Direction and side used to determine the extent of sensory block after subarachnoid anesthesia do not influence the level of the block.

Methods of sensory testing in neuraxial anesthesia may supposedly account for different results in reporting the extent of the block. To determine whether the caudad to cephalad versus the cephalad to caudad direction as well as the side of testing, left versus right, may affect the assessment of sensory block after subarachnoid anesthesia, two groups of patients undergoing transurethral surgery were studied. One group, 44 patients were tested for the influence of direction of block determination and another group 50 patients for the influence of side. Subarachnoid anesthesia was performed with 100 mg of 5% hyperbaric lidocaine using a 25 Whitacre needle with its opening consistently pointing cranially and the patient in the sitting position. To assess the sensory block four lines were drawn bilaterally along the posterior, middle, and anterior axillary lines and a line 5 cm medial to the anterior axillary line. A pressure palpator was moved along each of the four lines and patients were asked to answer if they detected a stimulus, with "yes/no". In the 44 patients assessment of sensory block was performed from caudad to cephalad direction on one side and viceversa on the other. In the other 50 patients the extent of the block was compared between the right and left side. In 44 patients, the level of sensory block determined 20, 25 and 30 minutes after the subarachnoid anesthesia in a cephalad to caudad direction was found at the T11 dermatome at each time point and did not differ when compared to the levels determined following the caudad to cephalad direction. In the second study in a different group of 50 patients, the level of sensory block 20, 25 and 30 minutes after the subarachnoid injection was found at the T11 dermatome on the right side at each time point and did not differ from the level determined on the left side. We conclude that the level of sensory block after subarachnoid anesthesia with lidocaine is independent of the direction of testing and the side the assessment is performed using the pressure palpator.

Assessment of the level of sensory block after subarachnoid anesthesia using a pressure palpator.

UNLABELLED: In a cross-over study, we compared two methods of assessing the level of sensory block during subarachnoid anesthesia: the traditional pinprick sensation or a novel pressure palpator exerting a pressure of 650 g. Fifty patients scheduled for transurethral surgery under subarachnoid anesthesia were randomly assigned to be tested for spread of sensory block. In Group 1, the pressure palpator was followed by pinprick; in Group 2, the reverse sequence was used. Evaluation was performed 15 and 25 min after the subarachnoid injection of 2 mL of 5% lidocaine hyperbaric solution. In Group 1, the level of sensory block assessed with the pressure palpator was 1.7 +/- 3.2 cm (0.5 +/- 1.2 dermatomes) higher than that with the pinprick at 15 min, and 2.2 +/- 3.4 cm (0.6 +/- 1.0 dermatomes) higher than that with the pinprick 25 min after the block. In Group 2, the difference was accentuated. The level of sensory block assessed by pinprick 15 min after subarachnoid lidocaine was 5.7 +/- 4.8 cm (1.2 +/- 0.9 dermatomes) lower than the level with the pressure palpator, and 4.2 +/- 3.3 cm (0.9 +/- 0.6 dermatomes) lower than that with the pressure palpator at 25 min. In all instances, the pressure palpator gave a significantly higher assessment than the pinprick. We conclude that the pressure palpator, when preceded by the pinprick test, is associated with an increased threshold. This method may be useful in assessing the sensory block produced by subarachnoid anesthesia. IMPLICATIONS: A novel pressure palpator that maintains the integrity of the epidermis was used to assess the level of sensory block after subarachnoid anesthesia and was compared with the standard method of the pinprick sensation. This method assessed the block consistently higher than the pinprick method, but it may have advantages as a noninvasive sensory test.

Effect of nimodipine on regression of spinal analgesia.

We have investigated the effect of infusion of nimodipine on the spread of spinal anaesthesia in 50 patients undergoing transurethral procedures. Patients were allocated randomly to receive during operation continuous infusion of nimodipine 10 ml h-1 (group N, n = 25) or normal saline (group C, n = 25) in a double-blind manner. All patients received hyperbaric lidocaine 100 mg (5% in 8% dextrose) intrathecally and were then placed in the lithotomy position. Twenty minutes after intrathecal injection the level of spinal anaesthesia was tested with a pressure palpator and a baseline was established. Assessments were repeated 5, 10 and 15 min thereafter. Five minutes after establishing baseline, mean regression of sensory analgesia did not differ between groups. Analgesia had regressed by 1.3 (SD 1.4) and 1.0 (1.9) cm, respectively. After 10 min, sensory block in group N regressed by 1.7 (1.7) cm and in group C by 1.5 (1.6) cm. After 15 min these values were 1.1 (1.7) cm and 2.2 (1.9) cm, respectively (P < 0.035). Similar results were found after normalizing the changes by dividing the change by patient height.

Nitrous oxide enhances the level of sensory block produced by intrathecal lidocaine.

UNLABELLED: We examined the effect of nitrous oxide (N2O) administration on the level of sensory block produced by intrathecal lidocaine in patients undergoing transurethral procedures. Twenty minutes after subarachnoid injection of 100 mg (5%) hyperbaric lidocaine, the level of block to pressure sensation was assessed. After establishing the baseline sensory block, patients were randomly assigned to receive either 50% nitrogen (control group) or 50% N2O in oxygen for 10 min, and the sensory level was reassessed. All patients then received 35% oxygen for 5 min, and the level of block to pressure was assessed again. Changes were measured in centimeters and standardized by dividing those results by the height of patients (in centimeters). Ten minutes after nitrogen or N2O administration, a 3.8-cm regression of sensory block was found in the control group, and a 1.8-cm cephalad increase was found in the treatment group (P < 0.0001). Discontinuation of N2O for 5 min resulted in a rapid regression of the level of sensory block (4 cm in the N2O group versus 1.9 cm in the control group, P < 0.0001). However, 5 min after discontinuation of N2O, the overall regression of the sensory block in the control group, when measured from the baseline, was 5.7 cm versus 2.2 cm in the N2O group (P < 0.001). The differences between the two groups before standardization are consistent with those after standardization (t = 9.02 at 10 min, t = 4.24 at 15 min, and t = 3.97 for the overall change at 15 min). The results suggest that inhalation of 50% N2O enhances the level of sensory block produced by intrathecal lidocaine. IMPLICATIONS: We measured the level of sensory block produced by subarachnoid anesthesia with lidocaine before and after inhalation of 50% nitrous oxide for 10 min. Nitrous oxide enhanced the level of subarachnoid anesthesia with minimal hemodynamic effects. These findings are of clinical importance when subarachnoid anesthesia subsides before the completion of surgery.

Tenoxicam does not enhance the spread of sensory block produced by intrathecal lidocaine.

Systemic opioids enhance the spread of spinal analgesia. This study was designed to determine whether i.v. tenoxicam, a nonsteroidal anti-inflammatory drug (NSAID), affects the spread of sensory block produced by lidocaine. Sixty patients undergoing transurethral procedures were randomly assigned in a double blind design to receive i.v. either 3 ml normal saline (N/S group, n = 20), or 150 micrograms fentanyl (F group, n = 20), or 40 mg tenoxicam (T group, n = 20), 20 minutes after spinal anesthesia. The level of sensory loss was tested with pinprick sensation 20 minutes after subarachnoid block, but before i.v. treatment, and 5, 10, and 15 minutes after i.v. treatment. Five minutes after the i.v. treatment the change in the level of sensory block was -0.8 +/- 3.1 cm in the N/S group, 4.0 +/- 3.5 cm in the F group and 0.0 +/- 3.9 cm in the T group. The changes in the height of sensory block among the three groups differed 5 minutes and 10 minutes (F = 10.627, df = 2.57, P < 0.001 and F = 4.219, df = 2.57, P < 0.05 respectively), but not 15 minutes after i.v. treatment. Individual comparisons showed a difference between the N/S and F groups (P < 0.01), and between the F and T groups (P < 0.01) 5 minutes after treatment, and between the N/S and F groups (P < 0.05) 10 minutes after treatment. The overall change in the level of sensory block 15 minutes after i.v. treatment was -4.6 +/- 6.3 cm in the N/S group, 2.4 +/- 6.0 cm in the F group, and -1.6 +/- 5.8 cm in the T group. The F group differed from the N/S group (P < 0.01). Intravenous administration of tenoxicam does not enhance the level of spinal analgesia produced by lidocaine.

Preemptive opioid analgesia does not influence pain after abdominal hysterectomy.

Opioid administration before surgical stimulus may reduce or prevent subsequent pain. We studied the effect of timing of opioid administration on the pain-related behaviour after abdominal hysterectomy. Eighty-five patients scheduled for abdominal hysterectomy were blindly randomized to receive fentanyl 10 micrograms.kg-1 before induction of anaesthesia (FA), after peritoneal incision (FB) or after removal of the uterus (FC), or sufentanil 1 micrograms.kg-1 before induction of anaesthesia (SA) or after peritoneal incision (SB) respectively. All patients received a standard postoperative analgesic regimen. The time from skin closure to the first analgesic request was recorded. Pain was assessed using the VAS and a verbal rating score (VSR 1 = no pain to 6 = intolerable pain) every 30 min until patients asked for the first analgesic, and 24 hr postoperatively. The times from skin closure to the first analgesic request did not differ among the five groups. The VAS scores using the two-way ANOVA with repeated measurements differed among the five groups (F = 4.046, df = 4, 213, P < 0.005). The VAS scores with one-way ANOVA differed among the five groups 30 min postoperatively (F = 4.542, df = 4, 58, P < 0.003), being higher in the FA (6.5 +/- 1.8) and SA (5.9 +/- 2.1) groups than in the FC (3.2 +/- 2.5) group, and at 120 min postoperatively (F = 3.217, df = 4, 18, P < 0.05), being higher in the FA than in the FB group (6.1 +/- 1.5 and 2.6 +/- 1.9 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Nerve stimulation in patients undergoing hysterectomy under general anaesthesia.

The possible impact of transcutaneous electrical nerve stimulation (TENS) on cardiovascular responses associated with tracheal intubation, surgery and postoperative period was evaluated in patients undergoing hysterectomy. Thirty-eight patients undergoing abdominal hysterectomy were randomly allocated either to the TENS group (n = 19), with electrical stimulation applied preoperatively and continued postoperatively for six hours on the stellate ganglion (SG), or to the control group (n = 19), with the stimulator turned off. Systolic arterial pressure (SAP) and heart rate (HR) were recorded before induction of anaesthesia, after cuff inflation, one minute, three minutes and five minutes later, every 15 minutes intraoperatively and every two hours postoperatively for eight hours. TENS of SG failed to prevent the cardiovascular responses associated with intubation of the trachea and surgery. HR, but not SAP, mean values were significantly lower in the TENS-treated group four and six hours postoperatively (p < 0.02, p < 0.01, respectively) when compared with the control group. These differences disappeared when TENS was discontinued.

Transcutaneous electrical nerve stimulation reduces the incidence of vomiting after hysterectomy.

The possible postoperative antiemetic effect of transcutaneous electrical nerve stimulation (TENS) on the P6 point (on the Pericardium Channel of Hand-Jueyin) was evaluated in 103 women undergoing hysterectomy. TENS on the P6 point was applied 30-45 min before induction of anesthesia in 51 patients and continued for 6 h postoperatively. The control group, 52 patients, was treated exactly in the same way but with the electrical stimulator turned off. Incidence of vomiting was assessed blindly 2 h, 4 h, 6 h, and 8 h postoperatively. The incidence of vomiting postoperatively was significantly less in the TENS-treated group when compared with the control group (between 0 h and 2 h: 23% vs 43%, P < 0.05; between 2 h and 4 h: 27% vs 50%, P < 0.025; and between 4 h and 6 h: 31% vs 67%, P < 0.001, respectively). Six hours postoperatively TENS was discontinued, and 8 h postoperatively the two groups did not differ significantly for incidence of vomiting (between 6 h and 8 h: 51% vs 65%). The authors conclude that TENS reduces the incidence of vomiting after hysterectomy.