume
Addit io n of a reserv oi r to the in le t
A lo wer I :E ra tio
View Answer3. Problems with delivering oxygen directly into the
resuscitation bag include
Diff iculty attaining high oxygen concentrat ions
Nonrebreathing valve locking in the inspiratory posit ion
Excessive pressureInabil i ty to deliver adequate t idal volume because the f lowmeter can only deliver up
to 15 L/minute
View Answer4. Characteristics of an open reservoir include
Oxygen f lows into the reservoir during i nspirat ion
If the t idal v olume is high, air may be added to the gases entering the resuscitat ion
bag
Oxygen enters the bag from the resevoir during exhalat ion
Amb ien t ai r can make up defic ien c ie s in ox ygen volu me duri ng inha lat io n
View Answer5. Characteristics of the closed reservoir include
A val ve to let in amb ien t ai r
A val ve to ven t exces s ga ses from the reservoi r
The presence of a bag
A val ve to prov id e wa rn ing of ex cess ox ygen pressure
View Answer6. What minimum oxygen concentration must a resuscitation
bag be capable of delivering?
Forty percent with up to 15 L/minute oxygen f low
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One hundred percent if the reservoir is smaller than the t idal volume
Eighty-f ive percent with the addit ion of a reservoir
Ninety percent if the reservoir is larger than the t idal volumeView Answer7. Benefits of manually restricting refill of the resuscitation
bag include
A lo wer f low of oxyg en may be us ed
A re serv oi r may no t be needed to deliver hig h oxygen conc en tra t ions
Higher oxygen concentrat ion wil l be d elivered
Higher minute volume can be achieved
View Answer8. Situations that can result in high a irway pressure include
Nonrebreathing valve st icking i n the expiratory posit ion
High oxygen i nf low
Kinking of the reservoir tai l
Use of a demand valve as the patient exhales
View Answer9. Causes of hypoventilation when using a manual
resuscitator include
Incomplete closure of the expiratory port
Low temperature
Venting through the pressure relief device
No auxil iary air intake
View Answer10. The ASTM standard on resuscitators includes the
following provisions concerning pressure limiting devices:
In adults, i f the override mechanism can be locked, i t must be designed so that the
operating mode is readily apparent to the user
For infant and child resuscitators, a device with an opening pressure of 45 cm H 2O
Optional override for infant and child resuscitators
For adults, a device with an opening pressure of 50 cm H2O
View Answer11. Hazards associated with use of a manual resuscitator
include
Barotrauma
Inhalat ion of foreign s ubstances
Delivery of low oxygen concentrat ions
Hyperventi lat ion
View Answer12. What techniques are useful to increase the tidal volume
delivered from a manual resuscitator?
Two-handed technique
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Slowed bag expansion
Compression against a s olid surface
Using the resuscitator at low temperaturesView Answer13. Which of the following are associated with retarding
resuscitating bag expansion?
Increased minute volume
Decreased respiratory rate
Activat io n of th e pressure limit ing de v ic e ma y inc rease th e ins pired ox yg en
concentrat ion
The nonrebreathing valve may jam
View Answer14. Concerning spontaneous respiration through a manual
resuscitator,
A wide vari at ion in ox ygen conc entr at io n ma y oc cur
Fishmouth valves are associated with a higher inspired oxygen concentrat ion
Room air may be inspired through the exhalation port
The bag inlet valve wil l jam
View Answer15. A decreased inspired oxygen concentration may be
caused by
A smal l res erv oi r
Low temperature
A val ve de fec t
Spontaneous venti lat ion
View Answer
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