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Correspondence  |   July 2000
Revisiting the ASA Guidelines for Management of a Difficult Airway
Author Notes
  • Professor and Chairman
  • Department of Anesthesiology
  • American University of Beirut
  • Beirut, Lebanon
Article Information
Correspondence
Correspondence   |   July 2000
Revisiting the ASA Guidelines for Management of a Difficult Airway
Anesthesiology 7 2000, Vol.93, 297-298. doi:
Anesthesiology 7 2000, Vol.93, 297-298. doi:
In Reply:—
Thank you for referring to me the letters to the editor from R. P. Haridas and Kenneth D. Candido et al.  regarding my manuscript, “Tension Pneumothorax as a Complication of Jet Ventilation via  a Cook Airway Exchange Catheter.”1 
The patient described could easily receive ventilation by a face mask after induction of anesthesia and before laryngoscopy and tracheal intubation. The exchange catheter was advanced until resistance was felt; the airway exchange catheter might have wedged in the bronchus, obstructing the air escape. As recommended in the editorial view of Benumof 2 that accompanied the report, “A prudent rule to follow is never to allow the centimeter calibration on the AEC to exceed a depth of 26 cm in an adult and never to insert an AEC when resistance is encountered [to avoid tear beneath the trachea].”
The tension pneumothorax that developed in our patient may be secondary to barotrauma or a result of direct trauma to the tracheobronchial tree by the tip of the catheter or by the force generated by the jet per se  . The case report 1 and the accompanying editorial view of Benumof 2 outlined the different precautions that may decrease the incidence of this serious complication, such as limiting the jet pressure and the inspiratory time. These parameters may be difficult to control with use of a hand-controlled jet ventilation technique. Automatic jet ventilation can be achieved by interrupting the pipeline oxygen (50–60 psi) by a Bird Ventilator Mark II (Bird Products Corp., Palm Spring, CA) or by a solenoid valve, which is electronically controlled;3–5 the system controls both the inspiratory and the expiratory times, and the delivered pressure of the jet.
We have used automatic jet ventilation safely in children anesthetized by the T-piece circuit 3 or undergoing rigid bronchoscopy. Also, the technique was used in adults undergoing airway surgery. 4,5 In all these situations, the jet is delivered via  the anesthesia circuit, the bronchoscope, or the endotracheal tube, not directly by a catheter placed in the tracheobronchial tree. This may attenuate the jet and does not interfere with the air exit during passive exhalation.
Barotrauma may be more frequent 6 when the oxygen jets are delivered by an exchange catheter directly into the tracheobronchial tree. Because of the “prohibitive dangers associated with jet ventilation through these catheters,” we recommended in our case report that jet ventilation through these catheters should not be necessary during the brief period of tube exchange. 1 
According to the editorial of Benumof, 2 air entry should not exceed air exit. The incidence of complicating barotrauma may be decreased by selecting a properly sized exchange catheter in proportion to the size of the endotracheal tube, by regulating the airway pressure to low levels, and by delivering oxygen jets of short duration followed by a long expiratory pause. Also, it is important to monitor chest inflation and chest deflation both. As suggested by Dr. Haridas, jet ventilation should be discontinued the moment there is incomplete chest deflation, and there should be a high index of suspicion regarding the development of tension pneumothorax.
References
Baraka AS: Tension pneumothorax complicating jet ventilation via  a Cook airway exchange catheter. A nesthesiology 1999; 91:557–8Baraka, AS
Benumof JL: Airway exchange catheters: Simple concept, potentially great danger. A nesthesiology 1999; 91:342–4Benumof, JL
Baraka A, Muallem M, Chidiac G, Ayyoub C: Automatic jet ventilation in children anesthetized by the T-piece circuit. Paediatric Anaesth 1994; 4:169–72Baraka, A Muallem, M Chidiac, G Ayyoub, C
Baraka A, Mansour R, Abou Jaoude C, Muallem M, Hatem J, Jaraki K: Entrainment of oxygen and halothane during jet ventilation in patients undergoing excision of tracheal and bronchial tumors. Anesth Analg 1986; 65:191–4Baraka, A Mansour, R Abou Jaoude, C Muallem, M Hatem, J Jaraki, K
Baraka A, Muallem M, Jamhoury M, Choueiry P: Jet ventilation in a case of tracheal obstruction secondary to a retrosternal goitre. Can J Anaesth 1993; 40:875–8Baraka, A Muallem, M Jamhoury, M Choueiry, P
Cooper RM: The use of an endotracheal ventilation catheter in the management of difficult extubation. Can J Anaesth 1996; 43:90–3Cooper, RM