EFFECT OF FLUMAZENIL ON MIDAZOLAM-INDUCED AMNESIA

We have studied the effect of i.v. flumazenil 0.01 mg kg^–1on the amnesia and sedation caused by midazolam 2 mg and 5 mgi.v. in volunteers in order to determine the relationship betweenthe actions of the antagonist on these two effects. Midazolamcaused dose-dependent central neural depression as assessedby critical flicker fusion frequency, and dose-dependent amnesiafor word cards. In subjects given flumazenil 5 min after administrationof midazolam, fusion frequency readings and memory were restoredto levels comparable to those before midazolam administration.These two effects of flumazenil were similar in time courseand extent, suggesting that they share the same mechanism ofaction. Flumazenil given alone had no effect on memory. Thestudy has demonstrated anterograde amnesia following benzodiazepineadministration and antagonism by flumazenil. There was neitherretrograde amnesia nor retrograde antagonism of amnesia.     

POSTOPERATIVE SEIZURES

Two young patients with extensive ulcerative colitis were treated with oral steroids and developed seizures between 36 and 72 h after emergency colectomy. These cases highlight the problem of postoperative seizures, related to previous steroid administration, fluid overload, postoperative hypertension and biochemical abnormalities.     

POSTOPERATIVE LARYNGEAL STRIDOR

A case is described of laryngeal stridor following endotrachealintubation in a baby with an upper respiratory tract infection.Conventional methods of treatment failed, but dramatic improvementfollowed removal of a nasogastric tube. The reasons for thisimprovement, and the cause of the stridor are discussed.     

RESPIRATORY EFFECTS AND AMNESIA AFTER PREMEDICATION WITH MORPHINE OR LORAZEPAM

Lorazepam, a new benzodiazepine, was compared with morphinefor premedication. Ten patients received morphine 10 mg/70 kgi.m. and 10 received lorazepam 4 mg/70 kg i.m. Respiratory effectswere assessed from the change in slope (S) and intercept (B)of the carbon dioxide response line, using a development ofRead's rebreathing method. Morphine depressed S by 47% (P<0.01),but after lorazepam S increased by 27% (P<0.05), neitherdrug altering B significantly. In two volunteers lorazepam wasassessed by both the rebreathing and the steady-state methods;after lorazepam S was smaller by the steady-state than by therebreathing technique. The findings for lorazepam are consistentwith the known effects of sleep on carbon dioxide sensitivity.Amnesia lasting 4–8 h occurred in all patients who receivedlorazepam so that pain and nausea during this period were notrecalled, but no patient who received morphine experienced amnesia.We conclude that lorazepam merits further study, particularlywhere sedation without respiratory depression is needed, asin obstetrics, and where amnesia for uncomfortable proceduresis required.     

NEFOPAM IN POSTOPERATIVE PAIN

Three comparable groups of surgical patients were given nefopam0.2 mg kg^–1 or 0.4 mg kg^–1 or morphine 0.15 mg kg^–1for pain relief after operation. Nefopam 0.4mg kg^–1 wasequi-analgesic with morphine 0.15 mg kg^–1 and producedno obvious cardiovascular or respiratory side-effects.     

ELECTROACUPUNCTURE AND POSTOPERATIVE PAIN

We studied 20 otherwise healthy women undergoing lower abdominalsurgery. Immediately after wound closure, while still anaesthetized,they received either electroacupuncture (EA) or no further treatment.They were allowed pethidine for postoperative analgesia by patientcontrolledinfusion pump. Signs of postoperative distress (pain, nausea,drowsiness) were evaluated after 2 and 6 h by visual analoguescale scores. The group receiving EA consumed half the quantityof pethidine as that used used by the no treatment group. Twopatients in the EA group had no postoperative analgesia in thefirst 2 h. There was no difference in the assessments of postoperativedistress between groups. No patient was aware of having receivedEA or not.     

POSTOPERATIVE EFFECTS OF METHYLPHENIDATE

A double-blind study is described in which the analgesic andanaleptic properties of methylphenidate were investigated in63 patients following surgery. No effect of methylphenidateon postoperative pain was observed. However, methylphenidatereduced sedation up to 30 min after operation, and improvedrespiratory function up to 180 min in patients receiving halothane.No conclusive evidence of improvement in mood was obtained,and occasional undesirable behavioural effects of methylphenidatewere seen.     

EFFECT OF PRE- VS POSTOPERATIVE INGUINAL FIELD BLOCK ON POSTOPERATIVE PAIN AFTER HERNIORRHAPHY

The analgesic effects of an identical inguinal field block,performed before or immediately after inguinal herniorrhaphy,were evaluated in 32 healthy patients in a double-blind, randomizedstudy. During surgery, all patients received a light generalanaesthesia with thiopentone, alfentanil and nitrous oxide inoxygen. After inducation of general anaesthesia, patients wereallocated randomly to receive an inguinal field block with lignocaine,either 15 min before operation or immediately after operation,after closure of the surgical wound, but before the patientswere awake. Pain score on a visual analogue scale and on a verbalscale at rest, during mobilization from supine into sittingposition and during cough was assessed 1, 2, 4, 6, 8 and 24h, and 7 days after operation. No significant differences betweenthe groups were observed in VAS scores or verbal pain scoresduring rest or ambulation at any time. There was no significantdifference in time to first request for morphine or total morphineconsumption. These results do not show pre-emptive analgesiawith a conventional inguinal field block to be of clinical importancecompared with a similar block administered after operation.     

PRE-AND POSTOPERATIVE MINOR DISCOMFORTS

One hundred female patients were interviewed on the days precedingand following the operation of gynaecological examination undera standard form of general anaesthesia, followed by cauteryof the uterine cervix. Certain physical and psychological discomfortswere revealed. Particular complaints concerned the pre-operativepreparation and catheterization, the tedium of the waiting period,and the disturbance associated with being placed next to illpatients. These are discussed with the object of reducing themto a minimum and thereby making the patient's stay in hospitalno more unpleasant than it has to be.     

POSTOPERATIVE ANALGESIA WITH DUROMORPH

The analgesic effects and bioavailability of a slow-releasepreparation of morphine (Duromorph) were studied in 12 patientswith acute postoperative pain. Duromorph produced significantanalgesia within 1–2 h of administration i.m., and therewas a progressive decrease in the mean pain score for at least8 h. None of the patients requested or received additional analgesiawithin 12 h, and the incidence of side-effects was similar tothat associated with i.m. morphine. During the 8-h study, plasmaconcentrations of morphine slowly increased for 3 h, and thengradually declined. After 3 h, concentrations were invariablygreater than those produced by conventional doses of morphinesulphate i.m. The study confirmed that Duromorph was an effectiveanalgesic with a prolonged duration of action, which was suitablefor the management of postoperative pain. Present address: Wyeth Laboratories, Maidenhead, Berks SL6 OPH.     

STUDIES ON POSTOPERATIVE RENAL FUNCTION

Renal function was studied during the early postoperative period in patients undergoing major surgery with considerable blood loss and incomplete substitution. Contrary to expectation, Cin and CPAH were widiin normal limits as early as 2 hours after operation. A moderate antidiuresis persisted for at least 24 hours. The excretion of sodium and potassium were within normal limits.

ZUSAMMENFASSUNG

Während der frühen postoperativen Periode wurde die Nierenfunktion bei Patienten studiert, die grosschirurgischen Eingriffen mit beträchtlichem Blut-verlust und unvollständiger Substitution unterzogen worden waren. Entgegen den Erwartungen blieben die Inulin-Clearance und die PAH-Clearance 2 Stunden nach der Operation innerhalb normaler Grenzen. Eine mässige Anti-diurese blieb für mindestens 24 Stunden bestehen. Die Ausscheidung von Natrium und Kalium hielt sich in normalen Grenzen.     

POSTOPERATIVE HYPOXAEMIA: PREOPERATIVE CONSIDERATIONS

In a group of 31 consecutive patients undergoing major abdominal surgery, severe postoperative arterial hypoxaemia was present In 10 cases (32%). The predictive value of the preoperative expiratory spirogram and the arterial PO₂ have been examined. It is concluded that a history of chronic bronchitis may be of more value than either of these investigations in predicting the likely occurrence of postoperative hypoxaemia.     

EARLY POSTOPERATIVE HYPOXIA DURING TRANSPORT

The incidence of immediate postoperative hypoxaemia followinggeneral anaesthesia was studied using a pulse oximeter in 120ASA category I and II patients during transport to the recoveryroom. Thirty-two percent of those not given oxygen during transportdeveloped desaturation (Sa_O2 less than 90%) in spite of receiving100% oxygen for 5 min before transport. In 14.3% of patientsSa_O2 decreased to less than 85%. None of the patients givenoxygen 2 litre min^–1 via a nasopharyngeal catheter duringtransport exhibited an Sa_O2 less than 90%. The only variablewhich correlated with the development of desaturation was theduration of anaesthesia.     

POSTOPERATIVE ANALGESIA WITH EXTRADURAL CLONIDINE

The analgesic effect of extradural clonidine was evaluated ina double-blind study. In the recovery room, following orthopaedicor perineal surgery 20 ASA I and II patients were allocatedrandomly to two groups. The extradural clonidine (EC) groupreceived clonidine 2 µg kg^–1 in isotonic salinesolution 15 µg ml^–1. The extradural saline (ES)group received the equivalent volume of plain isotonic salinesolution. Pain was evaluated by a visual analogue scale (VAS)at 15-min intervals for the first 2 h and subsequently at 30-minintervals for the following 4 h. Morphine 5 mg was given s.c.when patients complained of pain after extradural saline orclonidine. In the EC group, the mean (SD) maximum pain reliefwas 68.2 (24.1)% of the initial VAS score, but it was only 14.7(25.2)% in the ES group. The mean duration of analgesia, beforeinjection of morphine, was significantly longer in the EC group(210 (87) min) compared with the ES group (45 (27) min) (P <0.001). Drowsiness and moderate hypotension were observed inthe EC group.     

POSTOPERATIVE MUSCLE PAINS AND SUXAMETHONIUM

Two matched groups of patients with Hodgkin's disease undergoinga staging laparotomy received thiopentone, pancuronium bromideor suxamethonium 1.0 mg kg^–1 (group 2) to facilitate trachealintubation. There were no differences in the sites or degreeof postoperative myalgia between the groups. It is concludedthat efforts to reduce the frequency of suxamethonium musclepains in patients having major abdominal operations are notjustified.