Preoperative anterior thigh temperature does not correlate with perioperative temporal hypothermia during cesarean delivery with spinal anesthesia: Secondary analysis of a randomized control trial

BackgroundCore-to-peripheral redistribution of heat, secondary to sympathetic-mediated vasodilation, is the major mechanism leading to early perioperative hypothermia after neuraxial anesthesia. The study aim was to determine if preoperative anterior thigh (peripheral lower extremity) temperature predicted perioperative temporal (core) temperature decrease during cesarean delivery with spinal anesthesia.MethodsSecondary analysis of data derived from a prospective, randomized study of 46 healthy women undergoing scheduled cesarean delivery with spinal anesthesia was performed. Anterior thigh temperature was measured preoperatively prior to spinal anesthesia. The primary outcome was maximum perioperative temporal temperature decrease. Secondary outcomes included incidence of temporal hypothermia (temperature <36°C), shivering, and thermal comfort scores. This study ran concurrently with a previously published trial comparing no active intraoperative warming with active warming.ResultsThere was no correlation between preoperative anterior thigh temperature and maximum perioperative temporal temperature decrease (r=−0.049, P=0.751). The mean ± standard deviation preoperative anterior thigh temperature of women who developed temporal hypothermia compared to those who did not was 32.4 ± 0.8°C versus 32.4 ± 0.70°C respectively (P=0.995). Preoperative anterior thigh temperature did not correlate with the incidence of shivering (r=0.267, P=0.080) or thermal comfort scores (r=0.233, P=0.129).ConclusionPreoperative anterior thigh temperature does not correlate with the degree of perioperative temporal temperature decrease, likelihood of developing hypothermia, shivering, or thermal comfort during cesarean delivery with spinal anesthesia. Although core-to-peripheral redistribution of heat after neuraxial anesthesia is a major mechanism of perioperative heat loss, a lower extremity temperature prediction hypothesis was not confirmed in this population.     

Effect of low dose phenylephrine infusion on shivering and hypothermia in patients undergoing cesarean section under spinal anesthesia: a randomized clinical trial

BackgroundShivering is a common complication of spinal anesthesia. Phenylephrine, due to its peripheral vasoconstrictive effect, may limit the core to periphery redistribution of body temperature following spinal anesthesia, and reduce hypothermia and shivering. We hypothesized that prophylactic phenylephrine infusion would reduce shivering and hypothermia in women undergoing cesarean section under spinal anesthesia.MethodsA two-arm randomized, double-blind, placebo-controlled trial in term pregnant patients undergoing cesarean section. In the phenylephrine group (n=75) prophylactic phenylephrine infusion was administered at 25 µg/min immediately after initiation of spinal anesthesia and continued until the end of the operative period. In the placebo group (n=75) a normal saline infusion was administered during the same period. The primary outcome was the incidence of shivering; secondary outcomes were severity of shivering, changes in nasopharyngeal (core) temperature, and incidence of hypotension and bradycardia.ResultsThe incidence of shivering in the phenylephrine and control groups was 24.0% (95% CI 14.3% to 33.7%) and 53.3% (95% CI 42.0% to 64.6%), respectively. The severity of shivering was greater in the control group (P=0.002) and the mean (±SD) end of surgery core temperature was significantly higher in the phenylephrine group (35.84°C ± 0.60) compared with controls (35.61°C ± 0.48) (P=0.009). The incidence of hypotension was higher in controls (53.4% vs. 2.7%; P <0.001) but bradycardia more frequent in group P (P=0.023).ConclusionThe incidence of shivering and degree of hypothermia were significantly reduced by a prophylactic phenylephrine infusion during cesarean section under spinal anesthesia.     

Thermal balance and tremor patterns during epidural anesthesia

Five healthy, nonpregnant volunteers were studied before and after induction of lumbar epidural anesthesia to determine the cause of central hypothermia during epidural anesthesia. Cutaneous heat loss was measured from 10 area-weighted sites using thermal flux transducers. Oxygen consumption was measured and converted to heat production in watts (W). After a 2-h control period at approximately 20 degrees C, epidural anesthesia was induced by injection of 30-50 ml 3% chloroprocaine. Additional boluses were given to extend the sensory blockade to at least the T5 dermatome. Tremor during epidural anesthesia was compared with normal shivering induced by rapid central venous infusion of approximately 4 l iced saline in six unanesthetized volunteers. Average skin temperature and cutaneous heat loss decreased during the control period, while tympanic membrane temperature remained stable. During the 1st h of epidural blockade, tympanic membrane temperature decreased 1.1 +/- 0.3 degrees C, and average skin temperature increased 0.9 +/- 0.5 degrees C. Cutaneous heat loss increased 16 +/- 6% (15 +/- 5 W), but metabolic heat production increased even more (and was associated with a shivering-like tremor). Tremor during epidural anesthesia and shivering induced by iced saline infusion had similar synchronous waxing-and-waning patterns. No abnormal EMG patterns were detected during epidural anesthesia. We conclude that central hypothermia during the 1st h of epidural anesthesia does not result from heat loss to the environment in excess of metabolic heat production, but results primarily from redistribution of body heat from central to peripheral tissues. Analysis of the tremor patterns suggests that oscillations recorded during epidural anesthesia in nonpregnant individuals is normal thermoregulatory shivering. Shivering occurred sooner and was more intense during iced saline infusion than during epidural anesthesia, despite comparable central hypothermia. The low intensity of shivering during epidural anesthesia, and in some individuals the delay in onset, may result from blockade of afferent cutaneous cold signals.     

The effect of bupivacaine with fentanyl temperature on initiation and maintenance of labor epidural analgesia: a randomized controlled study

BackgroundLabor epidural analgesia is highly effective, but can be limited by slow onset and incomplete blockade. The administration of warmed, compared to room temperature, bupivacaine has resulted in more rapid onset epidural anesthesia. We hypothesized that the administration of bupivacaine with fentanyl at 37°C versus 20°C would result in improved initial and ongoing labor epidural analgesia.MethodsIn this prospective, randomized, doubled blinded study, 54 nulliparous, laboring women were randomized to receive epidural bupivacaine 0.125% with fentanyl 2 μg/mL (20 mL initial and 6 mL hourly boluses) at either 37°C or 20°C. Pain verbal rating scores (VRS), sensory level, oral temperature, and side effects were assessed after epidural loading (time 0), at 5, 10, 15, 20, 30, 60 min, and at hourly intervals. The primary outcome was the time to achieve initial satisfactory analgesia (VRS ⩽3). Secondary outcomes included ongoing quality of sensory blockade, body temperature and shivering.ResultsThere were no differences between groups in patient demographics, initial pain scores, cervical dilatation, body temperature or mode of delivery. Epidural bupivacaine at 37°C resulted in shorter mean (±SD) analgesic onset time (9.2 ± 4.7 vs. 16.0 ± 10.5 min, P = 0.005) and improved analgesia for the first 15 min after initial bolus (P = 0.001–0.03). Although patient temperature increased during the study (P < 0.01), there were no differences between the groups (P = 0.09). Six (24%) and 10 (40%) patients experienced shivering in the 37°C and 20°C groups, respectively (P = 0.23).ConclusionsThe administration of epidural 0.125% bupivacaine with fentanyl 2 μg/mL at 37°C versus 20°C resulted in more rapid onset and improved labor analgesia for the first 15 min. There was no evidence of improved ongoing labor analgesia or differences in side effects between groups.     

Epidural cooling for regional spinal cord hypothermia during thoracoabdominal aneurysm repair

Purpose: We investigated the feasibility of achieving regional hypothermia of the spinal cord with an infusion of iced (4° C) saline solution administered into an epidural catheter while monitoring cerebral spinal fluid (CSF) temperature in eight patients undergoing thoracic or thoracoabdominal aneurysm resection.Methods: As part of the anesthetic management, an epidural catheter was placed at T11-12, and a subarachnoid thermistor catheter was placed at L3-4. Approximately 30 minutes before aortic cross-clamping, iced (4° C) saline solution was infused into the epidural catheter until CSF temperature decreased to approximately 25° C. The infusion was then adjusted to maintain this temperature until the aorta was unclamped. The subarachnoid catheter was also used to measure CSF pressure and provide for CSF drainage. Surgery was performed in all patients with a clamp-and-sew technique with selective intercostal vessel reattachment.Results: Infusion of a mean volume of 489 ml (range 80 to 1700 ml) of iced saline solution into the epidural space before aortic cross-clamping led to a decrease in mean CSF temperature to 26.9° C (range 25° to 28.8° C) in 15 to 90 minutes. During cross-clamping and aortic replacement the mean CSF temperature was maintained between 25.2° to 27.6° C and, with discontinuation of the infusion, returned to within 1° C of body core temperature by the end of the procedure. Body core temperature was not significantly affected by the epidural infusion. Mean CSF pressure increased during the epidural infusion but could be reduced by removing saline solution from the epidural space. No postoperative neurologic deficits were observed.Conclusion: Epidural cooling appears to be a satisfactory method of achieving regional spinal cord hypothermia in patients requiring resection of thoracic or thoracoabdominal aortic aneurysms. (J VASC SURG 1994;20:304-10.)     

A randomized comparison of onset of anesthesia between spinal bupivacaine 5 mg with immediate epidural 2% lidocaine 5 mL and bupivacaine 10 mg for cesarean delivery

BackgroundPrevious studies using low-dose spinal anesthesia for cesarean delivery have focused on hypotension and efficacy. This study evaluated whether, using a combined spinal–epidural technique, there was a difference in onset of anesthesia for cesarean delivery between low-dose spinal with an immediate epidural local anesthetic bolus, and conventional-dose spinal anesthesia.MethodsForty healthy term nulliparous women undergoing elective cesarean delivery with a combined spinal–epidural technique were enrolled into this prospective, randomized, double-blind study. Patients were randomly allocated to the low-dose (Group L) or conventional-dose group (Group C). Patients in Group L received intrathecal isobaric bupivacaine 5 mg with sufentanil 2.5 μg followed by epidural 2% lidocaine 5 mL; patients in Group C received intrathecal isobaric bupivacaine 10 mg with sufentanil 2.5 μg followed by epidural saline 5 mL. The onset of anesthesia (defined as the time from spinal injection to a block to T6), incidence of hypotension, maximal sensory block, epidural supplementation and side effects were recorded.ResultsAll blocks reached T6 within 11 min except for one patient in Group L. There were no differences in onset of anesthesia (9.9 ± 3.2 min in Group L vs. 8.5 ± 1.2 min in Group C, P = 0.08), maximal block level and the number of patients who required epidural supplementation in both groups. Hypotension occurred in 8 patients (40%) in Group L and 15 patients (75%) in Group C (P = 0.02).ConclusionsIntrathecal bupivacaine 5 mg with immediate 2% epidural lidocaine 5 mL provided comparable onset and efficacy of anesthesia as bupivacaine 10 mg with immediate epidural normal saline 5 mL for cesarean delivery.     

Use of high-resolution thermography as a validation measure to confirm epidural anesthesia in mice: a cross-over study

BackgroundEffective epidural anesthesia is confirmed in humans by sensory assessments but these tests are not feasible in mice. We hypothesized that, in mice, infrared thermography would demonstrate selective segmental warming of lower extremities following epidural anesthesia.MethodsWe anesthetized 10 C57BL/6 mice with isoflurane and then inserted a PU-10 epidural catheter under direct surgical microscopy at T11-12. A thermal camera (thermal sensitivity ±0.05°C, pixel resolution 320x240 pixels, and spatial resolution 200 μm) recorded baseline temperature of front and rear paws, tail and ears. Thermography was assessed at baseline and 2, 5, 10, and 15 min after an epidural bolus dose of 50 μL bupivacaine 0.25% or 50 μL saline (control) using a cross-over design with dose order randomized and investigators blinded to study drug. Thermal images were recorded from video and analyzed using FLIR software. Effect over time and maximal effect (E_max) were assessed by repeated measures ANOVA and paired t-tests. Comparisons were between bupivacaine and control, and between lower vs upper extremities.ResultsEpidural bupivacaine caused progressive warming of lower compared with upper extremities (P <0.001), typically returning to baseline by 15 min after administration. Mean (±SD) E_max was +3.73 (±1.56) °C for lower extremities compared with 0.56 (±0.68) °C (P=0.03) for upper extremities. Following epidural saline, there was no effect over time (E_max for lower extremities −0.88 (±0.28) °C compared with the upper extremities −0.88 (±0.19) °C (P >0.99).ConclusionsThermography is a useful tool to confirm epidural catheter placement in animals for which subjective, non-noxious, sensory measures are impossible.     

Epidural fentanyl speeds the onset of sensory block during epidural lidocaine anesthesia

BACKGROUND AND OBJECTIVES: Shortening the onset time of sensory block is a practical goal to improve the quality of epidural anesthesia. The addition of fentanyl to a local anesthetic solution is widely used during epidural anesthesia. This randomized double-blind study examined the onset time of sensory block during epidural lidocaine anesthesia with and without added fentanyl to the epidural solution. METHODS: Thirty-six young male patients undergoing knee arthroscopy were randomly allocated into 3 groups of 12 patients each: epidural fentanyl (EF, epidural administration of 17 mL of 2% lidocaine plus 100 microg fentanyl and followed by intravenous (IV) injection of 2 mL of normal saline); IV fentanyl (IF, epidural administration of 17 mL of 2% lidocaine plus 2 mL of normal saline and followed by IV injection of 100 microg of fentanyl); and control (C, epidural administration of 17 mL of 2% lidocaine plus 2 mL of normal saline and followed by IV injection of 2 mL of normal saline). The sensory block was assessed by pinprick method. The hemodynamic changes, postepidural shivering, and side effects of epidural fentanyl were also recorded. RESULTS: There was no difference in the distribution of age, weight, and height among the 3 groups. The onset time of sensory block up to T(10) dermatome was significantly more rapid in the EF group (8.3 +/- 3.7 minutes) than that of the IF group (13.1 +/- 4.2 minutes, P <.05) or C group (14.2 +/- 5.4 minutes, P <.05). The upper level of sensory block was also significantly higher in the EF group. Although the incidence of shivering was lower in the EF group, this did not reach statistical significance. Postepidural arterial blood pressures and heart rates were no different among the 3 groups. No nausea, vomiting, pruritus, respiratory depression, urinary retention, or hypotension were observed in any patients. CONCLUSION: Epidural injection of the mixture of 100 microg fentanyl and 2% lidocaine solution accelerated the onset of sensory block during epidural lidocaine anesthesia without increased side effects.     

A mechanistic study of the tremor associated with epidural anaesthesia for intrapartum caesarean delivery

BackgroundIt is not known if the tremor associated with an epidural top-up dose for intrapartum caesarean delivery is thermoregulatory shivering. A tremor is only shivering if it has the same frequency profile as cold stress-induced shivering. Thermoregulatory shivering is a response to a reduction in actual body temperature, whereas non-thermoregulatory shivering may be triggered by a reduction in sensed body temperature. This mechanistic study aimed to compare: 1. the frequency profiles of epidural top-up tremor and cold stress-induced shivering; and 2. body temperature (actual and sensed) before epidural top-up and at the onset of tremor.MethodsTwenty obstetric patients received an epidural top-up for intrapartum caesarean delivery and 20 non-pregnant female volunteers underwent a cold stress. Tremor, surface electromyography, core temperature, skin temperature (seven sites) and temperature sensation votes (a bipolar visual analog score ranging from −50 to +50 mm) were recorded.ResultsThe mean (SD) primary oscillation (9.9 (1.9) Hz) frequency of epidural top-up tremor did not differ from that of cold stress-induced shivering (9.0 (1.6) Hz; P=0.194), but the mean (SD) burst frequency was slower (6.1 (1.2) × 10⁻² Hz vs 6.9 (0.7) × 10⁻² Hz, respectively; P=0.046). Before the epidural top-up dose, the mean (SD) core temperature was 37.6 (0.6) °C. Between the epidural top-up dose and the onset of tremor the mean (SD) core temperature did not change (–0.1 (0.1) °C; P=0.126), the mean (SD) skin temperature increased (+0.4 (0.4) °C; P=0.002) and the mean (SD) temperature sensation votes decreased (−12 (16) mm; P=0.012).ConclusionThese results suggest that epidural top-up tremor is a form of non-thermoregulatory shivering triggered by a reduction in sensed body temperature.     

Os efeitos do aquecimento de cristaloides sobre a temperatura corporal materna e nas condições fetais: ensaio clínico randômico

Background and objectives

Hypothermia occurs in about 60% of patients under anesthesia and is generally not managed properly during short lasting surgical procedures. Hypothermia is associated with adverse clinical outcomes. The current study is designed to assess the effects of crystalloid warming on maternal and fetal outcomes in patients undergoing elective cesarean section with spinal anesthesia.

Levobupivacaine vs racemic bupivacaine in spinal anesthesia for sequential bilateral total knee arthroplasty: a retrospective cohort study

Study objectivesTo compare the anesthetic potency and safety of spinal anesthesia with higher dosages of levobupivacaine and bupivacaine in patients for bilateral sequential for total knee arthroplasty (TKA).DesignRetrospective cohort study.SettingOperation theater with postoperative inpatient follow-up.PatientsThe medical records of 315 patients who underwent sequential bilateral TKA were reviewed.InterventionsPatients who received intrathecal levobupicavaine 0.5% were compared with patients who received hyperbaric bupivacaine 0.5% with fentanyl 25 μg for spinal anesthesia.MeasurementsThe primary outcome was the use of rescue analgesia (systemic opioids, conversion to general anesthesia) during surgery for both groups. Secondary outcomes included adverse effects of local anesthetics (hypotension and bradycardia) during surgery and morbidity related to spinal anesthesia (postoperative nausea, vomiting, and bleeding) during hospital stay.Main resultsOne hundred fifty patients who received intrathecal levobupivacaine 0.5% (group L) were compared with 90 patients given hyperbaric bupivacaine 0.5% with fentanyl 25 μg (group B). The mean volume of levobupivacaine administered was 5.8 mL (range, 5.0-6.0 mL), and that of bupivacaine was 3.8 mL (range, 3.5-4.0 mL). Both groups achieved similar maximal sensory level of block (T6). The time to maximal height of sensory block was significantly shorter in group B than group L, 18.2 ± 4.5 vs 23.9 ± 3.8 minutes (P< .001). The time to motor block of Bromage 3 was also shorter in group B (8.7 ± 4.1 minutes) than group L (16.0 ± 4.5 minutes) (P< .001). Patients in group B required more anesthetic supplement than group L (P< .001). Hypotension and postoperative bleeding were significantly less common in group L than group B.ConclusionLevobupivacaine at a higher dosage provided longer duration of spinal anesthesia with better safety profile in sequential bilateral TKA.     

Spinal cord ischemia and reperfusion metabolism: The effect of hypothermia

Purpose: The metabolic and neurologic functional effects of regional hypothermia induced by cold (4° C) heparinized saline perfusion on spinal cord ischemia were evaluated in 35 rabbits.Methods: Spinal cord ischemia was induced for 20 minutes by infrarenal aortic occlusion in anesthetized animals. Regional spinal cord hypothermia was obtained by perfusing the lumbar arteries supplying the spinal cord through an infrarenal aortic catheter. The lumbar spinal cord was "snap frozen" in situ with liquid nitrogen and harvested immediately at the conclusion of the ischemic period or after 24 hours of normothermic reperfusion and neurologic observation. Spinal cord metabolic studies included determination of the energy charge and the intracellular concentrations of adenosine triphosphate, glucose, lactate, glutamate, and aspartate.Results: Postoperative neurologic function was normal in all but one animal treated with hypothermia, while normothermic ischemia resulted in paralysis in all animals ( p = 0.002). Spinal cord temperature during 20 minutes of ischemia and hypothermic perfusion decreased from 37.5° ± 0.43° C to 22.8° ± 0.00° C ( p = 0.0001) compared to a fall in systemic temperature from 38.8 to 36.1 ( p = 0.0001). Hypothermia reduced the decline in energy charge, adenosine triphosphate concentration and glucose concentration during ischemia but had no effect on markedly elevated levels of lactate acid. High-energy phosphates were restored after reperfusion in both normothermic and hypothermic animals and were not predictive of postoperative paraplegia. Intracellular glutamate and aspartate concentrations were unchanged during normothermic ischemia but decreased after reperfusion in all paralyzed animals. Intracellular glutamate and aspartate concentrations increased during hypothermic perfusion and remained elevated after reperfusion in animals with a normal or mildly abnormal neurologic examination result.Conclusions: We conclude that spinal cord hypothermia induced by cold heparinized saline perfusion is a simple technique that prevents paraplegia after 20 minutes of ischemia and preserves intracellular concentrations of important metabolites. (J VASC SURG 1994;19:332-40.)     

Epidural Anesthesia Reduces the Gain and Maximum Intensity of Shivering

Background: Shivering can be characterized by its threshold (triggering core temperature), gain (incremental intensity increase), and maximum intensity. The gain of shivering might be preserved during epidural or spinal anesthesia if control mechanisms compensate for lower-body paralysis by augmenting the activity of upper-body muscles. Conversely, gain will be reduced approximately by half if the thermoregulatory system fails to compensate. Similarly, appropriate regulatory feedback might maintain maximum shivering intensity during regional anesthesia. Accordingly, the gain and maximum intensity of shivering during epidural anesthesia were determined.

Methods: Seven volunteers participated on two randomly ordered study days. On one day (control), no anesthesia was administered; on the other, epidural anesthesia was maintained at a T8 sensory level. Shivering, at a mean skin temperature near 33 [degree sign] Celsius, was provoked by central-venous infusion of cold fluid; core cooling continued until shivering intensity no longer increased. Shivering was evaluated by systemic oxygen consumption and electromyography of two upper-body and two lower-body muscles. The core temperature triggering an increase in oxygen consumption identified the shivering threshold. The slopes of the oxygen consumption versus core temperature and electromyographic intensity versus core temperature regressions identified systemic and regional shivering gains, respectively.

Results: The shivering threshold was reduced by epidural anesthesia by [nearly =] 0.4 [degree sign] Celsius, from 36.7 +/- 0.6 to 36.3 +/- 0.5 [degree sign] Celsius (means +/- SD; P < 0.05). Systemic gain, as determined by oxygen consumption, was reduced from -581 +/- 186 to -215 +/- 154 ml [center dot] min sup -1 [center dot] [degree sign] Celsius sup -1 (P < 0.01). Lower-body gain, as determined electromyographically, was essentially obliterated by paralysis during epidural anesthesia, decreasing from -0.73 +/- 0.85 to -0.04 +/- 0.06 intensity units/[degree sign] Celsius (P < 0.01). However, upper-body gain had no compensatory increase: -1.3 +/- 1.1 units/[degree sign] Celsius control versus -2.0 +/- 2.1 units/[degree sign] Celsius epidural. Maximum oxygen consumption was decreased by one third during epidural anesthesia: 607 +/- 82 versus 412 +/- 50 ml/min (P < 0.05).     

Nefopam and tramadol for the prevention of shivering during neuraxial anesthesia

BACKGROUND AND OBJECTIVES: In patients undergoing neuraxial anesthesia, heat loss and core-to-peripheral redistribution of body heat causes the core temperature to decrease. The shivering threshold is therefore reached soon, and more shivering is required to prevent further hypothermia. Because shivering has deleterious metabolic and cardiovascular effects, it should ideally be prevented by pharmacologic or other means. We evaluated the usefulness of intravenous (IV) nefopam and tramadol in preventing and reducing the severity of shivering in patients undergoing neuraxial anesthesia for orthopedic surgery. METHODS: Ninety patients, scheduled for neuraxial anesthesia (epidural or subarachnoid) for lower limb orthopedic surgery, were prospectively enrolled. Patients were randomly assigned to 1 of 3 groups. Immediately before neuraxial anesthesia, 30 patients received 0.15 mg/kg(-1) IV nefopam in 10 mL saline, 30 patients received 0.5 mg/kg(-1) IV tramadol in 10 mL saline, and a control group of 30 patients received 10 mL IV saline. Neuraxial anesthesia was induced at the L3-L4 or L4-L5 interspaces with 1 mg/kg(-1) mepivacaine for epidural anesthesia and 0.2 mg/kg(-1) for subarachnoid anesthesia. An investigator blinded to the antishivering drug injected recorded the frequency and degree of shivering. RESULTS: The overall frequency and the intensity of shivering was significantly lower in patients treated with nefopam than in those treated with tramadol or placebo (P <.05 and P <.01) and in patients treated with tramadol than in those treated with placebo (P <.05). CONCLUSIONS: As a pharmacologic means of preventing shivering in patients undergoing neuraxial anesthesia, nefopam may hold the greatest promise.     

Estudo prospectivo randômico,duplo‐cego e controlado comparando tramadol,clonidina e dexmedetomidina para tremores pós‐raquianestesia

Introduction

Shivering, a common intraoperative problem under spinal anesthesia increases the oxygen consumption considerably and is uncomfortable and distressing to the patient, anesthesiologist as well as surgeon. The present study was designed to explore the effectiveness of tramadol, clonidine and dexmedetomidine in the treatment of post spinal anesthesia shivering and to look for their adverse effects.

Cathétérisation accidentelle de l'espace sous-dural extra-arachnoïdien lors d'une analgésie péridurale en obstétrique

The authors describe a case of accidental catheterization of the subdural extra-arachnoid space during epidural analgesia for labour. The epidural catheter had been inserted at the L3–L4 interspace without any problem. A severe hypotension occurred 90 min after the onset of analgesia. A T4 upper sensory level was associated with a complete motor blockade. Total spinal anaesthesia was suspected but ruled out because of delayed onset of analgesia. Extensive epidural anaesthesia was also eliminated as the local anaesthetic dose (15 mL of bupivacaine 0.125 %) was not excessive for this patient. After delivery, a water-soluble contrast medium (10 mL of Omnipaque® 180) was injected through the catheter and subsequent radiograph of spine showed subdural spread of the contrast medium. This complication might occur more frequently than usually thought and may be life-threatening. Anaesthetic management is discussed in the case of Caesarean section during labour.     

Lower limb wrapping prevents hypotension, but not hypothermia or shivering, after the introduction of epidural anesthesia for cesarean delivery

The decrease of arterial blood pressure and body temperature after epidural or spinal anesthesia is thought to be the result of sympathetic block, which could cause pooling and redistribution of blood into the lower extremities. Studies have demonstrated that leg wrapping with elastic bandages may reduce the incidence of hypotension after spinal anesthesia. We tried to extend these previous observations to epidural anesthesia by testing the hypothesis that leg wrapping with elastic bandages should decrease the incidence of hypotension in patients receiving epidural anesthesia. Moreover, we evaluated the effect of this maneuver as regards hypothermia and shivering. Sixty parturients were randomly allocated to receive either leg wrapping with tight elastic bandages (leg-wrapped group) or not (control group) before anesthesia. Sublingual temperature was observed at five periods: baseline, immediately after epidural anesthesia, abdominal skin disinfection, skin incision, and delivery. Hypotension and shivering during the observation periods were also recorded. The incidence of hypotension was significantly less frequent (P = 0.03) in the leg-wrapped group (23%) compared with the control group (50%). Shivering incidences were similar in both groups (70% versus 70%). Sublingual temperature decreased significantly (P < 0.001) throughout the procedure in each group. However, no differences were found between the two groups at each designated observation, even if compared by the magnitude of temperature decrease. We conclude that although leg wrapping with elastic bandages prevents maternal hypotension after epidural anesthesia, it does not reduce the incidence or magnitude of hypothermia or prevent shivering.     

Effect of cooled hyperbaric bupivacaine on unilateral spinal anesthesia success rate and hemodynamic complications in inguinal hernia surgery

Purpose

We hypothesized that cooling hyperbaric bupivacaine from 23 to 5 °C may limit the intrathecal spread of bupivacaine and therefore increase the success rate of unilateral spinal anesthesia and decrease the rate of hemodynamic complications.

Methods

A hundred patients scheduled for elective unilateral inguinal hernia surgery were randomly allocated to receive 1.8 ml of 0.5 % hyperbaric bupivacaine intrathecally at either 5 °C (group I, n = 50) or at 23 °C (group II, n = 50). Following spinal block at the L2-3 interspace, the lateral decubitus position was maintained for 15 min. Unilateral spinal anesthesia was assessed and confirmed at 15 and 30 min. The levels of sensory and motor block on the operative side were evaluated until complete resolution.

Results

The rate of unilateral spinal anesthesia at 15 and 30 min was significantly higher in group I (p = 0.015 and 0.028, respectively). Hypotensive events and bradycardia were significantly rarer in group I (p = 0.014 and 0.037, respectively). The density and viscosity of the solution at 5 °C was significantly higher than at 23 °C (p < 0.0001). Compared with group II, sensory block peaked later in group I (17.4 vs 12.6 min) and at a lower level (T9 vs T7), and two-segment regression of sensory block (76.4 vs 84.3 min) and motor block recovery was shorter (157.6 vs 193.4 min) (p < 0.0001).

Conclusions

Cooling of hyperbaric bupivacaine to 5 °C increased the density and viscosity of the solution and the success rate of unilateral spinal anesthesia, and decreased the hemodynamic complication rate.

     

Spinal Ropivacaine for Cesarean Section: A Dose-finding Study

Background : The dose-response relation for spinal ropivacaine is undetermined, and there are few data available for obstetric patients.

Methods : In a prospective, randomized, double-blind investigation, the authors studied 72 patients undergoing elective cesarean delivery. An epidural catheter was placed at the L2-L3 vertebral interspace. Lumbar puncture was then performed at the L3-L4 vertebral interspace, and patients were randomized to receive a dose of spinal ropivacaine diluted to 3 ml with normal saline: 10 mg (n = 12), 15 mg (n = 20), 20 mg (n = 20), or 25 mg (n = 20). Sensory changes assessed by ice and pin prick and motor changes assessed by modified Bromage score were recorded at timed intervals. A dose was considered effective if an upper sensory level to pin prick of T7 or above was achieved and epidural supplementation was not required intraoperatively.

Results : Anesthesia was successful in 8.3, 45, 70, and 90% of the 10-, 15-, 20-, and 25-mg groups, respectively. A sigmoid dose-response curve and a probit log dose-response plot were obtained, and the authors determined the ED50 (95% confidence interval) to be 16.7 (14.1-18.8) mg and the ED95 (95% confidence interval) to be 26.8 (23.6-34.1) mg. Duration of sensory and motor block and degree of motor block, but not onset of anesthesia, were positively related to dose.     

Epidural fentanyl speeds the onset of sensory and motor blocks during epidural ropivacaine anesthesia

In this study we examined the onset times of sensory and motor block during epidural ropivacaine anesthesia with and without the addition of fentanyl to the epidural solution. Forty-five young male patients undergoing knee arthroscopic surgery were randomly allocated into 3 groups of 15 patients each: epidural fentanyl (EF; epidural administration of 15 mL of 1% ropivacaine plus 100 mug fentanyl followed by IV injection of 2 mL of normal saline); IV fentanyl (IF; epidural administration of 15 mL of 1% ropivacaine plus 2 mL of normal saline followed by IV injection of 100 mug fentanyl); and control (C; epidural administration of 15 mL of 1% ropivacaine plus 2 mL of normal saline followed by IV injection of 2 mL of normal saline). The sensory and motor blocks were assessed by pinprick and modified Bromage scale, respectively. The hemodynamic changes, postepidural shivering, and side effects of epidural fentanyl were also recorded. There was no difference in the distribution of age, weight, and height among the 3 groups. The onset time of sensory block to the T10 dermatome was significantly more rapid in the EF group (13.0 +/- 3.0 min) than in the IF group (16.2 +/- 3.5 min, P < 0.05) or C group (17.7 +/- 3.6 min, P < 0.05). The onset times of motor block up to Bromage scale 1 and 2 were significantly more rapid in the EF group (11.9 +/- 4.6 and 24.4 +/- 5.9 min) than in the IF group (16.9 +/- 4.7 and 30.8 +/- 5.6 min, P < 0.05) or C group (18.3 +/- 4.9 and 32.7 +/- 5.7 min, P < 0.05). There was no difference in the incidence of shivering among the three groups. Pruritus was observed in three patients of the EF group and one patient of the IF group. No nausea, vomiting, respiratory depression, urinary retention, or hypotension was observed in any patient. We conclude that epidural administration of the mixture of 100 mug fentanyl and 1% ropivacaine solution accelerated the onset of sensory and motor blocks during epidural ropivacaine anesthesia without significant fentanyl-related side effects.