Canadian Anaesthetists’ Society Journal

, Volume 22, Issue 3, pp 307–315 | Cite as

Anaesthesia for intestinal short circuiting in the morbidly obese with reference to the pathophysiology of gross obesity

  • Gordon S. Fox


Sixteen extremely obese patients were anaesthetized for intestinal short circuiting operations. Severe obesity may cause pathological cardio-pulmonary changes. Cardiovascular alterations include increased systemic, pulmonary artery and pulmonary capillary venous pressure. Cardiac output, total blood volume and left ventricular work increase.

Expiratory reserve volume and consequently functional residual capacity decrease with gross obesity. Functional residual capacity falls below closing volume and inspired gas may be distributed to non-dependent lung zones, resulting in decreased ventilation/perfusion ratios and arterial hypoxaemia. Low total respiratory compliance increases the oxygen cost of the work of breathing.

Obesity may change the dose requirements for regional anaesthesia and long-acting muscle relaxants. General anaesthesia may also reduce functional residual capacity.

We used a technique of anaesthesia which consisted of epidural analgesia with intra-operative mechanical ventilation and which specifically avoided volatile inhalation agents and long-acting muscle relaxants. All patients were extubated immediately after operation and returned to the recovery room for an average duration of 26 hours. Post-operative treatment included humidified oxygen, chest physiotherapy and elevation of the head of the bed to 45°. Each patient’s respiratory progress was monitored by repeated determinations of arterial blood gases and vital capacity and by serial chest X-rays. None of the patients in this group required post-operative tracheal intubation and mechanical ventilation.


Epidural Analgesia Functional Residual Capacity Arterial Oxygen Tension Total Blood Volume Airway Closure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


L’étude porte sur 16 malades très obèses anesthésiés pour “by-pass” iléal. Une obésité importante peut entraîner des changements cardio-pulmonaires. On observe fréquemment de l’hypertension artérielle, de l’hypertension pulmonaire artérielle et veineuse. Le débit cardiaque, le volume sanguin total et le travail du ventricule gauche sont augmentés.

Le volume de réserve expiratoire et, par conséquent, la capacité résiduelle fonctionnelle sont diminués dans l’obésité grave. La FRC baisse sous le volume de fermeture et les gaz inspirés peuvent se distribuer aux parties non dépendantes du poumon, entraînant une hypoxémie secondaire à une diminution du rapport ventilation/perfusion. La compliance pulmonaire totale est basse ce qui augmente le travail respiratoire et la consommation d’oxygène.

L’obésité peut modifier les doses requises en anesthésie régionale et en relaxants musculaires à longue action. L’anesthésie générale contribue à diminuer la capacité résiduelle fonctionnelle.

Notre technique d’anesthésie comprend : analgésie par épidurale et ventilation mécanique per-opératoire. On évite les agents volatiles et les relaxants musculaires à longue action.

Tous les malades sont extubés immédiatement après chirurgie, et transférés à la salle de réveil oú la durée du séjour moyen ne dépasse pas 26 heures. Le traitement post-opératoire comprend: oxygène humidifié, physiothérapie pulmonaire et tête du lit levée à 15°. On fait des contrôles de gaz artériels, de capacité vitale et des R-X pulmonaires.

Aucun des malades de ce groupe ne fut intubé, ni ventilé mécaniquement en post-opératoire.


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Copyright information

© Canadian Anesthesiologists 1975

Authors and Affiliations

  • Gordon S. Fox
    • 1
  1. 1.Department of AnaesthesiaRoyal Victoria Hospital & McGill UniversityMontreal

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