The Effect of Low-dose Intrathecal Fentanyl on Shivering during Spinal Anesthesia for Transurethral Resection of the Prostate (TURP). Ashraf E Alzeftawy MD and Nabil Elsheikh Anesthesia and Surgical Intensive Care Department, Faculty of Medicine,Tanta University Abstract: Introduction: The aim of this study was to investigate the effect of low-dose intrathecal fentanyl on the incidence and severity of shivering during spinal anesthesia for transurethral resection of the prostate (TURP). Materials and Methods: In a randomized controlled trial, 4 patients scheduled for TURP under spinal anesthesia were assigned into two groups, control and fentanyl groups. Spinal anesthesia was performed using 7.5 mg of hyperbaric bupivacaine.5% (.5ml ) plus fentanyl 7.5 mcgm (.5ml), in the fentanyl group and mg hyperbaric bupivacaine(ml) plus normal saline(ml) in the control group. Maximum level of sensory block was estimated. Data on mean arterial blood pressure, heart rate, arterial oxygen saturation, and body temperature were collected before the induction of anesthesia; 5, 5, and 3 minutes after the induction; and in the recovery room. Shivering episodes and severity were recorded during the operation and in the recovery room. Complications related to intrathecal opioids (nausea,vomiting, pruritis ) were recorded. Results: Maximum level of sensory block was comparable in the fentanyl and control groups and so did the motor block. Shivering was significantly lower in the patients who received fentanyl, (%),while in the control group, 7 (35%) experienced various degrees of shivering (P =.). Blood pressure, body temperature, and arterial oxygen saturation were comparable between the two groups. Side effects of fentanyl were unremarkable. Conclusion: Low-dose intrathecal fentanyl succeeded in reduction of the incidence of shivering associated with spinal anesthesia for TURP with good anesthetic criteria and unremarkable side effects. Key words: Intrathecal; fentanyl; Shivering; TURP Introduction: TURP is usually performed under spinal anesthesia so the TURP syndrome ( composed of volume overload and water intoxication) and bladder perforation can be easily and early diagnosed. () Spinal anesthesia is associated with high incidence of shivering. Although this incidence is lower in elderly than adults, it can be hazardous to this group of elderly patients with low cardiovascular reserve and frequent co-morbid diseases. Shivering increases O consumption, CO production, cardiac output,heart rate and hypoxemia. TURP uses large volume of irrigating fluids used usually at room temperature that increases hypothermia and shivering. (,3,4) Many drugs can be used for treatment of shivering as meperidine, clonidine, ketamine,doxapram and benzodiazepines. (5, 6, 7, 8) Treatment of shivering during spinal anesthesia is not without side effects. So, prophylaxis of shivering will be more safe to the patients than treatment. (9,,) Addition of low dose narcotics to spinal local anesthetic resulted in the use of lower doses of local anesthesia, improved the sensory levels, decreased the motor block with resultant lower incidence of hypotension, vascular stability and early patient ambulation. () Use of lower dose fentanyl to guard against spinal shivering had been tried in a limited number of studies. (3, 4, 5) In this work we will use a low dose of fentanyl (7.5mcg) combined with 7.5mg bupivacaine compared with mg hyperbaric bupivacaine as regards its effects and safety for decreasing the incidence and severity of shivering. Patients and Methods This study was approved by the ethics committee and written informed conscent was taken. It included 4 patients with ASA physical status scores of I - III scheduled for TURP under spinal anesthesia. Patients with tremor, history of allergy, and conditions that contraindicated spinal anesthesia were excluded from the study. Patients were assigned into fentanyl () and control ( I) groups by simple randomization. For induction of spinal anesthesia, a intravenous cannula 8 gauge was inserted and preloading with 5 ml crystalloid solution was given and maintained at 6-8ml /kg /hour during the intra-operative period. Intravenous fluids and glycine solution were given at the room temperature. The operating room temperature was maintained at C to 5 C.Standard monitoring were applied. ROAIC September 4 3
Spinal anesthesia was performed in the sitting position at the L3-L4 or L4-L5 interspaces with a midline approach using -gauge Quincke needle. In the fentanyl group, drugs for spinal anesthesia consisted of hyperbaric bupivacaine.5%, 7.5 mg, plus fentanyl 7.5 mcg in a total volume of 3 ml, while in the control group, mg of bupivacaine plus normal saline was administered. After spinal anesthesia induction, the patients were secured in the lithotomy position and the standard TURP was performed. Supplemental oxygen (5 L/min) was administered by a simple face mask during the operation and the recovery time. Systolic, diastolic blood pressure, heart rate, and arterial oxygen saturation were measured and recorded intermittently before induction, intra-operatively (5, 5, and 3 minutes after the induction of the anesthesia), and in the recovery room Sensory block was evaluated by pinprick using a - gauge needle in the midline every minutes from injection until it was stabilized for four times, this was the peak sensory level. The time to reach this level was recorded.motor block was evaluated using the Bromage scale. The incidence and severity of shivering were recorded during the operation and in the recovery room. Shivering was graded with a scale described by Crossley and Mahajan as follows (6) : zero, no shivering;, piloerection or peripheral vasoconstriction but no visible shivering;, muscular activity in only one muscle group; 3, muscular activity in more than Results: All the 4 patients completed the study. Patients characteristics and demographic data were comparable in the two groups. (table ). There were no differences between the groups regarding the basic data including baseline systolic blood pressure, diastolic blood pressure, heart rate, arterial oxygen saturation, and body temperature. Characteristics of anesthesia including the maximum sensory level,time to reach this level, motor block, time to two segments regression and time to S regression showed insignificant changes between the two groups. (Table ). 7 patients (35%) in the control group had variable degrees of shivering while only one patients in the fentanyl group(5%) experienced shivering (P =.). Evaluation of the shivering severity revealed that severity was significantly higher in the control group. (table 3 Discussion Prevention of shivering is beneficial for the patients who undergo surgical operation, especially for the elderly. Although irrigation with warmed solutions can reduce the risk of hypothermia and shivering in TURP, it may increase bleeding. (8) Fentanyl is a highly ionized, lipophilic molecule. When it is used spinally, the unionized component is rapidly transferred into the spinal cord with rapid systemic absorption also occurs as fentanyl dissociates from one muscle group but no generalized shivering; and 4, shivering involving the whole body.. Sublingual temperature was measured with a single calibrated mercury thermometer 3 minutes before induction(t o), 3 minutes after induction(t), 6 minutes after induction (t) and in the recovery room (t3). Severe shivering was treated with intravenous mepridine 5mg. Hypotension was defined as a decrease in the systolic blood pressure to less than 9 mm Hg or % less than the baseline value, which was treated with 5 mg to mg of intravenous ephedrine. Bradycardia ( HR less than 45/minute) was treated by atropine.5mg IV. Side effects of intrathecal fentanyl ( respiratory depression defined as SpO less than 9% and respiratory rate less than 8/minute,pruritus, nausea and vomiting) were recorded. Pruritus was to be treated with.5 mg of intravenous nalbuphine, and intravenous metoclopramide mg, was administered for nausea and vomiting. At the end of the surgery, the amount of glycine and the duration of surgery was recorded. Statistical Analysis: Sample size calculation was performed based on the results of Martyr et al., (7).The chi-square test was used to compare qualitative variables, and repeatedmeasures analysis of variance was used to compare numeral variables and a P value of less than.5 was considered statistically significant. Comparison of the patients body temperature showed a decrease in both groups without any significant difference (P =.46;)( table 4). Nausea was seen in patients of each group (P =.69) and vomiting occurred in patients with fentanyl and (.5%) in the control patients (P =.5). Hypotension and bradycardia occurred in patient in the fentanyl group and patients in the control group. Comparison of hemodynamic changes for each interval showed that the decreasing trends in systolic blood pressure and heart rate were similar in both groups and there were no differences in these parameters during the study course between the two groups. Use of supplemental oxygen resulted in maintaining the arterial oxygen saturation during the operation and no patient in both groups had respiratory depression, and. Pruritus was not reported in any of the patients (table 5). binding sites within the spinal cord. Intrathecally administered fentanyl has its analgesic action both in the spinal cord and systemically (9). The reduction of shivering in the present study may be postulated to the effect of fentanyl on thermoregulator and afferent thermal inputs at the spinal cord (). Its high lipophilicity prevents high concentration of fentanyl from reaching the brain through the cerebrospinal fluid and is unlikely to impair the thermoregulation effect of hypothalamus (,). Reduction of shivering increase ROAIC September 4 3
the risk of hypothermia because of lack of autonomic protective response. (3) Regarding the quality of surgical anesthesia, the authors found that there was no statistically significant difference in the onset and the highest level of sensory and motor blocks between the groups. The comparable level of sensory block in both groups of the present study emphasizes that, there were equal potential effects of block height on the development of hypothermia and shivering, and also, intrathecally administrated fentanyl did not influence level of sensory block. Belzarena et al., had examined the incidence of side effects following doses of, 4 and 6 µg intrathecal fentanyl and revealed that intraoperative respiratory depression and sedation were observed in those who received 4 µg or more (4). Hunt et al., (5) reported that there was significant increase in the incidence of nausea in only the group that received 6.5 µg fentanyl meanwhile, Meanwhile, Dahlgren et al., (4) reported that the addition of intrathecal fentanyl 6 µg for cesarean section reduced the need for intraoperative antiemetic medication. However, in the present study the incidence and severity of nausea / vomiting, sedation and respiratory depression did not increase in fentanyl group which could be postulated to smaller dose of fentanyl used 7.5 µg. Itching is another frequent complication of spinal opioid administration. Several studies reported no increase in incidence of itching with low doses of intrathecal fentanyl (< 5 µg) (5, 4, 5). In the present study, there is no incidence of itching in both groups. In conclusion, the present study revealed a beneficial effect of adding fentanyl into bupivacaine in spinal anesthesia for transuretheral resection of the prostate in preventing intraoperative and postoperative shivering in recovery without increasing the side effects. Table : Patient characteristics, duration of surgery and amount of glycine. Weight Height 66.8 ±8.7 67.8 ±6.8 I 68.5 ± 6.4 68. ±5.7 Age 67.5 ± 7.8 66.8 ±7. Duration of surgery Amount of glycine 6.4 ± 5.7 4.6 ± 8.5 6.8 ± 3.9 5.3 ±7.4 Table : Characteristics of spinal anesthesia Peak sensory level Time to peak sensory level(min) Time to two-segments regression(min) Time to s segment regression(min) Motor block duration(min) T(T5-T) 7. ±.5 6.4 ±4.5 9. ±. 6.6 ±.6 I T( T7-T) 6.8 ±.8 6.4 ±.6 9.4 ±4.5 8.5±.8 Table 3: Shivering assessment in both groups Incidence Severity * statistically significant difference (5%) I ( 35% ) 7 ( -4 ).5 ROAIC September 4 33
Table (4) Temperature changes in both groups Temperature Group I Group II T(before anesthesia) 36.66 ±.37 36.68 ±.35 T(3 min after anesthesia) T( 6 min after anesthesia) 35.83 ±.6 35.78 ±.7 35.89 ±.55 35.85 ±.59 T3 ( in recovery room) 36.6 ±.66 36. ±.73 Table 5 : Incidence of Side effects in each group I Hypotension Bradycardia Nausea Vomiting Pruritus Respiratory depression References: - Morgan GE, Mikhail MS, Murray MJ, et al. Anesthesia for genitourinary surgery. In: Murray MJ, Morgan GE, Mikhail MS, editors. Clinical anesthesiology. 3rd ed. New York: McGraw-Hill;. p. 695-6. - Alfonsi P, Hongnat JM, Lebrault C, Chauvin M. The effects of pethidine, fentanyl and lignocaine on postanaesthetic shivering. Anaesthesia. 995;5:4-7. 3-Kranke P, Eberhart LH, Roewer N, Tramer MR. Pharmacological treatment of postoperative shivering: a quantitative systematic review of randomized controlled trials. Anesth Analg ; 94: 453-6. 4- Chow TC, Cho PH. The influence of small dose intrathecal fentanyl on shivering during transurethral resection of prostate under spinal anaesthesia. Acta Anaesth Singapore 994; 3: 65-7. 5. Chu CC, Shu SS, Lin SM, Chu NW. The effect of intrathecal bupivacaine with combined fentanyl in caesarean section. Acta Anaesthesiol Singapore 995; 33: 49-54. 6. Chamberlain DP, Chamberlain BDL. Changes in the skin temperature of the trunk and their relationship to sympathetic blockade during spinal anesthesia. Anesthesiology 986; 65: 39-43. 7. Pflug AE, Aasheim GM, Foster C, Martin RW. Prevention of post-anaesthesia shivering. Can Anaesth Soc J 978; 5: 43-9. 8. Kurz A, Sessler DI, Shroeder M. Thermoregulatory response thresholds during spinal anesthesia. Anesth Analg 993; 77: 7-6. 9. Walmsley AJ, Giesecke AH, Lipton JM. Contribution of extradural temperature to shivering during extradural anaesthesia. Br J Anaesth 986; 58: 3-4.. Sharky A, Lipton JM, Murphy MT, Giesecke AH. Inhibit of postanesthetic shivering with radiant heat. Anesthesiology 987; 66: 49-5.. Shehabi Y, Gatt S, Buckman T, Isert P. Effect of adrenaline, fentanyl and warming of injectate on shivering following extradural analgesia in labor. Anaesth Intens Care 99; 8: 3-7. ROAIC September 4 34
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