Use of the ProSeal LMA in the ICU to facilitate weaning from controlled ventilation in patients with severe two episodic bronchospasm

EDITOR: We report the use of a ProSeal laryngeal mask airway (PLMA) to facilitate weaning from controlled ventilation in two patients in the intensive care unit (ICU) in whom weaning had previously been associated with repeated episodic bronchospasm. This had previously required tracheostomy to facilitate weaning in one of the patients. Case 1 A 68-yr-old female was admitted to the accident and emergency department in extremis, having developed acute severe bronchospasm at home without an obvious precipitant. She was severely hypoxic and neurologically obtunded with a Glasgow coma score of 3. She was intubated with propofol, alfentanil and rocuronium, and mechanically ventilated with propofol and alfentanil sedation. Initially her lungs were difficult to ventilate, with poor compliance and marked gas trapping resulting in severe hypercapnoea. After 4 days of treatment with nebulized beta-2 agonists and ipratropium bromide, intravenous (i.v.) corticosteroids and aminophylline her bronchospasm had improved to the point where extubation was being considered. Five months previously she had been admitted with a similar episode of acute severe bronchospasm requiring intubation and ventilation. At this time she was not known to be asthmatic. Standard management of her bronchospasm lead to resolution and early attempts to reduce sedation and wean from mechanical ventilation. However, each such attempt was complicated by acute severe bronchospasm. A single attempt at extubation leads to respiratory failure secondary to bronchospasm requiring emergency re-intubation. An echocardiogram was performed to exclude a cardiac cause for difficulty weaning which showed no abnormality. A percutaneous tracheostomy was performed after 5 days. Despite this, the bronchospastic episodes continued for approximately 28 days, after which they spontaneously resolved. Her tracheostomy was decannulated and she made a good recovery. Her asthma treatment was maintained with inhaled corticosteroids, beta-2 agonists and ipratropium bromide at home. In view of her previous history there was concern that reducing her sedation while intubated would precipitate further severe bronchospasm. A decision was made to attempt weaning from mechanical ventilation but that if bronchospasm recurred a percutaneous tracheostomy would be performed. Her endotracheal tube was removed under anaesthesia with propofol and alfentanil and neuromuscular blockade with rocuronium, and a size 4 PLMA was inserted. Biphasic positive airways pressure ventilation (BIPAP) via a Draeger Evita 4 ventilator was continued, with no airway leak measured by the ventilator at an inspiratory plateau pressure of 25 cmH 2 O. After resolution of the neuromuscular block (confirmed by peripheral nerve stimulation), sedation was discontinued. The patient emerged within a few minutes to the level of obeying commands without coughing and the PLMA was removed without bronchospasm or other complications. Her subsequent recovery was unremarkable. Case 2 A 20-yr-old male was admitted to the emergency department with a 3-day history of productive cough and a several hour history of increasing shortness of breath. He had had asthma since childhood, but this had never required hospital admission. He saw his general practitioner three times a year because of his asthma, requiring short courses of oral steroids. His peak flow was 200 L min−1 in the emergency department with a predicted value of 600 L min−1. He failed to respond to nebulisers or i.v. salbutamol or aminophylline, and was admitted to the intensive therapy unit (ITU) with increasing respiratory distress and use of accessory muscles. He initially was talking in sentences, but by the time he was admitted to ITU he could only speak in single words and was becoming more anxious. He initially settled with facemask non-invasive positive pressure ventilation and the above infusions, but became more anxious, making his bronchospasm worse. He was intubated and ventilated using the same drugs as in case 1 and the bronchospasm subsided rapidly. However, when sedation was reduced, he became anxious again, and the bronchospasm returned. This was repeated on further occasions over the next few hours. It was decided the following morning to replace the endotracheal tube with a PLMA with the intention of reducing tracheal stimulation and bronchospasm. Sedation was increased and a size 5 PLMA was inserted. A clonidine infusion was commenced to reduce anxiety and the other sedation was stopped. Within a few minutes he was able to obey commands and had no bronchospasm, and the PLMA was removed. His peak flow after extubation was 430L min−1. He was discharged to the care of the respiratory physicians and discharged home 4 days after admission to hospital. The classic laryngeal mask airway (cLMA) is associated with a lower incidence of coughing and airway complications during emergence from anaesthesia when compared to an endotracheal tube [1] and has been used for this reason in the ICU in the past [2]. However, the cLMA has disadvantages. It provides only a low-pressure seal with the airway (median 18-20 cmH2O) [3,4], therefore controlled ventilation of the lungs may be problematic. Increases in airway pressure are associated with increased gas leak and gastric inflation [3]. Further, the cLMA offers no protection in the case of regurgitation of gastric contents. The PLMA is also associated with less respiratory stimulation than the tracheal tube during emergence from anaesthesia [4,5]. The PLMA has also been shown to have benefits over the cLMA during controlled ventilation; the seal achieved with the airway with the PLMA is increased approximately 50% compared to the cLMA, allowing improved ventilation with reduced leakage of gas from the airway [5]. This feature was particularly pertinent in the cases reported here, as controlled ventilation in patients with bronchospasm might be expected to require considerably higher pressures than 20 cmH2O. In addition the drain tube of the PLMA minimizes the likelihood of gastric inflation and allows a route to vent regurgitated gastric contents if this occurs [5]. Finally in the first case the PLMA provided a suitable airway for percutaneous tracheostomy if this was required [6]. Use of the PLMA in the ICU has previously been restricted to the management of difficult airways [6,7] and as an airway during percutaneous tracheostomy [5,7]. To our knowledge, this is the first time the PLMA has been used to facilitate weaning from controlled ventilation. We have now used this technique in a total of five similar cases with success. When a supraglottic device is considered to assist such weaning we believe that the PLMA offers advantages over the cLMA (and other supraglottic devices) because of its greater facility for controlled ventilation in patients with reduced lung compliance, the likelihood of reduced gastric distension and reduction in aspiration risk. S. Laver C. McKinstry T. M. Craft T. M. Cook 1Department of Anaesthesia, Royal United Hospital, Combe Park, UK