Hesham Farag

Epidural ketamine for postoperative analgesia.

T WO factors have increased interest in ketamine for postoperative analgesia. The first was the discovery of the N-Methyl-D-asparrate (NMDA) receptor and its role in central pain processing and spinal cord neural plasticity. 1 Ketamine is one of two clinically useful NMDA receptor antagonists available (the other is dextromethorphan). Ketamine binds non-competitively to the PCI, (phencyclidine) recognition site in the NMDA receptor channel# In addition, interest in the concept of preemptive analgesia makes ketamine a natural candidate for investigation of postoperative pain relief since blockade of the NMDA receptor reduces noxious stimulusinduced allodynia and hyperalgesia. To avoid the well-known psychomimetic effects ofketamine, investigators have focused on the use of smaller doses than are required for general anaesthesia and alternative administration routes for postoperative analgesia. Spinal administration would seem to be especially interesting due to the proximity of the NMDA receptors and the potential for decrease in dose requirements. Reports on intraspinal administration of ketamine include caudal subarachnoid ketamine administration, with or without local anaesthetic agents, lumbar epidural ketamine alone or with local anaesthetic agents and/or opioids and thoracic epidural ketamine with opioids. There are several case reports, comments and uncontrolled studies related to epidural ketamine analgesia 3-s but only a few controlled clinical trials. 6~s Although two observational studies claimed epidural ketamine is effective as a postoperative analgesic s,4 other uncontrolled trials could find little or no postoperative analgesic effect, s Similarly, properly controlled trials using either small (4-8 mg)7or large (30 mg) s,s doses were unable to document effective postoperative epidural analgesia. Epidural ketamine may have an adjuvant effect when added to epidural morphine s or local anaesthetic agents. 9 Wong et al. s administered 10 mg ketamine and 0.5 mg morphine epidurally to patients scheduled for major joint replacement. The kelanainc/morphine combination produced the same degree of analgesia (with movement) as did 2 mg epidural morphine alone. In this study 10% of patients displayed psychomimetic effects requiting treatment. Yanli et aL, 9 in a controlled study, added 25 mg ketamine to a bupivacaine 0.5% with 1;200,000 adrenalin mixture and administered 20 ml epidurally to patients undergoing lower abdominal or orthopaedic surgery. There was a small but significant decrease in onset time to anaesthesia and a slightly higher segmental blockade in the ketamine group. There were no difference between the ketamine group and the non-ketamine group with regard to postoperative analgesic requirements and no adverse psychomimetic effects were seen. There are some claims that epidural ketamine and morphine combinations may have a preemptive analgesic effect. 1~ Choe et al. I1 in a controlled study added a large dose of ketamine (60 mg) to 2 mg epidural morphine and administered the combination before induction of general anaesthesia or 2-3 hr after the start of abdonfinal surgery. The only measure of analgesic efficacy was analgesic duration which was significantly prolonged in the preincisional group. No psychomimetic effects were noted. The comparative roles of the ketamine or the morphine in the possible preemptive effect are unclear. Wong et al. 1~ used a smaller dose of ketamine (20 mg) with 1.5 mg morphine given epidurally before or after incision to patients having knee joint replacement. Both groups received epidural anaesthesia with lidocaine intraoperatively. Postoperatively all patients received epidural ketamme (10 nag) mad morphine (1 mg) in lidocaine every 12 hr and also had additional PCA morphine available for rescue analgesia. Administration of the morphine/ketamine/fidocaine mixture before surgery resulted in less pain and lower PCA requirements than administration 30 rain after surgery had commenced. The preemptive effect of epidural ketamine alone is difficult to evaluate in this study as corn-Thirty-four patients of ASA physical status I or II scheduled for gall bladder surgery were studied in a comparative prospective trial to evaluate the efficacy of epidural and intramuscular ketamine for postoperative pain relief. They were divided randomly into three groups. Group I (11 patients) received 30 mg intramuscular ketamine. Group II (10 patients) and Group III (13 patients) received 10 and 30 mg ketamine in 10 ml saline respectively, through epidural catheters. Pain was evaluated every two hours for the first 24 hours post-operatively by using a linear analogue pain scale from 0-10. Ketamine was given on the patients request and whenever the pain score exceeded three. Ketamine produced analgesia in all patients studied. The reduction of pain score after two and four hours in Group I and III was significant when compared to Group II. Seven patients (54 per cent) in Group III did not require further analgesia after the initial injection. However, following 10 mg epidural ketamine or 30 mg IM ketamine, post-operative pain was more frequent. Four patients who received epidural ketamine complained of transient burning pain in the back during injection. No patient developed respiratory depression, psychic disturbance, cardiovascular instability, bladder dysfunction or neurologic deficit. It is concluded that 30 mg epidural ketamine is a safe and effective method for postoperative analgesia.

Anaesthetic considerations in Klippel-Feil syndrome.

Anaesthesia for the repair of a large occipito cervical encephalomyelocele in a neonate with Kippel-Feil syndrome is described. The fusion of the cervical spines, a short neck, low posterior hair line and Sprengel’s deformity, which were present in this patient, collectively indicated Klippel-Feil syndrome. In addition to the usual stigmata of the syndrome, this patient had a large encephalomyelocele and persistant patent ductus arteriosus complicated by congestive heart failure. Patients with this syndrome are vulnerable to cervical spinal cord injury and are at high risk for neurological injury not only during laryngoscopy and intubation but thereafter. Implications of Kippel-Feil syndrome for the anaesthetist are reviewed and discussed.RésuméL’anesthésie pour la répartation d’une encéphalomyocèle occipito cervicale chez un nouveau-né atteint d’un syndrome Klippel-Feil est décrite. La fusion de la vertèbre cervicale, un cou court, une insertion postérieure basse de la ligne du cuir chevelu et une déformité de Sprengel’s, présent chez ce patient signes le syndrome de Klippel-Feil. En plus des signes habituelles du syndrome ce patient avait un large encéphalomyocèle ainsi qu’un canal artériel persistant compliqué d’une insuffisance cardiaque. Les patients atteints de ce syndrome sont succeptibles de subir des lésions de la colonne cervicale, des lésions neurologiques non seulement lors de la laryngoscopie et de l’intubation mais aussi lors de la procédure. Les implications du syndrome de Klippel-Feil pour les anesthésistes sont discutées.

Epidural morphine for pain relief after lumbar laminectomy.

A prospective randomized trial was conducted to evaluate the effectiveness of epidural morphine for pain relief after lumbar laminectomy. Thirty-three male patients were studied in two groups. At the end of surgery, Group 1 patients (15) received 2 mg morphine in 5 ml saline through an epidural catheter. Doses were repeated on demand. Group 2 patients (18) received 10 mg morphine intramuscularly on request in the postoperative period. Pain was assessed at 2, 6, 12, and 24 hours postoperatively by the linear analog of pain scale. There was significantly greater pain relief in Group 1 than in Group 2 after 2, 6, and 12 hours, respectively. Furthermore, Group 2 received larger doses of morphine than Group 1. There was no respiratory or cardiovascular depression detected in patients in either group. Nine patients in Group 1 and five patients in Group 2 had transient postoperative urinary retention that required catheterization. Only one patient in Group 1 had mild pruritus and three patients in Group 2 had nausea.

Abnormal responses to muscle relaxants in a patient with primary hyperparathyroidism.

Un cas de reponse de sensibilite accrue a la succinylcholine probablement due a une activite reduite en cholinesterase plasmatique

Bilateral hydrothorax and hydromediastinum after a subclavian line insertion

A 28-year-old male patient developed bilateral hydrothorax due to extravasation of fluid into the mediastinum from a subclavian line. The injection of radio-opaque dye through the central venous cannula confirmed spillage into the mediastinum. There was no direct communication between the central venous cannula and the pleural cavities. The hydrothorax appeared to develop as a result of a shift of fluid from the mediastinum into the pleuracavities due to pressure differences in the two compartments. Bilateral chest tubes were inserted, the subclavian cannula was removed and the patient made a good recovery.RésuméUn patient de 28 ans a développé un hydrothorax bilatéral, par extravasation dans le médiastin, suite à l’ insertion de cathéter dans la veine sous-clavière. L’ injection de produit radio-opaque par la canule veineuse centrale a démontré la fuite dans le médiastin. Il n’ y avait aucune communication directe entre la canule veineuse centrale et les cavités pleurales. L’ hydrothorax s’ est développé comme résultat d’ un transfert de liquide du médiastin vers les cavités pleurales à cause des différences depression dans les deux compartiments. Les tubes de drainage thoracique bilatéraux ont été insérés, la canule sous-clavière a été enlevée et le patient fut conduit vers la guérison.

The Effect of Dextran on the Pharmacokinetics of Lignocaine during Epidural Anaesthesia

The clinical significance of combining local anaesthetics with dextran is controversial. Although a number of investigators have found that dextran can prolong the action of local anaesthetics, others have not been able to demonstrate any significant change in the duration of anaesthesia. A study was carried out to investigate the effect of dextran on the pharmacokinetic behaviour of lignocaine during epidural anaesthesia in 20 adult male patients, who were randomly allocated to two treatment groups: group 1 (n = 10) was given lignocaine – dextran; group 2 (n = 10) was given lignocaine – saline. The results of the study demonstrated that the addition of dextran to epidural lignocaine significantly slowed systemic absorption of lignocaine as indicated by a smaller absorption rate constant, a reduced peak plasma concentration (Cmax), a delayed time to reach Cmax, and a smaller area under the concentration – time curve. The observed findings suggest that dextran reduces vascular uptake of lignocaine from epidural space and that it may prolong the duration of action. The significance of these findings on systemic toxicity, dosage and onset of action of lignocaine need to be investigated.

Pharmacokinetic profile of epidural meperidine with and without dextran 70

To evaluate the effect of dextran 70 on the kinetics of epidural meperidine, 10 female patients anesthetized with nitrous oxide and halothane were studied. Meperidine, 1 mg· kg−1, was administered epidurally in either 10 ml dextran 70 in saline solution (group I) or 10 ml saline solution (group II, control subjects). Plasma concentration of meperidine was determined for 10 hours after its administration with GC. Meperidine plasma concentration‐time curves could be best resolved into three exponential terms with a lag time in both groups of patients. The disposition kinetics were described adequately by a three‐compartment model. This study demonstrated that apart from a significantly longer lag time and smaller k10 (apparent first‐order rate constant for elimination of meperidine from the central compartment), the addition of dextran did not alter significantly the kinetic parameters of epidural meperidine.

Anaesthesia with Continuous Thiopentone Infusion, Epidural Morphine and Relaxant

Twenty-three patients undergoing surgery below T.6 dermatome were anaesthetized with epidural morphine 20 mg in 15 ml of saline, thiopentone drip 0·04–0·1 mg/kg/min. and pancuronium 0·1 mg/kg. The patients had satisfactory analgesia intra-operatively. Post-operative analgesia lasted for varying periods ranging from 13 hours to 24 hours and above. The cardiovascular system was stable. Post-epidural morphine complications of respiratory depression (three patients), urinary retention (one patient) and pruritus (one patient) were seen and they were managed successfully.