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AMBULATORY ANESTHESIA

Intrathecal Anesthesia for Elderly Patients Undergoing Short Transurethral Procedures: A Dose-Finding Study

Edna Zohar, MD, MHA^*, Yossi Noga, BSc, MD, MHA^*, Uri Rislick, MD^*, Ilan Leibovitch, MD, and Brian Fredman, MB, BCh^*

From the Departments of *Anesthesiology, Critical Care and Pain Management, and Urology, Meir Medical Center, Kfar Saba, The Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.

Address correspondence and reprint requests to Brian Fredman, MB BCh, Department of Anesthesiology and Intensive Care, Meir Medical Center, Kfar Saba 44281, Israel. Address e-mail to fredman.brian{at}clalit.org.il.

	Abstract

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One hundred elderly men (65 yr) undergoing transurethral procedures (<45 min) received bupivacaine 7.5 mg, or bupivacaine 5 mg + fentanyl 20 µg, or bupivacaine 4 mg + fentanyl 20 µg, or bupivacaine 3 mg + fentanyl 20 µg, intrathecally. Intraoperative "rescue" fentanyl requirements were higher (P < 0.03) in group bupivacaine 3 mg + fentanyl. Times (min) to ambulation eligibility were decreased in a dose-dependant manner (157 ± 50 vs 147 ± 37 vs 128 ± 40 vs 116 ± 29, respectively). Of the techniques studied, intrathecal bupivacaine 4 mg + fentanyl 20 µg provided adequate analgesia and was associated with hemodynamic stability and a favorable recovery profile.

	Introduction

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To reduce the adverse hemodynamic effects associated with the spinal anesthesia-induced medical sympathectomy, combinations of very small doses of local anesthetic and adjuvant opioids are frequently administered (1–6). However, for elderly patients undergoing transurethral procedures, the optimal bupivacaine-fentanyl dose is unknown. Therefore, we performed a comparative study designed to establish the smallest possible effective dose of intrathecal bupivacaine when administered with adjuvant fentanyl (20 µg) among elderly patients undergoing transurethral procedures.

	METHODS

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One hundred consenting elderly ASA physical status I–III patients (65 yr) undergoing elective transurethral procedures were enrolled into this IRB-approved randomized, prospective, double-blind study.

In the operating room, prehydration (8 mL/kg Ringer’s lactate solution) was administered, monitoring equipment applied, and with the patient assuming the sitting position, intrathecal anesthesia was administered at the L4-5 vertebral interspace. Immediately thereafter, patients were placed in the supine lithotomy position.

The dose of heavy bupivacaine (5 mg/mL) was varied such that patients received bupivacaine 7.5 mg (control), bupivacaine 5 mg + fentanyl, bupivacaine 4 mg + fentanyl, and bupivacaine 3 mg + fentanyl, respectively. When appropriate adjuvant fentanyl 20 µg (50 µg/mL) and 10% glucose were added such that a total volume of 2 mL was administered. Drug preparation was performed using a high-resolution, small-degradation syringe. Barbotage was not performed. By moving a 21-gauge needle along the midclavicular lines, the height and regression of the sensory deficit was determined at 2-min intervals. A T10 sensory deficit was a prerequisite for beginning surgery. Immediately before the start and at the end of surgery, motor blockade was determined using a Bromage score.

Intraoperative pain was evaluated using a 100-mm visual analog score (VAS) (0 = no pain, 100 = worst imaginable pain). A VAS >30 mm was treated with IV fentanyl 25 µg. Five minutes thereafter, the VAS was assessed, and if necessary, additional fentanyl administered. This was repeated until a VAS <30 mm was recorded.

A decrease in mean arterial blood pressure (MAP) >20% of preinduction values was treated with ephedrine, 5 mg, IV.

Recovery milestones were assessed at 10-min intervals. Full motor and sensory recovery were prerequisites for ambulation. Postanesthesia care unit (PACU) discharge eligibility (time from PACU admission until fulfilling the modified Aldrete discharge criteria) was determined using a modified Aldrete Score (7). Time to ambulation eligibility was calculated as the time from spinal anesthesia until total regression of motor and sensory blockade. On PACU discharge, patient satisfaction with the anesthetic management was assessed (excellent, good, poor, unacceptable). Because of institutional policy, a 2-day hospital admission was mandatory.

Twenty-five patients per group were required to detect a significant difference of 25% or more in the rescue fentanyl requirements (power of 85%, = 0.05).

Demographics, time intervals, and continuous variables (MAP, heart rate, Spo₂, VAS) were analyzed and compared using the one-way analysis of variance (ANOVA) test. Categorical data (ASA, sex, highest motor block achieved), number of patients receiving intraoperative rescue fentanyl and patient satisfaction were analyzed using the ² test. In all cases, P < 0.05 was considered statistically significant.

	RESULTS

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Demographic characteristics and admission milestones (Table 1) as well as intraoperative MAP, heart rate, and Spo₂ were similar among groups. In no case was conversion to general anesthesia required. The Bromage score was significantly (P < 0.003) different when comparing group bupivacaine 7.5 mg to bupivacaine 3 mg + fentanyl.

Intraoperative rescue fentanyl requirements were significantly higher in group bupivacaine 3 mg + fentanyl when compared with those in the other three treatment groups (Table 2). In group bupivacaine 7.5 mg, there was a significant difference in ephedrine requirements (Table 2).

Time to total regression of sensory block was significantly longer in group bupivacaine 7.5 mg when compared with that in bupivacaine 4 mg + fentanyl and bupivacaine 3 mg + fentanyl groups. Time to total regression of motor blockade was longer in bupivacaine 7.5 mg when compared with that in group bupivacaine 3 mg + fentanyl (P < 0.05) (Table 2).

Ambulation eligibility times were 157 min ± 50 versus 128 ± 40 min versus 116 min ± 29 for groups bupivacaine 7.5 mg, bupivacaine 4 mg + fentanyl 20 µg, and bupivacaine 3 mg + fentanyl 20 µg, respectively (P < 0.05). In group bupivacaine 5 mg + fentanyl, ambulation eligibility times were significantly longer when compared with those of patients in group bupivacaine 3 mg + fentanyl (Table 1).

PACU discharge eligibility times were significantly longer in group bupivacaine 7.5 mg when compared with those in groups bupivacaine 4 mg + fentanyl and bupivacaine 3 mg + fentanyl (Table 1). For patients in group bupivacaine 5 mg + fentanyl, PACU discharge eligibility times were significantly longer when compared with those of patients in group bupivacaine 3 mg + fentanyl (Table 1). Postoperative nausea and vomiting, diclofenac requirements as well as patient satisfaction were comparable (Table 2).

	DISCUSSION

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This study demonstrates that, of the drug combinations studied, bupivacaine 4 mg + fentanyl 20 µg was most favorable for elderly patients undergoing short transurethral procedures. Although the shortest times to regression of sensory and motor blockade were recorded among patients receiving bupivacaine 3 mg + fentanyl, this anesthetic regimen was associated with a high incidence of rescue fentanyl administration. However, the incidence of rescue fentanyl administration among patients receiving bupivacaine 4 mg + fentanyl was significantly lower when compared with that in group bupivacaine 3 mg + fentanyl. Group 7.5 mg had excellent intraoperative analgesia and patient satisfaction, but the incidence of ephedrine administration was significantly higher in this group. Furthermore, ambulation and PACU discharge eligibility times after the administration of bupivacaine 4 mg + fentanyl were significantly shorter when compared with that in bupivacaine 7.5 mg. Finally, PACU discharge eligibility time was significantly shorter in group bupivacaine 4 mg + fentanyl when compared with that in group bupivacaine 5 mg + fentanyl.

Despite differences in study design, it is interesting to compare our results with those of other investigators. In a study by Kararmaz et al. (5), elderly men undergoing transurethral resection of the prostate were randomized to receive either intrathecal bupivacaine 7.5 mg or bupivacaine 4 mg with fentanyl 25 µg. The results of this study demonstrated that small-dose bupivacaine with adjuvant fentanyl provides adequate anesthesia for elderly men undergoing transurethral resection of the prostate and is associated with a lower incidence of hypotension when compared to bupivacaine 7.5 mg. This study differs from our current study in that Kararmaz et al. compared two anesthetic drug regimens, whereas we performed a study designed to establish the smallest possible effective dose of bupivacaine and fentanyl-induced intrathecal anesthesia for geriatric patients undergoing short transurethral procedures. Furthermore, all patients in the study by Kararmaz et al. received IV midazolam. As geriatric patients are particularly sensitive to drug interactions, it is possible that synergism between midazolam and intrathecal bupivacaine adversely affected the incidence of intraoperative hypotension (8). Furthermore, among geriatric patients, midazolam (0.5 or 2 mg) induces moderate and deep sedation in a dose-dependant fashion (9). As a result, for the dose administered (5–6 mg) the validity of an intraoperative VAS as an indicator of adequate anesthesia may be questioned. Finally, Kararmaz et al. provide no data on patient ambulation or PACU discharge.

In conclusion, of the doses investigated, bupivacaine 4 mg plus fentanyl 20 µg, provided adequate analgesia and the fewest side effects.

	Footnotes

 
Accepted for publication November 22, 2006.

	REFERENCES

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Zohar, E. Articles by Fredman, B. Search for Related Content PubMed PubMed Citation Articles by Zohar, E. Articles by Fredman, B. Related Collections Ambulatory Regional Anesthesia Pharmacology