Gastric rupture and laryngeal mask airway
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《英国医生杂志》
EDITOR—We wanted to highlight the risk of gastric inflation when the laryngeal mask airway is used for positive pressure ventilation and to draw attention to the inadequacy of the current Resuscitation Council (UK) guidelines for using the laryngeal mask airway in resuscitation.1 We did not intend to generate any negative "hype" about its use by non-anaesthetists.
Limiting airway pressure to less than 20 cm H2O to minimise the risk of gas leak when ventilating a patient using the laryngeal mask airway is important. Standard resuscitation equipment is, however, not equipped to achieve this easily. Therefore practitioners must be aware of the issues involved in the use of the device and have the appropriate degree of skill to use it safely. For this reason we take issue with some statements and recommendations given in current resuscitation guidelines for use of the laryngeal mask airway.
We accept that most gas leaking from around the laryngeal mask airway during lung inflation will indeed exit through the mouth, but this misses the point. Only a small proportion of the total gas leak need enter the stomach to cause substantial distension: 600 ml gas will enter the stomach in only 20 breaths with a tidal oesophageal leak of just 30 ml (< 5% of recommended tidal volume).
Furthermore, continuous, uninterrupted chest compression (100 per minute) will cause a surge in airway pressure 2-3 times per inspiration (inspiratory time 1-2 s). This is incompatible with the need to limit airway pressure, and makes a pharyngeal gas leak almost certain to occur. The current guideline dismisses the risk of gastric inflation and states that the only reason to cease continuous chest compression is if gas leakage results in inadequate ventilation.1
Practitioners trained to use the laryngeal mask airway should be taught that the presence of a pharyngeal gas leak during lung inflation is indicative of an oesophageal leak and should be actively sought for and corrected. They should be instructed, given there is no obvious leak through the mouth, to listen with a stethoscope over the anterior aspect of the neck to exclude pharyngeal gas leaks of lesser flow. We believe that if any gas leak is present cardiac compressions should be interrupted for ventilation (15:2).
Nathaniel Haslam, specialist registrar in anaesthesia
Freeman Hospital, Newcastle upon Tyne NE7 7DN nhaslam@doctors.org.uk
John E Duggan, consultant anaesthetist
Department of Anaesthesia, Wansbeck Hospital, Ashington, Northumberland NE63 9JJ
Competing interests: None declared.
References
Resuscitation Council (UK). Adult advanced life support. Resuscitation guidelines 2000 www.resus.org.uk/pages/als.htm#ccav (accessed 29 Jan 2005).
Limiting airway pressure to less than 20 cm H2O to minimise the risk of gas leak when ventilating a patient using the laryngeal mask airway is important. Standard resuscitation equipment is, however, not equipped to achieve this easily. Therefore practitioners must be aware of the issues involved in the use of the device and have the appropriate degree of skill to use it safely. For this reason we take issue with some statements and recommendations given in current resuscitation guidelines for use of the laryngeal mask airway.
We accept that most gas leaking from around the laryngeal mask airway during lung inflation will indeed exit through the mouth, but this misses the point. Only a small proportion of the total gas leak need enter the stomach to cause substantial distension: 600 ml gas will enter the stomach in only 20 breaths with a tidal oesophageal leak of just 30 ml (< 5% of recommended tidal volume).
Furthermore, continuous, uninterrupted chest compression (100 per minute) will cause a surge in airway pressure 2-3 times per inspiration (inspiratory time 1-2 s). This is incompatible with the need to limit airway pressure, and makes a pharyngeal gas leak almost certain to occur. The current guideline dismisses the risk of gastric inflation and states that the only reason to cease continuous chest compression is if gas leakage results in inadequate ventilation.1
Practitioners trained to use the laryngeal mask airway should be taught that the presence of a pharyngeal gas leak during lung inflation is indicative of an oesophageal leak and should be actively sought for and corrected. They should be instructed, given there is no obvious leak through the mouth, to listen with a stethoscope over the anterior aspect of the neck to exclude pharyngeal gas leaks of lesser flow. We believe that if any gas leak is present cardiac compressions should be interrupted for ventilation (15:2).
Nathaniel Haslam, specialist registrar in anaesthesia
Freeman Hospital, Newcastle upon Tyne NE7 7DN nhaslam@doctors.org.uk
John E Duggan, consultant anaesthetist
Department of Anaesthesia, Wansbeck Hospital, Ashington, Northumberland NE63 9JJ
Competing interests: None declared.
References
Resuscitation Council (UK). Adult advanced life support. Resuscitation guidelines 2000 www.resus.org.uk/pages/als.htm#ccav (accessed 29 Jan 2005).