Ketamine in war/tropical surgery (a final tribute to the racemic mixture)
Introduction
Ketamine is a very useful parenteral anaesthetic agent in situations where muscle relaxation is not necessary, in casualties where the patient is hypovolaemic or for extrication and transport under anaesthesia or sedation, in short minor procedures on spontaneous ventilation, and in uncooperative patients, e.g. children or psychiatric patients.
It is the systemic agent of choice in developing countries with scarce or no anaesthetic equipment and in war surgery where anaesthetic gases and oxygen cannot be used because of the risk of explosion and the handicap of carrying bulky equipment. All anaesthesia in developing countries, except in a few privileged centres, is done by three types of technique, i.e. draw over anaesthesia, spinal/epidural blocks and total intravenous anaesthesia with ketamine [1], [2]. The main advantages of ketamine are the convenient intramuscular route of administration as well as the intravenous one, the lack of hypotension (blood pressure is maintained or increases) and the maintenance of or increase in upper airway tone, which allows the patient to breathe spontaneously.
Drawbacks are increased salivation and lacrimation, an increase in blood pressure and heart rate, increased intracranial and intraocular pressures, and the high incidence of hallucinations and delirium on awakening. Extrapyramidal effects may appear during anaesthesia with normal or excessive dosages.
The drug is contraindicated in intracranial hypertension, head and eye injuries, glaucoma, thyrotoxicosis, ischaemic heart disease, hypertension and alcoholism.
A beneficial bronchodilator action in asthmatics has been reported [3], [4]. Atropine is often used as antisialogue, but it crosses the blood-brain barrier and the placenta, and it worsens the side-effects of ketamine such as the increase in heart rate and the hallucinations; furthermore, by interfering with pupil size it obscures a potential monitoring sign of the effects of the anaesthesia and by raising the temperature provokes unwanted effects, especially in a tropical environment.
Glycopyrrolate, which does not pass the blood-brain barrier or the placenta, is a preferable antisialogue because of its lesser chronotropic and psychotropic effects [5], [6].
Guidelines and dosages for total intravenous anaesthesia with ketamine have been drawn up but have a far too wide range [1], [2], [3], [4].
Section snippets
Materials and methods
This work was performed at Jowhar Hospital, Jowhar, Somalia, during the civil war in the period March–June 1994 and Kitgum Government Hospital, Kitgum, north Uganda, an area often subjected to attacks by antigovernment rebels in the period February–May 1999.
The two areas were similar in that surgery had to be performed with the real risk of rapid evacuation, scarce equipment and variably trained local staff. Sixty-two patients (age range 6 weeks–70 years, median 25 years) were anaesthetised
Technique
Local anaesthetic blocks were given as premedication when applicable to decrease the requirement for early postoperative analgesia. Lignocaine 1% with or without bupivacaine 0.5% infiltration was used in caesarian sections and herniae, lignocaine 1% plus adrenaline 1:200,000 infiltration in haemorrhoids and lateral sphincterotomies, and lignocaine 2% plus adrenaline 1:200,000 in axillary brachial plexus blocks for forearm amputation. Immediately after the local anaesthetic, in order to obtain
Results
Trismus and ventilatory rate were never a problem. No intraoperative or postoperative vomiting was reported. No gross extrapyramidal movements were observed in any patient.
The respiratory rate was maintained within a normally accepted physiological range of 10–18 breaths/min in all patients. In particular, no case of laryngospasm was observed. Awakening from anaesthesia was swift and smooth in the patients who had received diazepam as premedication, all of whom also went peacefully to sleep
Discussion
The reason for starting the maintenance infusion soon after reaching anaesthesia lies in the facility of monitoring the effect of continuous infusion from a known beginning and not from the unpredictable wearing off of the anaesthetic effect of the induction dose [3]. Furthermore, the overlapping effect between the induction bolus and the initial infusion of the maintenance drip would give better analgesia on the incision stimulus. The absence of sophisticated equipment and professionally
Conclusions
Diazepam is indispensable in decreasing the duration of postoperative hallucinations and is known to buffer the cardiovascular response to ketamine and to decrease the required dose of the anaesthetic [3], [4].
Glycopyrrholate, although useful and safer than atropine [5], [6], is not necessary in procedures lasting up to 2 h. Local anaesthesia is useful in decreasing postoperative requirements for analgesia. Limb and lower abdominal surgery can be performed safely without complications related to
Acknowledgements
I am grateful to the Italian Foreign Ministry for supporting me in acquiring the experience through InterSOS and AVSI NGOs, and to my old instructors at the Wythenshawe Hospital Department of Anaesthesia and Intensive Care, whose teaching has stood the test of time.
References (6)
- Boulton TB. Anaesthesia beyond a major medical centre: current techniques with ketamine. Oxford: Blackwell,...
- King M. Dissociative anaesthesia and intravenous analgesia. In: Primary anaesthesia. Oxford: Oxford University Press,...
- Dundee JW, Wyant GM. Ketamine. In: Intravenous anaesthesia, 2nd ed. Edinburgh: Churcill Livingstone, 1988. p....