• H Ponhold, A H Kulier, and P H Rehak.
• Klinik für Anästhesiologie, Universität Graz.
• Anaesthesist. 1993 Nov 1;42(11):788-92.

AbstractThe spread and intensity of lumbar epidural anaesthesia are unpredictable. Moreover, segments L5 and S1 are frequently missed. In this study the effect of 30 degrees trunk elevation on the spread and intensity of lumbar epidural sensory and motor blockade and on the cardiovascular system were studied. METHODS. After oral premedication with 7.5 mg midazolam, 30 patients 20 to 40 years of age, ASA 1-2, were randomly allocated to one of two groups according to their body position during injection of 20 ml 2% lidocaine (3 + 8 + 9 ml) into a lumbar epidural catheter (L2/3 or L3/4) and during the following 30 min: supine horizontal position or supine 30 degrees trunk elevation with 30 degrees leg elevation (hammock position). The patients received 500 ml Ringer solution before the epidural injection, followed by more Ringer solution. Systolic and diastolic blood pressures and heart rate were monitored noninvasively every 5 min; 30 min after the epidural injection the spread of analgesia (dullness of pinprick) and anaesthesia (no sensation of pinprick) as well as motor block according to Bromage were tested. A spread of anaesthetic segments including T12 to L3 was considered adequate for hip surgery, L3 to L5 for knee surgery, and L3 to S2 for foot surgery. Student's t-test, ANOVA, chi-square (Wilcoxon), and Mann-Whitney tests were used for statistical analysis. P < 0.05 was considered statistically significant. RESULTS. The median cephalad level of analgesia was lower in patients with the hammock position than those with the horizontal position (L1 vs T10; P < 0.05). There was no significant difference in the cranial level of anaesthesia (L2 vs L1) (Table 2). No significant difference was seen in the number of patients having adequate anaesthesia for hip surgery. Anaesthesia in the segments L5 and S1 was seen in 2/15 patients in the horizontal position and 8/15 patients in the hammock position (P < 0.05). The hammock position resulted in a higher percentage of patients having adequate anaesthesia for knee surgery (60% vs 13%; P < 0.05) and foot surgery (53% vs 13%; P < 0.05) (Table 3). Motor block was more profound in patients in the hammock position (Table 4). Blood pressure and heart rate did not change significantly in patients in the horizontal position (Fig. 1); there was a decrease in both systolic (7 mmHg) and diastolic (5 mmHg) blood pressures in patients in the hammock position. Heart rate did not change significantly (Fig. 2). No patient needed vasopressor support; the body position could be maintained in all patients during the observation period. One or two epidural reinjections according to the spread of anaesthesia 30 min after the first injection and to the scheduled operation resulted in adequate anaesthesia in every patient. DISCUSSION. More patients in the hammock position developed adequate anaesthesia in the relevant segments for knee and foot operations than patients in the horizontal position. These included the frequently missed segments L5 and S1. Patients in the hammock position had a clinically insignificant drop in systolic and diastolic blood pressure. In contrast to the young and healthy patients in this study, more severe cardiovascular changes might result in geriatric and/or ill patients subjected to a hammock position. For this reason, use of the technique in geriatric and/or ill patients requires special attention.

10 keywords...

hide…