Ambulance

Clinical Focus on Emergency Artificial Ventilation
Problems associated with the use
of self – reforming bags in emergency
artificial ventilation
By Dr David J Baker, M Phil DM FRCA FRSM
Emeritus Consultant Anaesthesiologist
SAMU de Paris
Hôpital Necker – Enfants Malades, Paris
Artificial ventilation of the lungs goes back to antiquity but the modern use of bag-valve-mask (BVM)
ventilation dates from the 1950s with the development of the self-reforming bag and non-return valve
by the Dutch anaesthetist Henning Ruben. Since then, BVM ventilation in emergency has been widelyaccepted
by emergency medical services throughout the world. The device is generally regarded as being
safe and effective. This view may be related to training experience in anaesthetic rooms on patients who
were asleep, had muscle relaxation and normal lung and airway characteristics. However, the use of BVM
in emergency has increasingly been shown to be associated with a number of potentially serious problems
including hypo - and hyperventilation, a view supported by a number of published studies. Portable
gas-powered ventilators, developed over the past 40 years have been shown to deliver more consistent
and effective ventilation while freeing an emergency responder from the requirement of squeezing a bag.
This paper reviews the published evidence concerning the use of BVM in emergency and discusses the
need for better training and awareness of the associated problems.
Introduction
Artificial ventilation of the lungs has long
been an established part of both basic and
advanced life support 1,2 . Although positive
pressure ventilation has only become an
integral part of medical practice over the
past 60 years its origins go back to antiquity.
Interest developed during the 17th and 18th
centuries with experiments on ventilating
animals and humans using bellows devices.
At that time the essential negative pressure
nature of normal breathing was not entirely
understood but ventilation of the lungs
was recognised as being an essential in the
resuscitation of drowned persons, and led
to the formation of societies such as the
Royal Humane Society in London and the
Society for the Resuscitation of Drowned
Persons in Amsterdam. Work continued
on positive pressure ventilation and the
protection of the airway through intubation
during the 19th century 3 . At the beginning
of the 20th century the first mechanical
ventilator, the Drager pulmoflator appeared.
At that time however mechanical ventilation
concentrated on reproducing the
physiological conditions of normal breathing
by creating a negative pressure around the
patient. This led to the development of the
cabinet ventilator (or ‘iron lung’) which was
widely used in hospital ventilation until the
1950s.
The requirement for mass ventilation
in Copenhagen during the 1952 polio
epidemic overwhelmed the supply
of cabinet ventilators available. The
anaesthetist Bjorn Ibsen had the idea of
using anaesthetic circuits containing a Boyles
bag to provide intermittent positive pressure
ventilation 4 . The bag was kept inflated by
a positive pressure of gas within the circuit
and could be squeezed by hand to provide
inflation. (Figure 1) Later the bag would
be modified to become self-reforming so
that it could be used independently of an
anaesthetic machine.
Figure 1: Bjorn Ibsen and the first manual
resuscitation circuit
The first bag ventilation circuits used a
canister of soda lime to absorb the exhaled
carbon dioxide. The incorporation of a
non-return valve, invented by the Dutch
anaesthetist Henning Ruben 5 led to
the development of the modern self –
reforming bag, the first example of which
was the Ambu bag in the late 1950s.
Biography:
Dr David J Baker
M Phil DM FRCA FRSM
David Baker was born in London
and studied medicine at St
Bartholomew’s Hospital. After
qualification he served as a
medical officer in the Royal Navy
for nearly 20 years specializing in
anaesthesia. He served in surface
vessels and in the hospital ship
Uganda during the Falklands War in 1982. Later he
worked for several years at the United Kingdom
Chemical Defence Establishment, where he conducted
research on the neurophysiology of organophosphate
poisoning, leading to a doctorate in medicine in 1986.
After leaving the navy in 1992, David moved to France
where he worked for many years as a consultant
in anaesthesia for the Paris emergency medical
service (SAMU) at the Necker University Hospital,
specializing in the management of mass toxic incidents.
From 2004 he also worked as a consultant medical
toxicologist for the Centre for Radiation, Chemical
and Environmental Hazards of the United Kingdom
Health Protection Agency.
David Baker has been a visiting professor at the
Universities of Harvard and Surabaya. He has
lectured in over 40 countries around the world and
is the author of numerous journal articles, textbook
chapters and monographs ,including the recently –
published ‘Toxic Trauma: a Basic Clinical Guide. He
was a Board Member of the World Association
for Disaster and Emergency Medicine and has
consulted for the World Health Organisation and the
International Committee of the Red Cross in Geneva.
Currently, he is continuing work on his long - standing
interest in emergency and transport ventilation and is
a consultant adviser in this area to Pneupac Ventilation,
a part of Smiths Medical International.
54 Spring 2016 | Ambulancetoday