ProSeal laryngeal mask airway for laparoscopic gastric banding in a myasthenic, morbidly obese patient
Padova, Italy
* E-mail: ulderico.freo{at}unipd.it
Editor—Although the actual incidence of difficult tracheal intubation in obese patients is questioned,1 a subset of morbidly obese patients with obstructive sleep apnoea, a large neck circumference, or a Mallampati score of 3 or higher,2 and restricted cranio-cervical movement3 is at greater risk of difficult tracheal intubation and hypoxia than normal-weight patients.4 Laryngeal masks have been recommended in the guidelines on difficult intubation and have been used in obese subjects, mostly as intubating or temporary ventilatory devices.5–8 We report the anaesthetic management of a morbidly obese patient for laparoscopic gastric banding using a ProSeal laryngeal mask airway (PLMA).
The female patient (age 45 yr BMI 51.9) had a previous history of asthma, arterial hypertension, depression, and myasthenia gravis. Two years earlier, she underwent thymectomy after having been intubated awake as conventional tracheal intubation was very difficult. She subsequently had further weight gain and refused an awake intubation as a first approach and she would agree to this only if attempts with an endotracheal tube or PLMA while she was asleep had failed. On preoperative evaluation, the patient presented a mild weakness with fatigability on effort without signs of bulbar dysfunction, a short and thick neck (54 cm circumference) with rather limited extension, and a Mallampati score of 2.
After overnight fasting, anaesthesia was induced i.v. with fentanyl 100 µg and propofol 250 mg. Laryngoscopy showed a Cormack–Lehane grade 3 view which did not improve after head repositioning or changing the blade. A size 5 PLMA was placed at the first attempt and its correct position was confirmed with a bronchoscope. The PLMA cuff was inflated to and maintained at 60 cm H2O and a 14 G Salem gastric tube was passed through the drainage tube of the PLMA and left in situ for deflation of the stomach. Anaesthesia was maintained with i.v. propofol infusion (6–8 mg kg–1 min–1) and i.v. fentanyl 150 µg. A single i.v. bolus of cisatracurium 0.025 mg kg–1 was given. Ventilation was set to a 30/70 oxygen/air mixture, 12 breaths min–1, and expiratory tidal volume 9–10 ml kg–1. Peritoneum insufflation with CO2 to a preset intra-abdominal pressure of 2 kPa produced significant [baseline vs post-carboperitoneum means (SD), paired t-test, P<0.01] increases in end tidal CO2 [3.8 (0.2) vs 4.4 (0.1) kPa] and in peak airway pressure [22.2 (0.7) vs 27.1 (2.0) cm H2O] and declines in minute ventilation [9.7 (0.4) vs 8.6 (0.2) litre min–1]. SpO2 remained >97% throughout anaesthesia. The laparoscopic gastric banding, emergence, and recovery were uneventful.
PLMA may provide specific advantages over other ventilation modalities in patients with obesity, or myasthenia gravis. In obese patients, the successful use of PLMA for surgery has been reported both anecdotally in cases of failure of tracheal intubation5 6 and in two systematic studies on patients undergoing urological, gynaecological, or abdominal surgery.7 8 In those patients, PLMA effectively maintained the airway ventilation and gastric emptying.5 PLMA has been proposed as an alternative to endotracheal intubation in obese patients.6 In grossly and morbidly obese patients, experience is limited to the use of PLMA as a temporary ventilation device before laryngoscope-guided tracheal intubation.6 No report exists on laparoscopic gastric banding probably because of potential problems. The oro-gastric balloon tube cannot be inserted with the PLMA and its replacement with a Salem gastric tube must be agreed with the surgeon. The risk of regurgitation and of pulmonary aspiration of the gastric content is increased by gastric manipulation and insufflation and can be attenuated by correct placement of PLMA.6 8–10 Finally, although clinical evidence of pulmonary aspiration during anaesthesia using PLMA was comparable with that of endotracheal tube, many anaesthetists remain anxious about its ability to provide protection from aspiration.10 In myastenic patients, PLMA may have advantages over the endotracheal tube in that it causes lesser airway resistance and bronchospasm, and it does not require neuromuscular blocking agent drugs for its insertion. In spite of its potential advantages, however, most do not support the use of PLMA for the duration of a surgical procedure because of the current lack of knowledge regarding the risk of pulmonary aspiration and of difficult ventilation.1 In our experience, obese patients may present a rapid, sometimes life-threatening, arterial oxygen desaturation that can be aggravated by failed or even by a slow fibrescope guided intubation.
In conclusion, in our case, PLMA was an effective ventilatory option and warrants further studies in obese surgical patients.
References
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