Core and thenar skin temperature variation during prolonged abdominal surgery: comparison of two sites of active forced air warming.

BACKGROUND: This study was designed to compare the efficacy of two different sites of active forced air warming, upper body or lower body, to maintain normothermia; and their respective effect on thenar skin temperature in relation to the accelerographic monitoring of neuromuscular blockade during long-lasting abdominal surgery. METHODS: Twenty-six patients were randomised into two groups: upper body, (n=13) and lower body, (n=13), for intraoperative forced air warming. General anaesthesia was induced with thiopentone, sufentanil, and maintained with a mixture of N2O/O2/isoflurane. Pancuronium, 0.1 mg x kg(-1) was used to facilitate tracheal intubation. Reinjection doses of 0.01 mg x kg(-1) were administered once 25% recovery of first twitch height of train-of-four stimulation had occurred, or if surgical relaxation was estimated as inadequate by the surgeon. Thenar skin temperature and core temperature were monitored continuously. RESULTS: A similar trend for core temperature profile was observed in both groups. After an initial mild hypothermia, normothermia was reached progressively. Normothermia was obtained faster with lower body forced air warming than with upper body (2 h versus 3 h), P<0.05. Thenar skin temperature significantly increased during the first 90 min of surgery. This rise was significantly higher in the upper body group at 40 min and 60 min, P=0.03 and P=0.01, respectively. Stabilisation of thenar skin temperature occurred after 2 h without any further significant difference between groups. Muscle relaxant requirements were not significantly different between the groups. CONCLUSION: This study suggests that during long-lasting abdominal surgery, normothermia is maintained after 2-3 h by either upper or lower body active forced air warming. After an initial post-induction mild hypothermia, normothermia was achieved faster with lower body surface warming. Thenar skin temperature trend showed that it remained above 32 degrees C during most of the procedure in both groups.

The lateral approach to the sciatic nerve at the popliteal fossa: one or two injections?

UNLABELLED: It has not been proven whether one or multiple nerve stimulations and injections provide a higher rate of complete sensory block in both major sciatic nerve sensory distributions below the knee when a popliteal sciatic nerve block is performed using the lateral approach. This prospective, randomized, single-blinded study compared the success rate of the sciatic nerve block using this approach when one or both major components of this nerve (i.e., tibial nerve and common peroneal nerves) are stimulated in 50 patients undergoing foot or ankle surgery. In Group 1 STIM, 24 patients received a single injection of 20 mL of a mixture of 2% lidocaine and 0.5% bupivacaine with 1:200,000 epinephrine after foot inversion had been elicited. In Group 2 STIM (n = 26), 10 mL of the same solution was injected after stimulation of each sciatic nerve component. For patients with complete sensory motor block, there was no difference in onset between groups. However, Group 2 STIM showed a greater success rate compared with the Group 1 STIM (2 STIM: 88% vs 1 STIM :54%; P = 0.007). When two stimulations were used, the onset time of anesthesia in the cutaneous distribution of the common peroneal nerves was shorter than in the tibial nerve (17.5 vs 30 min; P < 0.0001). We conclude that a two-stimulation technique provides a better success rate than a single-injection technique when a popliteal sciatic nerve block is performed using the lateral approach with 20 mL of local anesthetic. IMPLICATIONS: A better success rate is achieved with a double stimulation technique than with a single injection for the sciatic nerve block via the lateral approach at the popliteal fossa when 20 mL of local anesthetics is used.

Comparison between conventional axillary block and a new approach at the midhumeral level.

We undertook this prospective, randomized study to compare the success rate, time spent performing the blocks, onset time of surgical anesthesia, presence of complete motor blockade, and lidocaine plasma concentrations between conventional axillary block and a new approach at the midhumeral level. Both techniques were performed using a peripheral nerve stimulator. Two nerves were located at the axillary crease, whereas four nerves were located at the midhumeral level. Sixty patients undergoing upper limb surgery were assigned to one of the two techniques. The sensory block was evaluated before surgery for all of the distributions of the four major nerves of the upper extremity. A subset of patients had lidocaine plasma concentrations determined. Times to perform the blocks, mean maximum plasma lidocaine concentration, and time to peak concentration were not different between groups. The success rate of the block, as well as the incidence of complete motor blockade, was greater with the midhumeral approach compared with the axillary approach. However, the onset time to complete anesthesia of the upper extremity was shorter in the axillary approach. For brachial plexus anesthesia, we conclude that the midhumeral approach provided a greater success rate than the traditional axillary approach.

Hemodynamic effects of continuous spinal anesthesia: a comparative study between low and high doses of bupivacaine.

BACKGROUND AND OBJECTIVE: Arterial hypotension is a major side effect of spinal anesthesia. Continuous spinal anesthesia may allow titration of the amount of local anesthetic to obtain a level that is appropriate for the surgical procedure. METHODS: This study compared the hemodynamic effects and the quality of analgesia of spinal anesthesia performed with 3 ml of either 0.125% (n = 12) or 0.5% (n = 13) plain bupivacaine in 25 elderly patients undergoing orthopedic surgery. RESULTS: The initial dose's duration of action (time elapsed between the end of injection and the first patient's complaint of pain during surgery) was shorter in the group receiving 3 ml of 0.125% plain bupivacaine than in the group receiving 0.5% plain bupivacaine: 80 +/- 31 minutes versus 114 +/- 37 minutes, respectively (mean +/- SD; p less than 0.05). In 6 (50%) of 12 patients of the 0.125% group and in 2 (15%) of 13 of the 0.5% group, analgesia became insufficient during the surgical procedure, necessitating injection of an additional 1 ml (top-up) of the previous solution. All subjects obtained good anesthesia for the entire procedure. The mean dose of bupivacaine necessary for the procedure was significantly lower in the 0.125% group (4.8 +/- 1.3 mg) compared with the 0.5% group (16.1 +/- 3 mg). For a similar maximal upper level of analgesia (T4-T12 in the 0.125% group versus T2-T10 in the 0.5% group), the decrease in systolic arterial pressure was more pronounced in the 0.5% group than in the 0.125% group during the period 15-40 minutes after induction of spinal anesthesia (p less than 0.05%). The mean dose of ephedrine was threefold larger in the 0.5% group than in the 0.125% group. CONCLUSION: Continuous spinal anesthesia with small amounts of 0.125% plain bupivacaine produces effective anesthesia for orthopedic procedures in elderly patients with minimal hemodynamic changes.

Respiratory effects of epidural sufentanil after cesarean section.

The ventilatory response to CO2 was measured to evaluate the degree of respiratory depression after epidural sufentanil. After cesarean section performed with bupivacaine epidural anesthesia, 14 patients received either 30 micrograms (n = 7) or 50 micrograms (n = 7) of epidural sufentanil. Respiratory measurements were made before and 15, 45, and 120 min after sufentanil injection. The presence and severity of sedation and other nonrespiratory side effects were evaluated throughout the study. Plasma sufentanil assays were performed on blood samples obtained at frequent intervals during the first 2 h. Although changes in resting ventilation did not occur, both sufentanil doses depressed the ventilatory response to CO2. After sufentanil 30 micrograms, the slope of the CO2 response curve decreased significantly at 45 and 120 min (control value, 2.33 +/- 0.3 L.min-1.mm Hg-1 [mean +/- SEM] vs 1.61 +/- 0.24 and 1.72 +/- 0.15, respectively, P less than 0.05). After sufentanil 50 micrograms, significant decreases occurred at 15 and 45 min (control value, 2.84 +/- 0.71 vs 1.81 +/- 0.48 and 1.48 +/- 0.31 L.min-1.mm Hg-1, respectively). The mean maximal decrease in the slope occurred at 45 min and was more pronounced after 50 micrograms (-42.3% +/- 7.4%) than after 30 micrograms (-27.4% +/- 9.9%). Analgesia was similar in both groups. Side effects, particularly sedation, were more severe with the 50-micrograms dose. We conclude that 30 micrograms of epidural sufentanil is preferable to the higher dose with regard to both respiratory and nonrespiratory side effects. Even with the lower dose, monitoring of ventilation is advisable for a minimum of 2 h.

Temperature monitoring during epidural anesthesia for cesarean delivery.

Tympanic, rectal, and axillary temperatures were measured and compared in 12 ASA Physical Status I and II parturients during epidural anesthesia for cesarean delivery. Measurements were performed before (T0) and at 15 (T1), 30 (T2), 45 (T3), and 60 (T4) minutes after epidural anesthesia. At birth, rectal neonatal and maternal temperatures were measured. Before anesthesia, maternal tympanic and rectal temperatures were statistically not different but higher than axillary temperature (difference, 0.5 degrees C). During anesthesia, all three maternal temperatures decreased. There was no difference for the first 45 minutes between rectal and tympanic membrane temperatures and no difference between tympanic and axillary temperatures after 30 minutes. The difference between rectal and tympanic temperatures became significant at T4. During the same period, the difference between axillary and tympanic temperatures became nonsignificant at T3 and T4. At birth, both maternal and newborn rectal temperatures were similar at 36.0 +/- 0.2 degrees C. The relative hypothermia observed in the newborns at birth after regional anesthesia was well correlated with the decrease in maternal temperature. A decrease in tympanic temperature of 1.4 degrees C developed during the course of epidural anesthesia for cesarean delivery. This decrease was underestimated by the measurement of rectal and axillary temperatures.

[Postoperative analgesia after cesarean section: sublingual buprenorphine versus subcutaneous morphine]. / Analgésie postopératoire après césarienne: buprénorphine sublinguale versus morphine sous-cutanée.

This study aimed to compare the efficacy and side-effects of sublingual buprenorphine, a synthetic opioid agonist antagonist, with those of subcutaneous morphine. Fifty ASA class 1 patients were included in the study after having given their informed consent. Caesarean section was carried out under epidural block with 0.5% bupivacaine; no opioids were used during the procedure. The first dose of opioid was given 2 h after the first dose of bupivacaine. Patients were randomly given either 10 mg morphine (n = 25) or 0.4 mg buprenorphine (n = 25), followed by the same dose every 6 h for 36 h. When analgesia was insufficient, tablets containing dextropropoxyphene and paracetamol were given. No attempt was made to blind the study to the patient, but the investigator assessing pain was unaware of the drug given to the patient. Pain intensity was assessed before, and 2 h after each dose of opioid with a 100 mm visual scale, as well as systolic, diastolic and mean arterial blood pressures, heart and breathing rates, and SpO2. Side-effects (pruritus, nausea, vomiting, drowsiness) were also noted. In 2 patients in each group, the protocol was stopped before the 36th h, but after the fourth dose, either because of side-effects, or at the patient's request. Results were similar in both groups of patients, whether for degree of pain relief, or physiological effects. There was no clinically detectable respiratory depression. Duration and intensity of episodes of arterial oxygen desaturation, and the incidence of nausea, were similar in the 2 groups; pruritus was more common in the morphine group.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkalinization of epidural 0.5% bupivacaine for cesarean section.

Controversial results have been published in the literature concerning the efficacy of alkalinization of solutions of local anesthetics to shorten the time to onset of sensory block. Fifty-two parturients scheduled for cesarean section at term under epidural anesthesia were randomly allocated to one of four groups: group 1, 0.5% plain bupivacaine (pH = 5.38 +/- 0.05); group 2, 0.5% bupivacaine pH-adjusted with 1.4% sodium bicarbonate (pH = 6.87 +/- 0.01); group 3, 0.5% bupivacaine with 1:200,000 epinephrine (pH = 4.80 +/- 0.04); and group 4, 0.5% bupivacaine pH-adjusted with 1:200,000 epinephrine (pH = 6.68 +/- 0.01). The time to onset of the sensory block was evaluated using a nerve stimulator technique. Motor blockade was assessed using Bromage's scale. No differences in the characteristics of the onset of the sensory block were observed with epinephrine-containing solutions nor with pH-adjusted local anesthetics. The maximal degree of motor blockade was not significantly different in the four groups. We conclude that alkalinization of a 0.5% bupivacaine solution is not an effective way to shorten the latency of epidural block for cesarean section.

[Ambulatory practice of breast surgery]. / Pratique ambulatoire de la chirurgie du sein.

Breast surgery on an outpatient basis has been indicated by control trials to investigate the efficacy of mass screening with single-view mammography in reducing mortality. These trials have also increased surgery in benign breast pathology. Sixty patients were investigated and forty-seven answered a questionnaire. Ninety-two per cent of those who answered were satisfied with this short-stay hospitalisation and ninety-four per cent would be willing to do the same again if necessary. Seventeen per cent of the patients would have preferred to stay in the hospital the night after surgery. All patients preferred to be admitted the morning of surgery. Forty-three per cent of patients had local or regional anaesthesia and were satisfied to know the diagnosis during surgery. All personnel of the health service concerned find a benefit of this outpatient arrangement, that is, both patients and hospital authorities. This has been found to be a cost-saving measure as well as an effective way of diagnosing and treating benign breast tumors.

Ventilatory response to CO2 following axillary blockade with bupivacaine.

The systemic effect of bupivacaine on the control of ventilation was studied in eight ASA I (six male, two female) unpremedicated healthy subjects aged 30-55 yr (mean 43.5 yr) and weighing 59-82 kg (mean 69 kg) after axillary blockade with bupivacaine 0.5% without epinephrine, 3 mg/kg. The slope of the ventilatory response to CO2 was significantly increased (P less than 0.05) from its control value (1.77 +/- 1.03 l X min-1 X mmHg-1 [mean +/- SD]) 30 min (+19 +/- 32%) and 60 min (+32 +/- 37%) after axillary blockade, while plasma bupivacaine levels were 1.65 +/- 0.82 and 1.40 +/- 0.60 micrograms/ml, respectively. The correlation between individual plasma bupivacaine levels and the changes in the slope of the ventilatory response to CO2 was significant (r = 0.57, n = 16, P less than 0.05). Resting minute ventilation and end-tidal CO2 values did not change significantly. These results suggest that bupivacaine has a systemic stimulating effect on the ventilatory control mechanisms.

Ventilatory response to CO2 following intravenous and epidural lidocaine.

The authors determined the effects of intravenous infusion and epidural administration of lidocaine on the control of ventilation in two groups of eight healthy unpremedicated subjects. In the intravenous group, an injection of 1.5 mg/kg lidocaine was followed by an infusion at a rate of 60 micrograms X kg-1 X min-1 for 30 min. The slope of the ventilatory response to CO2 was significantly increased (P less than 0.05) from its control value (2.65 +/- 1.22 1 X min-1 X mmHg-1 [mean +/- SD]) at the end of the infusion (58%), while plasma lidocaine level was at 3.14 +/- 0.82 microgram/ml. The correlation between individual plasma lidocaine levels and the changes in the slope of the ventilatory response to CO2 was significant (r = 0.58, n = 24, P less than 0.01). In the epidural group, after the administration of 5 mg/kg of lidocaine, the slope of the ventilatory response to CO2 increased significantly (P less than 0.05) from its control value (1.52 +/- 0.75 1 X min-1 X mmHg-1) at 15 (+22%) and 25 min (+42%), while plasma lidocaine levels were at 1.79 +/- 0.42 and 2.22 +/- 0.47 microgram/ml, respectively. In both groups, resting minute ventilation and end-tidal CO2 values remained unchanged. These results suggest that epidural lidocaine has a stimulating effect on the ventilatory control mechanisms that results from the systemic effect of the drug.

Tissue extraction of amiodarone and N-desethylamiodarone in man after a single oral dose.

The hepatic extraction of amiodarone and N-desethylamiodarone has been investigated in seven patients following catheterization of the portal and hepatic veins under general anaesthesia. Amiodarone (600 mg) was administered orally 4 h before regional blood sampling. Concentrations of amiodarone and N-desethylamiodarone, determined by h.p.l.c., were about twice as high in the portal vein compared with those in the hepatic vein, the calculated hepatic extraction ratios of both compounds being 0.39 +/- 0.07 and 0.34 +/- 0.03, respectively. The presence of N-desethylamiodarone in the portal vein in higher concentrations than in the hepatic vein strongly suggests that N-dealkylation of amiodarone occurs in the gut wall or lumen, a finding which might account for the low and highly variable intersubject amiodarone bioavailability.

[Post-operative respiratory function after subcutaneous and epidural morphine analgesia (author's transl)]. / Fonction respiratoire post-opératoire après analgésie morphinique par voise sous-cutanée et péridurale.

In 20 elderly patients who underwent cholecystectomy post-operative analgesia was obtained with morphine given either subcutaneously (n = 10) or epidurally (n = 10). Both groups were comparable as to age and pre-operative respiratory function values. On the first post-operative day, vital capacity, forced expiratory volume in one second and and paO2 were significantly higher in the epidural morphine group (respectively 70 +/- 6 p. cent and 68 +/- 6 p. cent of pre-operative values, and 74 +/- 3 mmHg) (mean +/- s.e.m.) than in the subcutaneous morphine group, where the corresponding figures were 52 +/- 4 p. cent, 48 +/- 5 p. cent and 63 +/- 2 mmHg respectively. PaCO2 was unchanged in both groups. These data indicate that epidural morphine analgesia to some extent reduces the post-operative respiratory dysfunction observed after abdominal surgery.