Failure of phenylephrine to prolong isobaric bupivacaine spinal anesthesia in elderly patients.

BACKGROUND AND OBJECTIVES: The effects of phenylephrine on the duration of spinal anesthesia produced by plain bupivacaine were investigated in a double-blind study of 100 elderly patients. METHODS: Each patient received a basic solution of 3 ml 0.5% plain bupivacaine to which was added either 1 ml physiologic saline, 0.2 ml (1 mg) 0.5% phenylephrine plus 0.8 ml normal saline, 0.4 ml phenylephrine plus 0.6 ml normal saline, 0.6 ml phenylephrine plus 0.4 ml normal saline, or 0.8 ml phenylephrine plus 0.2 ml normal saline. RESULTS: The duration of sensory block (measured by two- and four-segment regression times and times to regression to T12 and L2 dermatomes) was not statistically prolonged by addition of phenylephrine. CONCLUSION: It is concluded that, in an attempt to prolong plain bupivacaine spinal anesthesia, the addition of phenylephrine does not appear to be advantageous for routine clinical practice.

[Metaraminol does not prolong the duration of spinal anesthesia using glucose-free bupivacaine in the upper dermatomes]. / Le métaraminol ne prolonge pas la durée de la rachianesthésie à la bupivacaïne sans glucose dans les dermatomes supérieurs.

The effects of metaraminol on the duration of plain bupivacaine spinal anaesthesia were investigated in a double-blind study of 80 elderly patients. Each patient received a basic solution of 0.5% plain bupivacaine to which was added either physiological saline, or 1 mg, 2 mg or 3 mg metaraminol. There were no significant differences between the four groups in the mean time from injection to recovery from analgesia in the two and four uppermost segments. However the addition of metaraminol increased the mean durations of analgesia at the L2 level and of the motor block. It is concluded that, in an attempt to prolong plain bupivacaine spinal anaesthesia in the uppermost segments, addition of metaraminol does not appear to be justified.

[Intrathecal and epidural administration of alpha adrenergic receptor agonists]. / Utilisation des alpha-stimulants par voies intrathécale et péridurale.

Alpha-agonists are frequently added to local anaesthetic agents to prolong the duration of spinal or extradural anaesthesia. Adrenaline and phenylephrine have been employed most commonly for this purpose. Recent controlled studies indicated that the alpha-adrenoceptor agonist clonidine, when administered spinally, has a dose-dependent antinociceptive effect. Clonidine seems to be as effective as adrenaline to prolong the duration of local anaesthetic blocks and is useful to decrease the incidence of tourniquet pain under spinal anaesthesia. As they improve the intensity and duration of opioid analgesia, intraspinal alpha-agonists have also a synergic analgesic effect with spinal opioids. Alpha-agonist effects are due: 1) to an activation of the post and/or presynaptic alpha 2-adrenoceptors in the substantia gelatinosa of the spinal cord, 2) to a local vasoconstriction by stimulating vascular smooth muscle alpha-receptors which decrease the rate of absorption of local anaesthetics from the subarachnoid or extradural space, 3) to a co-activation of the spinal opioid and alpha-adrenergic receptors at the spinal cord level. However, spinally administered alpha-agonists have side effects, which include vasoconstriction in the spinal cord, hypotension, bradycardia or tachycardia, somnolence and respiratory depression. To minimize such complications, great care may be needed, which is described in this review, assessing the minimal required amount of alpha-agonists and effective clinical monitoring. The development of this technique in the management of subarachnoid and extradural anaesthesia and of chronic pain is discussed.

A comparison of cardiovascular responses of normotensive and hypertensive elderly patients following bupivacaine spinal anesthesia.

The hypotensive effects of spinal anesthesia were investigated in 60 patients aged 75 years or older and divided into two groups: 30 normotensive patients (group 1) and 30 treated hypertensive patients (group 2). In both groups, spinal anesthesia was performed in lateral decubitus position with 3 ml 0.5% isobaric bupivacaine. Hemodynamic measurements were performed before the establishment of spinal blockade and repeated during the 60 minutes following intrathecal injection. Median cephalad level (T10) and ranges of sensory blockade were similar in the two groups. Changes from baseline to lowest blood pressures showed significant decreases in group 2 compared with group 1:10.7% in SPB, 11.2% in MBP, and 14.8% in DBP. Hypotension was observed in three group 1 patients and ten group 2 patients. Five patients in group 2 (but none in group 1) had a SBP decrease of 40% from baseline or more. The decreases in MBP and DBP were persistent after 60 minutes. These results suggest that pre-existing hypertension can be recognized as an important factor to explain blood pressures changes during isobaric bupivacaine spinal anesthesia in elderly patients.

[Intraoperative sedation by midazolam during spinal anesthesia. A study of elderly women undergoing surgery of the hip and femur neck]. / Sédation per-opératoire par le midazolam au cours des rachianesthésies. Etude chez la femme âgée en chirurgie de la hanche et du col du fémur.

Midazolam was studied as an IV sedative agent in 30 women aged of 75 years or more, undergoing hip surgery or Ender nailing, who received a spinal anaesthesia with 15 mg of plain bupivacaine. A mean dose of midazolam 0.077 mg.kg-1 was required to induce adequate sedation which was maintained by repeated doses of 2.5 mg. Post-operatively, no somnolence was noted at 2 hr. A marked amnesic effect was observed in 77% of cases. No clinically adverse cardiovascular or respiratory effects were encountered. It is concluded that midazolam is a useful sedative agent for spinal anaesthesia of short duration in the elderly.

Subarachnoid anaesthesia produced by hyperbaric lignocaine in elderly patients. Prolongation of effect with adrenaline.

The effects of adrenaline on the duration of spinal anaesthesia induced with hyperbaric lignocaine were investigated in 60 elderly patients in a double-blind study. Each patient received 5% lignocaine 2 ml in 7.5% dextrose to which was added physiological saline 1 ml, 1:1000 adrenaline 0.2 ml (0.2 mg) plus normal saline 0.8 ml, or adrenaline 0.4 ml with normal saline 0.6 ml. The duration of sensory block (measured by two- and four-segment regression times, and times to regression to T12 and L2 dermatomes) was prolonged significantly by both doses of adrenaline. The addition of adrenaline also produced a significant increase in the duration of complete motor block.

Effect of adding sodium bicarbonate to bupivacaine for spinal anesthesia in elderly patients.

The effect of added sodium bicarbonate on plain bupivacaine spinal anesthesia is unknown. Forty patients aged 75 years or older, ASA II or III, undergoing orthopedic lower limb surgery under spinal anesthesia were randomly classified into two groups. Just before injection, either 0.2 ml normal saline (group I) or 0.2 ml 0.42% NaHCO3 solution (group II) was added to 20 ml 0.5% bupivacaine hydrochloride. All patients then received intrathecally 3 ml (14.85 mg) of the bupivacaine solution in the lateral decubitus position. The segmental level of sensory loss was tested using forceps. The median time required to achieve maximal height of the sensory blockade and the median highest level of sensory anesthesia did not differ in the two groups. Alkalinized bupivacaine increased significantly the median times for regression to the T12 and L2 segments by 15 and 25 minutes, and the duration of complete motor block by 15 minutes, as compared to the hydrochloride salt. The clinical importance of such modest prolongations seems limited.

Spinal analgesia with hyperbaric bupivacaine: influence of age.

The effects of age were investigated on characteristics of spinal analgesia with hyperbaric bupivacaine in 38 younger patients (less than 50 yr: group I), and 48 older patients (greater than 80 yr: group II). Four millilitre of 0.375% bupivacaine in 2.5% dextrose was injected via the L3-4 space in a lateral position, and the patients were immediately turned supine. In group II, the time to maximum spread was significantly shorter, and the sensory spinal blockade higher (one dermatome) than in group I. The mean sensory recovery of the two uppermost segments did not differ between the two groups. The mean duration of analgesia at the L2 level was increased by only 15 min in the older group. Complete motor blockade of the lower limbs developed most rapidly in group II, while duration of all degrees of motor blockade did not differ significantly with age. Because of great individual variation, the clinical significance of such differences is limited. In the older group, there was a greater decrease in systolic arterial pressure from resting values, despite rapid infusion of lactated Ringer's solution.

[Prolongation of spinal anesthesia with hyperbaric bupivacaine by adrenaline and clonidine in the elderly]. / Prolongation de la rachianesthésie à la bupivacaïne hyperbare par l'adrénaline et la clonidine chez le vieillard.

So as to determine the effects of vasoconstriction on the duration of hyperbaric bupivacaine spinal anaesthesia, a prospective controlled study was carried out on 80 ASA class II or III patients, aged 75 years or more, who were scheduled for spinal anaesthesia for lower limb surgery. They were randomly allocated to four groups, and were each given 3 ml (15 mg) of 0.5% bupivacaine in plain solution with 0.5 ml of 30% dextrose solution, together with 1 ml normal saline in group I, 0.15 mg clonidine in group II, 0.2 mg adrenaline in group III, and 0.4 mg adrenaline in group IV. All patients therefore received 4.5 ml of 0.33% bupivacaine solution in 3.3% dextrose solution. The injection was made in the lateral position, and the patients turned supine immediately afterwards. The segmental level of sensory loss was tested using forceps. The time course required for maximal spread of the sensory blockade did not differ in the four groups. No difference was observed between median highest levels of sensory analgesia. Adding 0.15 mg clonidine or 0.4 mg adrenaline significantly prolonged mean times for two- and four-segment regression and mean times for regression to L2 level. The addition of 0.2 mg adrenaline only prolonged the mean regression time to L2 level. Regression times tended to increase more with 0.4 mg than with 0.2 mg adrenaline. Significant prolongation of motor block was also associated with the addition of vasoconstrictors. It is concluded that addition of 0.15 mg clonidine or 0.4 mg adrenaline may be useful to increase duration of hyperbaric bupivacaine spinal anaesthesia in elderly patients.

Effect of increasing amounts of epinephrine during isobaric bupivacaine spinal anesthesia in elderly patients.

The effects of adding epinephrine to isobaric bupivacaine spinal anesthesia were investigated in 96 ASA class II-III patients aged 75 yr or more scheduled for lower extremity surgery. The subjects were randomly allocated into six groups. All patients received 15 mg bupivacaine plain solution in 4 ml, in the horizontal position. Patients in group 1 received bupivacaine plus 1 ml normal saline; patients in other groups received bupivacaine plus increasing dosages of epinephrine: 0.1 mg (group 2), 0.2 mg (group 3), 0.3 mg (group 4), 0.4 mg (group 5), 0.5 mg (group 6). The segmental level of sensory loss was tested using forceps. The time required for maximal spread of the sensory blockade was significantly 50% greater in group 5 than in group 1. No difference was observed, however, between mean highest levels. Addition of 0.2 mg epinephrine prolonged by a significant 25% regression time to L-2 level. Addition of 0.3 and 0.4 mg epinephrine significantly prolonged two-segment regression time by 36 and 53%, respectively, and regression to L-2 level by 29 and 44%, respectively. Addition of 0.5 mg epinephrine did not result in further prolongation of anesthesia. Motor blockade was also increased by addition of epinephrine. It is concluded that addition of 0.3 mg epinephrine may be useful to increase duration of isobaric bupivacaine spinal anesthesia.

Prolongation of isobaric bupivacaine spinal anesthesia with epinephrine and clonidine for hip surgery in the elderly.

The effects of vasoconstrictors on the duration of isobaric bupivacaine spinal anesthesia are unknown. A prospective controlled study was conducted on 60 ASA class II or III patients aged 75 yr or more who were scheduled for spinal anesthesia for orthopedic hip surgery. The subjects were randomly allocated into three groups. All patients received 15 mg bupivacaine plain solution in 4 ml in the horizontal position. Group I patients received bupivacaine plus 1 ml normal saline; group II patients received bupivacaine plus 0.2 mg epinephrine; group III patients received bupivacaine plus 0.15 mg clonidine. The segmental level of sensory loss was tested using forceps. In one case in group III, anesthesia was unsatisfactory. The time course required for maximal spread of the sensory blockade did not differ in the three groups. No difference was observed between mean highest levels of sensory anesthesia. The mean time to two-segment regression from the highest level was significantly longer in group III than in groups I and II. Mean time for regression to the L2 segment was also significantly longer in groups II and III than in group I. This time tended to increase more with the bupivacaine plus clonidine solution than with the bupivacaine plus epinephrine solution. Significant prolongation of motor block was also associated with the addition of clonidine.

[Failure of an intravenous locoregional anesthesia in a hypertensive patient]. / Echec d'une anesthésie locorégionale intraveineuse chez une hypertendue.

A case is reported of a congested arm occurring during intravenous regional anaesthesia with a double cuff tourniquet in a female elderly patient suffering from hypertension. The proximal cuff was apparently inflated adequately to 300 mmHg. Recent studies showed that the use of only the proximal tourniquet was associated with a risk of venous leakage. In elderly hypertensive patients, when intravenous regional anaesthesia was necessary, one would be justified in inflating the two cuffs before injection of the local anaesthetic.