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Comparison of Blood Gases During
Transport Using Two Methods of Ventilatory Support.
Hurst
JM, Davis K, Branson RD, Johannigman JA. Journal of Trauma.
1989; 29:
Pages 1637-1640.
Having previously shown that all members of the health care
team (physicians, respiratory therapists and nurses) tended
to ventilate patients at a more rapid rate and lower tidal
volume during manual resuscitation, the authors examined 28
critically-ill patients (19 males and 9 females with a mean
age of 27 +/- 12 years) requiring ventilation during transport,
in a prospective, randomized fashion. Manual ventilation with
a bag-valve resuscitator was compared to that provided by a
transport ventilator. Patients were ventilated to their destination
with one method and returned with the other (Average transport
time 9 +/- 3 mins during manual ventilation and 8 +/- 3 mins
using transport ventilator). While oxygenation remained stable
under both methods, all patients showed a marked respiratory
alkalosis (pH increased 7.39 to 7.51 and pCO2 decreased from
39 to 30 mmHg) after manual ventilation. No appreciable changes
in pH or pCO2 were noted with the transport ventilator. No
patient suffered hemodynamic instability although two patients
developed cardiac arrythmias (supraventricular tachycardia)
during manual ventilation. The authors discuss the myriad of
complications associated with sudden hypocarbia and respiratory
alkalosis, such as that experienced during the manual ventilation
protocol. These include impaired oxygen delivery at the tissue
level, reduced cerebral and coronary blood flow, increased
susceptibility to arrythmias and hypotension, and coronary
vasospasm. They conclude that transportation of patients requiring
diagnostic studies will continue to represent a challenge.
When ventilatory support is required during transport, a transport
ventilator
produces reliable control of ventilation.
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