Epidural administered buprenorphine in the perioperative period

Purpose

To study the effect of epidural buprenorphine on minimum alveolar concentration (MAC) of volatile anaesthetics, duration of analgesia and respiratory function in the perioperative period.

Methods

One hundred and twenty patients, ASA I–II undergoing gynaecological surgery were randomly divided into three studies. The forty patients in each study were randomly divided into four groups depending on the dosage; Group I (control), Group II (80 μg · kg^?1 morphine), Group III (4 μg · kg^?1 buprenorphine), Group IV (8 μg · kg^?1 buprenorphine). The MAC of halothane was measured following epidural administration of the agents in each group. The duration of analgesia was assessed by the first request for pentazocine. Postoperative analgesic effects were assessed by the total dosage of pentazocine required for the 48 hr after surgery. Respiratory rate (RR), minute volume (MV), and PaCO₂ were measured during surgery and the postoperative period. The MAC of halothane was reduced in Group IV (P < 0.01). The duration of analgesia was 10.0 ± 5.1 hr (Mean ± SE) in Group 1, 37.7 ± 4.7 hr in Group II, 27.1 ± 7.1 hr in Group III, and 44.4 ± 4.1 hr in Group IV. Total dosage of pentazocine was lower in Group IV (P < 0.05) than in the other groups. The decrease of RR, MV and the increase of PaCO₂ were observed within 60 min in Group III and IV dose dependently.

Conclusion

Epidural buprenorphine administered in a dose of 4 or 8 μg · kg^?1 provides postoperative analgesia that is no less effective than that of morphine.     

Antinociceptive effects of epidural and intravenous ketamine to somatic and visceral stimuli in rats

Purpose

To evaluate the antinociceptive effect of epidural and intravenous ketamine on somatic and visceral stimuli and to address the emergency reaction.

Methods

Rats were randomly allocated into nine groups (n = 6); five groups with chronically implanted epidural catheters received saline or 0.5, 1, 2 and 4 mg · kg^?1 ketamine epidurally, four groups received saline, or 1, 5 and 10 mg · kg^?1 ketamine iv. To assess somatic and visceral antinociceptive effects, tail flick (TF) test and colorectal distension (CD) test were carried out, respectively. Emergence reactions were graded. Maximal possible effects (% MPE) were calculated.

Results

Epidural ketamine increased % MPE in both tests in a dose-dependent fashion for 30 min (vs saline group, P < 0.05). Epidural ketamine 0.5 mg · kg^?1 produced an increase in % MPE in the CD test (P < 0.05) but failed in the TF test. Intravenous ketamine, 10 mg · kg^?1, produced 100 ± 0 (mean ± SE) % MPE in the CD test but 36 ± 15 % MPE in the TF test. Dose response curves indicated greater visceral antinociception than somatic. All rats showed emergence reactions following intravenous ketamine 10 and 5 mg · kg^?1.

Conclusion

Both epidural and intravenous ketamine produce greater antinociceptive effects to visceral than to somatic stimulation, and that epidural ketamine has a low incidence of emergence reactions.     

Intravenous ketorolac vs diclofenac for analgesia after maxillofacial surgery

Purpose

To compare the efficacy of the nonsteroidal antiinflammatory drugs (NSAID), ketorolac and diclofenac in prevention of pain after maxillofacial surgery.

Methods

Sixty ASA I– II patients (30 in each group) received randomly, and double blindly either ketorolac 0.4 mg · kg^{? 1} or diclofenac 1.0 mg · kg^{? 1} iv after general anaesthesia induction, before surgical incision. In the ketorolac group, the same dose was repeated iv three times at six hour intervals. The diclofenac group patients received diclofenac 1.0 mg μ kg^{? 1} after 12 hr iv. Rescue analgesic medication consisting of oxycodone 0.03 mg · kg^{? 1} iv, was administered by a patient controlled analgesia apparatus.

Results

Two patients in the ketorolac and three patients in the diclofenac group did not need oxycodone during the study period. On average, 12 and 11 doses of oxycodone were needed in the ketorolac and the diclofenac groups, respectively (NS). Sideeffects were similar in both groups. All patients except one were satisfied with the pain therapy.

Conclusion

Parenteral ketorolac (0.4 mg · kg^{? 1} four times in 24 hr) and diclofenac (1 mg · kg^{? 1} twice in 24 hr) were similar, but insufficient alone, for analgesia after maxillofacial surgery.     

Comparative effects of three doses of intravenous ketorolac or morphine on emesis and analgesia for restorative dental surgery in children

Purpose

The optimal dose of intravenous ketorolac tromethamine (ketorolac), a nonsteroidal antiinflammatory drug has not been determined in children. There are only limited published data on the use of intravenous ketorolac for paediatric analgesia. This study compares the analgesic and emetic effect of three different doses of ketorolac with morphine in paediatric dental surgical outpatients.

Methods

Following institutional approval and parental consent, 120 ASA I or II children, age 2– 10 yr were randomized to four groups and received ketorolac 0.75, 1.0, and 1.5 mg · kg^{? 1} or morphine 0.1 mg · kg^{? 1} iv at induction of a standardized anaesthetic. At 15 and 30 min after arrival in the recovery room a blinded observer assessed pain using the Objective Pain Score (OPS). Twentyfour hours after surgery a telephone interview was carried out with a parent at home.

Results

There were no differences in demographic data, anaesthesia time, recovery and daycare unit time, OPS and postoperative analgesic requirements in the four groups. Postoperative vomiting in the first 24 hr occurred more frequently in the morphine group than in the other groups (P <0.0166). No patient had excessive surgical bleeding.

Conclusions

Ketorolac, in all doses studied (0.75, 1.0 and 1.5 mg · kg^{? 1}) was as effective an analgesic as morphine 0.1 mg · kg^{? 1} given intravenously at induction to children having restorative dental surgery. Its use was associated with a significant reduction in the incidence of postoperative vomiting.     

Comparison between epidural infusion of fentanyl/bupivacaine and morphine/bupivacaine after orthopaedic surgery

Purpose

To compare epidural infusions of bupivacaine-fentanyl and bupivacaine-morphine mixtures for postoperative pain relief after total hip replacement.

Methods

In a prospective, randomized, double-blind study, 30 ASA physical status I–II patients undergoing total hip replacement were studied. Anaesthesia was provided by combined general/epidural anaesthesia without epidural opioids. Postoperative epidural analgesia was by continuous infusion of bupivacaine 0.125% (4 ml·hr^?1) with either 0.05 mg·ml^?1 morphine (morphine, n = 15) or 0.005 mg·ml^?1 fentanyl (fentanyl, n = 15). Visual analogue pain scale (VAS), sedation (fourpoint scale), respiratory rate, pulse oximetry, rescue analgesics and supplemental oxygen were recorded by a blind observer at 1,3, 6, 9, 12 and 24 hr after surgery.

Results

No differences in pain relief, sedation, or non-respiratory side effects were observed between the two groups. Rescue analgesics were required in three patients in the fentanyl group (20%) and in two receiving morphine (13.3%) (P:NS). Two patients in the fentanyl group and three in the morphine group required oxygen due to SpO₂ < 90% (P:NS). Both opioid/bupivacaine mixtures decreased haemoglobin oxygen saturation compared with preoperative values. The mean ± SD SpO₂ values measured at 3,6, 12 and 24 hr were 94.4 ± 1, 92.6 ± 0.9, 92 ± 0.8, and 92.8 ± 1 in the morphine group, 95.3 ± 0.5, 95 ± 0.5, 94.6 ± 1.2, and 95.6 ± 1 in the fentanyl group (P < 0.05).

Conclusion

Continuous epidural infusion of bupivacaine-morphine or bupivacaine-fentanyl mixtures provided similar pain relief. Patients receiving morphine showed a more marked decrease in SpO₂ than those receiving fentanyl. However, the average SpO₂ remained > 90% in both groups.     

Thoracic epidural block attenuates cardiovascular response to apnea in rabbits

Purpose

Apnea is one of the potential complications during anaesthesia. If sympathetic nerve activity is blocked by epidural anaesthesia, circulatory responses to apnea might change. Our objective was to assess the potential modifying effects of epidural anaesthesia on the cardiovascular responses to apnea in the animals.

Methods

Twenty rabbits anaesthetised with pentobarbital (25 mg·kg^?1 iv, 8 mg·kg^?1·hr^?1) and pacuronium bromide (0.2 mg·kg^?1·hr^?1 iv) were randomly assigned to one of two groups: control (n = 10) and epidural (n = 10). In the control group, 0.6 ml saline, and in the epidural group, 0.6 ml lidocaine 1% was injected into the epidural space respectively. After mechanical ventilation with FIO₂ 0.4, apnea was induced by disconnecting the anaesthetic circuit from the endotracheal tube, and mean arterial pressure (MAP), heart rate (HR), and time to cardiac arrest were measured.

Results

Before apnea MAP was lower in the epidural than in the control group (73 ± 10vs 91 ± 10 mmHg,P < 0.05). Heart rate was not different between groups (264 ± 36vs 266 ± 24 bpm). Mean arterial pressure increased in the control group after apnea, but not in the epidural group. The time to cardiac arrest was less in the epidural group than in the control group (420 ± 67vs 520 ± 61 sec,P < 0.05). Heart rate decreased markedly after apnea in the control group whereas it decreased gradually in the epidural group.

Conclusion

Thoracic epidural anaesthesia attenuated cardiovascular response to apnea and reduced the time to cardiac arrest.     

Esmolol versus ketamine-remifentanil combination for early postoperative analgesia after laparoscopic cholecystectomy: a randomized controlled trial

Purpose

Controversy surrounds the optimal technique to moderate pain after laparoscopic cholecystectomy (LC). Opioid analgesics, sympatholytic drugs, and adjuvants, such as ketamine, have all been used. We compared esmolol with a combination of remifentanil plus ketamine in patients undergoing LC to determine the impact of these drugs on morphine requirements and pain control.

Methods

Sixty American Society of Anesthesiologists physical status I-II patients undergoing LC and anesthetized with sevoflurane were randomized to one of two groups. Group E patients received a bolus of esmolol 0.5?mg·kg^?1 iv at induction followed by an infusion of 5-15???g·kg^?1·min^?1, and Group R-K patients received a bolus of ketamine 0.5?mg·kg^?1 iv and remifentanil 0.5???g·kg^?1 iv at induction followed by a remifentanil infusion titrated over a range of 0.1-0.5???g·kg^?1·min^?1. All patients received paracetamol, dexketoprofen, and levobupivacaine via infiltration of laparoscopic port sites. After surgery, a predetermined bolus of morphine was administered according to a verbal numerical rating scale (VNRS) for pain intensity. The primary outcome of interest was postoperative morphine requirement.

Results

Median consumption of morphine was higher in Group R-K than in Group E (5?mg [4-6] vs 0?mg [0-2], respectively; P?<?0.001). In the postanesthesia care unit, patients in Group R-K had higher pain scores than patients in Group E (difference in maximum VNRS, -11; 95% confidence interval (CI), -19 to -3). The concentration of sevoflurane to maintain a bispectral index~40 was higher in Group E than in Group R-K (between-group difference 0.3%; 95% CI, 0.15 to 0.40). The incidence of postoperative nausea and vomiting was similar between the two groups.

Conclusion

Intraoperative esmolol infusion reduces morphine requirements and provides more effective analgesia compared with a combination of remifentanil-ketamine given by infusion in patients undergoing LC.     

Postoperative patientcontrolled epidural analgesia with opioid bupivacaine mixtures

Purpose

To determine the efficacy and safety of patient-controlled epidural analgesia of morphine or fentanyl in combination with bupivacaine for postoperative pain relief.

Methods p]Forty ASA 1–11 patients scheduled for major abdominal surgery were studied. After insertion of a lumbar epidural catheter, patients were given a non-opioid general anaesthetic. After surgery patients complaining of pain, received a loading dose of 2 mg morphine (Group I) or 50 μg fentanyl (Group II). For continuing pain, 1 mg morphine in 4 ml bupivacaine 0.125% (0.25 mg·ml^?1 morphine and 1 mg·ml^?1 bupivacaine, Group I) or 20 μg fentanyl in 4 ml bupivacaine 0.125% (5 μg·ml^?1 fentanyl and 1 mg·ml^?1 bupivacaine Group II) were administered. Blood pressure, heart rate, respiratory rate and SpO₂ were monitored. Assessments of pain (VAS), nausea-vomiting, motor block, pruritus and sedation were recorded for 24 hr.

Results

No difference in pain or sedation was observed between groups, The 24 hr postoperative opioid consumption was 15.50 ± 7.53 mg morphine and 555.10 ± 183.85μg fentanyl. Total bupivacaine 0.125% consumption was 58.00 ± 30.14 ml in Group I and 101.05 ± 36.77 ml in Group II. One patient in Group II complained of motor weakness in one leg. The incidence of nausea (Group I 45%, Group II 10%P < 0.05) and pruritus (Group I 30%, Group II 5%P < 0.05) was less in patients receiving fentanyl. Conclusion: Both methods were effective in the prevention of pain but, because of fewer side effects, fentanyl may be preferable to morphine.     

Smoking increases the requirement for rocuronium

Purpose

To compare the potency of rocuronium in non-smokers and smokers during general anaesthesia.

Methods

In a randomized, open clinical study, 40 patients, 17–62 yr of age, were anaesthetized with propofol, alfentanil and nitrous oxide in oxygen. After obtaining individual dose-response curves for rocuronium, bolus doses of rocuronium were given to maintain neuromuscular block at 90–99% for 60 min. Evoked adductor pollicis electromyography (EMG) was used to monitor neuromuscular block.

Results

The ED₉₅ values (± SEM) for rocuronium were 460.5 ± 28.9 and 471.5 ± 22.1 μg·kg^?1 for nonsmokers and smokers, respectively (P:NS). However, doses of rocuronium to maintain 90–99% neuromuscular block (± SEM) were 620.1 ± 46.7 and 747.4 ± 56.0 μg·kg^?1·hr^?1 for non-smokers and smokers, respectively (P = 0.0504).

Conclusion

The results may indicate increased metabolism of rocuronium in smokers rather than increased requirement of rocuronium at the receptor site.     

Continuous caudal anaesthesia with chloroprocaine as an adjunct to general anaesthesia in neonates

Purpose

The authors prospectively evaluated the use of a continuous caudal epidural infusion of chloroprocaine as an adjunct to genera! anaesthesia during intra-abdominal surgery in neonates.

Clinical features

The technique was used in 25 neonates ranging in age from 1 to 28 days and in weight from 2.2 to 4.9 kg. Following anaesthetic induction and tracheal intubation, an initial bolus dose of chloroprocaine 3% (1 or 1.5 ml · kg^?1) was followed by a continuous infusion of 1 or 1.5 ml · kg^?1 · hr^?1 administered through a caudal epidural catheter. No parenteral opioids were administered. The duration of the surgical procedures varied from one hour five minutes to three hours 15 min. The first three neonates received a bolus dose of 1.0 ml kg^?1 followed by an infusion of 1.0 ml · kg^?1 · hr^?1 chloroprocaine 3%. These three neonates required an additional bolus dose followed by an increase in the infusion to 1.5 ml · kg^?1 · hr^?1 to provide surgical anaesthesia. Adequate intraoperative anaesthesia was achieved in all 25 neonates with an infusion of 1.5 ml · kg^?1· hr^?1 of chloroprocaine 3%. This was evidenced by a lack of haemodynamic response to surgical manipulation. No neonate required more than 0.2% isoflurane or 70% nitrous oxide in oxygen. No episodes of haemodynamic instability (decreased blood pressure/bradycardia) related to the caudal epidural anaesthesia were noted. Twenty-three of 25 of the neonates’ tracheas were extubated immediately (within 10 minutes) following the surgical procedure.

Conclusions

Caudal anaesthesia with a continuous infusion of chloroprocaine can be used as an adjunct to general anaesthesia during abdominal surgery in neonates. Our initial experience suggests that the combined technique may eliminate the need for parenteral opioids and limit the intraoperative requirements for inhalational anaesthetic agents.     

Ropivacainevs bupivacaine in major surgery in infants

Purpose

To assess and compare the onset time and duration of neuroblockade obtained after ropivacaine or bupivacaine in infants undergoing major abdominal surgery. We also evaluated the efficacy and safety of employing ropivacaine instead of bupivacaine to provide operative anesthesia and postoperative analgesia.

Methods

In a prospective double blind study 28 infants, aged 1–12 months, undergoing elective major abdominal surgery, were randomly allocated to receive, after induction of general anesthesia, either 0.7 ml· kg^?1 bupivacaine 0.25% (group B) or ropivacaine 0.2% (group R) via lumbar epidural block. The onset time, total surgical time and duration of analgesia were recorded.

Results

No differences were noted in demographic data, hemodynamic variables or duration of surgery. The onset time for sensory blockade was 13.1 min ± 2.1 (group B) and 11.7 ± 2.4 min (group R). The duration of analgesia was 491 ± 291 (group R) and 456 min ± 247 (group B). Eight patients in group B and six in group R needed codeine and acetaminophen rescue on at least one occasion during the 24 hr study period. No major side effects were noted in either groups.

Conclusions

In infants undergoing major abdominal surgery under combined epidural/light general anesthesia, ropivacaine 0.2% produces sensory and motor blockade similar in onset, duration of action and efficacy to that obtained from an equal volume, 0.7 ml· kg^?1, of bupivacaine 0.25%.     

Preoperative ketorolac increases bleeding after tonsillectomy in children

Purpose

To compare the incidence of vomiting following codeine or ketorolac for tonsillectomy in children.

Methods

We had planned to enrol 240 patients, aged 2–12 yr undergoing elective tonsillectomy into a randomized, single-blind study in University Children’s Hospital. The study was terminated, after 64 patients because interim analysis of the data by a blinded non-study scientist concluded that the patients were at undue risk of excessive perioperative bleeding. After induction of anaesthesia by inhalation with N₂O/halothane or with propofol 2.5?3.5 mg· kg^?1 iv, the children were administered 150 μg· kg^?1 ondansetron and 50 μg · kg^?1 midazolam. Maintenance of anaesthesia was with N₂O and halothane in O₂. Subjects were administered either 1.5 mg · kg^?1 codeine im or 1 mg· kg^?1 ketorolac iv before the commencement of surgery. Intraoperative blood loss was measured with a Baxter Medi-Vac® Universal Critical Measurement Unit. Postoperative management of vomiting and pain was standardized. Vomiting was recorded for 24 hr after anaesthesia. Data were compared with ANOVA, Chi-Square analysis and Fisher Exact Test.

Results

Thirty-five subjects received ketorolac. Demographic data were similar. The incidence of vomiting during the postoperative period was 31% in the codeine-group and 40% in the ketorolac-group. Intraoperative blood losses was 1.3 ± 0.8 ml · kg^?1 after codeine and 2.2 ± 1.9 ml · kg^?1 after ketorolac (mean ± SD) P < 0.05. Five ketorolac-treated patients had bleeding which led to unscheduled admission to hospital, P < 0.05, Exact Test.

Conclusion

Preoperative ketorolac increases perioperative bleeding among children undergoing tonsillectomy without beneficial effects.     

Thiopentone induced enhancement of somatic motor responses to noxious stimulation: influence of GABAA receptor modulation

Purpose

This study was conducted to determine whether hyperalgesic effects of subanaesthetic concentrations of thiopentone could be attributed to GABA_A receptor effects.

Methods

All studies were performed on 50 rats in a prospective, randomized, blinded fashion using saline-injected animals as controls. Using a modified Randall-Selitto technique, the motor behavior stimulated by noxious stimulation was quantified by determining the lowest tail pressure required to provoke a withdrawal response (somatic motor response threshold, SMRT). In the first protocol (21 rats), we studied the effects of 0.5, 1.5 and 5 mg · kg^?1 iv of the GABA_A agonist, muscimol, on SMRT. In the second protocol (20 rats), the effects of administration of saline, muscimol 0.5 mg · kg^?1, or the competitive GABA_A antagonist, bicuculline 0.25 mg · kg^?1, upon the SMRT-reducing effects of a standardized thiopentone infusion were observed.

Results

No dose of muscimol produced hyperalgesia. The highest dose of muscimol used (5 mg · kg^?1) produced pronounced analgesic effects, raising the SMRT above 750 g. No change in SMRT was detected with the smaller doses of muscimol. Given in combination with muscimol (0.5 mg · kg^?1), thiopentone produced analgesia, as shown by an increase in SMRT (P = 0.009). In the bicuculline treated animals, SMRT decreased linearly with increasing plasma thiopentone concentrations (P < 0.001). The slope of the relationship in the bicuculine group was not significantly different from that observed in the saline-treated group, indicating that bicuculline did not block the hyperalgesic effects of thiopentone.

Conclusion

The results of these studies suggest that hyperalgesia associated with thiopentone is not mediated primarily by GABA_A receptors.     

Labour pain management in a parturient with an implanted intrathecal pump

Purpose

We report the peripartum anaesthetic management for vaginal delivery of a chronic pain patient with an implanted intrathecal pump. This is the first report describing labour analgesia in a patient with such a device. As intrathecal systems become more popular for the management of nonmalignant pain, this situation is likely to be encountered with increasing frequency in the future.

Clinical features

The patient was a nulliparous 23-yr-old with a history of chronic hereditary pancreatitis whose intractable pain had been managed with intrathecal morphine 3 mg·day^?1 via an implantable pump for four years. Inadequate time between presentation and onset of labour prevented us from using this system. Intravenous patient controlled analgesia with fentanyl using a bolus of 25 μg and a lockout of five minutes was ineffective and epidural analgesia using buprvacaine was initiated and resulted in satisfactory analgesia.

Conclusion

The presence of an existing intrathecal delivery system does not preclude the use of supplemental epidural analgesia during labour.     

Epidural analgesia for labour and delivery: fentanyl or sufentanil?

Purpose

The highly lipid soluble opioids, fentanyl and sufentanil, are used in combination with local anaesthetics with/ without epinephrine to provide epidural analgesia during labour and delivery. Our aim was to determine whether either opioid was superior when used with low dose local anaesthetic.

Methods

In a double-blind study patients were randomized to two epidural infusion groups: Group I (n = 50) fentanyl 2 μg · ml^?1 with bupivacaine 0.015% and epinephrine 2 μg · ml^?1, Group II (n = 50) sufentanil 1 μg · ml^?1 with bupivacaine 0.015% and epinephrine 2 μg · ml^?1. Following a 20 ml bolus of the study solution an infusion was started at 10 ml · h^?1. To achieve analgesia patients could receive two boluses of 5 ml of the study solution and if analgesia was still inadequate, a further 5 ml bupivacaine 0.25% was used. Pain and overall satisfaction were assessed with a 10-point visual scale. Plasma samples obtained from the mother at the time the infusion was discontinued and from the umbilical cord vein at delivery were assayed to determine opioid concentration.

Results

Pain scores were greater for Group I than for Group II patients throughout the first and second stages of labour (P = 0.002). More patients in Group I (42%) requested a dose of bupivacaine 0.25% than in Group II (6%) (P < 0.0001) and the total dose of bupivacaine given to Group I patients was greater than that of Group II, 26.0 ± 22.0 mg vs. 13.4 ± 12.6 mg, P = 0.005. There were no differences with respect to first or second stage duration, incidence of side effects, infusion duration, outcome of labour or neonatal Apgar scores. There was no opioid accumulation in either maternal or foetal blood.

Conclusion

Epidural opioid infusion with very low dose bupivacaine (0.015%) achieved an overall high level of patient satisfaction in both groups without serious maternal or neonatal side effects. At the fentanyl-to-sufentanil ratio used here patients receiving sufentanil had lower pain scores and substantially fewer patients required bupivacaine rescue.     

Patient-controlled epidural analgesia after Caesarean section using meperidine

Purpose

To determine the effects of the addition of a background infusion to patient-controlled epidural analgesia (PCEA) using mependine for analgesia after Caesarean section.

Methods

In a randomized, double-blind study. we assigned 40 patients having elective Caesarean section to receive postoperative analgesia by patient-controlled epidural analgesia (PCEA) using mependme 5 mg · ml^?1 with (group Pi) or without (group Po) a background infusion of 10 mg · hr^?1. The PCEA settings (20 mg bolus. 10 mm lockout interval, four-hour maximum dose 150 mg) were otherwise identical. We compared pain at rest, pain on coughing, side effects, number of PCEA demands, drug consumption and patient satisfaction between groups in the first 24 hr after surgery.

Results

Total consumption of mependme was greater in group Pi (median 390 mg) than in group Po (median 240 mg; P = 0.017) and the number of PCEA demands was greater in group Po (median 12) than in group Pi (median 7.5;P = 0.012). Analgesia, side effects and patient satisfaction was similar between groups.

Conclusion

Addition of a background infusion to PCEA using mependine after Caesarean section has no clinical benefit.     

Terbutaline inhalation suppresses fentanyl-induced coughing

Purpose

To study the suppressive effect of inhalation of a selective β₂-adrenergic bronchodilator terbutaline, and the effect of an intravenous anticholinergic, atropine, on fentanylinduced coughing.

Methods

We studied 131 ASA class I patients, aged 16–45 yr, scheduled for elective surgery, randomized into four groups. Fifteen minutes before bolus fentanyl (5 μg · kg^?1, iv), patients inhaled either normal saline (4 ml; Croup 1, n = 30) or terbutaline (5 mg in 2 ml normal saline; Group 2, n = 34) via a jet nebulizer. After inhalation of normal saline, patients in Group 3 (n = 32) received sterile water iv instead of fentanyl. Patients in Group 4 (n = 35) were pretreated with atropine (0.01 mg · kg^?1, iv) 10 min before iv fentanyl bolus. The onset, frequency and intensity of cough were observed immediately by an anaesthetist blinded to the study.

Results

The cough frequency was higher in Groups 1 (43%) and 4 (46%) than in Groups 2 (3%) and 3 (0%) (P < 0.05). The onset time and intensity of cough showed no difference among groups. No truncal rigidity was observed in patients receiving fentanyl bolus iv. The blood pressure, heart rate, and peripheral oxygen saturation did not change in Groups 1, 2, and 3, while patients in Group 4 showed an increase in heart rate (25.5 ± 15.2%).

Conclusions

The inhalation of a selective β₂-adrenergic bronchodilator, terbutaline, effectively inhibited fentanylinduced cough, whereas atropine, an antimuscarinic vagolytic, had no efficacy. Our results suggest that bronchoconstriction may underlie the mechanism on fentanyl-induced cough.     

Heparin and protamine titration do not improve haemostasis in cardiac surgical patients

Purpose

Weight-based heparin and protamine dosing strategies for cardiopulmonary bypass (CPB) do not take into account interpatient variability in drug sensitivity and may result in bleeding complications. We compared the Hemochron® RxDx heparin and protamine titration system with standard weight based management with regard to heparin dose, protamine dose, and perioperative bleeding.

Methods

One hundred and thirty-five cardiac surgical patients were randomised into four groups. Group I received standard heparin and protamine management: Group 2 received heparin and protamine byin vitro titration. Group 3 had the heparin dose titrated, and group 4 had the protamine dose titrated. Coagulation tests, bleeding, and transfusion requirements were measured.

Results

The initial heparin bolus predicted by the titration was < 300 U· kg^?1 in all patients. Group 2 received a lower heparin bolus for the initiation of bypass but total heparin doses were not different among groups (group 1 = 365 ± 43, group 2= 348 ± 73 U · kg^?1, group 3= 394 ± 86 U · kg^?1, group 4= 376 ± 60; P = 0.06). Groups 2 and 4 received a lower initial and a lower total protamine dose (total dose group 1 = 4.03 ± 0.65 mg · kg^?1, group 2 = 3.56 ±1.11 mg · kg^?1, group 3= 4.22 ± 0.90 mg · kg^?1, group 4= 3.38 ± 0.98 mg· kg^?1,P = 0.001). The incidences of incomplete heparin neutralisation (P = 0.14) and heparin rebound (P = 0.1) were not different among groups. Postoperative bleeding and transfusion requirements did not differ.

Conclusion

In cardiac surgical patients, heparin and protamine titration did predict a lower protamine dose but did not result in a measurable improvement in haemostasis during the perioperative period.     

Respiratory depression after low-dose caudal morphine

Purpose

To report a case of respiratory depression after a small dose of caudal morphine administered to a 15-mo-old child.

Clinical features

A 15 mo, 9.8 kg boy underwent ureteral reimplantation with general endotracheal anaesthesia and 10 ml bupivacaine 0.25% (2.5 mg · kg^?1). Ninety minutes after the bupivacaine, 0.4 mg (1 mg · ml^?1, 0.4 ml, 0.04 mg · kg^?1) preservative-free morphine was injected after negative aspiration. Slighly more than two hours after caudal morphine, the patient became lethargic and developed decreases in oxygen saturation (to 62%) without change in heart rate or respiratory rate. Intravenous naloxone 0.1 mg (0.01 mg · kg^?1) markedly improved his level of consciousness. Racemic epinephrine was administered for treatment of coincident stridor. The patient required 11 hr continuous naloxone infusion (0.001–0.002 mg · kg^?1 · hr^?1) in the intensive care unit. He was discharged on the second postopertive day without further complication.

Conclusion

Respiratory depression can occur in children greater than one year of age, even when small doses of caudal morphine are used. Decreased arterial oxygen saturation and lethargy are important heralds. A normal respiratory rate despite substantial hypoxaemia argues that pulse oximetry (without supplemental oxygen where possible) has a clear advantage over impedance pneumography for electronic monitoring.     

Anaesthesia Equipment Patient controlled oral analgesia with morphine

Purpose

When using strong oral opioids for postoperative pain management, demand titration is desirable. A device for patient controlled oral analgesia (PCORA) and first results of its use for oral titration of morphine are presented.

Methods

The PCORA-device is a modified Baxter-PCA-on-demand system (maximum bolus volume: 0.5 ml; flow rate for filling bolus volume: 0.5 ml · hr^?1). The demand PCORA-volumes were measured at specific time intervals and PCORA was compared with customarily prescribed pain therapy (CPPT) for postoperative pain management. On the first post-operative day, 20 orthopaedic ASA I or II patients received, in a randomised, cross-over trial, either PCORA (300 min) followed by CPPT (300 min) (Group I) or vice versa (Group II). The PCORA-device permitted a maximum dose of 15 mg morphine per 60 min and CPPT was performed by the ward doctor or nurse. Pain intensity (101-point numerical rating scale) and side effects were evaluated at 30 min intervals.

Results

The accuracy of the bolus volume delivered by the PCORA-device was 89.2 ± 0.85% (mean ± SEM), of manufacturer’s specifications. PCORA pain intensity decreased over time whereas CPPT pain intensity did not (P < 0.001). PCORA-morphine requirements were 61.5 ± 5.2 mg (Group I) and 52.5 ± 8.5 mg (Croup II) (NS; mean ± SEM). The handling of the PCORA-device presented no problem to any patient.

Conclusion

Patient controlled oral analgesia is an effective and non-invasive mode of postoperative pain management. The PCORA-device is reliable and easy to use.