23. Obesity

23. Obesity

The grossly and morbidly obese Patients are more likely to regurgitate during anaesthesia even when fasted and are considered unsuitable candidates for Tulip usage, unless no other mechanism is suitable for airway support and control, such as the failed intubation scenario. Grossly obese Patients frequently require high ventilating pressures (>20cmH2O) which pre-disposes them to possible gastric insufflation, dilation and its sequelae when using a Tulip. Management of such Patients with low and normal ventilation pressures (<20cmH2O) is recommended when using a Tulip. The risks of regurgitation and aspiration may be reduced by using H2 receptor antagonists (Ranitidine), proton pump inhibitors (Omeprazole), antacids (Sodium Citrate) or drugs which increase gastric emptying, such as Metoclopramide.

The Tulip is considered safe in the mild and moderately obese so long as care is taken that an adequate plane of anaesthesia has been achieved prior to introduction of the Tulip and that normal ventilating pressures (+/-20cmH2O) are used. The possibility of reflux and regurgitation must be monitored in all such Patients.

It is recommended that a second syringe of induction agent is prepared in anticipation of any problems. The Patient must be adequately anaesthetized prior to any transfer or movement as anaesthetic lightness will induce coughing and straining and may well induce laryngeal spasm. In such cases where the Patient is straining secondary to inadequate anaesthesia it is recommended that the Tulip be left firmly in place as a secure, ventilating airway and that a second dose of intravenous induction agent is given to induce surgical anaesthesia.

In such situations it is wise to maintain ventilation upon higher concentrations of both oxygen and anaesthetic vapor, to maintain saturation and anaesthetic depth. In such a situation hand-bagging is recommended as this will reflect the Patient’s chest compliance and indeed will allow the maintenance of some P.E.E.P. (Positive End Expiratory Pressure) which will allow the maximal oxygen in-flow through the cords in laryngeal spasm.

Should the Patient’s laryngeal spasm be persistent or the compliance of the chest be excessive secondary to muscular activity, then it may be prudent to deliver a dose of short acting neuromuscular paralysis to maintain control and oxygenation. If, in this scenario, the ventilation pressures seem excessively high, a cause must be sought. Initially the level of muscular activity and inadequate depth of anaesthesia must be excluded. The elevation of ventilating pressures may be secondary to bronchospasm itself due to asthma, C.O.A.D. or anaphylaxis.

Mechanical obstruction of the breathing lumen by secretions, kinking or anatomical obstruction is possible and should be excluded by visualization, suction and manipulation of the airway in the adequately anaesthetized Patient as previously described.

There is always the possibility of regurgitation and aspiration, particularly in the obese patient, and this may be confirmed by placing the Patient in the head down position and looking for fluid in the breathing tube lumen. This may be complemented by using fiberoptic laryngoscopy for visualization.

The obese Patient may be maintained using either the spontaneously ventilation technique, or controlled ventilation, and such decisions are usually determined by the type of surgery and its duration. Obese Patients may maintain excellent saturations and levels of anaesthesia, but may require ventilatory support, and indeed controlled ventilation to maintain adequate oxygenation and normocapnia.

In cases involving C.O.A.D. and Patients with respiratory compromise, the Tulip carries the benefit of avoiding intubation but will still continue to allow excellent airway and manual ventilation control.