Abstract and Introduction
Abstract
Introduction: Endotracheal intubation is a common intervention in critical care patients undergoing helicopter emergency medical services (HEMS) transportation. Measurement of endotracheal tube (ETT) cuff pressures is not common practice in patients referred to our service. Animal studies have demonstrated an association between the pressure of the ETT cuff on the tracheal mucosa and decreased blood flow leading to mucosal ischemia and scarring. Cuff pressures greater than 30 cmH2O impede mucosal capillary blood flow. Multiple prior studies have recommended 30 cmH2O as the maximum safe cuff inflation pressure. This study sought to evaluate the inflation pressures in ETT cuffs of patients presenting to HEMS.
Methods: We enrolled a convenience sample of patients presenting to UMass Memorial LifeFlight who were intubated by the sending facility or emergency medical services (EMS) agency. Flight crews measured the ETT cuff pressures using a commercially available device. Those patients intubated by the flight crew were excluded from this analysis as the cuff was inflated with the manometer to a standardized pressure. Crews logged the results on a research form, and we analyzed the data using Microsoft Excel and an online statistical analysis tool.
Results: We analyzed data for 55 patients. There was a mean age of 57 years (range 18–90). The mean ETT cuff pressure was 70 (95% CI= [61–80]) cmH2O. The mean lies 40 cmH2O above the maximum accepted value of 30 cmH2O (p<0.0001). Eighty-four percent (84%) of patients encountered had pressures above the recommended maximum. The most frequently recorded pressure was >120 cmH2O, the maximum pressure on the analog gauge.
Conclusion: Patients presenting to HEMS after intubation by the referral agency (EMS or hospital) have ETT cuffs inflated to pressures that are, on average, more than double the recommended maximum. These patients are at risk for tracheal mucosal injury and scarring from decreased mucosal capillary blood flow. Hospital and EMS providers should use ETT cuff manometry to ensure that they inflate ETT cuffs to safe pressures.
Introduction
Endotracheal intubation is a common intervention in critical care patients undergoing helicopter emergency medical services (HEMS) transportation. A standard adult endotracheal tube (ETT) is secured at its distal end in the trachea using an inflatable cuff. This cuff serves to minimize aspiration risk and provides a seal to allow for delivery of a positive pressure gradient. The pressure in an ETT cuff must be high enough to occlude the lumen of the trachea in order to serve these primary functions.
Excess pressure, however, may increase the risk of damage to the tracheal mucosa.[1–3] ETT cuff pressures (ETTCP) that exceed the capillary perfusion pressure of the mucosa upon which the cuff is pressing may prevent the flow of blood through those capillaries and lead to mucosal ischemia.[2,3] Animal and human studies have demonstrated that ETTCP in excess of 30 cmH2O may cause decreased blood flow to the tracheal mucosa in as little as 25 minutes.[1–3] While guidelines for inflation pressures exist,[4] available equipment to measure cuff pressure is not routinely used in all settings, and even experienced operators are prone to over-inflation.[5–7]
We hypothesized that in patients intubated by referral EMS agencies or referral hospitals, the initial cuff pressure measured by the HEMS crew would be within the accepted safe range.
Reduction in tracheal blood flow as a consequence of higher-than-recommended ETTCP has been associated with ischemic lesions to the trachea.[8] Identifying the frequency at which patients are presented for transfer with ETTCP higher-than-recommended safe values will allow modification of practice.
Western J Emerg Med. 2016;17(6):721-725. © 2016 Western Journal of Emergency Medicine
