The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

Are Emergency Medical Technicians Predisposed To Administer Pejorative Ventilatory Strategies To Patients Intubated For Acute Severe Asthma?

Jeffrey M. Haynes RRT RPFT  St. Joseph Hospital, Nashua, New Hampshire.

Background:
 Positive pressure ventilatory strategies that incorporate large tidal volumes (Vt), rapid respiratory rates (RR), and long inspiratory time (Ti) are known to cause pulmonary volutrauma and hemodynamic depression due to dynamic hyperinflation in patients with obstructive airways disease.1 Since a fatal or near fatal asthma attack can occur unexpectedly and with a short duration of increased symptoms,2 emergency medical technicians (EMT) might be the first clinicians to care for the critically-ill asthmatic. Moreover, most patients who have fatal asthma attacks die before reaching the hospital.2 Therefore, this study sought to determine whether EMTs are predisposed to administer pejorative ventilatory strategies while using a bag-valve ventilator to ventilate patients intubated for acute severe asthma without cardiac arrest.

Methods: An anonymous, convenience sample survey was given to 62 EMTs which included a clinical scenario question which was the focus of this study. Most of the surveys were taken in the presence of the author. The respondents were asked to choose one of three ventilatory strategies for an adult patient with a pulse who was being ventilated with a bag-valve ventilator following intubation for acute severe asthma. The ventilatory strategy choices were: (a) large Vt/high RR; (b) small-moderate Vt/lower RR; (c) long Ti/high RR.

RESULTS:
 59 of the 62 surveys were included in the study; 1 survey was not returned and 2 were discarded because they were not filled out properly. Only 13 (22%) chose the small-moderate Vt/lower RR strategy. 8 (13%) chose the large Vt/high RR strategy, and 38 (64.4%) chose the long Ti/high RR strategy.

Conclusions: Many EMTs appear predisposed to manually ventilate patients intubated for acute severe asthma with ventilatory strategies that would likely result in severe iatrogenic dynamic hyperinflation. Greater awareness of the potential hazards of using such ventilatory strategies for patients with obstructive airways disease is needed.

References
1. Tuxen DV. Detrimental effects of positive end-expiratory pressure during controlled mechanical ventilation of patients with severe airflow obstruction. Am Rev Respir Dis 1989:140:5-9.
2. Hannaway PJ. Demographic characteristics of patients experiencing near-fatal and fatal asthma: results of a regional survey of 400 asthma specialists.
Ann Allergy Asthma Immunol 2000;84:587-593.

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