In addition, we evaluated whether block analgesia could lessen the anesthetic re- quirements. ... Age and body weight values are mean ± standard deviation.
SCIENTIFIC REPORT
Effects of Block Analgesia on Attenuating Intraoperative Stress Responses During Oral Surgery Hideki Mamiya, DDS, PhD, Tatsuya Ichinohe, DDS, PhD, and Yuzuru Kaneko, DDS, PhD Department of Dental Anesthesiology, Tokyo Dental College, Chiba, Japan
Surgical intervention affects cardiorespiratory function and deteriorates the homeostatic mechanisms. The aim of this study was to evaluate the effect of block analgesia, which may minimize the intraoperative stress responses during oral surgery. In addition, we evaluated whether block analgesia could lessen the anesthetic requirements. Twenty-eight operative patients were randomly allocated to one of four groups: group 1, 1.3MAC without block analgesia; group 2, 1.6MAC without block analgesia; group 3, 1.OMAC with block analgesia; and group 4, 1.3MAC with block analgesia. Systolic blood pressure (SBP), heart rate (HR), and plasma norepinephrine levels (NE) were measured and compared. Results showed that the increases in SBP, HR, and NE in groups 1 and 2 were greater than those in groups 3 and 4. SBP elevation in group 1 was the greatest among all groups. These results suggest that block analgesia appears to be effective for preventing hyperreactivity of the sympathetic nervous and endocrine systems. In conclusion, general anesthesia combined with block analgesia assures safer anesthesia for patients with cardiovascular diseases or elderly patients who require cardiovascular stability during surgery. Key Words: Block analgesia; General anesthesia; Minimum alveolal concentration; Oral surgery; Stress response.
Surgical intervention affects cardiorespiratory function and endocrine secretion, which deteriorates the homeostatic mechanisms in surgical patients.' Although increased depth of anesthesia is usually required to attenuate such responses to surgery, the anesthesia itself depresses the cardiorespiratory and metabolic functions in patients and delays the emergence time. In this study, we investigated the effect of block analgesia,
METHODS
The study was approved by our Medical Ethics Committee. All patients gave their written informed consent. Twenty-eight patients classified as physical status 1 of the American Society of Anesthesiologists underwent sagittal splitting osteotomy of the bilateral mandibular ramus. Table 1 summarizes the patients' backgrounds. The patients were randomly allocated to one of four groups based on the combination of the block analgesia and the anesthetic depth, which was quantified with minimum alveolar concentration (MAC) of the inhalation anesthetics used. The groups were as follows: (1) 1.3MAC no block group included the patients under 1.3MAC anesthesia without block analgesia; (2) 1.6MAC no block group included the patients under 1.6MAC anesthesia without block analgesia; (3) 1.OMAC block group included the patients under 1.OMAC anesthesia with block analgesia;
which may minimize the intraoperative stress responses in association with surgical procedures, on the cardiorespiratory functions during oral surgery. In addition, we evaluated whether block analgesia could lessen the anesthetic requirements during surgery.
Received September 25, 1996; accepted for publication August 19, 1997. Address correspondence to Dr. Hideki Mamiya, 1-2-2 Masago, Mihama-ku, Chiba City, 261 Japan. Anesth Prog 44:101-105 1997 X 1997 by the American Dental Society of Anesthesiology
ISSN 0003-3006/97/$9.50 SSDI 0003-3006(97)
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Table 1. Patient Demographics Sex (M/F) 2/4
1.3MAC no block group 1.6MAC no block group 6/0 LOMAC block group 0/8 1.3MAC block group 1/7 Abbreviation: MAC, minimum alveolar concentration.
Age (yr) Body Weight (kg) 54.2 ± 4.3 22.3 ± 3.6 23.8 ± 8.3 49.7 ± 5.9 24.0 ± 4.5 48.9 ± 4.7 23.0 ± 3.8 63.2 ± 5.8 Age and body weight values are mean ± standard deviation.
(4) 1.3MAC block group included the patients under 1.3MAC anesthesia with block analgesia. In groups 3 and 4, the mandibular nerve block at the foramen ovale was performed with 4 ml of 0.5% bupivacaine at each side more than 30 min after the induction of anesthesia when cardiorespiratory stability was obtained. In group 1, 8 ml of saline containing 0.03 IU/ml felypressin was injected for vasoconstriction. In groups 2 and 3, 8 ml of 1% lidocaine solution containing 10 ,ug/ml epinephrine was injected for local anesthesia and vasoconstriction as infiltration anesthesia. In group 4, 8 ml of 3% propitocaine solution containing 0.03 IU/ml felypressin was injected for the same purpose. Any local anesthetic or saline with felypressin was used around the operative field that required vasoconstriction. All patients received 0.5 mg atropine sulfate intramuscularly and 1-2 mg/kg hydroxyzine hydrochloride 60 min before the induction of anesthesia. General anesthesia was induced with 4 mg/kg thiopental sodium. Endotracheal intubation was facilitated with 1.5 mg/kg suxamethonium chloride after precurarization with 3 mg d-tubocurarine chloride. Anesthesia was maintained with appropriate concentrations of isoflurane and 40% nitrous oxide in oxygen. The patients breathed spontaneously. End-tidal isoflurane concentration was continuously monitored with an anesthetic gas monitor (Capnomac, Datex, Helsinki). Total MAC was calculated by adding the MAC values of nitrous oxide and isoflurane. Hemodynamic variables investigated included ra-
dial artery blood pressure and heart rate. The blood pressure was continuously monitored with a pressure transducer (Statham, Ohmeda, NJ). Heart rate was recorded by the R wave of the electrocardiogram. The plasma norepinephrine level was investigated for the evaluation of the sympathetic responses using high-performance liquid chromatography (BAS LC304 type, Tokyo). The control measurement was performed 4 min after the intraoral administration of local anesthetic solution or saline containing felypressin following the mandibular nerve block. The measurement was repeated during the ramus osteotomy, which was considered as the maximum surgical intervention. The difference between the control value and the respective value during the osteotomy was calculated and submitted to statistical comparison. Data were shown as the mean standard deviation in this study. One-way analysis of variance followed by the Student-Newmann-Keuls test was used for intergroup comparisons. P-values less than 0.05 indicated statistical significance. ±
RESULTS
Table 2 and Figures 1-3 summarize the results. The elevations of systolic blood pressure, heart rate, and plasma norepinephrine level in the two block groups were significantly smaller than those in the two no block groups. No statistically significant difference was ob-
Table 2. Change in Parameters Control Osteotomy ± 1.3MAC no block 97.2 14.8 125.2 ± 22.9 1.6MAC no block 95.5 ± 5.3 105.6 ± 6.4 LOMAC block 99.1 t 3.9 99.4 t 4.2 1.3MAC block 97.5 t 12 98.7 ± 10.4 Heart rate 1.3MAC no block 81 ± 10.1 98 ± 7.2 (beats/min) 1.6MAC no block 101.4 t 4.9 119.4 ± 5.2 LOMAC block 89.1 ± 4.9 92.1 t 4.3 1.3MAC block 84.8 ± 7.6 85.5 t 15.7 Plasma norepinephrine level 1.3MAC no block 241.1 ± 60.8 377.7 ± 75 (pg/ml) 1.6MAC no block 272.9 ± 25.9 377.9 ± 21 LOMAC block 236.2 t 17 218.8 ± 20.8 1.3MAC block 214.1 ± 39 164.9 ± 30.1 Abbreviation: MAC, minimum alveolar concentration. Values are mean t standard deviation.
Systolic blood pressure (mmHg)
Delta 28 ± 8.8 10.1 + 9.0 0.25 ± 7.5 1.2 t 7.3 17 ± 4.3 18 ± 8.0 3 t 7.4 0.67 t 12.0 136.6 t 160.1 105 t 105.3 -17.4 t 35.7 -49.2 t 65.1
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