Optimizing preoxygenation in adults

[Inspiratory support versus spontaneous breathing during preoxygenation in healthy subjects. A randomized, double blind, cross-over trial]

OBJECTIVE

Applying an inspiratory support (AI) and a positive end expiratory pressure (PEP) could increase the effectiveness of the preoxygenation.

STUDY DESIGN

This randomized double blinded controlled study compares the impact on the expiratory oxygen fraction (FEO(2)) of two levels of AI with PEP to a traditional preoxygenation.

PATIENTS AND METHODS

Twenty healthy volunteers were studied. The criteria of exclusion were a body mass index >30, the presence of beard or moustache and the claustrophobia. Each subject went through three modes of preoxygenation during 3 minutes each in a random order: 1-spontaneous ventilation (VS), 2-preoxygenation with AI with 4 cmH(2)O/PEP 4 cmH(2)O (AI-4/PEP-4), 3-preoxygenation with AI with 6 cmH(2)O/PEP 4 cmH(2)O (AI-6/PEP-4). Subject's tolerance and leaks were also noted.

RESULTS

The FEO(2) at the end of the 3 minutes of preoxygenation was higher (p<0,001) with AI-4/PEP-4 (94+/-3%) and AI-6/PEP-4 (94+/-4%) than with technique VS (89+/-6%). One hundred percent and 90% of the participants reached one FEO(2)=90% with AI-4/PEP-4 and AI-6/PEP-4 respectively vs 65% with VS (p=0.0013). The participants tolerated better the VS and the AI-4/PEP-4 than the AI-6/PEP-4. More leaks were noted with the AI-6/PEP-4 than with the VS and the AI-4/PEP-4.

CONCLUSION

This study shows applying AI plus PEP during preoxygenation improves its effectiveness in the healthy subjects. It also suggests that, in a population of healthy volunteers, combination AI-4/PEP-4 is preferable to AI-6/PEP-4 because so effective, but better tolerated.

Anaesthesia in prehospital emergencies and in the emergency room

AIMS

To review anaesthesia in prehospital emergencies and in the emergency room, and to discuss guidelines for anaesthesia indication; pre-oxygenation; anaesthesia induction and drugs; airway management; anaesthesia maintenance and monitoring; side effects and training.

METHODS

A literature search in the PubMed database was performed and 87 articles were included in this non-systematic review.

CONCLUSIONS

For pre-oxygenation, high-flow oxygen should be delivered with a tight-fitting face-mask provided with a reservoir. In haemodynamically unstable patients, ketamine may be the induction agent of choice. The rocuronium antagonist sugammadex may have the potential to make rocuronium a first-line neuromuscular blocking agent in emergency induction. An experienced health-care provider may consider prehospital anaesthesia induction. A moderately experienced health-care provider should optimise oxygenation, fasten hospital transfer and only try to intubate a patient in extremis. If intubation fails twice, ventilation should be resumed with an alternative supra-glottic airway or a bag-valve-mask device. A lesser experienced health-care provider should completely refrain from intubation, optimise oxygenation, fasten hospital transfer and only in extremis ventilate with an alternative supra-glottic airway or a bag-valve-mask device. With an expected difficult airway, the patient should be intubated awake. With an unexpected difficult airway, bag-valve-mask ventilation should be resumed and an alternative supra-glottic airway device inserted. Senior help should be called early. In a "can-not-ventilate, can-not-intubate" situation an alternative airway should be tried and if unsuccessful because of severe upper airway pathology, a surgical airway should be performed. Ventilation should be monitored continuously with capnography. Clinical training is important to increase airway management skills.