Markus C. Schneider

Transient Neurologic Symptoms After Spinal Anesthesia

We recently reported several cases consistent with transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine.The present prospective, blind, nonrandomized study was performed to determine the incidence of these transient neurologic symptoms and to identify factors that might be associated with their occurrence. We studied 270 patients scheduled for gynecologic or obstetric procedures under spinal anesthesia. For spinal anesthesia, either 5% lidocaine in 7.5% glucose or 0.5% bupivacaine in 8.5% glucose was used. Patients were evaluated on postoperative day 3 by a quality assurance nurse who was unaware of the drug given or details of the anesthetic technique. Transient neurologic symptoms were observed in 37% of patients receiving 5% lidocaine, whereas only one patient receiving 0.5% bupivacaine had transient hypesthesia of the lateral aspect of the right foot. These results suggest that symptoms were the result of a specific drug effect. However, because of the limitations of the study one cannot conclude that lidocaine per se was the cause. (Anesth Analg 1995;81:1148-53)

A similar incidence of transient neurologic symptoms after spinal anesthesia with 2% and 5% lidocaine

Recent reports suggest that transient neurologic symptoms are common after spinal anesthesia with 5% lidocaine.To determine whether reducing the anesthetic concentration might decrease the incidence of symptoms, 50 ASA class I or II patients undergoing brief gynecologic procedures under spinal anesthesia were randomly allocated to receive 1 mg/kg of either 5% or 2% lidocaine in 7.5% glucose. Patients were evaluated on the first postoperative day by an anesthesiologist who was unaware of the solution administered or the details of the anesthetic procedure. Symptoms suggestive of transient radicular irritation were observed in 8 patients (32%) receiving 5% lidocaine, and in 10 patients (40%) receiving 2% lidocaine (NS). These results confirm our previous findings that transient neurologic symptoms may occur in up to one third of the patients receiving 5% lidocaine, and indicate that a modest reduction in lidocaine concentration does not reduce risk. (Anesth Analg 1996;83:1051-4)

Transient Neurologic Symptoms after Spinal Anesthesia A Lower Incidence with Prilocaine and Bupivacaine than with Lidocaine

Background Recent evidence suggests that transient neurologic symptoms (TNSs) frequently follow lidocaine spinal anesthesia but are infrequent with bupivacaine. However, identification of a short‐acting local anesthetic to substitute for lidocaine for brief surgical procedures remains an important goal. Prilocaine is an amide local anesthetic with a duration of action similar to that of lidocaine. Accordingly, the present, prospective double‐blind study compares prilocaine with lidocaine and bupivacaine with respect to duration of action and relative risk of TNSs. Methods Ninety patients classified as American Society of Anesthesiologists physical status I or II who were scheduled for short gynecologic procedures under spinal anesthesia were randomly allocated to receive 2.5 ml 2% lidocaine in 7.5% glucose, 2% prilocaine in 7.5% glucose, or 0.5% bupivacaine in 7.5% glucose. All solutions were provided in blinded vials by the hospital pharmacy. Details of spinal puncture, extension and regression of spinal block, and the times to reach discharge criteria were noted. In the evening of postoperative day 1, patients were evaluated for TNSs by a physician unaware of the drug administered and the details of the anesthetic procedure. Results Nine of 30 patients receiving lidocaine experienced TNSs, 1 of 30 patients receiving prilocaine (P = 0.03) had them, and none of 30 patients receiving bupivacaine had TNSs. Times to ambulate and to void were similar after lidocaine and prilocaine (150 vs. 165 min and 238 vs. 253 min, respectively) but prolonged after bupivacaine (200 and 299 min, respectively; P < 0.05). Conclusions Prilocaine may be preferable to lidocaine for short surgical procedures because it has a similar duration of action but a lower incidence of TNSs.

Repeated dural punctures increase the incidence of postdural puncture headache.

Previous studies have failed to find a significant correlation between the number of dural punctures and the incidence of postdural puncture headache (PDPH), questioning the hypothesis that leakage of cerebrospinal fluid (CSF) through the dural tear is the cause of PDPH.We hypothesized that insufficient statistical power of these studies was the cause for this unexpected finding, and reexamined whether repeated dural punctures increase the incidence of PDPH by analyzing prospectively collected data on 8034 spinal anesthetics. Uneventful spinal anesthetics, including a single subarachnoid injection of local anesthetics, occurred in 7865 (97.9%) cases, whereas failed spinal anesthetics requiring repeated dural puncture for a second subarachnoid injection of local anesthetics occurred in 165 (2.1%) cases. The two groups were similar with regard to age, sex, and ASA physical status. We found that repeated dural punctures significantly increased the incidence of PDPH. We conclude that increased risk of PDPH is a disadvantage of performing a second subarachnoid injection of local anesthetics after a failed spinal anesthetic. Moreover, this result suggests that leakage of CSF through the dural tear is the most plausible cause of PDPH. (Anesth Analg 1996;82:302-5)

Small-dose intrathecal clonidine and isobaric bupivacaine for orthopedic surgery : a dose-response study

We examined the dose-response relationship of intrathecal clonidine at small doses (≤150 &mgr;g) with respect to prolonging bupivacaine spinal anesthesia. We aimed for establishing doses of intrathecal clonidine that would produce clinically relevant prolongation of spinal anesthesia and pain relief without significant side effects. Eighty orthopedic patients were randomly assigned to intrathecally receive isobaric 0.5% bupivacaine, 18 mg, plus saline (Group 1), clonidine 37.5 &mgr;g (Group 2), clonidine 75 &mgr;g (Group 3), and clonidine 150 &mgr;g (Group 4). Duration of the sensory block (regression below level L1) was increased in patients receiving intrathecal clonidine: 288 ± 62 min (Group 1, control), 311 ± 101 min in Group 2 (+8%), 325 ± 69 min in Group 3 (+13%), and 337 ± 78 min in Group 4 (+17%) (estimated parameter for dose 0.23 [95% confidence interval −0.05–0.50]). Duration of pain relief from intrathecal clonidine administration until the first request for supplemental analgesia was significantly prolonged: 295 ± 80 min (Group 1, control), 343 ± 75 min in Group 2 (+16%), 381 ± 117 min in Group 3 (+29%), and 445 ± 136 min in Group 4 (+51%) (estimated parameter for dose 1.02 [95% confidence interval 0.59–1.45]). Relative hemodynamic stability was maintained and there were no between-group differences in the sedation score. We conclude that small doses of intrathecal clonidine (≤150 &mgr;g) significantly prolong the anesthetic and analgesic effects of bupivacaine in a dose-dependent manner and that 150 &mgr;g of clonidine seems to be the preferred dose, in terms of effect versus unwarranted side effects, when prolongation of spinal anesthesia is desired.

Effects of intravenous lidocaine and/or esmolol on hemodynamic responses to laryngoscopy and intubation: a double-blind, controlled clinical trial.

STUDY OBJECTIVES To evaluate the efficacy of intravenous lidocaine and two doses of esmolol for attenuating the cardiovascular responses to laryngoscopy and intubation, and to assess whether a combination of both drugs is more effective than either drug alone. DESIGN Randomized, prospective, double-blind, placebo-controlled study. SETTING University hospital. PATIENTS 90 ASA status I and II normotensive women scheduled for elective gynecologic procedures with general anesthesia. INTERVENTIONS Induction of anesthesia was standardized for all patients. The first group received lidocaine 1.5 mg/kg (Group LID); the second and third groups received esmolol 1 mg/kg and 2 mg/kg, respectively (Groups E1 and E2, respectively); the fourth group received lidocaine 1.5 mg/kg and esmolol 1 mg/kg (Group LID-E1); the fifth group received lidocaine 1.5 mg/kg and esmolol 2 mg/kg (Group LID-E2); the sixth group received saline as a placebo (Group PLAC). MEASUREMENTS AND MAIN RESULTS Systolic blood pressure and heart rate (HR) were recorded before induction, before injection of the first test drug, immediately before laryngoscopy, and 1, 2, and 5 minutes following intubation. Duration of laryngoscopy was recorded. Only patients receiving placebo had increased HR values after intubation compared with baseline values (p < 0.05). The proportion of patients with a maximum HR exceeding 90 beats/min was significantly higher in the placebo group (8 of 15 patients) than in both esmolol groups (E1 2 of 15; E2 2 of 15) (p < 0.05). Systolic blood pressure values after tracheal intubation did not differ among groups except for those receiving the combinations of lidocaine and esmolol, and they had significantly lower blood pressure (BP) values compared with placebo (p < 0.05). CONCLUSIONS Esmolol 1 to 2 mg/kg is reliably effective in attenuating HR response to tracheal intubation. Neither of the two doses of esmolol tested nor that of lidocaine affected the BP response. Only the combination of lidocaine and esmolol attenuated both HR and BP responses to tracheal intubation.

Intrathecal clonidine and fentanyl with hyperbaric bupivacaine improves analgesia during cesarean section

Seventy-eight pregnant women at term, scheduled for elective cesarean section, were enrolled in this multicenter trial to compare the analgesic efficacy and side effect profile of a spinal block with hyperbaric bupivacaine alone (Group B) or combined with 75 [micro sign]g of clonidine (Group BC) or with clonidine 75 [micro sign]g and fentanyl 12.5 [micro sign]g (Group BCF). Intraoperatively, clonidine increased the spread of the sensory block and decreased pain (pain scores 23 +/- 7 mm vs 17 +/- 6 and 2 +/- 1 mm for Group B versus Groups BC and BCF; P < 0.05) and analgesic supplementation. This improved analgesia was best with the clonidine-fentanyl combination (Group BC versus Group BCF; P < 0.05). Postoperative analgesia was prolonged only in Group BCF (215 +/- 79 min vs 137 +/- 35 and 183 +/- 80 min for Group BCF versus Groups B and BC; P < 0.05). Blood pressure and heart rate changes were not significantly different among groups, whereas sedation and pruritus were significantly more frequent in Group BCF. Nausea and vomiting were decreased in Groups BC and BCF. Apgar scores and umbilical artery blood pH were not different among groups. We conclude that adding a small dose of intrathecal clonidine to bupivacaine increases the quality of intraoperative analgesia and decreases pain during cesarean section. Combining clonidine with fentanyl further improved analgesia. Implications: In this study, we demonstrate improved intraoperative spinal analgesia by adding 75 [micro sign]g of clonidine to bupivacaine; side effects were not increased. The combination of clonidine and fentanyl further improved analgesia but moderately increased sedation and pruritus. (Anesth Analg 1998;87:609-13)

Extradural abscess complicating lumbar extradural anaesthesia and analgesia in an obstetric patient.

A 33‐year‐old nulliparous woman with severe pre‐eclampsia was treated with extradural analgesia to control blood pressure and relieve pain during delivery. Nine hours after extradural catheter insertion a Caesarean section was performed due to uterine inertia. The extradural catheter was kept in place for 88 hours. Ten days following the extradural block she developed an extradural abscess and had to undergo a laminectomy. In a retrospective and, in part, prospective analysis on more than 13,000 extradural blocks, we studied the incidence of this dreaded complication and reviewed the literature on clinical findings, diagnosis and treatment.

Impact of spinal anaesthesia and obesity on maternal respiratory function during elective Caesarean section

Spinal anaesthesia for Caesarean section has gained widespread acceptance. We assessed the impact of spinal anaesthesia and body mass index (BMI) on spirometric performance. In this prospective study, we consecutively assessed 71 consenting parturients receiving spinal anaesthesia with hyperbaric bupivacaine and fentanyl for elective Caesarean section. We performed spirometry during the antepartum visit (baseline), immediately after spinal anaesthesia, 10–20 min, 1 h, 2 h after the operation, and after mobilisation (3 h). Baseline values were within normal ranges. There was a significant decrease in all spirometric parameters after effective spinal anaesthesia that persisted throughout the study period. The decrease in respiratory function was significantly greater in obese (BMI > 30 kg.m−2) than in normal‐weight parturients (BMI < 25 kg.m−2), e.g. median (IQR) vital capacity directly after spinal anaesthesia; −24 (−16 to −31)% vs. −11 (−6 to −16)%, p < 0.001 and recovery was significantly slower. We conclude that both spinal anaesthesia and obesity significantly impair respiratory function in parturients.

General anaesthesia for surgery can influence circulating melatonin during daylight hours

Background: Both melatonin and anaesthetics have been shown to affect sleep and behaviour. The effect of general anaesthesia on circulatory melatonin has not been reported, but anaesthetic‐related alterations in hormone profiles are known. We hypothesize that differences in recovery from anaesthesia may be associated with differences in circulatory melatonin levels because of melatonins sedative effect in humans.