Dr David Baker DM FRCA, SAMU de Paris 2000
The International Liaison Committee on Resuscitation (ILCOR) is a global
organisation which unites all the major groups in North and Central America,
Europe and Australia who set standards for basic and advanced life support. In
its issued advisory statements ILCOR brings together the various approaches to
cardiopulmonary resuscitation (CPR) held by the member organisations (1,2).
Control of the airway and emergency ventilation has long been recognised as an
essential part of life support since the pioneering work of Safar and his
colleagues. Although there has recently been an attempt to reduce the importance
of emergency ventilation in CPR (3) this has been vigorously refuted (4,5). In
prehospital emergency care for trauma the value of airway management and
effective ventilation hold an undisputed place in management in an area where
much controversy exists concerning techniques of management.
In emergency medicine there are many conditions apart from cardiac arrest that
affect breathing. There may be failure of the central control and the peripheral
mechanism of breathing from a variety of traumatic, toxic and other pathological
causes. Emergency ventilation with an increased inspired oxygen concentration is
necessary to overcome the alterations in physiological dead space, lung
compliance and resistance and diffusion that may result. The production of
effective emergency ventilation may not always be straightforward. Unlike
artificial ventilation in a hospital which is initiated in a controlled
environment with detailed patient assessment and monitoring, emergency
ventilation is usually carried out under difficult circumstances. There is often
little detailed information about the patients respiratory status and the
decision to ventilate is usually taken on clinical grounds.
Options for emergency ventilation depend on the equipment available and the
skill and experience of the responders. Although bag valve mask (BVM)
ventilation is a familiar concept and apparently effective in the controlled
conditions of an operating theatre it presents difficulties in emergency and has
been shown in experimental models to be less effective than automatic
ventilation through a mask.Alternatives to the BVM include pressure controlled
insufflators which have a number of limitations and gas powered emergency
ventilators, many of which now have demand valve technology included to be able
to respond to the situation of partial respiratory failure.
Apart from specifying protocols for life support ILCOR is currently concerned
with how much ventilation is necessary in emergency, particularly in CPR where
reduction of the time spent on ventilation allows optimisation of circulatory
support by chest compression. Although certain member organisations still favour
high tidal volumes of 800 1000ml a new school has recommended consideration of
a lower volume of 400ml with the same chest compression: ventilation (CV) ratios
of 15:2 for single and 5:1 for two person CPR (6). The rationale for this change
is that in cardiac arrest less carbon dioxide is being delivered to the lungs
and therefore less ventilation is required during the early resuscitation
stages. Prospective studies in this field however are difficult and there is
relatively little data on which to build new protocols. It seems likely that
revised CV ratios will be considered in the future but these will require a
major reteaching programme for the general public who are involved with basic
life support.
The strength of the ILCOR guidelines is that they provide a uniform basis for
development and teaching of CPR procedures. ILCOR has reaffirmed the classical
airway breathing circulation approach and placed emphasis on early airway
and ventilation management. Through improved training emergency services may
expand their airway and ventilation skills and options with the wide range of
equipment suitable for emergency use that is now available in all parts of the
world.
References
1 Handley AJ,Becker LB, Allen M et al. Single rescuer basic life support; an
advisory statement from the BLS working group of ILCOR. Resuscitation 1997;
34(2): 101 8.
2 Kloeck W, Cummin R, Chamberlain D et al. The universal ALS algorithm: an
advisory statement from the ALS working group of ILCOR. Resuscitation 1997;
34(2): 109 13.
3 Becker LB,Berg RA, Pepe LE et al. A reappraisal of mouth to mouth ventilation
during bystander CPR. Circulation 1997; 96: 2112 12.
4 Safar P,Bircher N, Petto E et al. Letter to the editor. Resuscitation 1998;
36(3), 75 80.
5 Dick WF, Brambrink AM, Kern T. 'Topless' cardiopulmonary resuscitation. Should
heart lung resuscitation be performed without artificial resuscitation?
6 Baskett P,Nolan J and Parr M. Tidal volumes which are perceived to be adequate
for resuscitation. Resuscitation 1996; 31(1): 231 234.