Prophylactic epidural administration of fentanyl for the suppression of tourniquet pain

Severe dull pain on the side of tourniquet application and marked rises in blood pressure and heart rate associated with that pain are often observed even under adequate regional analgesia. The purpose of this study was to evaluate the effect of epidural fentanyl on the suppression of tourniquet pain during orthopedic surgical procedures. Forty-five patients undergoing orthopedic surgery of the lower extremities with a tourniquet were maintained by continuous epidural anesthesia with 2% lidocaine through an epidural indwelling polyethylene catheter (L3–4). The patients were randomly allocated to the following three groups: epidural fentanyl (100μg) (epidural group,n=15); intravenous fentanyl (100μg) (intravenous group,n=15); control (no fentanyl) (control group,n=15). The epidural or intravenous fentanyl was administered at the time of the second lidocaine injection. The severity of tourniquet pain based on the patient's level of complaint and the total dose of supplemental analgesics requested in the epidural group were significantly lower than those in the control group. Blood pressure during tourniquet application in the epidural group was more stable than in the other two groups. No severe side-effects were observed in any patient. Prophylactic epidural administration of fentanyl might be useful in the suppression of tourniquet pain.     

Etomidate infusion in thoracic anaesthesia

An etomidate infusion was used in the place of nitrous oxide during one lung anaesthesia for 40 patients undergoing thoracic surgery. Analgesia was provided by fentanyl. A mixture of oxygen and air was used to maintain arterial oxygen tension within normal limits despite one lung anaesthesia and enabled the use of nitrous oxide to be avoided in several patients who had lung cysts. Recovery was fairly rapid (mean (SEM) 11.5 (1.4) minutes). There was no incidence of awareness or dreams. This technique provides satisfactory anaesthesia and oxygenation during thoracic surgery when one lung only is being ventilated.     

Day case anaesthesia and memory

Two simple anaesthetic techniques were administered to forty healthy women undergoing minor gynaecological surgery. There was a significantly shorter immediate recovery period following the use of a fentanyl and methohexitone technique. Memory function testing revealed an impairment of the ability to retain new information following anaesthesia. This returned to normal within 3 hr.     

Spinal anesthesia for arthroscopic knee surgery

BACKGROUND AND OBJECTIVE: The purpose of the study was to compare the effects of adding 50 microg of morphine, 25 microg of fentanyl or saline to 6 mg of hyperbaric bupivacaine on postoperative analgesia and time to urination in patients undergoing arthroscopic knee surgery under spinal anesthesia. METHODS: The study was designed in a prospective, randomized, double-blinded and placebo-controlled manner. Sixty ASA I-II patients were randomized into the following three groups: Group BM: 6 mg of bupivacaine and 50 microg of morphine, Group BF: 6 mg of bupivacaine and 25 microg of fentanyl, and Group BS: 6 mg of bupivacaine and saline. Selective spinal anesthesia was performed in a lateral decubitus position, with the operative knee dependent for 10 min. RESULTS: In all groups satisfactory anesthesia was provided during the operation. There was a statistically significant difference between all the groups in times to voiding [Group BM 422 +/- 161 min; Group BF 244 +/- 163 min; Group BS 183 +/- 54 min (mean +/- SD)]. The incidence of pruritus was significantly greater in Group BM (80%) and BF (65%) in comparison with Group BS (no pruritus) (P < 0.05). The incidence of nausea was significantly increased in Group BM (35%) in comparison with Group BF (10%) and Group BS (P < 0.05). Analgesic consumption was significantly greater in Group BS in comparison with Groups BM and BF (P < 0.01). CONCLUSIONS: We conclude that during spinal anesthesia even mini-dose intrathecal morphine is not acceptable for outpatient surgery due to side-effects, especially severely prolonged time to urination.     

Racemic ketamine does not abolish cerebrovascular autoregulation in the pig

BACKGROUND: Little is known about the influence of racemic ketamine on autoregulation of cerebral blood flow (CBF), and available reports regarding its influence on cerebral hemodynamics are contradictory. This study was designed to evaluate cerebrovascular responses to changes in the mean arterial pressure (MAP) during ketamine anesthesia. METHODS: In eight normoventilated pigs anesthesia was induced with propofol and maintained by i.v. infusion of ketamine (15.0 mg kg(-1) x h(-1)) during measurements. The intra-arterial xenon clearance technique was used to calculate CBF. Balloon-tipped catheters were introduced in the inferior caval vein and mid-aorta, and increases or decreases by up to 40% in mean arterial pressure (MAP) in random order were achieved by titrated inflation of these balloon catheters. Cerebral blood flow was determined at each MAP level. Regression coefficients of linear pressure-flow curves were calculated in all animals. RESULTS: From the mean baseline level (101 mmHg) MAP was reduced by 20% and 40%, and increased by 26% and 43%. The maximal mean increase and decrease in MAP induced a 12% increase and a 15% decrease, respectively, of CBF from the mean baseline level (52.6 ml.100 g(-1) x min1). The 95% confidence interval (-0.02; 0.38) of the mean regression coefficient of individual pressure-flow curves does not include the regression coefficient (0.64) of a linear correlation between MAP and CBF including origo (correlation coefficient 0.99), which indicates complete lack of cerebrovascular autoregulation. CONCLUSIONS: We conclude that autoregulation of CBF is not abolished during continuous ketamine infusion in normoventilated pigs and that previous divergent conclusions are unlikely to be associated with severe impairment of cerebrovascular autoregulation.     

The minimally effective concentration of adrenaline in a low-concentration thoracic epidural analgesic infusion of bupivacaine,fentanyl and adrenaline after major surgery. A randomized,double-blind,dose-finding study

BACKGROUND: We have documented that adrenaline 2.0 micro g.ml- 1 markedly improves relief of dynamic pain when added to a thoracic epidural analgesic infusion of bupivacaine 1 mg.ml- 1 and fentanyl 2 micro g.ml- 1. Concern about possible adverse effects on spinal cord blood flow, expressed by others, prompted us to find the lowest concentration of adrenaline needed to produce effective and reliable pain relief after major surgery. METHODS: A prospective, randomized, double-blind, parallel group study was carried out in 36 patients after major thoracic or upper abdominal surgery. Patients with only mild pain when coughing during titrated thoracic epidural infusion of approximately 9 ml per hour of bupivacaine 1 mg.ml- 1, fentanyl 2 micro g.ml- 1, and adrenaline 2.0 micro g.ml- 1 were included. The study was conducted as a dose-finding study comparing three different adrenaline concentrations in the epidural mixture (0.5, 1.0, and 1.5 micro g.ml- 1) with each other and with adrenaline 2.0 micro g.ml- 1 in our standard epidural mixture. On the 1st postoperative day, the patients were randomly allocated into three equal groups of 12 patients each, and given a double-blind epidural infusion at the same rate, but with different adrenaline concentrations (0.5, 1.0, or 1.5 micro g.ml- 1). The effects were observed for 4 h or until pain when coughing became unacceptable in spite of rescue analgesia. Rescue analgesia consisted of up to two patient-controlled epidural bolus injections per hour (4 ml) and subsequent i.v. morphine, if necessary. All patients received rectal paracetamol 1 g, every 6th hour. Main outcome measures were pain intensity at rest and when coughing, evaluated by a visual analogue scale and an overall quality of pain relief score. The extent of sensory blockade was evaluated by determining dermatomal hypaesthesia to cold. RESULTS: Pain intensity when coughing increased (P < 0.001) and the number of hypaesthetic dermatomal segments decreased (P < 0.002) when the concentration of adrenaline was reduced below 1.5 micro g.ml- 1 in the triple epidural mixture. This change started within two hours after reducing the concentration of adrenaline below 1.5 micro g.ml- 1. The differences in pain intensities at rest were less pronounced. After 4 h with adrenaline 0.5 or 1.0 micro g.ml- 1 pain intensity when coughing was unacceptable in spite of rescue analgesia. After restarting the standard epidural mixture with adrenaline 2.0 micro g.ml- 1, pain intensity was again reduced to mild pain when coughing and the sensory blockade was restored. Occurrence of pruritus increased with a decreasing adrenaline concentration. CONCLUSIONS: Adrenaline in a dose-related manner improves the pain-relieving effect and sensory blockade and decreases the occurrence of pruritus of a low-concentration thoracic epidural analgesic infusion of bupivacaine 1 mg. ml- 1 and fentanyl 2 micro g.ml- 1 after major thoracic or upper abdominal surgery. The minimally effective concentration of adrenaline, when added to bupivacaine 1 mg.ml- 1 and fentanyl 2 micro g.ml- 1, to maintain relief of dynamic pain is approximately 1.5 micro g.ml- 1. The data clearly document that dynamic, cough-provoked pain is a more sensitive outcome measure for postoperative pain relief than pain at rest.     

Comparison of fentanyl-bupivacaine or midazolam-bupivacaine mixtures with plain bupivacaine for caudal anaesthesia in children

BACKGROUND: The aim of this study was to evaluate the intensity and effectiveness of 0.75 ml.kg-1 bupivacaine 0.25% with the addition of fentanyl or midazolam for caudal block in children undergoing inguinal herniorrhaphy. METHODS: Seventy-five children were allocated randomly to three groups to receive a caudal block with either 0.25% bupivacaine with fentanyl 1 microg.kg(-1) (group BF) or with midazolam 50 microg.kg(-1) (group BM) or bupivacaine alone (group B) after induction of anaesthesia. Haemodynamic parameters, degree of pain, additional analgesic requirements and side-effects were evaluated. RESULTS: The mean systolic arterial pressure at 10, 20, 30 min after caudal block was higher in group B compared with groups BF and BM. Mean intraoperative heart rate was lower in group BF than the other groups. Adequate analgesia was obtained in all patients (100%) in group BF, 23 patients (92%) in group BM and 21 patients (84%) in group B (P > 0.05). The time to recovery to an Aldrete score of 10 was significantly shorter in group B than group BM (P < 0.05). Although not significant, it was also shorter in group B than group BF. There was no difference in additional analgesic requirements between the groups in the first 24 h. Sedation score was higher in the midazolam group at 60 and 90 min postoperatively than the other groups. CONCLUSIONS: Caudal block with 0.75 ml.kg(-1) 0.25% bupivacaine and 50 microg.kg(-1) midazolam or 1 microg.kg(-1) fentanyl provides no further analgesic advantages to bupivacaine alone when administered immediately after induction of anaesthesia in children undergoing unilateral inguinal herniorrhaphy.