Unilateral spinal anaesthesia for outpatient surgery: a comparison between hyperbaric bupivacaine and bupivacaine-clonidine combination.

BACKGROUND: Low-dose hyperbaric bupivacaine has been used to produce unilateral spinal anaesthesia for outpatient surgery. Unilateral spinal anaesthesia is associated with reduction of hypotension, faster recovery and increased patient satisfaction. Small doses of clonidine have shown effectiveness in intensifying spinal anaesthesia. We investigated the effect of adding 15 microg of clonidine to 5 mg hyperbaric bupivacaine on unilaterality. METHODS: Sixty patients undergoing outpatient knee arthroscopy were randomly allocated to receive either 1.2 ml (6 mg) of hyperbaric bupivacaine or a 1.2 ml solution containing 1.0 ml (5 mg) hyperbaric bupivacaine, 0.1 ml (75 microg) clonidine and 0.1 ml sterile water. The motor block was assessed by a modified Bromage scale and the sensory block by a pinprick. RESULTS: There was a significant difference in the spread of anaesthesia between the operated and contralateral sides in both groups. Seventy-seven per cent of the blocks were unilateral in group B and 73% in group B-C. There was no significant difference between the groups, in unilaterality. The motor block was prolonged in group B-C but it did not affect home-readiness. Patients receiving clonidine needed more vasopressors. There was a significant difference in blood pressures between the groups, being lower in group B-C after 1 h 45 min. CONCLUSION: Using 5 mg hyperbaric bupivacaine with 15 microg of clonidine, the unilaterality can be achieved and spinal anaesthesia intensified without affecting home-readiness. More vasopressors are needed in the beginning, but after the surgery patients experienced less pain.

Spinal anesthesia with hypobaric bupivacaine for knee arthroscopies: effect of posture on motor block.

BACKGROUND AND OBJECTIVES: The clinical impact of patient positioning on motor block during unilateral spinal anesthesia was the focus of our study. It was assumed that a 45 degrees rotation toward the prone position would minimize blocking the ventral motor roots compared with using the conventional lateral decubitus position. METHODS: Spinal anesthesia with 3.4 mL of hypobaric 0.18% bupivacaine via a 27-gauge Whitacre needle was administered to 70 patients undergoing knee arthroscopy. The patients were kept either in a lateral decubitus position (group I) or rotated approximately 45 degrees toward the prone position (group II). No prophylactic vasopressors or infusions were used. The intensity of motor block (modified Bromage scale) was assessed for both the operative and the contralateral side. RESULTS: The patients in group I had a slightly more pronounced motor block, but statistical significance could be shown only 20 minutes following the block. There was no statistical difference between the groups in the need of additional analgesics during the operation. None of the patients needed general anesthesia. The hemodynamics were stable and none of the patients developed postspinal headache or backache. CONCLUSIONS: The position of the patient affects the spread of the spinal anesthesia when clearly hypobaric agents are used. However, this small modification in positioning of the patient did not lead to a clinically meaningful difference in the spread of the motor block.

A low dose of plain or hyperbaric bupivacaine for unilateral spinal anesthesia.

BACKGROUND AND OBJECTIVES: Unilateral spinal anesthesia may be advantageous, especially in the outpatient setting. A low dose of anesthetic solution, pencil-point needle, low speed of intrathecal injection, and a lateral position have been reported to facilitate the production of unilateral distribution of spinal anesthesia. We compared the effects of plain and hyperbaric bupivacaine in attempting to obtain a unilateral spinal anesthesia for patients undergoing outpatient knee arthroscopy. METHODS: Sixty patients were randomly allocated to 2 groups to receive either 1.2 mL (6 mg) of plain 0.5% bupivacaine (group 1; n = 30) or 1.2 mL (6 mg) of hyperbaric 0.5% bupivacaine in 8% glucose (group 2; n = 30). Drugs were administered at the L2-3 interspace with the patient in the lateral position. Patients remained in this position for 20 minutes before being turned supine for the operation. Spinal block was assessed by pinprick and modified Bromage scale and compared between the operated and nonoperated sides. RESULTS: There was a significant difference between the operated and nonoperated side in both groups at all testing times, but a more unilateral spinal block was achieved with hyperbaric bupivacaine. Unilateral motor and sensory block was observed in 25 patients in group 2 (83%) and in 11 patients in group 1 (37%) (P <.01). The hemodynamic changes were minimal, since hypotension occurred only in 5.0% and bradycardia in 1.7% of all patients. CONCLUSION: In conclusion, the spinal anesthesia in both groups are suitable alternatives for adult outpatient knee arthroscopies, but hyperbaric bupivacaine provides us with a more unilateral spinal block.

The use of bupivacaine and fentanyl for spinal anesthesia for urologic surgery.

We evaluated the effect of 25 microg of fentanyl added to bupivacaine on sensory and motor block. By using a double-blinded study design, 80 men undergoing urologic surgery were randomized into the following four groups: Group I, bupivacaine 10 mg; Group II, bupivacaine 10 mg + fentanyl 25 microg; Group III, bupivacaine 7.5 mg + fentanyl 25 microg; Group IV, bupivacaine 5 mg + fentanyl 25 microg. The final volume of intrathecal injectate was adjusted to 2. 5 mL with sterile distilled water. Spinal anesthesia was administered with the 27-gauge Whitacre needle at the L2-3 interspace with the patient in the sitting position. Neural block was assessed by using pinprick and a modified Bromage scale. The degree of motor block was more profound in Group II compared with Group I at the end of operation. In Group IV, there was no motor block at the end of operation in any of the patients. The median level of the upper limit of the sensory block was higher than T(7) in all groups before the start of surgery. The addition of 25 microg of fentanyl to 5 mg of bupivacaine resulted in short-acting motor block. When 25 microg of fentanyl was added to 10 mg of bupivacaine, it increased the intensity and duration of motor block. Only 5 (6. 3%) of the patients needed supplemental analgesia during the operation. ¿abs¿

Low-dose bupivacaine: a comparison of hypobaric and near isobaric solutions for arthroscopic surgery of the knee.

The results of studies on the effect of volume, concentration or total dose of local anaesthetic on the spread of spinal anaesthesia are inconclusive. Most support the assumption that the total dosage is more important than the volume. We compared low-dose bupivacaine (6 mg) in 0.5% and 0.18% solutions as sole anaesthetic to achieve predominantly unilateral spinal anaesthesia for knee arthroscopy. Sixty patients were randomly allocated to two groups to receive either 1.2 ml 0.5% bupivacaine (6 mg) (n = 30) or 3.4 ml 0.18% hypobaric bupivacaine (6.1 mg) (n = 30). Drugs were administered at the L3-4 interspace with the patient in the lateral position. Patients remained in this position for 20 min before being turned supine for the operation. Spinal block was assessed by pinprick and modified Bromage scale and compared between the operated and nonoperated sides. No significant changes were found in the spread or duration of sensory or motor block (p > 0.05). The haemodynamic changes were also similar between the groups. The same pinprick level of analgesia, degree of motor block and duration of spinal anaesthesia was obtained with bupivacaine (6 mg) in low (1.2 ml) or high (3.4 ml) volumes.

Restricted spinal anaesthesia for ambulatory surgery: a pilot study.

The increasing use of ambulatory surgery requires methods of anaesthesia that allow patients to be discharged soon after the operation is completed. Spinal anaesthesia is usually simple and quick, and the incidence of post-spinal headache has been reduced by using non-cutting small-gauge needles. Limiting the spread of spinal anaesthesia, as long as it still provides analgesia for surgery, should reduce the haemodynamic effects and speed recovery. Restricted spinal anaesthesia, intended to be unilateral using 0.18% hypobaric bupivacaine via a 25G or 27G Whitacre unidirectional needle, was compared with epidural anaesthesia (using a mixture of lignocaine and prilocaine) in 64 matched-pair patients undergoing ambulatory arthroscopy. Motor blockade, assessed for the specific myotomes L2 to S1, was significantly more unilateral in the spinal group. Two patients in the spinal group and nine patients in the epidural group were treated for hypotension (P < 0.05). One patient in the spinal group developed a post-spinal headache. One patient in the epidural group rated the anaesthesia poor.

A low-dose hypobaric bupivacaine spinal anesthesia for knee arthroscopies.

BACKGROUND AND OBJECTIVES: Ambulatory surgery requires anesthesia methods that allow rapid recovery and safe discharge of the patient. Spinal anesthesia is easy and quick to perform, and the use of noncutting small gauge needles reduces the occurrence of postdural puncture headache. For minimal hemodynamic consequences and faster recovery and discharge it would be optimal to limit the spread of spinal anesthesia only to the area which is necessary for surgery. In this study, the possibility in achieving unilateral spinal anesthesia with 0.18% hypobaric bupivacaine was studied. METHODS: Spinal anesthesia with 3.4 mL of hypobaric 0.18% bupivacaine (6.12 mg), without any intravenous infusion or prophylactic vasopressors, was administered with 27-gauge Whitacre unidirectional needle to 70 ASA I and II patients undergoing knee arthroscopies. The patients were allocated randomly to be kept either 20 (group I) or 30 (group II) minutes in the lateral position operation side uppermost. Sensory and motor block (pinprick/modified Bromage scale) were compared between the operation and the contralateral side. RESULTS: The motor and sensory block between operation and contralateral sides were significantly different at all testing times in both groups (P < .001, Mann-Whitney U test). The motor block was completely unilateral in 14 patients (39%) in group I and in 22 patients (65%) in group II. The hemodynamics were stable in all 70 patients. CONCLUSIONS: Approximately three and a half milliliters hypobaric 0.18% bupivacaine (6.12 mg) provides a predominantly unilateral spinal block. Thirty minutes spent in the lateral position does not provide benefits over 20 minutes. The main advantages of our method are the hemodynamic stability and the patient satisfaction.

Static-charge-sensitive bed ballistocardiography in cardiovascular monitoring.

We evaluated the autonomic influence on balistocardiograms recorded by a static-charge-sensitive bed for cardiovascular monitoring in nine healthy males (20-44 years) and its clinical use in 11 patients who underwent coronary bypass surgery (51-59 years). The ballistocardiogram displayed a distorted low amplitude from the empty beating heart during bypass surgery, impaired by a reduced effective transmural filling pressure of the heart, and returned to its pre-bypass level when the preload to the heart and its pumping was restored. Submaximal dynamic exercise and isoprenaline caused the heart rate to rise to 90-114 beats min-1, and increased the ballistocardiographic amplitude threefold, while at the same time shortening the interval between the R-wave of the electrocardiogram and the peak of the ballistocardiographic waveform (P < 0.01). In contrast, atropine accelerated the heart rate to 96 beats min-1, but did not significantly change the amplitude or temporal pattern of the ballistocardiogram. Thus, the ballistocardiogram reflects sympathetic and parasympathetic influence on the contractility of the myocardium and the effect of cardiac filling (e.g. during bypass surgery).

Inverse correlation between the peak venous serum concentration of bupivacaine and the weight of the patient during interscalene brachial plexus block.

Thirty-five adult patients with rheumatoid arthritis received for 36 interscalene brachial plexus blocks a standard dose of bupivacaine 200 mg, regardless of the weight (range 39.2-102.5 kg) of the patient. The peak venous serum concentrations (Cmax) of bupivacaine, measured by HPLC, were in the range 0.82-4.30 mg litre-1; there were no signs of toxicity. There was a very significant inverse correlation between the Cmax of bupivacaine and the weight of the patient (r = -0.5922; t = -4.285; P = 0.0001, Pearson's test). In spite of the correlation, only 35.1% of the total variance could be explained by regression. Thus weight had little influence on Cmax under interscalene brachial plexus block.

Extradural administration of bupivacaine: pharmacokinetics and metabolism in pregnant and non-pregnant women.

We found a similar time (about 0.4 h) to maximum serum concentration after extradural administration of bupivacaine 1.78 (SD 0.27) mg kg-1 to six pregnant patients at term, 1.58 (0.13) mg kg-1 to six women younger than 65 yr and 1.50 mg kg-1 to six women older than 65 yr. There were no significant differences in terminal half-life. No unconjugated 4'-hydroxy-bupivacaine was detected in the serum and urine of pregnant patients, in contrast with the other groups. The pregnant patients had significantly greater serum concentrations of the N-dealkylated metabolite, N-desbutyl-bupivacaine (DBB), than the non-pregnant groups. In contrast with 4'-hydroxy-bupivacaine, no conjugated forms of bupivacaine and desbutyl-bupivacaine were detected in urine. The mean total urinary excretion of bupivacaine and its metabolites and their conjugates varied between 2.46 and 3.22% of the total dose administered in the three patient groups, indicating that both 4'-hydroxylation and N-dealkylation are minor metabolic pathways in man.

Pharmacokinetics of scopolamine during caesarean section: relationship between serum concentration and effect.

The pharmacokinetics (radioreceptor assay, RRA) and some of the clinical effects of the anticholinergic agent, scopolamine, were studied in 16 parturients during caesarean section. Following a single 0.005 mg/kg intramuscular injection (deltoid muscle), a very fast rate of absorption was found with mean peak serum concentrations occurring after only 10 min (n = 6). Due to severe bradycardia, 0.5 mg of atropine i.v. had to be given in addition to the i.m. scopolamine treatment to one parturient. The RRA measured the total concentration produced by the two anticholinergic agents in both serum and urine. There was a fundamental difference in the diffusion of scopolamine through the placenta and the blood-lumbar (CSF-barrier (n = 15). There was significant drug penetration in the foeto-placental unit, indicating an efficient drug transfer to the child, but there were measurable levels of the drug in the lumbar CSF in only three cases. The apparent elimination phase half-life of scopolamine in serum was only around 1 h. The urinary excretion of scopolamine and/or its antimuscarinic metabolites lasted only for 6 h (2.63 +/- 1.14% of the dose). The onset of the clinical effects of scopolamine appeared to be delayed, but long-lasting in contrast to the rapid absorption and quick disappearance from the serum. Both the heart rate changes, sedative and antisialogogue effects and serum concentrations did not show any correlation. There appears to be a surprisingly great difference between the pharmacokinetic parameters and the clinical effects of scopolamine.

Lack of effect of cimetidine on the pharmacokinetics of bupivacaine in healthy subjects.

1. The possibility of a pharmacokinetic interaction between the H2-receptor antagonist cimetidine and the long-acting local anaesthetic agent bupivacaine was studied in seven healthy, non-smoking volunteers. 2. The study consisted of two sessions at a minimum interval of 4 days. In a randomized, crossover fashion, the volunteers received bupivacaine HCl 1.4 mg kg-1 by i.m. injection at two occasions, once after no premedication, and once after two oral doses of 400 mg cimetidine. The concentrations of bupivacaine and its metabolites, 4'-hydroxybupivacaine and desbutylbupivacaine, were assayed by h.p.l.c., in serum up to 8 h and in urine fractions up to 24 h. 3. No influence of cimetidine on the pharmacokinetics of bupivacaine or on the serum cumulation of urinary recovery of its measured metabolites was detected. 4. These data suggest that cimetidine may be used safely as a premedication before local anaesthetic procedures with bupivacaine.

Bupivacaine with and without adrenaline in interscalene brachial plexus blockade. Studies in patients with rheumatoid arthritis.

The action of adrenaline on the pharmacokinetics of bupivacaine has been tested during two successive interscalene brachial plexus blocks in 10 patients with rheumatoid arthritis. The mean venous serum Cmax of bupivacaine after using it with or without adrenaline 1:200000 were 1.49 +/- 0.41 micrograms ml-1 and 2.46 +/- 0.85 micrograms ml-1, respectively. In spite of relatively high total serum concentrations, we could not detect any evidence of toxicity from bupivacaine. Significant tachycardia was seen after bupivacaine with adrenaline, but systolic and diastolic arterial pressures did not change significantly in any session. Marked subjective side effects were noticed only after bupivacaine with adrenaline (shivering twice and palpitations once). The serum protein bound fraction of bupivacaine was higher in rheumatic patients than in our healthy controls: 97.1 +/- 2.4% and 91.3 +/- 3.6%, respectively. Thus bupivacaine as a local anaesthetic agent seems to be even safer in patients with rheumatoid arthritis than in normal healthy volunteers, because of lower free fraction in the former.

Ethanol and the absorption of oral penicillin in man.

The effect of alcohol on the pharmacokinetics of phenoxymethylpenicillin was studied in six healthy volunteers. Ethanol had no influence on peak penicillin serum concentrations, times of the penicillin peaks, elimination half-lives (t1/2), AUC0-8h values and 24-h urinary excretion.

Elimination of and heart rate response to atropine in the elderly are independent of sex.

Sex-related changes in the pharmacokinetics and pharmacodynamics (heart rate) of atropine were studied in female (n = 9) and male (n = 9) elderly patients after a single 0.02 mg/kg i.v. injection of the drug at the beginning of a combination anaesthesia. No significant differences were found between the sexes, which indicates that there are no sex-related alterations in the response to this anticholinergic agent.

Oral scopolamine hydrobromide solution as an antisialagogic agent in dentistry.

Antisialagogue, cardiac, and subjective effects of oral scopolamine hydrobromide solution (ScHBr), 0.02 mg/kg total body weight, were studied in a double-blind, randomized, placebo-controlled manner with ten healthy volunteers. ScHBr was rinsed in the mouth for 5 minutes before swallowing. ScHBr reduced nonstimulated and paraffin-stimulated salivation at 40 minutes by 52% and 62%, and at 60 minutes by 81% to 80%, respectively. The heart rate decreased significantly (p less than 0.01) when compared with placebo. With the same drug dosing method, the effects of ScHBr also were tested in clinical dental examination procedures in two dental student groups. In the ScHBr group, salivation decreased by 70%, and in the placebo group, it increased by 22% as a result of mechanical stimulus. Subjective sedation and relaxation were experienced by most of the volunteers.

Placental and blood-CSF transfer of intramuscularly administered atropine in the same person.

Both placental and blood-CSF transfer of atropine (0.01 mg/kg intramuscularly) was measured (by RIA) in 11 parturients undergoing Caesarean section under spinal analgesia. In the foeto-placental unit a significant penetration into amniotic fluid was found, whereas in CSF there was a measurable level of the drug (greater than 1.5 ng/ml) in only one mother. Our results show that there is a fundamental difference in the penetrability of tertiary ammonium alkaloids like atropine through these two biological membranes. However, our results concern penetration into human lumbar CSF and do not necessarily reflect potential penetration into the ventricular CSF, choroid plexus or brain ventricular ependyma.

Noradrenergic and dopaminergic effects of nomifensine in healthy volunteers.

Intravenous doses (100 mg in 20 minutes) of the antidepressant drug nomifensine, administered to male volunteers, increased heart rate and blood pressure, elevated the plasma levels of norepinephrine and its metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG), and powerfully stimulated growth hormone release and inhibited the secretion of prolactin. Oral nomifensine, either as a single 100 mg dose or as a similar dose after 2 weeks' treatment with the drug (150 mg/day), caused none of the above effects. This was in line with the limited (less than 30%) oral bioavailability of the active, unconjugated form of the drug, estimated in the same subjects. MHPG in plasma was slightly but consistently reduced by the 2 weeks' treatment, suggesting reduced turnover of norepinephrine. The observed clinical effects of nomifensine are compatible with uptake inhibition and augmented release of norepinephrine and dopamine and possibly direct agonistic effects on dopamine receptors. Although nomifensine was withdrawn from the market because of immunologic complications, it serves as a model compound of a new pharmacologic class of antidepressants, devoid of many of the disturbing side effects of the tricyclic drugs.

Simultaneous determination of bupivacaine and its two metabolites, desbutyl- and 4'-hydroxybupivacaine, in human serum and urine.

A sensitive and selective high-performance liquid chromatographic (HPLC) method for the determination of bupivacaine and its two metabolites, desbutyl- and 4'-hydroxybupivacaine, in human serum and urine is described. Bupivacaine, both metabolites and the internal standard, etidocaine, are extracted with diethyl ether and then back-extracted into an acidic aqueous phase. After subsequent extraction into diethyl ether, evaporation and reconstitution in the mobile phase, bupivacaine and the metabolites are determined by HPLC using a reversed-phase C8 column with tetrahydrofuran-potassium phosphate buffer (8:92, v/v, pH 2.4) as the mobile phase. The sensitivity of the method is 10 micrograms/l for bupivacaine and both metabolites and the extraction efficiencies are 95, 54 and 92% for bupivacaine and desbutyl- and 4'-hydroxybupivacaine, respectively. The reproducibility of the method is good, the coefficients of variation varying between 1.8 and 7.4% in the concentration range 0.10-2.00 mg/l. The procedure was applied to human serum and urine samples from two elderly women who had been operated on under epidural analgesia (plain bupivacaine, 1.5 mg/kg) because of uterine prolapse.

Oropharyngeal absorption of atropine.

The oropharyngeal absorption of atropine was studied following 0.02, 0.04, 0.06 and 0.07 mg/kg doses of the drug to pregnant patients at term and compared with a 0.02 mg/kg dose given either intramuscularly or subcutaneously. The rate of systemic drug absorption was comparable following the two parenteral drug injections, but oropharyngeal atropine administration is of minor clinical significance.