ANAESTHESIA IN A GROSSLY OBESE PATIENT

Erit. J. Anaesth. (1968), 40,139

ANAESTHESIA IN A GROSSLY OBESE PATIENT A Case Report BY A. J. P. LESSING AND M. J. DE KOCK

SUMMARY

The hazards of anaesthesia in the obese patient are well known and may cause concern both during and after operation. There are mechanical as well as physiological difficulties. Of the mechanical variety the following are the most common: venepuncture may be impossible or there might be diSculties in maintaining the position of a needle or cannula during surgery; an artery may be entered in attempts to reach a deep vein in the cubital fossa; endotracheal intubation can be difficult, as can positioning of the patient for the surgical procedure. The physiological hazards revolve round the cardiopulmonary system and pharmacological action of drugs (Catenacci, Anderson and Boersma, 1961). Pre-operatively these authors found that the most common pathological finding is arterial hypertension, followed by myocardial disease and diabetes mellitus in that order. These patients also are hampered by serious pulmonary derangement. Due to weight distribution, the elastic recoil of the thoracic cage is increased, with resultant reduction in residual functional capacity, especially in the supine and Trendelenburg positions. The oxygen cost of breathing is frequently elevated and though ventilation/perfusion discrepancies are present these patients can live, exhibiting only mild hypoxia while the Pco, is sometimes not elevated (Miller and Bashour, 1963). When the respiratory system is stressed by suppressant drugs, however, the delicate balance may be disturbed. This preoperative ventilatory disadvantage can be aggra-

vated by operative interference, especially in upper abdominal operations (Gould, 1962). General anaesthetics or muscle relaxants may enhance the muscular weakness present in the inactive obese person (Miller and Bashour, 1963). Pulmonary artery pressure is increased, due to an increase in venous return and to cephalad movement of the diaphragm, with limitation of pulmonary expansion in certain positions. In our experience and that of others (Catenacci, Anderson and Boersma, 1961; Miller and Bashour, 1963) obese patients need larger amounts of drugs for induction and maintenance of anaesthesia, but relatively smaller doses on a weight basis. Average induction doses of thiopentone sodium may lead to laryngospasm and time is needed to settle them on inhalational techniques. The larger doses of thiopentone sodium needed may lead to severe ventilatory depression and arterial hypotension. All these factors were taken into account when the case to be described confronted us for an emergency operation and neuroleptanaesthesia was chosen. CASE REPORT A female, aged 56, was admitted with severe pain in the upper abdomen. The provisional diagnosis of perforated peptic ulcer was made by the surgeons and immediate operation was advised. She weighed 471 lb. (214 kg) and was 5 feet 6 inches tall (168 cm). Apart from her surgical condition, arterial hypertension (230/120 mm Hg) and breathlessness with atrial fibrillation were found on examination. The medicaments

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A case is reponed of an extremely obese patient (214 kg) who required operation for an acute abdominal condition. Because of arterial hypertension, cardiac arrhythmia and the problems envisaged in controlling anaesthesia using conventional inhalation agents, neuroleptanaesthesia was chosen. This varies from the technique of neuroleptanalgesia in that oxygen and nitrous oxide are added. This method gave excellent control and there was freedom from the usual problems encountered when anaesthetizing obese patients.

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BRITISH JOURNAL OF ANAESTHESIA

DISCUSSION This patient fitted the definition of Catenacci, Anderson and Boersma (1961) of an obese patient,

that is one weighing more than 200 lb. (91 kg) and being under 5 feet 6 inches (168 cm) tall. The following factors influenced us to use neuroleptanaesthesia (Foldes et al., 1966): (a) Difficulty was envisaged in her case in stabilizing anaesthesia on fat-soluble inhalational drugs. (b) The response to pethidine 100 mg led the authors to expect that good analgesia would be obtained with fentanyl. (c) In view of the treatment with digitalis and the cardiac arrhythmia, halothane was considered unsafe. The neuroleptic drugs when used in relatively small doses are reputed to have little or no effect on the circulation. Fentanyl, a 4-anilopiperidine derivative, is a very potent but shortacting analgesic with no effect on the circulation apart from a possible vagal action. (d) Depression of ventilation by fentanyl can be reversed efficiently by nalorphine. It is not difficult to differentiate respiratory insufficiency due to fentanyl from that due to muscle relaxants. In the case reported respiratory insufficiency due to fentanyl presented with a slow but deep respiratory rate, without tracheal tug. The pulmonary hypertension present in the obese patient might be aggravated by intermittent positive pressure ventilation, through reduction in the size of the pulmonary capillary bed. However, through pulmonary inflation and correction of hypoxia and hypercarbia ventilation will tend to decrease pulmonary vascular resistance (Miller and Bashour, 1963). ACKNOWLEDGEMENTS

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taken were digoxin tablets and diuretics. There was slight peripheral cyanosis. Her obesity was of the exogenous variety and the urine was dear of sugar and acetone. Pulmonary function was not tested due to inability of the patient to co-operate and also because her respiratory distress, aggravated by the upper abdominal condition, was clinically obvious. The pulse rate was 100 beats /min and irregular. It was noted that 45 minutes previously she had been given pethidine 100 mg with good effect. This response, as well as the cardiac arrhythmia, supported our decision to use neuroleptanaesthesia. This differs from the conventional technique of neuroleptanalgesia by the addition of nitrous oxide and oxygen for anaesthesia, Premedication prescribed and given by the surgeons was atropine 0.6 mg with promethazine 50 mg. She was wheeled to the theatre on her bed, and by tying two standard operating tables together a large enough table was constructed to accommodate her comfortably. In view of expected difficulty with venepuncture, a vein was exposed beforehand. Induction of anaesthesia was started with inhalation of 100 per cent oxygen and intravenous injection of dehydrobenzperidol 110 /ig/kg body weight followed, after 5 minutes, by fentanyl 50 /ug. Within 3 minutes she appeared well sedated and methohexitone 80 mg with suxamethonium 100 mg were given before intubation; this was easy. Increments of 20-40 /Mg of fentanyl were added after the return of spontaneous respiration. Pulmonary ventilation was assisted, using a carbon dioxide absorption system, and 50 per cent oxygen with 50 per cent nitrous oxide. When the total dose of fentanyl was 240 ^g an upper abdominal transverse incision was made and accepted by the patient. Diallyl nortoxiferine was given and artificial ventilation by Engstrom ventilator started. After a total of 20 mg of diallyl nortoxiferine, inspiratory pressures were still above 35 cm H,O and arterial hypotension threatened. By virtue of previous experience with difficulty in reversal after high doses of this drug, tubocurarine was substituted in 6-mg doses, a watch being kept for bronchospasm. After this the inspiratory pressure adjusted to 25 cm H,O and the systolic blood pressure stabilized at 215 mm Hg. Cardioscope monitoring demonstrated no deterioration in arrhythmia but also no improvement. On opening the abdomen the patient was found to suffer from acute cholecystitis. Although relaxation was maximal, the weight of the fatty layer in the abdominal wall hampered surgical exposure. Operation time was 2 hours, during which no further difficulties were encountered. A total of 500 /ig of fentanyl and 24 mg of tubocurarine was used; decurarization was accomplished with atropine 0.8 mg mixed with neostigmine 2.5 mg because of a fast pulse rate. Signs of residual curarization were noted and a further 2-mg dose of neostigmine was injected. A tracheostomy was performed after an additional 50-/ig dose of fentanyl had been injected. After nalorphine 10 mg the patient awoke and breathed well. Although she lost her tracheostomy tube during a bout of coughing in the ward, she made a good recovery without respiratory trouble. Physiotherapy was facilitated by using two beds tied together and rolling her from one bed to the other in order to change her position.

We are indebted to Professor O. V. S. Kok of the Anaesthesia Department for help and support; to Dr. P. N. Swanepoel, Superintendent of our hospital, for permission to publish this case report. REFERENCES

Catenacci, A., Anderson, J., and Boersma, D. (1961). Anesthetic hazard of obesity. J. Amtr. med. Ass., 175, 657. Foldes, F. F., Kepes, E. R., Kronfeld, P. P., and Shiffman, H. P. (1966). A rational approach to neuroleptanesthesia. Anesth. Analg. Curr. Res., 45,642. Gould, A. (1962). Effect of obesity on respiratory complications following general anesthesia. Anesth. Analg. Curr. Res., 41, 448. Miller, W. F., and Bashour, F. F. (1963). Cardiopulmonary changes in obesity; Clinical Anesthesia 3/1963, p. 128. Philadelphia: Davis.

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ANAESTHESIA LN A GROSSLY OBESE PATIENT ANESTHESIE CHEZ UN PATIENT FORTEMENT OBESE

NARKOSE BEI EINEM PATIENTEN MIT AUSGEPRAGTER FETTSUCHT

SOMMAIRE

Es wird von einem extrem fettsiichtigen Patienten (214 kg) berichtet, der wegen eines akuten abdominalen Zustands operiert werden muflte. Wegen der arteriellen Hypertension, der kardialen Arrhythmie und den Schwierigkeiten, die bei der Oberwachung der Narkose nach dex Verwendung von konventionellen Inhalationsnarkotika in Betracht gezogen werden mfissen, wurde die Entscheidung zugunsten einer NeuroleptanSsthesie gefallt Diese Methode weicht von der Neuroleptanalgesie ab, bei der zusatzlich Sauerstoff und T jr-hgn^ verwendet werden. Sie ermSglichte cine ausgezeichnete tJberwachung des Patienten. Aufierdem traten die ilblichen Schwierigkeiten nicht auf, mit denen bei der Narkose fettsuchtiger Patienten gerechnet werden sollte.

ZUSAMMENFASSUNG

FOURTH WORLD CONGRESS OF ANAESTHESIOLOGISTS, LONDON September 9-13,1968 REGISTRAR STEWARDS FOR SCIENTIFIC SESSIONS The Organising Committee wish to recruit volunteer Stewards to serve as aides to the Chairmen and Secretaries of Scientific Sessions from amongst the Senior Registrars and Registrars in the United Kingdom. Stewards will be admitted to the Congress free of charge on the day on which they are on duty, but no guarantee can be given that they will be allocated to a particular Session. Those who undertake one or two days' stewardship will be offered one additional day's admission free of charge; those who undertake three day's stewardship will be offered two additional days free of charge. A Senior Registrar or Registrar will thus be able to attend all the scientific sessions of the Congress free of charge (three days' stewardship and two extra days free of charge). Daily travelling expenses will be paid only from an address in London or the Home Counties. Volunteers for stewardship duty should write to: THE SECRETARY, FOURTH WORLD CONGRESS OF ANAESTHESIOLOGISTS, ROYAL MARSDEN HOSPITAL, FULHAM ROAD, LONDON,

S.W.3

enclosing a letter of consent from the Head of the Department in which they work. Further details and an application form will then be supplied. Heads of Departments may prefer to offer "a Registrar" or "a Senior Registrar" for stewardship duty, leaving the actual name to be supplied nearer the time of the Congress. Assistance of this kind will be most welcome. Please write to the above address. If the number of offers in response to this appeal is greater than the number of steward* required, the Organizing Committee reserve the right to select the team from amongst the volunteers.

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Les auteurs rapportent le cas (Tun patient extremement obese (214 kg), devant subir une intervention chiniTgicale par suite d'un abdomen aigu. On decida de pratiquer la neuroleptanesthesie, en raison de rhypertension arterielle, de rarrhythmie cardiaque, et des difficultes de controller l'anesthesie avec des anesthesiques inhalatoires conventionnels. La neuroleptanesthesie differe de la neuroleptanalgesie par l'addition d'oxygene et protoxyde d'azote. Cette methode permit un excellent contrfile, et il n'y cut aucun des problemes, rencontres habituellement en anesthesiant des patients obeses.