Post cardiac arrest therapeutic hypothermia in adult patients, state of art and practical considerations.

The importance of therapeutic hypothermia in selected categories of patients has been widely demonstrated. Laboratory, animal, and human studies permitted to understand the molecular mechanisms underlying cooling and its importance in preventing the ischemia/reperfusion injury of the brain. The development of new technologies offered the possibility to reach the desired temperature effectively and rapidly, reducing related side effects. Nevertheless, the application of systematic protocols of cooling has not been adequately reached in many hospitals. In this paper the most recent findings regarding hypothermia, its physiological bases and ways of application are reviewed.

The effects of single or multiple injections on the volume of 0.5% ropivacaine required for femoral nerve blockade.

UNLABELLED: We compared the effects of using a single- or multiple-injection technique on the volume of 0.5% ropivacaine required to block the femoral nerve, in a prospective, randomized, blinded fashion in which 50 premedicated patients received a femoral nerve block with 0.5% ropivacaine by use of a nerve stimulator and either a single- (n = 25) or multiple- (n = 25) injection technique. Muscular twitches were elicited at < or =0.5 mA before anesthetic injection. The designated volume of local anesthetic was equally divided among contraction of the vastus medialis, vastus intermedius, and vastus lateralis for the multiple injections, or it was injected at the contraction of the vastus intermedius with motion of the patella for the single injection. The local anesthetic volumes were varied for consecutive patients by using an up-and-down staircase method; a blinded observer determined the adequacy of nerve blockade (loss of pinprick sensation in the medial, patellar, and lateral portions of the knee, with concomitant block of the quadriceps muscle) 20 min after injection. The mean (95% confidence interval) volume required for blocking the femoral nerve with the multiple-injection technique (14 [12-16] mL) was significantly smaller than that observed with the single injection (23 [20-26] mL) (P = 0.001). According to logistic regression analyses, the 95% effective volumes of ropivacaine required to block the femoral nerve within 20 min after injection were 29 and 21 mL with a single or multiple injection, respectively. We conclude that searching for multiple muscular twitches reduces the volume of 0.5% ropivacaine required to produce blockade of the femoral nerve. IMPLICATIONS: We evaluated the effects of using a single- or multiple-injection technique on the volume of 0.5% ropivacaine required to block the femoral nerve. The 95%effective concentration values for producing the same degree of sensory and motor blockade of the femoral nerve within 20 min after injection were 29 mL after elicitation of a patella twitch and 21 mL when the three main branches of the femoral nerve were identified, potentially leading to an important benefit for patients receiving peripheral nerve blocks.

Improving postoperative analgesia after axillary brachial plexus anesthesia with 0.75% ropivacaine. A double-blind evaluation of adding clonidine.

BACKGROUND: The aim of this prospective, randomized, double-blind study was to evaluate the effects of adding 1 microg/kg clonidine to 20 ml of ropivacaine 0.75% for axillary brachial plexus anesthesia. METHODS: With Ethical Committee approval and written consent, 30 ASA physical status I-II in-patients, undergoing upper extremity orthopedic procedures were randomly allocated to receive axillary brachial plexus block with 20 ml of 0.75% ropivacaine alone (group ropivacaine, n = 15) or 0.75% ropivacaine + 1 microg/kg clonidine (group ropivacaine-clonidine, n = 15). Nerve blocks were placed using a nerve stimulator with the multiple injection technique (stimulation frequency was 2 Hz; stimulation intensity was decreased to < or = 0.5 mA after each muscular twitch; the anesthetic volume was equally divided among arm flexion, arm extension, wrist flexion, and thumb adduction). A blinded observer recorded the time required to achieve surgical block [loss of pinprick sensation in the innervation areas of the hand (C6-C8) with concomitant inability to move the wrist and hand] and first analgesic request. RESULTS: No differences in demography, degree of sedation, peripheral oxygen saturation, and hemodynamic variables were observed between the two groups. Readiness for surgery required 15 min (5-36 min) with 0.75% ropivacaine and 20 min (5-30 min) with the ropivacaine-clonidine mixture. The degree of pain measured at first analgesic request, and consumption of postoperative analgesics were similar in the two groups; while first postoperative analgesic request occurred after 13.8 h (25th-75th percentiles: 9.1-13 h) in the ropivacaine group and 15.2 h (25th-75th percentiles: 10.7-16 h) in the ropivacaine-clonidine group (p = 0.04). CONCLUSIONS: Adding 1 microg/kg clonidine to 20 ml of ropivacaine 0.75% for axillary brachial plexus anesthesia provided a 3 h delay in first analgesic request postoperatively, without clinically relevant effects on the degree of sedation and cardiovascular homeostasis.

Interscalene brachial plexus anaesthesia with small volumes of ropivacaine 0.75%: effects of the injection technique on the onset time of nerve blockade.

BACKGROUND AND AIM: We evaluated the effect of the injection technique on the onset time and efficacy of interscalene brachial plexus anaesthesia. METHODS: With Ethical Committee approval and written consent, 30 patients undergoing elective shoulder acromioplasty or capsuloplasty were randomly allocated to receive interscalene brachial plexus block with 20 mL of ropivacaine 0.75% by using either a single injection (Single group, n = 15) or multiple injection (Multiple group, n = 15). Nerve blocks were placed with the aid of a nerve stimulator using short bevelled, Teflon coated needles. The stimulation frequency was set at 2 Hz and the intensity of stimulating current, initially set at 1 mA, was gradually decreased to < or = 0.5 mA after each muscular twitch was observed. In the Single group, the anaesthetic solution was slowly injected after the first muscular twitch had been observed. In the Multiple group, 8 mL were injected at shoulder abduction, 6 mL were injected at arm flexion, and 6 mL at the extension of the arm. RESULTS: Placing the block required 5 min (4-8 min) in the Multiple group and 3 min (1-10 min) in the Single group (P = 0.001); however, total preoperative time (from skin disinfection to complete loss of pinprick sensation from C4 to C7 with inability to elevate the limb from the operating table) was shorter in the Multiple group (15 min; range 10-28 min) than in the Single group (23 min; range 14-60 min) (P = 0.03). Additional intravenous fentanyl supplementation was required in two patients of the Multiple group (13%) and eight patients of the Single group (53%) (P = 0.05). CONCLUSION: We conclude that using a multiple injection technique shortened the preparation time and improved the quality of interscalene brachial plexus anaesthesia performed with small volumes of ropivacaine 0.75%.

Minimum local anesthetic volume blocking the femoral nerve in 50% of cases: a double-blinded comparison between 0.5% ropivacaine and 0.5% bupivacaine.

UNLABELLED: Recent studies demonstrated that ropivacaine was nearly 40% less potent than bupivacaine in the first stage of labor, but contrasting results have been reported. We, therefore, conducted a prospective, randomized, double-blinded study to determine the effects of the ropivacaine/bupivacaine potency ratio on the minimum volume of local anesthetic required to produce effective block of the femoral nerve in 50% of patients. Fifty adults premedicated with IV midazolam, 0.05 mg/kg, undergoing elective knee arthroscopy received femoral nerve blocks with a multiple-injection technique with a nerve stimulator (contractions of vastus medialis, vastus intermedius, and vastus lateralis were elicited with a 0.5-mA stimulating current). Patients randomly received either 0.5% ropivacaine (n = 25) or 0.5% bupivacaine (n = 25). The anesthetic volume was decided according to Dixon's up-and-down method, starting from 12 mL and being equally divided among the three elicited twitches. Successful nerve block was loss of pinprick sensation in the femoral nerve distribution with concomitant block of the quadriceps muscle within 20 min after injection, as assessed by a blinded observer. Positive or negative responses determined a 3-mL decrease or increase for the next patient, respectively. According to the up-and-down sequences, the minimum local anesthetic volume providing successful nerve block in 50% of cases was 14 +/- 2 mL in the ropivacaine group (95% CI: 12-16 mL) and 15 +/- 2 mL (95% CI: 13-17 mL) in the bupivacaine group (P: = 0.155). We conclude that the volume of 0.5% ropivacaine required to produce effective block of the femoral nerve in 50% of patients is similar to that required when using 0.5% bupivacaine. IMPLICATIONS: Considering the risk for drug-related systemic toxicity, the equipotency ratio between ropivacaine and bupivacaine is crucial for daily practice. Despite the 40% reduction in the analgesic potency of ropivacaine reported during epidural analgesia for labor pain, results of this prospective, randomized, double-blinded study demonstrated that the same volume of 0.5% ropivacaine or 0.5% bupivacaine is required to produce an effective block of the femoral nerve in 50% of cases.

Combined spinal-epidural anaesthesia for Caesarean section in a paraplegic woman: difficulty in obtaining the expected level of block.

We describe the satisfactory use of combined spinal epidural (CSE) anaesthesia in the management of a 29-year-old paraplegic woman, with a spinal cord lesion at the T7 level, suffering from episodes of autonomic hyper-reflexia, during elective Caesarean section.

Small-dose clonidine prolongs postoperative analgesia after sciatic-femoral nerve block with 0.75% ropivacaine for foot surgery.

UNLABELLED: To evaluate the effects of adding small-dose clonidine to 0.75% ropivacaine during peripheral nerve blocks, 30 ASA physical status I and II patients undergoing hallux valgus repair under combined sciatic-femoral nerve block were randomly allocated in a double-blinded fashion to receive block placement with 30 mL of either 0.75% ropivacaine alone (group Ropivacaine, n = 15) or 0.75% ropivacaine plus 1 microg/kg clonidine (group Ropivacaine-Clonidine, n = 15). Hemodynamic variables, oxygen saturation, and levels of sedation, as well as the time required to achieve surgical block and time to first analgesic request, were recorded by a blinded observer. Time to surgical blockade required 10 min in both groups. Patients in the Ropivacaine-Clonidine group were more sedated than patients in the Ropivacaine group only 10 min after block placement. No differences in oxygen saturation and hemodynamic variables, degree of pain measured at first analgesic request, and consumption of postoperative analgesics were observed between the two groups. The mean time from block placement to first request for pain medication was shorter in group Ropivacaine (13.7 h; 25th-75th percentiles: 11. 8-14.5 h) than in group Ropivacaine-Clonidine (16.8 h; 25th-75th percentiles: 13.5-17.8 h) (P = 0.038). We conclude that adding 1 microg/kg clonidine to 0.75% ropivacaine provided a 3-h delay in first request for pain medication after hallux valgus repair, with no clinically relevant side effects. IMPLICATIONS: This prospective, randomized, double-blinded study demonstrated that, when providing combined sciatic-femoral nerve block for hallux valgus repair, the addition of 1 microg/kg clonidine to 0.75% ropivacaine prolongs the duration of postoperative analgesia by 3 h, with only a slight and short-lived increase in the degree of sedation and no hemodynamic adverse effects.

The effects of the single or multiple injection technique on the onset time of femoral nerve blocks with 0.75% ropivacaine.

UNLABELLED: We evaluated the effect of the injection technique on the onset time and efficacy of femoral nerve block performed with 0.75% ropivacaine. A total of 30 patients undergoing arthroscopic knee surgery were randomly allocated to receive femoral nerve blockade with 0.75% ropivacaine by using either a single injection (Single group, n = 15) or multiple injection (Multiple group, n = 15). Nerve blocks were placed by using a short-beveled, Teflon-coated, stimulating needle. The stimulation frequency was set at 2 Hz, and the intensity of stimulating current, initially set at 1 mA, was gradually decreased to <0.5 mA after each muscular twitch was observed. In the Single group, 12 mL of 0.75% ropivacaine was slowly injected, as soon as the first muscular twitch was observed. In the Multiple group, the stimulating needle was inserted and redirected, eliciting each of the following muscular twitches: contraction of vastus medialis, vastus intermedius, and vastus lateralis. At each muscular twitch, 4 mL of the study solution was injected. Placing the block required 4.2 +/- 1.7 min (median, 5 min; range, 2-8 min) in the Multiple group and 3.4 +/- 2.2 min (median, 3 min; range, 1-5 min) in the Single group (P = 0.02). Onset of nerve block (complete loss of pinprick sensation in the femoral nerve distribution with concomitant inability to elevate the leg from the operating table with the hip flexed) required 10 +/- 3.7 min in the Multiple group (median, 10 min; range, 5-20 min) and 30 +/- 11 min in the Single group (median, 30 min; range, 10-50 min) (P < 0.0005). Propofol sedation was never required to complete surgery; although 0.1 mg fentanyl at trocar insertion was required in two patients of the Multiple group (13%) and nine patients of the Single group (60%) (P = 0.02). We conclude that searching for multiple muscular twitches shortened the onset time and improved the quality of femoral nerve block performed with small volumes of 0.75% ropivacaine. IMPLICATIONS: This prospective, randomized, blinded study was conducted to evaluate the effect of searching for multiple muscular twitches when performing femoral nerve block with small volumes of 0. 75% ropivacaine. Our results demonstrated that multiple injections markedly shortened the onset time and improved the quality of nerve blockade. This technique-related effect must be carefully considered when different clinical studies evaluating the use of new local anesthetic solutions for peripheral nerve blocks are compared.

Interscalene brachial plexus anesthesia with either 0.5% ropivacaine or 0.5% bupivacaine.

BACKGROUND: To compare intra- and postoperative clinical properties of interscalene brachial plexus block performed with either 0.5% ropivacaine or 0.5% bupivacaine. EXPERIMENTAL DESIGN: prospective, randomized, double-blind study. SETTING: in patient at the University Hospital, Department of Orthopedic Surgery. PATIENTS: 30 ASA physical status I-II patients scheduled for elective shoulder surgery. INTERVENTIONS: interscalene brachial plexus block was performed using the multiple injection technique and a nerve stimulator by injecting 20 ml of either 0.5% ropivacaine (n = 15) or 0.5% bupivacaine (n = 15). Postoperative analgesia consisted of 100 mg intravenous ketoprofen, if required. A blind observer evaluated hemodynamic variables as well as sensory and motor blocks from the end of injection to achieve a surgical anesthesia (readiness for surgery: loss of pinprick sensation from C4 to C7 with the inability to elevate the operated limb against gravity). The time lasting from block placement to first requirement for postoperative pain medication was also recorded. RESULTS: No differences in anthropometric parameters and hemodynamic variables were observed throughout the study, and no signs of central nervous system (CNS) and cardiovascular toxicity, or other untoward events were reported in any patients. Readiness for surgery was obtained after 28 +/- 15 min with 0.5% bupivacaine and 22 +/- 8 min after 0.5% ropivacaine (p = NS). No differences in postoperative pain relief was observed between the two groups (11.1 +/- 5 hrs after 0.5% ropivacaine and 10.9 +/- 3.9 hrs after 0.5% bupivacaine, respectively). CONCLUSIONS: This study confirmed that 0.5% ropivacaine has clinical properties similar to those of 0.5% bupivacaine, when used for interscalene brachial plexus block, providing similarly long duration in postoperative pain relief. Compared with bupivacaine, ropivacaine has the further advantage of a lower potential for central nervous system and cardiovascular toxicity.

The pressor response after laryngeal mask or cuffed oropharyngeal airway insertion.

BACKGROUND: Since the cuffed oropharyngeal airway (COPA) has been suggested to cause less pharyngeal trauma than the laryngeal mask airway (LMA), we conducted a prospective, randomised study to compare haemodynamic changes after placing either the COPA or LMA in healthy anaesthetised adults. METHODS: After standard midazolam premedication (0.05 mg kg(-1) IV), general anaesthesia (IV propofol 2 mg kg(-1)) was induced in 60 ASA physical status I-II, 18-65-yr-old patients, who were randomly allocated to receive COPA (n=30) or LMA (n= 30) placement and then mechanically ventilated using a 60% nitrous oxide and 1% isoflurane in oxygen mixture (TV=8 ml kg(-1), RR=12 b.p.m., I/E=1/2). Haemodynamic variables were recorded 20 min after the midazolam premedication (baseline), and then every 1 min until 10 min after general anaesthesia induction. RESULTS: Nine patients of group COPA (30%) required chin lift, jaw thrust or head tilt to maintain adequate ventilation, while no problems were observed in the LMA group (P<0.0005); however, in no case did the designed extratracheal airway have to be removed due to unsuccessful mechanical ventilation, and no signs of gastric insufflation or regurgitation were reported. The maximum mean changes in haemodynamic variables were more marked after LMA placement (SAP: 12%+/-13%; DAP: 11%+/-18%; HR: 13%+/-16%) than COPA placement (SAP: -3%+/-18%; DAP: -5%+/-16%; HR: 4%+/-13%) (P<0.005, P<0.005, and P<0.01 for SAP, DAP and HR, respectively). Group LMA showed higher SAP and DAP values than group COPA only during the first 3 min after airway insertion. CONCLUSION: In healthy, anaesthetised patients, placing a cuffed oropharyngeal airway is associated with smaller cardiovascular changes after airway insertion compared with the laryngeal mask airway.

A clinical comparison of ropivacaine 0.75%, ropivacaine 1% or bupivacaine 0.5% for interscalene brachial plexus anaesthesia.

In order to compare interscalene brachial plexus block performed with ropivacaine or bupivacaine, 45 healthy, unpremedicated patients, undergoing elective shoulder surgery, were randomly allocated to receive interscalene brachial plexus anaesthesia with 20 mL of either ropivacaine 0.75% (n = 15), ropivacaine 1% (n = 15), or bupivacaine 0.5% (n = 15). Readiness for surgery (loss of pinprick sensation from C4 to C7 and inability to elevate the limb from the bed) was achieved later with bupivacaine 0.5% (28 +/- 15 min) than with ropivacaine 1% (10 +/- 5 min) (P = 0.005) and ropivacaine 0.75% (15 +/- 8 min) (P = 0.0005). No differences in success rate were observed between the three groups; however, seven patients receiving bupivacaine 0.5% required intra-operative analgesic supplementation (fentanyl 0.1 mg intravenous) compared with one patient receiving ropivacaine 0.75%, and two patients treated with ropivacaine 1% (P = 0.02). The time from the block placement to first request for pain medication was similar in the three groups (10.7 +/- 2 h, 11 +/- 2.4 h, and 10.9 +/- 3.9 h after 0.75% and 1% ropivacaine or 0.5% bupivacaine, respectively). We conclude that interscalene brachial plexus block performed with 20 mL of either 0.75% or 1% ropivacaine allows for a prolonged post-operative pain relief, similar to that provided by bupivacaine 0.5%, with short onset time of surgical anaesthesia.

Block distribution and cardiovascular effects of unilateral spinal anaesthesia by 0.5% hyperbaric bupivacaine. A clinical comparison with bilateral spinal block.

BACKGROUND: A low dose of hyperbaric local anaesthetic solution, pencil point needle and slow speed of intrathecal injection have been reported to obtain a unilateral distribution of spinal anaesthesia. This should also minimize cardiovascular effects of spinal block. The aim of this prospective, randomized, parallel group study was to evaluate cardiac performance during unilateral subarachnoid block and to compare it with that produced by standard bilateral spinal anaesthesia. METHODS: With Ethic Committee approval and patients' consent we studied 30 ASA I-II patients scheduled for one leg surgery. Dural puncture was performed by 25-G Whitacre needle with patients lying in the lateral position and the side to be operated on dependent. Patients then randomly received 8 mg of 0.5% hyperbaric bupivacaine injected over 80 sec with needle hole orientated towards the dependent side (Unilateral, n = 15), or 15 mg of the same solution injected over 6 sec with needle bevel cranially directed (Control, n = 15). Only patients of the Unilateral group remained in the lateral position for 15 min. Noninvasive Arterial blood pressure, heart rate, stroke volume index and cardiac index were measured before spinal block (baseline) and then at 5, 15, 30 and 45 min; while sensory and motor blocks were evaluated at 15, 30 and 45 min on both sides. RESULTS: Unilateral spinal anaesthesia was observed in 11 patients of the Unilateral group (73%). Three patients of the Control group (20%) required colloids for intraoperative hypotension. Mean arterial blood pressure and heart rate decreased from baseline only in the Control group (p = 0.001 and p = 0.0003 respectively), while heart rate was decreased in Control even when compared to Unilateral group (p = 0.01). The stroke volume index was unchanged in the two groups (p = 0.22), while the cardiac index showed a 15-20% decrease from baseline in Control group (p = 0.001), with a significant decrease at 30 and 45 min when compared to Unilateral (p = 0.01). DISCUSSION: The use of 8 mg of 0.5% hyperbaric bupivacaine slowly injected through a directional needle provided a spinal block relatively restricted to the operative side with minimal effects on cardiovascular homeostasis.

A double-blind comparison of ropivacaine, bupivacaine, and mepivacaine during sciatic and femoral nerve blockade.

UNLABELLED: No study has evaluated the efficacy of ropivacaine in peripheral nerve block of the lower extremity. The purpose of this prospective, randomized, double-blind study was to compare ropivacaine, bupivacaine, and mepivacaine during combined sciatic-femoral nerve block. Forty-five ASA physical status I or II patients scheduled for elective hallux valgus repair with thigh tourniquet were randomized to receive combined sciatic-femoral block with 0.75% ropivacaine (ROPI, n = 15), 0.5% bupivacaine (BUPI, n = 15), and 2% mepivacaine (MEPI, n = 15). Time required for onset of sensory and motor block on the operated limb (readiness for surgery) and resolution of motor block, as well as onset of postsurgical pain and time of first analgesic requirement, were recorded. The three groups were similar with regard to demographic variables, duration of surgery, and measured visual analog pain scores. Onset of sensory and motor blockade was similar in Groups ROPI and MEPI and significantly shorter than in Group BUPI (P = 0.002 and P = 0.001, respectively). Resolution of motor block occurred later in Groups ROPI and BUPI than in Group MEPI (P = 0.005 and P = 0.0001, respectively). Duration of postoperative analgesia was significantly longer in Groups ROPI (670+/-227 min) and BUPI (880+/-312 min) compared with Group MEPI (251+/-47 min) (P = 0.0001), with a significant decrease in postoperative pain medication requirements (P < 0.05). We conclude that for sciatic-femoral nerve block, 0.75% ropivacaine has an onset similar to that of 2% mepivacaine and a duration of postoperative analgesia between that of 0.5% bupivacaine and 2% mepivacaine. IMPLICATIONS: Quick onset of block with prolonged postoperative analgesia is an important goal in peripheral nerve blockade. We evaluated the clinical properties of 0.5% bupivacaine, 2% mepivacaine, and 0.75% ropivacaine for sciatic-femoral nerve block and demonstrated that ropivacaine has an onset similar to that of mepivacaine but allows for postoperative analgesia between that of bupivacaine and mepivacaine.

Cardiovascular effects of two different regional anaesthetic techniques for unilateral leg surgery.

BACKGROUND: Cardiovascular function was assessed in 20 ASA I-II patients, scheduled for elective orthopaedic surgery with tourniquet in order to compare the haemodynamic changes induced by unilateral spinal anaesthesia and combined sciatico-femoral nerve block. METHODS: After baseline measurement of cardiovascular parameters, patients were randomized to receive unilateral spinal anaesthesia or combined sciatico-femoral nerve block. Spinal anaesthesia was obtained by 8 mg of hyperbaric bupivacaine 0.5% slowly injected (speed=0.02 ml s[-1]) through a 25-G Whitacre spinal needle with the bevel orientated towards the dependent side and patients lying on their operated side for 15 min (group S, n=10). Combined sciatico-femoral nerve block was obtained by 7 mg kg(-1) of mepivacaine 2% (group NB, n=10). Haemodynamic variables were recorded 5, 10, 15, and 30 min after anaesthetic injection before surgery was started. RESULTS: Anthropometric data, duration of surgery and acceptability of anaesthetic techniques were similar in the 2 groups. In 8 patients of group S, spinal block was restricted to the operated side (pinprick test and Bromage scale), while the other 2 patients developed bilateral spinal block after being turned supine. NB patients showed no haemodynamic changes during the study, whereas patients in group S showed a small but significant decrease of mean arterial blood pressure (P<0.002 vs baseline and P<0.04 vs NB), cardiac index (P<0.01 vs baseline and P<0.01 vs NB), and stroke volume index (P<0.01 vs baseline and P<0.01 vs NB). CONCLUSION: Both sciatico-femoral and unilateral spinal blockade provide adequate anaesthesia for unilateral leg surgery with tourniquet. The former technique affects cardiovascular performance less than the latter one.

Cardiac performance during unilateral lumbar spinal block after crystalloid preload.

PURPOSE: The haemodynamic effects of crystalloid preload were evaluated in a randomised blind study in 20 ASA status I-II, 50-80 yr-old patients, undergoing unilateral spinal anaesthesia for leg surgery produced with low doses of hyperbaric bupivacaine. METHODS: Baseline non-invasive blood pressure (oscillometry), heart rate, stroke volume and cardiac index (transthoracic electrical bioimpedance) were recorded. Then, patients were randomly allocated to receive 10 ml.kg-1 Ringer's Lactate solution over 20 min (preload group, n = 10) or no crystalloid infusion (no-preload group, n = 10). Spinal block was performed using 8 mg hyperbaric bupivacaine 0.5% injected slowly at the L2-L3 interspace (0.02 ml.sec-1 through a 25-gauge Whitacre needle) with patients lying on their operated side and with the needle opening directed towards the dependent side. Lateral decubitus position was maintained for up to 15 min after anaesthetic injection to facilitate hyperbaric bupivacaine distribution towards dependent regions of the subarachnoid space. Haemodynamic variables were recorded 5, 10, 15 and 30 min after spinal injection, while sensory level and motor block were evaluated 10, 15 and 30 min after anaesthetic injection on both operated and unoperated side. RESULTS: No differences of upper sensory level and motor block were observed between the two groups on the operated and non-operated sides. Diastolic blood pressure was decreased compared with baseline in the no-preload group only (P = .0001). Systolic arterial pressure and heart rate did not change in either group. Stroke volume and cardiac index were decreased in the no-preload group compared with both baseline (P = .02; P = .001) and the preload group (P = .04; P = .02). CONCLUSION: Crystalloid preload influences cardiovascular function during spinal block, and may be useful when very low bupivacaine doses and lateral decubitus are used to achieve unilateral spinal block.

Haemodynamic monitoring during alkalinized lignocaine epidural block: a comparison with subarachnoid anaesthesia.

Cardiovascular responses after epidural alkalinized lignocaine and subarachnoid hyperbaric bupivacaine administration were studied using a non-invasive cardiac output measurement in 32 ASA Grade I-II patients undergoing orthopaedic leg surgery (hip hemi-arthroplasty or Ender nailing). All patients achieved adequate surgical anaesthesia. The block onset time was faster (P = 0.003), and the range of final sensory level wider (P = 0.006) in patients receiving spinal anaesthesia compared with the epidural group. Diastolic arterial pressure was significantly reduced when compared with base-line (P = 0.002) only in the spinal group. No significant changes in stroke volume, systemic vascular resistance or left ventricular stroke work were observed in either group. Heart rate and cardiac index were significantly reduced in the spinal group when compared both with base line (P = 0.002; P = 0.04) and the epidural group (P = 0.001; P = 0.006). The results demonstrated that the block onset time and the cardiovascular effects produced by lumbar epidural anaesthesia, with alkalinized solutions, remain less than after spinal anaesthesia involving the same segments.