Ambulance

Clinical Focus on Emergency Artificial Ventilation
The function of the automatic ventilator is
important (whether the device is a pressure
or a volume generator) in replacing BV
ventilation. Pressure cycled ventilators
have been shown to be unreliable in
emergency use. L’Her and Roy 22 have
conducted laboratory trials of a number of
portable ventilators. They concluded that
while most of the volume-cycled ventilators
proved to be technically efficient and reliable
pressure cycled ventilators (they examined
the Oxylator EMX and the Vortran RTM)
gave rise to concern since they did not
deliver consistent tidal volumes and under
certain conditions could be unsafe. Further
comment on this is found in a review by
Branson 23 .
Recently, Kreft 24 has conducted bench
studies using a calibrated test lung to
assess BV vs automatic ventilation. Trained
responders using the bag-valve device
showed considerable variation in the rate
and volumes of the ventilation delivered
(Figures 4 and 5).
Conclusions
There is increasing evidence to show the
variability of ventilation delivered by bag
– valve devices when used in emergency
ventilation. In particular, high inflation
pressures and large tidal volumes may be
delivered which can cause barotraumas and
volutrauma, as well as gastric insufflation
if the BV device is being used with a
pharyngeal mask.
These findings are accompanied by the
scarcity of studies about emergency
ventilation in the literature.
There is a need for greater awareness of
the potential problems of intermittent
positive pressure ventilation in emergency.
To achieve this better training is required
for the use of the BVM and also automatic
emergency ventilators.
A better understanding of the limitations
of the BV device and the advantages of
the portable ventilator is also required.
In addition more research studies are
needed to provide a better evidence base
for ventilation in emergency, to support
international guidelines, and to bring
emergency ventilation skills in line with basic
and advanced airway management.
Figure 4. The Ventcheck (IngMar Medical,
USA) experimental set –up. Ventilation of a
manikin using a BVM is monitored using an
Ingmar test lung linked to a computer display
of the ventilation parameters.
(Photograph courtesy of Smiths Medical International (Luton,
UK)
Figure 5 (a) Variation in tidal volume delivered
by BVM for two operators. There is significant
variation from the target volume of 600 ml,
both for individual ventilations and in the mean
delivered ventilation over a period of 5 minutes
Figure 5 (b) Ventcheck recording with the
test lung ventilated by a volume targeted
automatic ventilator ( Pneupac Parapac Plus)
set to deliver a tidal volume of 600ml. The
individual variation in tidal volume between
delivered breaths is negligible compared with
the bag valve recordings of tidal volume from
two subjects shown above.
(Photographs courtesy of Smiths Medical International
(Luton, UK)
References
1 Koster RW, Baubin MA, Bossaert L et al. European
Resuscitation Council Guidelines for Resuscitation 2010,
section 2 : adult basic life support and the use of the
automatic external defibrillator. Resuscitation 2010;
81:1277 – 1292
2 Deakin CD, Nolan JP, Soar J et al. European
Resucitation Council Guidelines for Resuscitation 2010,
section 4: adult advanced life support. Resuscitation 2010;
81:1305 – 1352
3 Wilkinson DJ. The History of Trauma Anaesthesia. In
Grande CM (ed) Textbook of Trauma Anaesthesia and
Critical Care, 1993; Chapter 1: 10 - 11
4 Ibsen B. Aanaesthetist’s viewpoint on the treatment
of respiratory complications in poliomyelitis during the
epidemic in Copenhagen in 1952. Proc Roy Soc Med
London 1954; 47:72 – 74
5 Ruben H. A new non – rebreathing valve.
Anesthesiology 1955; 16: 643.
6 Ruben H. The immediate treatment of respiratory
failure. Brit J Anaesth 1964; 36: 542 – 569.
7 Cooper JA, Cooper JD, Cooper JM, Cardiopulmonary
Resuscitation: History, Current Practice, and Future
Direction, Circulation. 2006:114;2839–49.
8 Aufterheide TP, Sigurdsson G, Lurie KG et
al., Hyperventilation-induced hypotension during
cardiopulmonary resuscitation, Circulation.
2004;109:1960–65.
9 Losert H, Sterz F, Koehler K et al. Quality of
cardiopulmonary resusctitation among highly – trained
Spring 2016 | Ambulancetoday
staff in an emergency department setting. Arch Intern
Med 2006;166:2375 - 80
10 O’Niell JF, Deakin CD. Do we hyperventilate cardiac
arrest patients? Resuscitation 2007; 73: 82-85
11 Updike G, Moesseno VN, Auble TE et al.
Comparison of bag valve mask, manually – triggered
ventilator and automatic ventilator devices used while
ventilating a non – intubated mannikin model. Prehosp
Emerg Care 1998; 2(1): 52 – 5
12 Salas N, Wisor B, Agazio J, et al., Comparison of
Ventilation and Cardiac Compressions When Utilizing
the Impact Model 730 Automatic Transport Ventilator
Versus Valve with a Facemask in a Model of Adult
Cardiopulmonary Arrest, Resuscitation, 2007; 74(1):
94–101.
13 Ruben H, Knudsen EJ, Carugati G, Gastric inflation in
relation to airway pressure, Acta Anaesthesiol Scand,
1961;5:107–14.
14 Bowman FP, Menegazzi JJ, Check BD, Duckett TM,
Lower esophageal sphincter pressure during prolonged
cardiac arrest and resuscitation, Ann Emerg Med,
1995;26: 216–19.
15 Cheiftz IM, Craig DM, Quick G, et al., Increasing tidal
volumes and pulmonary over distention adversely affect
pulmonary vascular mechanics and cardiac output in a
pediatric swine model, Crit Care Med. 1998:26:710–16.
16. Stallinger A, Wenzel V, Wagner-Berger H, et al. Effects
of decreasing inspiratory flow rate during simulated basic
life support ventilation of a cardiac arrest patient on
lung and stomach tidal volumes. Resuscitation 2002;54:
167–73.
17. Noordergraaf GJ, van Dun PJ, Kramer BP, et al. Can
first responders achieve and maintain normocapnia
when sequentially ventilating with a bag-valve device and
two oxygen-driven resuscitators? A controlled clinical
trial in 104 patients. Eur J Anaesthesiol 2004;21:367–72.
18 Lachman B. Open up the lung and keep it open.
Intensive Care Med 1992: 18; 319 - 321
19 Weiss SJ, Ernst AA Jones R et al. Automatic
transport ventilator versus bag valve in the EMS setting:
a prospective randomized trial. South Med J. 2005;
98(10): 970 – 6.
20 Goedeke A, Wenzel V, Hoermann S et al. Effects of
face mask ventilation in apnoeic patients with a with
resuscitation ventilator in comparison with a bag valve
mask. Journal Emerg Med 2006; 30(1); 63 – 67
21 Noordergraaf GJ, Van Dan DJ, Shors MP et al.
Efficacy and safety in patients on an EM 100 resuscitator
in comparison with a bag valve device. Am J Emerg Med
2004; 22(7): 537 - 543
22 L’Her E, Roy A. Bench tests of simple , handy
ventilators for pandemics: performance, autonomy and
ergonomy. Respiratory Care 2011; 56(6) 751 – 767.
23 Branson R. Patient needs should drive ventilator
selection for stockpiling; ‘handy’ ventilators may not
‘lend a hand’ Respiratory Care 2011;56(6) 879
24 Kreft R. 2014 Personal communication
57 3