Assessment of anaesthetists' ability to predict difficulty of bag-mask ventilation.

examination was normal. An arterial blood gas showed respiratory alkalosis with pH 7.51, PCO2 3.2 kPa, PO2 20 kPa, and HCO3 20.4. A repeat brain CT with bone window showed right frontal pneumocephalus and a large defect near the cribriform plate on the right side (Fig. 1C).The pneumocephalus was managed with supportive care and the patient was discharged on posttrauma day 27. Recurrent pneumocephalus has been reported with positive pressure ventilation strategies like mask ventilation during anaesthetic induction, continuous positive airway pressure, and also with simple nasal O2 cannulae. 1 – 3 It has been advised that in patients with the base of skull and facial bone fractures, excessive positive pressure during mask ventilation should not be used. Rapid induction and intubation with intubating LMA in a patient with difficult airway and pneumocephalus has been described. To avoid the above complication, we had planned for the surgery of the forearm under regional anaesthesia. But as the patient was uncooperative, LMAwas used with the preservationofspontaneousventilation. Unfortunately, positive pressure ventilation (PPV) with LMA to check its correct position after insertion seems to have reopened the breach in the duramater. The respiratory embarrassment caused by paralytic ileus may also have aggravated the pneumocephalus. The resulting hypocapnia may have decreased the intracranial pressure, thereby creating subatmospheric pressure and causing indrawing of air into the cranium. Therefore, causes of hyperventilation like respiratory embarrassment, poor analgesia, and anxiety should be treated promptly. In conclusion, we would like to caution that pneumocephalus can recur during PPV with LMA in patients with recent fracture of the skull base and face. The technique of rapid induction and intubation with fast-acting neuromuscular blocking agents without positive pressure mask ventilation (PPMV) and definitive airway control with the tracheal tube is probably the best way to avoid recurrent pneumocephalus. Any cause of hyperventilation in the postoperative period which may aggravate pneumocephalus should be corrected.