Contained neck emphysema: an enigma?
A 30-year-old 70 kg woman, G2 P2 at 37 weeks gestation, presented unbooked to the obstetric emergency department of Lok Nayak Hospital, having had a generalised tonic-clonic convulsion.
She was slightly drowsy but otherwise oriented in time, place and person. Generalised oedema was present and on direct questioning she gave a history of decreased urine output. Her blood pressure was 170/110 mmHg and she was commenced on intravenous magnesium sulphate and labetalol. Investigations showed a haemoglobin of 6 g/dl, 3+ proteinuria on urine dipstick, and normal bleeding, clotting and clot retraction times. The patient was taken to the operating room for an urgent caesarean section under general anaesthesia. During induction, special consideration was given to optimisation of her intravascular volume, preparation for difficult airway management and blunting of the response to laryngoscopy. After preoxygenation for five minutes, a rapid sequence induction was performed using intravenous thiopentone, suxamethonium and lignocaine. Sixty seconds later, laryngoscopy was performed and the airway secured at the first attempt with a 6.5 mm cuffed orotracheal tube. Positive pressure ventilation was started once the tube position was confirmed by capnography. Due to poor initial ventilatory compliance, the tracheal tube was repositioned slightly and this improved bilateral breath sounds and compliance.
Fifteen minutes later, by chance, crepitus was palpated and the patient was found to have subcutaneous emphysema, limited to the neck. The inspired oxygen fraction was increased to 1.0 and she was monitored for progression of emphysema during the surgery, but this remained confined to the neck. Intraoperatively the patient's haemodynamic parameters and pulse oximetry remained stable. Blood loss was replaced with blood components as required.
Because of her poor preoperative condition including severe anaemia, eclampsia and the possible progression of airway oedema over the next few days, elective ventilation in the intensive care unit was organised. In view of the contained area of neck emphysema, a flexible fibreoptic bronchoscope was used to view the airway and a linear laceration over the posterior wall (membranous) of the trachea, approximately 3 cm in length at 6 cm proximal to the carinal spur, was seen. The inflated cuff of the tracheal tube was located such that it was just sealing the laceration.
We believe the subcutaneous emphysema was 'contained' in this case because initially the tip of the tracheal tube, which had delivered gas into the subcutaneous plane during the initial positive pressure inflation, had been incidentally repositioned distally 1 to 2 cm, as warranted by the initial low compliance. This may have stopped subcutaneous insufflation, improving compliance and incidentally sealing the laceration, which limited further extension of the subcutaneous emphysema. Cessation of nitrous oxide may also have limited extension.
The patient deteriorated progressively following the operation, developing ventilator-associated pneumonia, urinary tract infection, disseminated intravascular coagulation and sepsis and she died on the fifth postoperative day.
This case raises some unanswered questions, including--are patients with pre-eclampsia or eclampsia prone to this type of airway injury? This disease is associated with low oncotic pressure and soft tissue oedema and fragility, and this injury occurred despite gentle direct laryngoscopy and intubation at the first attempt. There are reports of tracheal rupture and pneumomediastinum in non-obstetric cases (1-3), but not to our knowledge in pregnancy or pre-eclampsia. We have not found any similar reports of subcutaneous emphysema confined to the neck, which in this patient appears to have been due to the cuff of the tracheal tube approximating the length of the laceration and thus containing any further escape of inflated gas.
(1.) Molins L, Buitrago LJ, Vidal G. Conservative treatment of 1. tracheal lacerations secondary to endotracheal intubation. Ann Thorac Surg 1997; 64:1227-1228.
(2.) Van Klarerbosch J, Meyer J, Delange JJ. Tracheal rupture after tracheal intubation. Br J Anaesth 1994; 73:550-551.
(3.) Regragui JA, Fagan AM, Natrajan KM. Tracheal rupture after tracheal intubation.Br J Anaesth 1994; 72:705-706.
R. K. Phulara
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|Author:||Bharti, M.; Sareen, B.; Luckwal, M.; Bansal, P.; Phulara, R.K.|
|Publication:||Anaesthesia and Intensive Care|
|Article Type:||Clinical report|
|Date:||May 1, 2009|
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