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Should We Measure Endotracheal Tube Intracuff Pressure?

McCain-KingAirway-manometerB

In today’s changing healthcare climate where performance is constantly measured, procedures performed in the prehospital setting need to be reevaluated for their impact on patient outcomes. With the introduction of the Affordable Care Act, medical conditions caused by the action, inaction or conditions within the healthcare system will no longer be reimbursed by insurance. For example, if a hospital patient develops an infection, the hospital won’t be compensated for the extra treatment or longer stay.

Some complications may occur due to the environment in which EMS care is provided (e.g., dust from a motor vehicle collision causing a wound infection). However, some problems may be preventable, such as tracheal damage caused by excessive pressure in the cuff of an endotracheal (ET) tube or supraglottic airway.

ET intubation has been an airway management mainstay for decades and is part of most protocols. However, many protocols fail to mention the caution that should be taken to avoid excessive ET tube cuff pressure, explain a technique for proper cuff inflation, or provide a procedure to measure or monitor cuff pressure.

A study found that most ET tube pressures exceeded the recommended limits and that the time spent in the ED or prehospital setting may be long enough for tracheal damage to occur.1 However, the routine measuring of cuff pressure is rarely done in EMS.

Excessive ET tube cuff pressure by over-inflation of the cuff may lead to tracheal necrosis, stenosis and even rupture. At a minimum, the patient will develop a sore throat. Even a simple sore throat could have an impact on the hospital’s patient satisfaction or Hospital Consumer Assessment of Healthcare Providers and Systems (HCAPS) score. A low HCAPS score can have a negative impact on hospital reimbursement. (See “The ‘Patient Experience’ Revolution: The Affordable Care Act’s emphasis on patient-centered care will transform our industry,” by Doug Hooten, MBA and Matt Zavadsky, MS-HSA, EMT, in the February issue of JEMS.)

Cuffed ET tubes are designed to maintain a seal for positive pressure ventilation and prevent pulmonary aspiration in ventilated patients. The pressure exerted on the tracheal wall is directly related to the cuff pressure. The perfusion pressure for the tracheal mucosa is 40 cmH2O, so a cuff pressure in excess of 40 cmH2O will reduce or eliminate blood flow to the tissue.

The recommended safe cuff pressure is between 20 and 30 cmH2O. Many clinicians from anesthesiologist to paramedics have been taught to inflate the cuff with the minimal amount of air to prevent a leak and then monitor the pressure by feeling the pilot balloon, but studies have shown this to be inaccurate.4 Additionally, clinicians were found to be unable to inflate ET tube cuffs to safe pressures by measuring the amount of air used.4 Conversely, an underinflated cuff not only affects tidal volume because of an air leak but has also been shown to be a leading cause of aspiration, which is directly related to ventilator-associated
pneumonia (VAP). Mortality associated with the development of VAP is high, with mortality rates ranging from 20–41%.2

As an alternative to bag-valve mask ventilation and ET intubation, the supraglottic airway has changed the way airways are managed both in and out of the hospital. Supraglottic airways have been shown to be effective, easy to insert and sometimes considered a BLS skill. However, supraglottic airways also have a cuff and, in some cases, more than one.

Even though most supraglottic airways never enter the trachea, excessive cuff pressure can still lead to tissue and nerve damage. According to researchers at the University of Washington in Seattle, the average supraglottic airway cuff pressure measured was 90 cmH2O—well above the recommended safe zone of 60 cmH2O.3

So, with the problem identified, how should EMS approach the problem? Currently there’s no universal standard of how and when to check cuff pressures. However, there are studies that support continuous monitoring and automatic adjustments. Cuff pressure can change due to patient movement or an increase or decrease in airway swelling. Clinicians should consider using manometers to facilitate safe inflation and accurate measurement of ET tube and supraglottic airway cuff pressure, with the best alternative being a device that not only monitors but also adjusts the volume of air in the cuff automatically.

EMTs and paramedics need to view patient care as a continuum that begins with at-patient and ends with patient discharge. Every action by one provider potentially influences the actions of the next, both good and bad. For example, placing certain airways can make it difficult for the ED doctor to intubate. While this may be unavoidable, systems should work in conjunction with their primary receiving facilities to use the airways best suited for the cooperative airway management of patients. On the other hand, some complications, such as tracheal damage by cuff pressure that may not present itself until long after the patient is admitted, could potentially be mitigated by the actions of EMS.

References
1. Svenson JE, Lindsay MB, O’Connor JE. Endotracheal intracuff pressures in the ED and prehospital setting: Is there a problem? Am J Emerg Med. 2007;25(1):53–56.
2. Kollef M. Ventilator-associated pneumonia: A multivariate analysis. JAMA. 1993;270(16):1965–1970.
3. McNamara D. (April 2013.) Intracuff monitoring could prevent overinflation injuries. Anesthesiology News. Retrieved June 2, 2014, from www.anesthesiologynews.com/ViewArticle.aspx?d=Clinical+Anesthesiology&d_id=1&i=April+2013&i_id=945&a_id=22888.
4. Stewart SL, Secrest JA, Norwood BR, et al. A comparison of endotracheal tube cuff pressures using estimation techniques and direct intracuff measurement. AANA J. 2003;71(6):443–447.

Resources

  • Chapman J, Pallin D, Ferrara L, et al. Endotracheal tube cuff pressures in patients intubated before transport . Am J Emerg Med. 2009;27(8):980–982.
  • Hoffman RJ, Parwani V, Hahn IH. Experienced emergency medicine physicians cannot safely inflate or estimate endotracheal tube cuff pressure using standard techniques. Am J Emerg Med. 2006;24(2):139–143.
  • Parwani V, Hoffman RJ, Russell A, et al. Practicing paramedics cannot generate or estimate safe endotracheal tube cuff pressure using standard techniques. Prehosp Emerg Care. 2007;11(3):307–311.
 

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