Cerebrospinal fluid density influences extent of plain bupivacaine spinal anesthesia

BACKGROUND: The attempts to explain the unpredictability of extent of spinal block provided by plain local anesthetic solutions have resulted in many clinical reports; however, causes of this uncertainty are as yet unknown. Recently, normal values of the human cerebrospinal fluid densities have been studied showing important interindividual variations, especially between females and males. The current study was designed to evaluate as primary endpoint the influence of cerebrospinal fluid density values on the extent of spinal block with plain bupivacaine. The ancillary endpoints were search of factors explaining the interindividual differences in cerebrospinal fluid density values reported and determination of the relation between upper extent and regression of spinal anesthesia. METHODS: Sixty-four consecutive patients undergoing peripheral orthopedic surgery with spinal block were enrolled. Spinal anesthesia was performed in the lateral decubitus position with the operated side upward. Two milliliters of cerebrospinal fluid was sampled before injection of 3 ml plain bupivacaine 0.5%. The patient was immediately turned supine and remained in the horizontal position until the end of the study. Maximal sensory block level and time to sensory regression to L4 were determined for each patient enrolled. Cerebrospinal fluid and bupivacaine densities as well as cerebrospinal proteins, glucose, sodium, and chloride concentrations were measured. RESULTS: A highly significant correlation between cerebrospinal fluid density and maximal sensory block level was found (P = 0.0004). However, this correlation was poorly predictive (R(2) = 0.37). Cerebrospinal fluid density, proteins, and glucose concentrations were significantly higher in men than in women: 1.000567 +/- 0.000091 versus 1.000501 +/- 0.000109 g/ml (P = 0.014), 0.46 +/- 0.18 versus 0.32 +/- 0.13 g/l (P = 0.001), and 3.27 +/- 0.7 versus 2.93 +/- 0.5 mM (P = 0.023), respectively. A highly significant (P = 0.0004) and predictive (R(2) = 0.73) inverse correlation was found between maximal upper sensory extent and sensory regression to L4. CONCLUSION: These findings indicate an influence of cerebrospinal fluid density on subarachnoid distribution of 3 ml plain bupivacaine 0.5% and show that with higher cerebrospinal fluid densities, a higher spinal block level can be expected.     

Influence of lumbosacral cerebrospinal fluid density, velocity, and volume on extent and duration of plain bupivacaine spinal anesthesia

BACKGROUND: The current study was designed to investigate the influence of lumbosacral cerebrospinal fluid (CSF) density, velocity, and volume on the extent and duration of plain bupivacaine spinal anesthesia. METHODS: Forty-one patients scheduled to undergo orthopedic surgery with spinal block were enrolled. Lumbosacral CSF volumes were calculated from low thoracic, lumbar, and sacral axial magnetic resonance images. CSF velocity at the L3-L4 level was derived from phase-contrast magnetic resonance images. Spinal anesthesia was performed in the lateral decubitus position. CSF (2 ml) was sampled to measure CSF density before injection of 3 ml plain bupivacaine (0.5%). Statistical correlation coefficients (rho) between CSF characteristics and measurements of spinal anesthesia were assessed by Spearman rank correlation. In addition, stepwise multiple linear regression models were used to select important predictors of measures of spinal anesthesia. RESULTS: There was a significant correlation between CSF density and peak sensory block level (rho = 0.33, P = 0.034). Lumbosacral CSF volume inversely correlated with peak sensory block level (rho = -0.65, P < 0.0001) and positively correlated with onset time of complete motor block (rho = 0.42, P = 0.008). CSF volume also inversely correlated with time required for regression of the sensory block to L1 (rho = -0.35, P = 0.026) and L2 (rho = -0.33, P = 0.039). There was a significant inverse correlation between peak diastolic CSF velocity and duration of motor blockade (rho = -0.44, P = 0.005). Multiple regression analysis revealed that weight and CSF volume significantly contributed to the peak sensory block level (R2 = 0.46). CONCLUSIONS: These findings indicate that CSF density and volume influence the spread of spinal anesthesia with plain bupivacaine and that CSF volume also influences the duration of spinal anesthesia. CSF velocity might also influence the duration of plain bupivacaine spinal anesthesia.     

Influence of Lumbosacral Cerebrospinal Fluid Density, Velocity, and Volume on Extent and Duration of Plain Bupivacaine Spinal Anesthesia

Background: The current study was designed to investigate the influence of lumbosacral cerebrospinal fluid (CSF) density, velocity, and volume on the extent and duration of plain bupivacaine spinal anesthesia.

Methods: Forty-one patients scheduled to undergo orthopedic surgery with spinal block were enrolled. Lumbosacral CSF volumes were calculated from low thoracic, lumbar, and sacral axial magnetic resonance images. CSF velocity at the L3-L4 level was derived from phase-contrast magnetic resonance images. Spinal anesthesia was performed in the lateral decubitus position. CSF (2 ml) was sampled to measure CSF density before injection of 3 ml plain bupivacaine (0.5%). Statistical correlation coefficients ([rho]) between CSF characteristics and measurements of spinal anesthesia were assessed by Spearman rank correlation. In addition, stepwise multiple linear regression models were used to select important predictors of measures of spinal anesthesia.

Results: There was a significant correlation between CSF density and peak sensory block level ([rho] = 0.33, P = 0.034). Lumbosacral CSF volume inversely correlated with peak sensory block level ([rho] = -0.65, P < 0.0001) and positively correlated with onset time of complete motor block ([rho] = 0.42, P = 0.008). CSF volume also inversely correlated with time required for regression of the sensory block to L1 ([rho] = -0.35, P = 0.026) and L2 ([rho] = -0.33, P = 0.039). There was a significant inverse correlation between peak diastolic CSF velocity and duration of motor blockade ([rho] = -0.44, P = 0.005). Multiple regression analysis revealed that weight and CSF volume significantly contributed to the peak sensory block level (R2 = 0.46).     

Spinal 2-chloroprocaine: a comparison with small-dose bupivacaine in volunteers

Ambulatory surgery continues to increase nationwide. Because spinal lidocaine is associated with transient neurologic symptoms, many clinicians have switched to small-dose bupivacaine for outpatient spinal anesthesia. However, bupivacaine often produces inadequate surgical anesthesia and has an unpredictable duration. Preservative-free 2-chloroprocaine (2-CP) has reemerged as an alternative for outpatient spinal anesthesia. We designed this double-blind, randomized, crossover, volunteer study to compare 40 mg of 2-CP with small-dose (7.5 mg) bupivacaine with measures of pinprick anesthesia, motor strength, tolerance to tourniquet and electrical stimulation, and simulated discharge criteria. Peak block height (2-CP average T7 [range T3-10]; bupivacaine average T9 [range T4-L1]), regression to L1 (2-CP 64 +/- 10 versus bupivacaine 87 +/- 41 min), and tourniquet tolerance (2-CP 52 +/- 11 versus bupivacaine 60 +/- 27 min) did not differ between drugs (P = 0.15, 0.12, and 0.40, respectively). However, time to simulated discharge (including time to complete block regression, ambulation, and spontaneous voiding) was significantly longer with bupivacaine (2-CP 113 +/- 14, bupivacaine 191 +/- 30 min, P = 0.0009). No subjects reported transient neurologic symptoms or other side effects. We conclude that spinal 2-CP provides adequate duration and density of block for ambulatory surgical procedures, and has significantly faster resolution of block and return to ambulation compared with 7.5 mg of bupivacaine.     

Isobaric versus hypobaric spinal bupivacaine for total hip arthroplasty in the lateral position

Total hip arthroplasty (THA) is frequently performed under spinal anesthesia using either isobaric or hypobaric anesthetic solution. However, these two solutions have never been compared under similar surgical conditions. In the present study, we compared the anesthetic and hemodynamic effects of isobaric and hypobaric bupivacaine in 40 ASA physical status I-II patients undergoing THA in the lateral decubitus position under spinal anesthesia. With operative side up, patients randomly received, in a double-blinded manner, a spinal injection of 3.5 mL (17.5 mg) of plain bupivacaine mixed with either 1.5 mL of normal saline (isobaric group) or 1.5 mL of distilled water (hypobaric group). Sensory level and degree of motor block were evaluated on the nondependent and dependent sides until regression to L2 and total motor recovery. Hemodynamic changes during the first 45 min after spinal injection, and the time between spinal administration and first analgesic for a pain score >3 (on a 0-10 scale) were noted. Demographic characteristics of both groups were comparable. Upper sensory level and maximal degree of motor block were comparable between the operative and nonoperative sides in each group and between corresponding sides in both groups. Compared with the isobaric group, in the hypobaric group there was a prolonged time to sensory regression to L2 on the operative side (287 +/- 51 versus 242 +/- 36 min, P < 0.004) and a prolonged time to first analgesic (290 +/- 46 versus 237 +/- 39 min, P < 0.001). No difference in quality of motor block was noted at the end of surgery. Hemodynamic changes were comparable. We conclude that for THA in the lateral position, spinal hypobaric bupivacaine seems to be superior to isobaric in that it prolongs the sensory block on the operative side and delays the use of analgesics after surgery without further compromising hemodynamic stability. IMPLICATIONS: For total hip arthroplasty in the lateral position, spinal hypobaric bupivacaine compared with isobaric prolonged sensory block at the operative side and delayed the time to first analgesic.     

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.     

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.     

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.     

A comparison of epidural levobupivacaine 0.75% with racemic bupivacaine for lower abdominal surgery

Levobupivacaine, the S(-) isomer of bupivacaine, is less cardiotoxic than racemic bupivacaine. In this prospective, randomized, double-blinded study of epidural anesthesia, the onset, extent, and duration of sensory and motor block produced by 0.75% levobupivacaine (20 mL, 150 mg) was compared with that of 0.75% racemic bupivacaine in 56 patients undergoing elective lower abdominal surgery. The time to onset of adequate sensory block (T10 dermatome) was similar in both treatment groups (13.6 +/- 5.6 min for levobupivacaine and 14.0 +/- 9.9 min for bupivacaine), with an average peak block height of T5 reached at 24.3 +/- 9.4 and 26.5 +/- 13.2 min, respectively. Time to complete regression of sensory block was significantly longer with levobupivacaine (550.6 +/- 87.6 min) than bupivacaine (505.9 +/- 71.1 min) (P = 0.016). Abdominal muscle relaxation was adequate for the scheduled procedure in all patients, and there were no significant differences between the groups in rectus abdominis muscle scores (P = 0.386) and quality of muscle relaxation as determined by the surgeon and anesthesiologist (P = 0. 505 and 0.074, respectively). In conclusion, both 0.75% levobupivacaine and 0.75% bupivacaine produced effective epidural anesthesia and their effects were clinically indistinguishable. Implications: The results of this study indicate that the sensory and motor block produced by 0.75% levobupivacaine is equivalent to that of 0.75% racemic bupivacaine. Both local anesthetics are well tolerated and effective in producing epidural anesthesia for patients undergoing lower abdominal surgery.     

Combined spinal-epidural anesthesia using epidural volume extension leads to faster motor recovery after elective cesarean delivery: a prospective, randomized, double-blind study

Epidural volume extension (EVE) via a combined spinal-epidural (CSE) technique is the enhancement of a small-dose intrathecal block by epidural saline boluses. In this prospective, randomized, double-blind study, we compared the EVE technique with single-shot spinal anesthesia with respect to its sensory and motor block profile and hemodynamic stability. Sixty-two parturients (n = 31 in each group) undergoing elective cesarean deliveries were administered either spinal anesthesia with hyperbaric 0.5% bupivacaine 9 mg and fentanyl 10 microg or CSE comprising intrathecal hyperbaric 0.5% bupivacaine 5 mg with fentanyl 10 microg, followed by 0.9% saline 6.0 mL through the epidural catheter 5 min thereafter. In each group, the lowest systolic blood pressure (SBP), sensory block level to loss of pain from pinprick, and modified Bromage scores were recorded at 2.5-min intervals. The visual analog pain score (VAS), peak sensory block height, highest modified Bromage motor score, time for sensory regression to the tenth thoracic dermatome (T10), and motor block recovery were compared between groups. Both groups were comparable in demographic data, VAS scores, peak sensory block height, time for sensory regression to T10, and lowest SBP recorded. Patients in the EVE group demonstrated significantly faster motor recovery to modified Bromage 0 (73 +/- 33 min versus 136 +/- 32 min, P < 0.05). IMPLICATIONS: When compared with conventional, single-shot spinal anesthesia, epidural volume extension of a small-dose spinal block provides satisfactory anesthesia for cesarean delivery with only 55% of the bupivacaine dose required and is associated with faster motor recovery of the lower limbs.     

Spinal 2-chloroprocaine: a comparison with procaine in volunteers

Recent studies using preservative-free 2-chloroprocaine (2-CP) for spinal anesthesia have shown it to be a reliable short-acting drug that provides similar anesthesia to lidocaine. In this randomized, double-blind, crossover study, we compared the characteristics of spinal 2-CP (30 mg) with those of procaine (80 mg) in eight volunteers to determine whether either drug produces spinal anesthetic characteristics ideal for outpatient surgery. By using sensation to pinprick, transcutaneous electrical stimulation, tolerance to thigh tourniquet, and motor blockade as surrogates for surgical efficacy, 2-CP compared similarly to procaine. Peak block height (T9 [range, T6 to T12] versus T6 [T4 to T8]; P = 0.0796), time to two-segment regression (51 +/- 17 min versus 53 +/- 10 min; P = 0.7434), tourniquet time tolerance (37 +/- 16 versus 49 min +/- 17 min; P = 0.1755), and time to return of motor strength (Bromage scale: 54 +/- 23 min versus 55 +/- 44 min, P = 0.9366; return of 90% quadriceps strength: 78 +/- 9 min versus 98 +/- 30 min; P = 0.0721) were all similar. Procaine did produce overall longer sensory blockade (P = 0.0011) and motor blockade at the gastrocnemius (P = 0.0004) and quadriceps (P = 0.0146) muscles. Times until the resolution of sensory blockade (103 +/- 12 min versus 151 +/- 26 min; P = 0.0003), ambulation (103 +/- 12 min versus 151 +/- 26 min; P = 0.0003), and micturition (103 +/- 12 min versus 156 +/- 23 min; P < 0.0001) were all prolonged after procaine. In conclusion, at the doses tested, spinal 2-CP (30 mg) may be a better choice for short outpatient procedures because it provides anesthesia with similar efficacy as procaine (80 mg) but with more rapid fulfillment of discharge criteria.     

Randomized double-blind comparison of ropivacaine-fentanyl and bupivacaine-fentanyl for spinal anaesthesia for urological surgery

BACKGROUND: Early studies have suggested that ropivacaine causes less motor block than bupivacaine, which might be advantageous in spinal anaesthesia for short procedures. The aim of this study was to compare plain ropivacaine 10 mg and plain bupivacaine 10 mg, both with fentanyl 15 microg, for spinal anaesthesia in urological surgery. Methods: This was a prospective randomized double-blind study. After written informed consent had been obtained, 34 ASA I-III patients scheduled for urological surgery were randomly assigned to receive intrathecal injection of either plain ropivacaine 10 mg with fentanyl 15 microg (ropivacaine group) or plain bupivacaine 10 mg with fentanyl 15 microg (bupivacaine group) using a combined spinal-epidural technique. RESULTS: All patients achieved sensory block to the T10 dermatome or higher at 15 min after intrathecal injection. One patient in the ropivacaine group was excluded because of unexpectedly prolonged surgery. The primary outcome, the duration of motor block, was shorter in the ropivacaine group (median, 126 min; interquartile range, 93-162 min) compared with the bupivacaine group (median, 189 min; interquartile range, 157-234 min; difference between medians, 71 min; 95% confidence interval, 28-109 min; P = 0.003). The duration of complete motor block was also shorter in the ropivacaine group compared with the bupivacaine group. There was no difference in the onset time of motor block. The characteristics of sensory block and the haemodynamic changes were similar between the groups. CONCLUSION: Plain ropivacaine 10 mg plus fentanyl 15 microg provided similar sensory anaesthesia, but with a shorter duration of motor block, compared with plain bupivacaine 10 mg plus fentanyl 15 microg when used for spinal anaesthesia in urological surgery.     

A double-blind comparison of intrathecal S(+) ketamine and fentanyl combined with bupivacaine 0.5% for Caesarean delivery

BACKGROUND: In this prospective, randomized, double-blind, controlled study, we investigated the sensory, motor and analgesic block characteristics of S(+) ketamine, fentanyl and saline given intrathecally (IT) in addition to 0.5% plain bupivacaine (10 mg) for spinal analgesia. METHODS: Ninety ASA I or II adult patients undergoing Caesarean section were randomly allocated to receive 1.0 mL of 0.9% saline in Group S (n = 30), 0.05 mg kg-1 of S(+) ketamine (1.0 mL) in Group K (n =30) or 25 microg (1.0 mL) of fentanyl in Group F (n =30) following 10 mg of plain bupivacaine 0.5% IT. We recorded onset and duration of sensory and motor block, time to reach the maximal dermatomal level of sensory block and duration of spinal analgesia. RESULTS: The onset time of sensory and motor block was significantly shorter in Groups K and F than in Group S (P < 0.014). Their duration was significantly longer in Group F than in Groups K and S (P < 0.009). The time to reach the maximal dermatomal level of sensory block was significantly shorter in Groups K and F than in Group S (P < 0.001). The duration of spinal analgesia was significantly longer in Group F than in Groups K and S (P < 0.001). CONCLUSION: In patients undergoing Caesarean section with spinal analgesia, the addition of S(+) ketamine (0.05 mg kg-1) IT to 10 mg of spinal plain bupivacaine (0.5%) led to rapid onset of both sensory and motor blockade and enhanced the segmental spread of spinal block without prolonging the duration of spinal analgesia, whereas fentanyl provided prolonged analgesia.     

Unilateral bupivacaine spinal anesthesia for outpatient knee arthroscopy

PURPOSE: To compare unilateral and conventional bilateral bupivacaine spinal block in outpatients undergoing knee arthroscopy. METHODS: One hundred healthy, premedicated patients randomly received conventional bilateral (n = 50) or unilateral (n = 50) spinal anesthesia with 8 mg hyperbaric bupivacaine 0.5%. A lateral decubitus position after spinal injection was maintained in unilateral group for 15 min. Times from spinal injection to readiness for surgery, block resolution, and home discharge were recorded. RESULTS: Three patients in each group were excluded due to failed block. Readiness for surgery required 13 min (5 - 25 min) with bilateral and 16 min (15 - 30) with unilateral spinal block (P = 0.0005). Sensory and motor blocks on the operated limb were T9 (T12 - T2) with a Bromage score 0/1/2/3: 0/2/0/45 in the unilateral group and T7 (T12 - T1) with Bromage score 0/1/2/3: 4/1/6/36 with bilateral block(P = 0.026 and P = 0.016, respectively). Vasopressor was required only in five bilateral patients (P = 0.02). Two segment regression of sensory level and home discharge required 81+/-25 min and 281+/-83 min with bilateral block, and 99+/-28 min and 264+/-95 min with unilateral block (P = 0.002 and P = 0.90, respectively). CONCLUSION: Seeking unilateral distribution of spinal anesthesia provided more profound and longer lasting block in the operated limb, less cardiovascular effects, and similar home discharge compared with bilateral spinal anesthesia, with only a slight delay in preparation time.     

Does the use of low dose bupivacaine/opioid epidural infusion increase the normal delivery rate?

To investigate whether using low dose epidural infusion improves the normal delivery rate, outcome of labour was studied in women with singleton vertex presentations randomised to receive either 0.0625% bupivacaine opioid, or plain bupivacaine 0.125% for labour. The infusion rate was titrated to maintain analgesia and a sensory level to T10. Data were analysed using the unpaired t test, Mann-Whitney U test and for categorical variables chi2 test. Adjusted odds ratios for factors significantly associated with non-normal delivery were calculated using stepwise logistic regression. There were 291 women in the low dose and 296 in the plain bupivacaine group. There were no significant differences between groups in parity, race, induction of labour, use of augmentation, cervical dilatation at epidural insertion, duration of any stage of labour or duration or volume of infusion. Total dose of bupivacaine (126 +/- 47 mg versus 91 +/- 32 mg) and the proportion of women with motor block at the end of labour (45% versus 27%) were significantly greater in the plain bupivacaine than in the low dose group (P < 0.0001). The adjusted odds ratios (95% CI) for factors significantly associated with non-normal delivery were primiparity: 4.68 (2.78-7.88), older maternal age: 1.1 (1.05-1.14), longer active second stage of labour: 1.01 (1.005-1.017), total bupivacaine dose: 1.01 (1.005-1.016) and greater cervical dilatation at epidural insertion 1.22 (1.08-1.37). Treatment group and motor block at the end of labour had no significant effect. We found no increase in normal delivery rate with low dose infusions.     

Spinal 2-chloroprocaine: a comparison with lidocaine in volunteers

Subarachnoid lidocaine has been the anesthetic of choice for outpatient spinal anesthesia. However, its use is associated with transient neurologic symptoms (TNS). Preservative-free formulations of 2-chloroprocaine are now available and may compare favorably with lidocaine for spinal anesthesia. In this double-blinded, randomized, crossover study, we compared spinal chloroprocaine and lidocaine in 8 volunteers, each receiving 2 spinal anesthetics: 1 with 40 mg 2% lidocaine and the other with 40 mg 2% preservative-free 2-chloroprocaine. Pinprick anesthesia, tolerance to transcutaneous electrical stimulation and thigh tourniquet, motor strength, and a simulated discharge pathway were assessed. Chloroprocaine produced anesthetic efficacy similar to lidocaine, including peak block height (T8 [T5-11] versus T8 [T6-12], P = 0.8183) and tourniquet tolerance (46 +/- 6 min versus 38 +/- 24 min, P = 0.4897). Chloroprocaine anesthesia resulted in faster resolution of sensory (103 +/- 13 min versus 126 +/- 16 min, P = 0.0045) and more rapid attainment of simulated discharge criteria (104 +/- 12 min versus 134 +/- 14 min, P = 0.0007). Lidocaine was associated with mild to moderate TNS in 7 of 8 subjects; no subject complained of TNS with chloroprocaine (P = 0.0004). We conclude that the anesthetic profile of chloroprocaine compares favorably with lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects make chloroprocaine an attractive choice for outpatient spinal anesthesia. IMPLICATIONS: The spinal anesthetic profile of chloroprocaine (40 mg) compares favorably with the same dose of spinal lidocaine. Reliable sensory and motor blockade with predictable duration and minimal side effects and without signs of transient neurological symptoms make chloroprocaine an attractive choice for outpatient spinal anesthesia.     

Hyperbaric bupivacaine 2.5 mg prolongs analgesia compared with plain bupivacaine when added to intrathecal fentanyl 25 microg in advanced labor

We investigated the effect of sequential administration of intrathecal (IT) hyperbaric bupivacaine (after the initial administration of IT hypobaric fentanyl) on the duration of spinal analgesia. Thirty-seven nulliparous parturients with a cervical dilation >/= 5 cm were randomized to receive either IT fentanyl 25 micro g and plain bupivacaine 2.5 mg (group P; n = 19) or IT fentanyl 25 micro g and hyperbaric (with 8% glucose) bupivacaine 2.5 mg (group H; n = 18). The two components of the IT injectate were administered sequentially (fentanyl 25 micro g diluted in 2 mL of normal saline, immediately followed by 0.5 mL of 0.5% bupivacaine). Patients were then positioned with their torso elevated at 30 degrees for 30 min. Pain scores using 0-100 visual analog scales were collected before combined spinal/epidural analgesia and at 5, 15, and 30 min after the block. Patients in Group H had a longer median duration of analgesia (122 min; range, 80-210 min) than Group P (95 min; range, 75-125 min) (P < 0.01). Group H also had a more limited dermatomal spread (median highest sensory level of T8 versus T4 in group P; P < 0.05). The side-effect profile was similar. Under these circumstances, hyperbaric bupivacaine conferred an increased duration of IT analgesia compared with plain bupivacaine.     

Effect of low-dose dexmedetomidine or clonidine on the characteristics of bupivacaine spinal block

BACKGROUND: The purpose of this study was to compare the onset and duration of sensory and motor block, as well as the hemodynamic changes and level of sedation, following intrathecal bupivacaine supplemented with either dexmedetomidine or clonidine. METHODS: In a prospective, double-blind study, 60 patients undergoing transurethral resection of prostate or bladder tumor under spinal anesthesia were randomly allocated to one of three groups. Group B received 12 mg of hyperbaric bupivacaine, group D received 12 mg of bupivacaine supplemented with 3 microg of dexmedetomidine and group C received 12 mg of bupivacaine supplemented with 30 microg of clonidine. The onset times to reach peak sensory and motor levels, and the sensory and motor regression times, were recorded. Hemodynamic changes and the level of sedation were also recorded. RESULTS: Patients in groups D and C had a significantly shorter onset time of motor block and significantly longer sensory and motor regression times than patients in group B. The mean time of sensory regression to the S1 segment was 303 +/- 75 min in group D, 272 +/- 38 min in group C and 190 +/- 48 min in group B (B vs. D and B vs. C, P < 0.001). The regression of motor block to Bromage 0 was 250 +/- 76 min in group D, 216 +/- 35 min in group C and 163 +/- 47 min in group B (B vs. D and B vs. C, P < 0.001). The onset and regression times were not significantly different between groups D and C. The mean arterial pressure, heart rate and level of sedation were similar in the three groups intra-operatively and post-operatively. CONCLUSIONS: Dexmedetomidine (3 microg) or clonidine (30 microg), when added to intrathecal bupivacaine, produces a similar prolongation in the duration of the motor and sensory block with preserved hemodynamic stability and lack of sedation.     

Hyperbaric spinal for elective Cesarean section--ropivacaine vs bupivacaine

PURPOSE: To compare hyperbaric spinal ropivacaine to hyperbaric spinal bupivacaine for elective cesarean delivery in a prospective, randomized, double blinded study. METHODS: With the University Ethics Committee approval, 66 parturients for elective cesarean deliveries received either 15 mg of hyperbaric ropivacaine (N = 33) or 11.25 mg of hyperbaric bupivacaine (N - 33) with 0.1 mg of preservative-free morphine and 0.01 mg fentanyl. The sensory and motor blockades were assessed at 3, 6, and 9 min after injection. The APGAR scores, umbilical cord gases, intra-operative side effects and the total duration of motor and sensory blockade, were recorded. RESULTS: The two groups had similar demographics, and similar times for sensory block to T6 and Bromage score 3 motor blockade. The median levels of sensory blockade were T3 and T2 for the ropivacaine and bupivacaine groups respectively. Duration of sensory block was shorter in the ropivacaine group (174 +/- 24 min vs 217 +/- 46 min; P < 0.001). Duration of motor block was shorter in the ropivacaine group (85 +/- 26 vs 159 +/- 56 min; P < 0.001). The obstetricians rated intra-operative anesthesia as excellent in both groups. None of neonates had Apgar scores less than 7. There was no difference in cord gases between the two groups. Side effects did not differ between the two groups. The ropivacaine patients expressed significantly higher satisfaction levels (P < 0.016). DISCUSSION: 15 mg of hyperbaric ropivacaine with 0.1 mg morphine and 0.01 mg fentanyl provided excellent anesthesia for cesarean delivery. The advantages of hyperbaric ropivacaine consist of faster regression of the block and higher patient satisfaction.