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Correspondence |
* Brigham and Women’s Hospital, Boston, USA
Grosshadern Medical Center, Munich, Germany
Tübingen University Hospital, Tübingen, Germany, E-mail: heltzschig{at}partners.org
To the Editor:
We report the case of a morbidly obese patient with acute postoperative respiratory failure and the use of a laryngeal mask airway (LMA) to avoid tracheal re-intubation.
A 52-yr-old male patient presented for inguinal hernia repair under general anesthesia. Past medical history included chronic obstructive pulmonary disease, morbid obesity (body mass index 48 kg·m–2), claustrophobia, and sleep apnea. After premedication (midazolam 2 mg iv, fentanyl 50 µg iv), a rapid sequence induction was performed with iv propofol (200 mg) and succinylcholine (160 mg), and tracheal intubation was easy. Anesthesia was maintained with desflurane and nitrous oxide. After an uneventful operation, the patient was extubated, as he was wide awake, followed commands, and was breathing spontaneously (respiratory rate = 20/min, tidal volume = 500 mL, SpO2 = 99% with supplemental oxygen). However, shortly after his arrival in the postanesthesia care unit, the patient developed upper airway obstruction and acute respiratory failure (pH = 7.26, pCO2 = 68 mmHg, pO2 = 53 mmHg). To avoid additional sedation associated with tracheal re-intubation and the risk of prolonged weaning from the ventilatory support due to his body habitus, non-invasive ventilation was considered a therapeutic option as the patient demonstrated good pharyngeal reflexes. However neither a facial nor nasal mask was tolerated. In contrast, a LMA #5 (LMA North America, Inc, San Diego, CA, USA), placed after topical anesthesia of the upper airway was tolerated without gagging or agitation. Pressure support ventilation (10 cm H2O, positive end-expiratory pressure 5 cm H2O) was applied for alveolar recruitment. Thereafter, the patient’s breathing pattern normalized, as did the arterial blood gas analysis. The LMA was removed after two hours of ventilatory support. The patient was transferred to the floor and discharged home the next day.
In comparison to conventional mask ventilation, LMA results in higher tidal volumes and lower dead space ventilation during spontaneous ventilation.1 In anesthetized patients, the LMA is not associated with significant gastric insufflation2 and has been used for emergence from anesthesia in patients with severe reactive airway disease.3 However, its utility in the management of transient postoperative respiratory failure is largely unknown. Postoperative non-invasive ventilation is applied if tracheal intubation may be disadvantageous for the patient.4 However, fitting a facial or nasal mask may be difficult in patients with a beard or large nose, or in the presence of severe agitation. Insertion of the LMA does not require laryngoscopy, and as the present case report points out, additional sedation may not be required for airway tolerance.
References
1 Casati A, Fanelli G, Torri G. Physiological dead space/tidal volume ratio during face mask, laryngeal mask, and cuffed oropharyngeal airway spontaneous ventilation. J Clin Anesth 1998; 10: 652–5.[Medline]
2 Keller C, Sparr HJ, Luger TJ, Brimacombe J. Patient outcomes with positive pressure versus spontaneous ventilation in non-paralysed adults with the laryngeal mask. Can J Anaesth 1998; 45: 564–7.
3 Groudine SB, Lumb PD, Sandison MR. Pressure support ventilation with the laryngeal mask airway: a method to manage severe reactive airway disease postoperatively. Can J Anaesth 1995; 42: 341–3.
4 Tobias JD. Noninvasive ventilation using bilevel positive airway pressure to treat impending respiratory failure in the postanesthesia care unit J Clin Anesth 2000; 12: 409–12.[Medline]
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