Combined spinal and epidural anesthesia for orthopaedic surgery in the elderly]

The pros and cons as to which anesthesia is more beneficial, either spinal or epidural, prompted us to perform combined spinal and epidural block in the elderly undergoing lower limb surgery. The selected epidural space was entered with a 17-gauge Tuohy needle and a longer 26-gauge spinal needle was passed through it and into the subarachnoid space. Following the injection of required dose of 2% preservative-free lidocaine (isobaric), spinal needle was withdrawn and an epidural catheter was inserted. We could use this combined technique on 17 patients older than 80 yr (mean age; 84.5 +/- 3.9 years) with satisfactory results and without any serious cardiovascular change, as with 17 middle-aged patients (57.5 +/- 5.2 years). This combination of techniques provides a rapid onset and reliability of spinal block with high quality analgesia by supplementation through the epidural catheter during and after surgery. In the orthopaedic procedures on the lower limbs, combined spinal and epidural block is more useful even for the elderly over the age of 80 yr than spinal or epidural anesthesia alone.     

A prospective, randomized, double-blind comparison of unilateral spinal anesthesia with hyperbaric bupivacaine, ropivacaine, or levobupivacaine for inguinal herniorrhaphy

In 60 patients undergoing inguinal hernia repair, we compared the clinical profile of unilateral spinal anesthesia produced with either 8 mg of hyperbaric bupivacaine 0.5% (n = 20), 8 mg of hyperbaric levobupivacaine 0.5% (n = 20), or 12 mg of hyperbaric ropivacaine 0.5% (n = 20). The study drug was injected slowly through a 25-gauge Whitacre directional needle and patients maintained the lateral decubitus position for 15 min. The onset time and intraoperative efficacy were similar in the three groups. The maximal level of sensory block on the operative and nonoperative sides was T6 (T12-5) and L3 (/[no sensory level detectable]-T4) with bupivacaine, T8 (T12-5) and L3 (/-T3) with levobupivacaine, T5 (T10-2) and T11 (/-T3) with ropivacaine (P = 0.11, P = 0.23, respectively). Complete regression of spinal anesthesia occurred after 166 +/- 42 min with ropivacaine, 210 +/- 63 min with levobupivacaine, and 190 +/- 51 min with bupivacaine (P = 0.03 and P = 0.04, respectively); however, no differences were observed in time for home discharge (329 +/- 89 min with bupivacaine, 261 +/- 112 min with levobupivacaine, and 332 +/- 57 min with ropivacaine [P = 0.28]). We conclude that 8 mg of levobupivacaine or 12 mg of ropivacaine are acceptable alternatives to 8 mg of bupivacaine when limiting spinal block at the operative side for inguinal hernia repair.     

Posture and the spread of hyperbaric bupivacaine in parturients using the combined spinal epidural technique

This study was undertaken to analyze the effect of posture on the spread of hyperbaric bupivacaine in pregnant women using a combined spinal extradural technique, and to assess the quality of analgesia provided by 10 mg bupivacaine when using this technique. Fifty parturients undergoing elective Caesarean section under regional anaesthesia were randomly allocated to receive 2.0 ml hyperbaric bupivacaine 0.5% in either the sitting or left lateral position. Spinal injection was performed with a 27 gauge, 120 mm long spinal needle using a single space combined spinal extradural technique. The onset time to analgesia at T₄, and grade 3 motor block was on average 7.7 min and 6.9 min respectively in the lateral group, compared with 10.8 min (P < 0.05) and 9.4 min (P < 0.05) in the sitting group. Nine women in the sitting group and one woman (P < 0.05) in the lateral group required epidural supplementation. Hypotension occurred in 48% of the parturients in the lateral group and in 13% (P < 0.05) of the parturients in the sitting group. Nausea was noted in 61% of the parturients in the lateral group and in 22% (P < 0.05) of the parturients in the sitting group. There was no difference between the two groups in neonatal outcome. Overall, the position of the patient during induction of spinal anaesthesia does influence the rate of onset of analgesia and motor blockade. Injection of 10 mg hyperbaric bupivacaine in the sitting position would not provide adequate analgesia for Caesarean section when using a single space combined spinal extradural technique.     

The median effective dose of intrathecal hyperbaric bupivacaine is larger in the single-shot spinal as compared with the combined spinal-epidural technique

The combined spinal-epidural technique (CSE) has been associated with prolonged motor recovery and more frequent arterial hypotension as compared with a single-shot spinal (SSS) technique. We determined the median effective dose (MED) of intrathecal hyperbaric bupivacaine for CSE and SSS by using the up-down sequential allocation technique. Sixty male patients were randomly allocated to receive intrathecal administration through an SSS or CSE technique. Needle insertion occurred at the L3-4 interspace in all patients. In SSS, 9.5 mg of hyperbaric bupivacaine was administered through a 27-gauge Whitacre spinal needle. In CSE, a 17-gauge Tuohy needle with 4 mL of air was used to locate the epidural space, through which a 27-gauge Whitacre spinal needle was introduced and 7.0 mg of hyperbaric bupivacaine was administered. The dosing adjustment was 0.5 mg. A "successful" outcome was arbitrarily defined as sensory anesthesia at or above the T6 dermatome lasting for 60 min. A "success" resulted in a 0.5-mg decrement, whereas a "failure" resulted in a 0.5-mg increment in the next patient. There were 13 successes in both groups. The MED of bupivacaine was 9.18 mg (95% confidence interval, 8.89-9.47 mg) for CSE as compared with 11.37 mg (95% confidence interval, 10.88-11.86 mg) for SSS (P < 0.001). CSE required 19.3% (95% confidence interval, 14.9%-23.6%) less local anesthetic to achieve the defined clinical target. We found significant discrepancies in the MED of hyperbaric bupivacaine between the two techniques. Under similar clinical conditions, a 20% decrement in the dose of bupivacaine may be warranted whenever CSE is intended in place of SSS.     

Spinal anesthesia with isobaric bupivacaine for percutaneous nephro-ureterolithotomy

The duration of analgesia and the cardiovascular changes during anesthesia of spinal blockade with isobaric bupivacaine were examined in 36 patients between 21 and 75 years old undergoing percutaneous nephro-ureterolithotomy. Injection of 0.25% or 0.5% bupivacaine 3.0-4.0 ml through the L3-4 or L2-3 intervertebral space in the horizontal posture resulted in spread of hypalgesia to T6 in 30 patients and of analgesia to T6 in about a half of the patients. In six patients, another intrathecal injection of 2 ml of bupivacaine was performed because their analgesia level had been under T8. Although the operation took 32-141 min. (mean 77.7 +/- 27.5 min.), there was no case requiring exigent exchanging anesthesia for general anesthesia. The frequencies of the hypotension, bradycardia and nausea in spinal blockade with isobaric bupivacaine were not so different from those of the previous epidural anesthesia in 29 patients undergoing the same operation. Most of the cardiovascular changes in the spinal blockade with isobaric bupivacaine happened within 20-30 min. after intrathecal injection of bupivacaine. Spinal anesthesia with isobaric bupivacaine proved satisfactory for percutaneous nephro-ureterolithotomy.     

COMPARISON OF FOUR SUBARACHNOID SOLUTIONS IN A NEEDLE-THROUGH-NEEDLE TECHNIQUE FOR ELECTIVE CAESAREAN SECTION

We have used both spinal and extradural anaesthesia with a 26-gauge,long spinal needle through a 16-gauge Tuohy needle for electiveCaesarean section. Four different subarachnoid solutions ofbupivacaine were compared: 0.5% heavy bupivacaine alone, orwith adrenaline, fentanyl or adrenaline and fentanyl. The incidenceof complications and time of regression of the sensory blockwere analysed. The technique is recommended because it allowsrapid onset of anaesthesia and the advantages of an extraduralcatheter. The subarachnoid solution of choice was 0.5% heavybupivacaine 12.5 mg with fentanyl 10 µg     

The influence of lumbosacral cerebrospinal fluid volume on extent and duration of hyperbaric bupivacaine spinal anesthesia: a comparison between seated and lateral decubitus injection positions

We designed the present study to examine the influence of lumbosacral cerebrospinal fluid (CSF) volume on the spread and duration of hyperbaric bupivacaine spinal anesthesia when the injection is made with the patient in the lateral position compared with that when the patient is in a seated position. Seventy-four patients undergoing peripheral orthopedic or urogenital surgery with spinal block were enrolled. Lumbosacral CSF volumes were calculated from axial magnetic resonance images. Patients were randomly assigned to 1 of 2 groups: the lateral (L) and seated (S) groups (n = 37 each). Spinal anesthesia (3 mL hyperbaric 0.5% bupivacaine) was administered using a 25-gauge pencil-type needle with the needle aperture directed cephalad and the patient in the lateral decubitus position with the non-operated side up (L group) or with the patient in a seated position (S group). Patients were turned supine immediately after spinal injection (L group) or after remaining seated for 2 min (S group). Statistical correlation coefficients (rho) were assessed using Spearman's rank correlation. There were negative correlations between CSF volume and peak sensory block level in both the L (rho = -0.69, P < 0.0001) and S groups (rho = -0.68, P < 0.0001). In the S group, but not in the L group, CSF volume significantly correlated with onset time of peak sensory block level (rho = -0.48, P = 0.004), and time required for regression to L1-4 (P < 0.05-0.01). We conclude that CSF volume influences the spread of spinal anesthesia with hyperbaric bupivacaine regardless of patient position when the spinal injection is made. CSF volume influenced the duration of spinal sensory anesthesia when the injection was made with the patient in a seated position, but not in the lateral position. IMPLICATIONS: Patient position during the spinal injection does not alter the influence of cerebrospinal fluid (CSF) volume on the spread of hyperbaric bupivacaine spinal anesthesia. However, CSF volume influences the duration of spinal sensory anesthesia when the injection is made with the patient in a seated position, but not in the lateral position.     

Comparison of three catheter sets for continuous spinal anesthesia in patients undergoing total hip or knee arthroplasty

BACKGROUND AND OBJECTIVES: Continuous spinal anesthesia (CSA) with microcatheters may be complicated because of technical problems. In elderly patients, some of the problems may be solved by using thicker catheters. A recent invention, involving a catheter-over-needle system, may prevent leakage of cerebrospinal fluid (CSF) and may also improve the prediction of the intrathecal position of the catheter tip. METHODS: This study included 90 patients undergoing primary hip or knee replacement, randomly allocated into 3 groups, with 30 patients in each group: Group EC, a 24-gauge epidural catheter through a 19-gauge Tuohy needle; group MC, a 28-gauge microcatheter through a 22-gauge spinal needle; group SC, a 22-gauge spinal catheter over a 27-gauge spinal needle through an epidurally placed 18-gauge Crawford needle. All subarachnoid catheterizations were performed with the patient in the lateral position and the initial spinal block dose was 2 mL of plain 0.5% bupivacaine. Increments of 0.5 mL were administered when required. The block performance characteristics were recorded, and the level of analgesia was studied in a blinded fashion. Catheter function during the postoperative infusion was assessed. Afterwards the needles and catheters were examined by microscopy. RESULTS: The frequency of the successful catheterization was higher in the EC and MC groups (90% in each) than in the SC group (63%) (P <.05). The mean duration of the successful catheterizations, as well as the median level of analgesia, were similar in the groups. The postoperative infusion had to be stopped in 3, 1, and 1 patients in groups EC, MC, and SC, respectively, because of a technical reason. No neurologic sequelae occurred in this study. Microscopy showed 4 distorted spinal needle tips (2 each with MC and SC) and minor material damage of the SC catheters when bone had been met during block performance. CONCLUSIONS: Placement of the SC catheters was unsuccessful to a high degree, and bone contact produced distortion of the tip of some of these catheters. Otherwise, the quality associated with catheterization time, anesthetic distribution, and catheter function was similar with the 3 catheters.     

Spinal anaesthesia using hyperbaric 0.75% vs hyperbaric 1% bupivacaine: a double blind comparison

AIM: The aim of this study was to compare the anesthetic effects, potency and postoperative outcome of 0.75% and 1% concentrations of hyperbaric bupivacaine in selective spinal anesthesia. METHODS: We enrolled 40 patients in a double blind fashion in 2 groups (A= 0.75% bupivacaine; B= 1% bupivacaine). Demographic data were respectively for Groups A and B: age 40.6+/-16 and 67+/-16, weight 74+/-14.4 and 68+/-10.2; sex 10M/10F and 6M/14F; ASA I-II 11/9 and 14/6. All patients received 11.25 mg bupivacaine. In all cases a 27G Whitacre needle was introduced at L1-L2, L2- L3, L3-L4 introduced with a midline approach. Time to onset and offset of sensitive and motor block, dermatomeric extension non invasive blood pressure, heart rate, ephedrine dose, deambulation time, diuresis time and request for supplemental analgesia were recorded. RESULTS: No statistically significant differences between the 2 groups for demographic data were found. Group B revealed a faster onset and a more adequate dermatomeric extension (4.1+/-0.8 min vs 6.5+/-1.2 min). Both concentrations guaranteed good hemodynamic stability. Motor offset times were 115.8+/-145 min and 142+/-4.8 min respectively in groups A and B. Sensitive offset times were 197.5+/-12 min and 168+/-5.2 min respectively in groups A and B. No statistically relevant differences were noticed for intraoperative Bromage, sensitive block or for postoperative motor and sensitive offset time, diuresis time and deambulation time. There are no advantages of 1% hyperbaric bupivacaine over 0.75% for selective spinal anesthesia, while several disadvantages presented shorter duration of postoperative analgesia and higher incidence of headache.     

Intrathecal anesthesia: ropivacaine versus bupivacaine

We compared intrathecal ropivacaine to bupivacaine in patients scheduled for transurethral resection of bladder or prostate. Doses of ropivacaine and bupivacaine were chosen according to a 3:2 ratio found to be equipotent in orthopedic surgery. One hundred patients were randomly assigned to blindly receive either 10 mg of isobaric bupivacaine (0.2%, n = 50) or 15 mg of isobaric ropivacaine (0.3%, n = 50) over 30 s through a 27-gauge Quincke needle at the L2-3 level in the sitting position. Onset and offset times for sensory and motor blockades and mean arterial blood pressure were recorded. Pain at surgical site requiring supplemental analgesics was recorded. Cephalad spread of sensory blocks was higher with bupivacaine (median level, cold T(4) and pinprick T(7)) than with ropivacaine (cold T(6) and pinprick T(9)) (P<0.001). Eight patients in Group Ropivacaine received IV alfentanil (P<0.01). Onset time (mean +/- SD) to T(10) anesthesia and offset time at L2 were not different (bupivacaine = 13 +/-8 min, 127+/-41 min; ropivacaine = 11+/-7 min, 105+/-29 min). Complete motor blockade occurred in 43 patients with bupivacaine and in 41 patients with ropivacaine (not significant). Total duration of motor blockade was not different. No difference in hemodynamic effects was detected between groups. No patient reported back pain. We conclude that 15 mg of intrathecal ropivacaine provided similar motor and hemodynamic effects but less potent anesthesia than 10 mg of bupivacaine for endoscopic urological surgery.     

EFFECT OF SPEED OF INJECTION OF 0.5% PLAIN BUPIVACAINE ON THE SPREAD OF SPINAL ANAESTHESIA

We have studied the influence of two different speeds of injectionon the spread of spinal anaesthesia of bupivacaine in 40 orthopaedicpatients. In a random order, 0.5% plain bupivacaine 3 ml wasadministered in 10 or 180 s into the subarachnoid space usinga 27-gauge needle with the patients in a lateral horizontalposition. The slower speed produced a higher spread of spinalanaesthesia (median difference 2.5 segments, P < 0.05).     

Hypotension in spinal anesthesia: a comparison of isobaric tetracaine with epinephrine and isobaric bupivacaine without epinephrine

Two isobaric spinal anesthetic solutions (bupivacaine 0.5%/20 mg without epinephrine and tetracaine 0.5%/15 mg with 0.2 mg epinephrine) were compared in a double-blind study of 60 patients. Patients were injected while in the lateral recumbent position and were immediately turned supine and horizontal. Up to 30 min after injection, no differences were found between the groups regarding segmental level of analgesia, changes in heart rate, and onset to or maximum decrease in mean arterial pressure (MAP). No correlation was found between maximum decrease in MAP and level of analgesia. At time of maximum decrease in MAP (tetracaine group - 16.7 +/- 12.8% (mean + SEM), bupivacaine group -19.4 + 14.8%) the level of analgesia was significantly higher in the tetracaine group (T5-6) than in the bupivacaine group (T7-8). Hypotension occurred in five patients in the bupivacaine group and in six in the tetracaine group. Two patients in the tetracaine group (but none in the bupivacaine group) had bradycardia. Hypotension together with bradycardia was observed in one patient in the tetracaine group but in no patient in the bupivacaine group. Two patients in each group developed postlumbar puncture headache. The authors conclude that the choice of local anesthetic agent, by itself, is not the sole cause of hypotension seen with spinal anesthesia.     

Spinal clonidine prolongs labor analgesia from spinal sufentanil and bupivacaine

We sought to determine whether spinal clonidine 50 microg prolongs the analgesia from the spinal administration of sufentanil 7.5 microg and bupivacaine 2.5 mg early in the first stage of labor. Thirty patients were randomized to receive a 2-mL spinal injection of sufentanil 7.5 microg + bupivacaine 2.5 mg with or without clonidine 50 microg using a combined spinal-epidural (CSE) technique. Pain, nausea, pruritus, sedation, motor block, blood pressure, and heart rate were assessed until the patient requested additional analgesia. Analgesia was significantly prolonged in patients who received spinal sufentanil + bupivacaine + clonidine (197 +/- 70 vs 132 +/- 39 min; P = 0.004). Pain scores and side effects, including motor block, sedation, and hypotension, were similar between groups. Spinal clonidine significantly prolongs labor analgesia from spinal sufentanil and bupivacaine without producing serious adverse side effects. IMPLICATIONS: We studied the effects of spinal clonidine administered with spinal sufentanil and bupivacaine on labor analgesia using a combined spinal-epidural technique and conclude that spinal clonidine significantly prolongs labor analgesia from spinal sufentanil and bupivacaine without producing serious adverse effects.     

Subarachnoid Sufentanil for Early Postoperative Pain Management in Orthopedic Patients: A Placebo-controlled, Double-blind Study Using Spinal Microcatheters

Background: Continuous spinal anesthesia is frequently used for intraoperative anesthesia but rarely for postoperative pain management. Because even small doses of local anesthetics can be associated with motor deficits, subarachnoid opioid injection may be an alternative.

Methods: Eighty patients randomly received a subarachnoid injection of 10 [mu]g sufentanil, 5 mg bupivacaine, 2.5 [mu]g sufentanil plus 2.5 mg bupivacaine, or saline through 28-gauge spinal microcatheters for early postoperative pain relief after major lower-limb surgery (n = 20 in each group). Hemodynamic and respiratory parameters, pain scores, and motor function were monitored, and sufentanil concentrations in plasma and cerebrospinal fluid were measured. Ten additional patients received up to three repetitive injections of 10 [mu]g sufentanil over 24 h.

Results: All drugs provided excellent pain relief within 15 min after injection, lasting 128 +/- 61 min with sufentanil, 146 +/- 74 min with bupivacaine, and 167 +/- 78 min with the mixture. Patients receiving bupivacaine showed the highest cephalad extension of sensory block (median, T6) and the most intense motor block, whereas patients given only sufentanil had no motor deficit. The duration of analgesia was shorter after subsequent sufentanil injection (100-115 min) than after the first injection (198 +/- 70 min). Six of 50 patients with sufentanil experienced a short episode of respiratory depression within 30 min after the first injection. Cerebrospinal fluid concentrations of sufentanil peaked at 5 min after injection (183 +/- 167 ng/ml) but were at the level of detection in the plasma.     

Subarachnoid sufentanil for early postoperative pain management in orthopedic patients: a placebo-controlled, double-blind study using spinal microcatheters

BACKGROUND: Continuous spinal anesthesia is frequently used for intraoperative anesthesia but rarely for postoperative pain management. Because even small doses of local anesthetics can be associated with motor deficits, subarachnoid opioid injection may be an alternative. METHODS: Eighty patients randomly received a subarachnoid injection of 10 microg sufentanil, 5 mg bupivacaine, 2.5 microg sufentanil plus 2.5 mg bupivacaine, or saline through 28-gauge spinal microcatheters for early postoperative pain relief after major lower-limb surgery (n = 20 in each group). Hemodynamic and respiratory parameters, pain scores, and motor function were monitored, and sufentanil concentrations in plasma and cerebrospinal fluid were measured. Ten additional patients received up to three repetitive injections of 10 microg sufentanil over 24 h. RESULTS: All drugs provided excellent pain relief within 15 min after injection, lasting 128 +/- 61 min with sufentanil, 146 +/- 74 min with bupivacaine, and 167 +/- 78 min with the mixture. Patients receiving bupivacaine showed the highest cephalad extension of sensory block (median, T6) and the most intense motor block, whereas patients given only sufentanil had no motor deficit. The duration of analgesia was shorter after subsequent sufentanil injection (100-115 min) than after the first injection (198 +/- 70 min). Six of 50 patients with sufentanil experienced a short episode of respiratory depression within 30 min after the first injection. Cerebrospinal fluid concentrations of sufentanil peaked at 5 min after injection (183 +/- 167 ng/ml) but were at the level of detection in the plasma. CONCLUSIONS: Sufentanil injected through microspinal catheters provided profound pain relief without impairing motor function when compared with bupivacaine. However, close monitoring remains mandatory in this setting.     

Subarachnoid anaesthesia for elective Caesarean section

Forty patients who underwent elective lower segment Caesarean section under subarachnoid anaesthesia received either 2.0 ml 0.5% cinchocaine in 6% dextrose or 2.5 ml 0.5% bupivacaine in 8% dextrose via a 26-gauge needle with the patient in the left lateral position. Onset time was rapid in both groups and the distribution of maximum ascent of sensory analgesia was T1-T6. Efficacy of analgesia was greater in the bupivacaine group, although the duration of both sensory and motor blockade was shorter than following cinchocaine. There were no significant differences between the two groups either in the incidence and severity of complications or in the condition of the neonates. The high incidence (50-65%) and often profound extent of hypotension seen throughout the trial, confirm the ineffectiveness of crystalloid preload of 1500 ml as a single prophylaxis against hypotension.     

Knee-chest vs horizontal side position during induction of spinal anaesthesia in patients undergoing lumbar disc surgery

In the prone knee-chest position the spread of plain 0.5% bupivacaine in the cerebrospinal fluid and associated haemodynamic changes may be different compared with the horizontal position. A randomized comparison was performed in 40 ASA I-II patients, aged 24-61 yr, undergoing lumbar disc surgery. Subarachnoid injection (27-gauge needle) at the L2-3 interspace with 3 ml of 0.5% bupivacaine was performed with the patient in the operative knee-chest position (prone knee-chest group, n = 20) or in the horizontal side position (supine side horizontal group, n = 20). Patients in the supine side horizontal group were turned into the horizontal supine position for 20 min, and subsequently they were placed in the operative knee-chest position. In three patients in the prone knee-chest group, the spinal needle was replaced by a larger needle (25-gauge). The final cephalad extension of sensory analgesia on skin tested by pinprick was T5 (median) in the prone knee-chest group and T6 in the supine side horizontal group. Recovery was also similar, on average 210 min from injection in both groups. The mean decrease in systolic arterial pressure was somewhat greater in the prone knee-chest group (30 mm Hg) than in the supine side horizontal group (13 mm Hg). The need for ephedrine occurred earlier in the supine side horizontal group (three patients, all within 10 min from local anaesthetic injection) than in the prone knee-chest group (six patients, all after 15 min). Four of the latter patients also required administration of an anticholinergic for bradycardia compared with two patients in the supine side horizontal group. Light sedation was given to five patients in the prone knee-chest group and to four in the supine side horizontal group because of numbness and aching in the shoulders. We conclude that spinal block was similar in the two groups but there was a tendency to more frequent episodes of haemodynamic deterioration in the knee-chest position.      

The spread and time to two-segment regression of spinal anesthesia with 0.25% hyperbaric bupivacaine

The spread and time to two-segment regression of spinal anesthesia with 0.25% hyperbaric bupivacaine 2.0 ml (5 mg) were studied clinically in 20 patients for elective lower extremity, urological or gynecological surgery. Lumbar puncture was performed at the L 3-4 interspace with the patient in horizontal lateral decubitus positions using a 25-G Quincke needle. After injection of the local anesthetic solution at the rate of 0.2 ml.sec-1, the patient was placed immediately in supine position. Sensory block was assessed by using pinprick and motor block was assessed by using a four-point Bromage scale in every 5 min until 30 min, then every 10 min thereafter until two-segment regression of sensory block had recovered. Results were expressed as mean values +/- SD. Maximum sensory block level was Th 10.6 +/- 2.3, and time to two-segment regression was 51.5 +/- 14.6 min. Complete motor block was observed in three out of twenty patients (15%). These results indicate that spinal anesthesia with 0.25% hyperbaric bupivacaine is useful for a short case, which dose not require motor block or is performed as day-care surgery.     

Spinal anesthesia for endoscopic urological surgery--low dose vs. varying doses of hyperbaric bupivacaine

BACKGROUND AND OBJECTIVE: The aim of this study is to compare the efficiency of low dose vs. varying doses of hyperbaric bupivacaine in spinal anesthesia for endoscopic urological procedures. METHODS: Sixty consecutive patients were studied in a randomized prospective manner. They received either of 5 (Gr I), 7.5 (Gr II) or 10 mg (Gr III) of hyperbaric bupivacaine 0.5% combined with 25 microg of fentanyl, through a 25-gauge W hitacre spinal needle placed in the L3-L4 interspace. Characteristics of sensory and motor block, dose of ephedrine required, secondary effects, the patients, and the surgeons satisfaction, were noted. RESULTS: The maximum number of blocked segments was 14 +/- 1 (Gr I), 15 +/- 2 (Gr II) and 16 +/- 2 (Gr III). Time to T12 regression was significantly shorter for Gr I (53 +/- 13 min) than for Gr II (69 +/- 20 min) or Gr III (94 +/- 14 min). Bromage 3 block was not found in Gr I compared to 4 patients in Gr II and 15 patients in Gr III. The duration of motor block was shorter in Gr 1(51 +/- 18 min) than in Gr II (86 +/- 19 min) and in Gr III (138 +/- 21 min). Ephedrine was used for 16 patients in Gr III (9.8 +/- 12.2 mg), 5 patients in Gr II (3.7 +/- 7.8 mg) and 2 patients in Gr I (0.5 +/- 1.5 mg). The difference is statistically significant between Gr III and the other groups. CONCLUSIONS: These results suggest that the use of a low dose of bupivacaine (5 mg) added to fentanyl (25 microg) for endoscopic urological surgery, resulted in short-acting sensory block, without motor block and a lower incidence of cardiovascular side effects, as compared to either of 7.5 or 10 mg bupivacaine with 25 microg fentanyl.     

Epidural blood flow and regression of sensory analgesia during continuous postoperative epidural infusion of bupivacaine

Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours for postoperative pain relief. The epidural blood flow was measured by a local 133Xe clearance technique in which 15-35 MBq 133Xe diluted in 1 ml saline was injected through the epidural catheter on the day before surgery (no bupivacaine), 30 minutes after the initial dose of bupivacaine on the morning before surgery, and 8, 12, and 16 hours later during the continuous infusion. Initial blood flow was 6.0 +/- 0.7 ml/min per 100 g tissue (mean +/- SEM). After epidural bupivacaine, blood flow increased in all seven patients to 7.4 +/- 0.7 ml (P less than 0.02). Initial level of sensory analgesia was T4.5 +/- 0.17 (mean +/- SEM). Postoperatively, two patients maintained the initial level of sensory analgesia and low pain score throughout the 16-hour study. In these two patients epidural blood flow remained constant after the initial increase. Flow increased further to 10.3 +/- 0.8 ml/min per 100 g tissue (P less than 0.03) in the other five patients as the level of sensory analgesia regressed postoperatively. These data suggest that changes in epidural blood flow during continuous epidural infusion of bupivacaine, and thus changes in rates of vascular absorption of bupivacaine from the epidural space, may be an important factor contributing to differences in rates of regression of sensory analgesia.