Dixyrazine premedication for cataract surgery. A comparison with diazepam

Peroral dixyrazine (15–30 mg, n = 50) and diazepam (4–10 mg, n = 50) were used as premedicants for geriatric patients having cataract surgery under regional block. Compared to the diazepam patients, a larger number of the dixyrazine medicated patients appeared anxious, and there was a statistically significant difference between the groups, when summing up changes in anxiety throughout the study period. The dixyrazine patients needed more frequent supplementation with intravenous sedative drugs, compared with their diazepam counterparts. Peroral dixyrazine is an applicable choice for calm patients, when only slight sedation, or avoidance of somnolence are required.     

Forum Aminophylline reversal of diazepam sedation

A double-blind randomised study was performed to investigate whether aminophylline reversed the sedative effect of diazepam. Thirty-two patients undergoing genito-urinary surgery with spinal or topical anaesthesia were given diazepam to maintain a state of deep sedation. Postoperatively patients received either aminophylline (60-120 mg) or physiological saline intravenously. The aminophylline group showed a rapid reversal of sedation, which persisted throughout the observation period of 2 hours. No such effect was seen in the patients who received saline and the difference was still obvious after 2 hours. It is concluded that aminophylline is a potent antagonist to the sedative effect of diazepam.     

Intravenous sedation for cataract surgery

Fifty-five unpremedicated outpatients scheduled for cataract surgery were randomly allocated to receive either a fixed dose of nalbuphine and methohexitone or fentanyl and diazepam administered in a dose adjusted to produce the required sedative effect. Statistical analysis revealed no difference between groups with regard to immediate side effects, intra-ocular pressure or postoperative nausea or vomiting. Recovery time from administration of the sedative until compliance with simple commands was significantly longer in the nalbuphine/morphine group (89 vs 196 seconds) but this was not felt to be of clinical importance. This combination was better in terms of sedation at the time of insertion of the nerve blocks, lack of recall of insertion of the nerve block, incidence of intra-operative complications, surgeon's assessment of operating conditions and patient acceptability. This fixed dose by weight drug combination for intravenous sedation should be applied widely.     

Intravenous regional analgesia with prilocaine for foot surgery

Intravenous regional analgesia for foot surgery with an ankle tourniquet was used for 48 cases. Prilocaine 0.5% 3 mg/kg body weight was injected either quickly over about 2 minutes or slowly over about 5 minutes. The tourniquet was inflated either to occlusion pressure plus 100 mmHg or to occlusion pressure plus 200 mmHg. Plasma prilocaine levels were measured while the tourniquet remained inflated and after release of the tourniquet. All four techniques resulted in a low incidence and magnitude of prilocaine leak and low prilocaine plasma levels after tourniquet release. The data suggest that slow injection with the high tourniquet inflation pressure is better, although the differences in leakage with an intact tourniquet were not statistically significant. Excellent analgesia was achieved in over 90% of patients and there were no complete failures. No dangerously high prilocaine plasma levels were produced and no serious side effects observed.     

Intravenous regional analgesia – a new modification

A modification of the standard intravenous regional analgesia technique is described whereby excess local anaesthetic solution is removed from the veins of the isolated arm once analgesia has been established. This simple procedure was shown to reduce the incidence of oozing at the site of operation without affecting the quality of analgesia. Measurement of the quantity of local anaesthetic agent removed from the isolated arm 15 min after injection revealed that the amounts removed were small, indicating rapid uptake and binding in the tissues. This would imply that removal of excess local anaesthetic agent from the isolated arm after 15 min does not confer added safety as regards reducing the risk of leakage of agent into the general circulation in the event of cuff failure.     

Pain and clinical thrombophlebitis following intravenous diazepam and lorazepam

Eighty-seven per cent of surgical patients receiving undiluted diazepam experienced pain on injection while 6-16%, depending on the dose, manifested evidence of clinical thrombophlebitis. This was improved when diazepam, 10 mg, was diluted to 20-40 ml with intravenous solution. In contrast, lorazepam appeared to have minimal irritative or injurious effects on veins whether undiluted or diluted. In view of these results and clinical studies reporting a higher patient acceptance of lorazepam than diazepam, lorazepam may be a superior drug for use in anaesthesia.     

Intravenous regional analgesia using bupivacaine

A double-blind comparison of bupivacaine and lignocaine for intravenous regional analgesia (Bier's block) was carried out in seventy-two patients presenting for upper limb surgery. Thirty-eight patients received lignocaine and thirty-four received bupivacaine. Onset of analgesia and recovery times were similar for the two drugs. The degree of both analgesia and muscle relaxation was significantly better in the bupivacaine group. Adverse effects were seen only in patients who had received lignocaine and these were unrelated to the tourniquet time.     

Intravenous regional analgesia using bupivacaine

Intravenous regional analgesia using bupivacaine (Marcain) was employed as the anaesthetic technique in a series of 50 cases undergoing a variety of surgical procedures on the upper limb. A short pilot study was undertaken to determine the optimal dosage and concentration of bupivacaine. This was found to be 1-5 mg/kg in 0-2% concentration and proved suitable for all patients regardless of age or physical condition. The use of bupivacaine produced highly successful results in 98% of cases. Onset of analgesia was very rapid (3-5 minutes) and profound muscular relaxation occurred in approximately half of the cases. The degree of muscle relaxation was, however, always adequate for the successful reduction of fractures. Only one patient exhibited an adverse reaction to the dose of bupivacaine used and this was limited to a brief period of slight drowsiness. The results of this series suggest that bupivacaine may provide advantages over previously used local analgesic agents for intravenous regional analgesia and that it may be the agent of choice for this useful technique.     

Ketamine sequelae

The ability of a number of drugs to abolish the emergence delirium and unpleasant dreams which follow anaesthesia induced with 2 mg/kg ketamine was studied. These included three benzodiazepines, droperidol and 'neurolept' combinations and four commonly-used premedicants. When given intravenously 10 min before induction of anaesthesia flunitrazepam and lorazepam gave best results. In a subsequent study, these two benzodiazepines and diazepam were given intravenously 30-40 min before induction of anaesthesia. There was no doubt that 4 mg lorazepam gave the greatest protection and is worthy of further study in this respect.     

Postoperative analgesia with ketamine and pethidine

A double-blind trial compared ketamine with pethidine, pethidine alone at two dose levels and a placebo, in patients with postoperative pain. By assessment of pain intensity, observed relief and side-effects, the active drugs were clearly distinguishable from the placebo. With the doses used, however, the combination of ketamine with pethidine showed no advantage over pethidine alone.     

Local complications following intravenous benzodiazepines in the dorsum of the hand. A comparison between midazolam and Diazemuls in sedation for dentistry

Two hundred patients requiring sedation for minor oral surgery were randomly allocated to receive either midazolam or diazepam as Diazemuls intravenously through a 23-gauge indwelling needle in the dorsum of the hand. The site of injection was inspected at 7 days and 14 days post injection and assessed for pain, tenderness, redness, induration, painless thrombosis, and thrombophlebitis. The mean dose administered was 0.119 mg/kg of midazolam and 0.298 mg/kg of Diazemuls. At 7 days there was no significant difference in venous complications. At the 14 day follow up, the midazolam group had a significantly greater incidence of tenderness and redness (p less than 0.001 and p less than 0.05 respectively using Chi squared test). The incidence of thrombophlebitis in the midazolam group was 2% at 7 days and 1% at 14 days, the corresponding figures in those given Diazemuls being none and 1% respectively. We conclude that the dorsum of the hand is a satisfactory site of injection for administration of these drugs. The higher incidence of minor complications at 14 days following midazolam was offset by its more reliable amnesic properties.     

Postoperative analgesia

Postoperative analgesia both by drugs and regional techniques is reviewed. In the United Kingdom in the last 25 years or more there has been little advance on either front. Some marginal improvement in regard to drugs might be brought about by better education of both doctors and nurses and better patient contact. Extradural analgesia and intercostal block do not offer a complete solution, though a judicious increase in the use certainly of the former might be beneficial. The problem awaits a radical new approach.