Severe respiratory depression in a patient with gastroparesis while receiving opioids for pain

OBJECTIVE

To increase awareness of the possibility of severe respiratory depression when oral opioids are used in patients with gastrointestinal motility disorders.

SETTING

A major county hospital affiliated with a university.

PATIENT

A patient with severe pain from diabetic muscle necrosis with a history of gastroparesis.

INTERVENTIONS

Attempted pain control with oral and transdermal opioids.

RESULTS AND CONCLUSIONS

Pain control in our patient was attempted using potent oral opioids on two occasions. However, this patient suffered severe respiratory depression after each attempt. Transdermal delivery of fentanyl eventually provided satisfactory pain relief without side effects. We conclude that patients with gastrointestinal motility disorders may be at high risk for side effects of oral opioids due to altered absorption kinetics. Suggestions are made for alternative strategies for opiate delivery in patients with gastrointestinal motility disorders.

[Pre-incisional administration of ketamine reduced the postoperative pain]

This study was designed to examine the postoperative analgesic effect of pre-/post-incisional administration of ketamine. Thirty-nine female patients scheduled for transabdominal hysterectomy were randomly allocated into 3 groups. Patients in group-K1 (n = 13) received intravenous ketamine 100 mg before surgical incision and patients in group-K2 (n = 13) received the same after laparotomy. Group-C (n = 13) did not receive any ketamine. All patients were anesthetized with combined spinal/epidural anesthesia supplemented with sevoflurane 0.5% and nitrous oxide in oxygen. Postoperative pain was controlled by epidural infusion of the mixture of fentanyl (25 mcg.ml-1) and bupivacaine (3.8 mg.ml-1) at 2.1 ml.hr-1. Analgesic effect was assessed by visual analogue scale (VAS) and verbal rating scale (VRS). VAS and VRS in group-K1 were significantly lower compared with those in group-C, while there was no difference between group-K2 and C. The incidence of side effects and additional use of analgesics were similar among the three groups. In conclusion, pre-incisional administration of ketamine reduced the postoperative pain, but post-incisional ketamine was not effective.

Combined spinal-epidural analgesia in labour: comparison of two doses of intrathecal bupivacaine with fentanyl

We have compared intrathecal bupivacaine 1.25 mg and fentanyl 25 micrograms (group A) with bupivacaine 2.5 mg and fentanyl 25 micrograms (group B), for combined spinal-epidural analgesia in 49 labouring parturients in a prospective, randomized, double-blind study. Onset and quality of analgesia were similar in both groups, with median visual analogue scale pain scores of 0 achieved in 5-10 min. Median duration of analgesia was longer in group B (median 120 (range 90-120) min) compared with group A (75 (75-105) min) (P = 0.013). Median upper sensory level was higher in group B compared with group A at 15 min (T6-7 vs T11, P = 0.003) and at 30 min (T6 vs T11-12; P = 0.001). Motor block was greater in group B: seven patients had a modified Bromage score > or = 1 compared with none in group A at 15 min (P = 0.017). Group B also had a greater decrease in arterial pressure. Patient-midwife satisfaction scores and other side effects were similar. We conclude that intrathecal bupivacaine 1.25 mg with fentanyl 25 micrograms provided analgesia of similar onset and quality compared with bupivacaine 2.5 mg and fentanyl 25 micrograms. Although the duration of analgesia was shorter, the incidences of motor block and hypotension were less with the smaller dose.

Ketoprofen and fentanyl for pain after uvulopalatopharyngoplasty and tonsillectomy

OBJECTIVES

The treatment of postoperative pain after uvulopalatopharyngoplasty (UPPP) and tonsillectomy presents a challenge. Opioids can cause sedation and respiratory depression. Nonsteroidal antiinflammatory drugs can increase postoperative bleeding. The authors have evaluated the severity of postoperative pain and the consumption of opioid in 53 adult patients undergoing either UPPP or tonsillectomy.

STUDY DESIGN

A prospective, parallel-groups study.

METHODS

A general endotracheal anesthesia was used in each patient. After surgery patients received ketoprofen 1 mg/kg as an intravenous bolus, followed by a continuous infusion of 4 mg/kg during 24 hours. For rescue analgesia patient-controlled intravenous fentanyl was used.

RESULTS

Both UPPP and tonsillectomy are associated with intense postoperative pain. More than 40% of the patients had high pain scores during the first 24 postoperative hours. Postoperative pain after UPPP was more severe and the difference was significant during swallowing (P < .05). The need for fentanyl in the UPPP group was twice that of the tonsillectomy group (P < .01). There was a high interindividual scatter in the patient-controlled fentanyl attempts in both groups. The patients in the UPPP group needed significantly more oxygen supply during recovery (P = .007). No serious adverse effects occurred and none of the patients experienced postoperative bleeding that required any intervention.

CONCLUSION

Individually tailored analgesic treatment protocol is essential for patients undergoing UPPP and tonsillectomy to ensure safe and effective pain alleviation.

[First experience with clinical use of intravenous anesthetic recofol: effectiveness and safety]

Clinical trials of a new anesthetic Recofol were carried out. This analog of well-known drug diprivan is characterized by a predominantly hypnotic effect. The effect of recofol on hemodynamics, gas exchange, and EEG was studied in 30 clinical trials during anesthesia for bronchoscopic manipulations and operations on the abdominal and thoracic organs, microsurgery, and during peripheral vessel repair. The results indicate that recofol is virtually identical to diprivan (propofol). Clinical course of induction and anesthesia, hemodynamic reactions and effect on the respiratory system of patients were virtually the same. Recofol was well tolerated, its allergenic activity was relatively low, it was rapidly metabolized, there were virtually no side effects. Positive results of recofol trials carried out by Leiras Oy firm recommend the drug for wide use in anesthesiology.

Comparison of low-dose epidural with combined spinal-epidural analgesia for labour

We have performed a randomized comparison of two low-dose epidural regimens for analgesia in labour, differing only in the manner in which initial analgesia was established. In the epidural (EPI) group, 484 women received a loading dose of 20 ml of 0.1% bupivacaine with fentanyl 2 micrograms ml-1. In the combined spinal-epidural (CSE) group, 524 women received a spinal injection of plain bupivacaine 2.5 mg with fentanyl 25 micrograms. In both groups, these initial doses were followed by 0.1% bupivacaine with fentanyl 2 micrograms ml-1 infused at a rate of 12 ml h-1, with 20-ml top-ups for breakthrough pain. The groups were compared for midwife assessment of analgesic efficacy, delivery mode, patient assessments of first stage analgesia, second stage analgesia, overall analgesia, motor block and complications. Midwives, who were not blinded to the treatment groups, assessed 61.6% of CSE as providing 'excellent' analgesia compared with 56.4% of epidurals (P = 0.02). Patients assessed overall analgesia as 'excellent' in 74.8% of CSE compared with 71.7% of epidurals (P = 0.14). Other comparisons between groups revealed no differences. These findings may have been affected by an uneven distribution of multiparous women between the groups (25% in the EPI group and 34.2% in the CSE group; P = 0.002). However, subgroup analysis of primiparous and multiparous women did not alter the results.

Total intravenous anesthesia in greyhounds: pharmacokinetics of propofol and fentanyl--a preliminary study

OBJECTIVE

To evaluate concomitant propofol and fentanyl infusions as an anesthetic regime, in Greyhounds.

ANIMALS

Eight clinically normal Greyhounds (four male, four female) weighing 25.58 +/- 3.38 kg.

DESIGN

Prospective experimental study.

METHODS

Dogs were premedicated with acepromazine (0.05 mg/kg) by intramuscular (i.m.) injection. Forty five minutes later anesthesia was induced with a bolus of propofol (4 mg/kg) by intravenous (i.v.) injection and a propofol infusion was begun (time = 0). Five minutes after induction of anesthesia, fentanyl (2 microg/kg) and atropine (40 microg/kg) were administered i.v. and a fentanyl infusion begun. Propofol infusion (0.2 to 0.4 mg/kg/min) lasted for 90 minutes and fentanyl infusion (0.1 to 0.5 microg/kg/min) for 70 minutes. Heart rate, blood pressure, respiratory rate, end-tidal carbon dioxide, body temperature, and depth of anesthesia were recorded. The quality of anesthesia, times to return of spontaneous ventilation, extubation, head lift, and standing were also recorded. Blood samples were collected for propofol and fentanyl analysis at varying times before, during and after anesthesia.

RESULTS

Mean heart rate of all dogs varied from 52 to 140 beats/min during the infusion. During the same time period, mean blood pressure ranged from 69 to 100 mm Hg. On clinical assessment, all dogs appeared to be in light surgical anesthesia. Mean times (+/- SEM), after termination of the propofol infusion, to return of spontaneous ventilation, extubation, head lift and standing for all dogs were 26 +/- 7, 30 +/- 7, 59 +/- 12, and 105 +/- 13 minutes, respectively. Five out of eight dogs either whined or paddled their forelimbs in recovery. Whole blood concentration of propofol for all eight dogs ranged from 1.21 to 6.77 microg/mL during the infusion period. Mean residence time (MRTinf) for propofol was 104.7 +/- 6.0 minutes, mean body clearance (Clb) was 53.35 +/- 0.005 mL/kg/min, and volume of distribution at steady state (Vdss) was 3.27 +/- 0.49 L/kg. Plasma concentration of fentanyl for seven dogs during the infusion varied from 1.22 to 4.54 ng/mL. Spontaneous ventilation returned when plasma fentanyl levels were >0.77 and <1.17 ng/mL. MRTinf for fentanyl was 111.3 +/- 5.7 minutes. Mean body clearance was 29.1 +/- 2.2 mL/kg/min and Vdss was 2.21 +/- 0.19 L/kg.

CONCLUSION AND CLINICAL RELEVANCE

In Greyhounds which were not undergoing any surgical stimulation, total intravenous anesthesia maintained with propofol and fentanyl infusions induced satisfactory anesthesia, provided atropine was given to counteract bradycardia. Despite some unsatisfactory recoveries the technique is worth investigating further for clinical cases, in this breed and in mixed breed dogs.

Effects of nicardipine-, nitroglycerin-, and prostaglandin E1-induced hypotension on human cerebrovascular carbon dioxide reactivity during propofol-fentanyl anesthesia

STUDY OBJECTIVE

To investigate the effects of nicardipine-, nitroglycerin-, and prostaglandine E1-induced hypotension on cerebrovascular carbon dioxide (CO2) reactivity over a wide range of arterial CO2 tension (PaCO2) (PaCO2; range 25 to 50 mmHg).

DESIGN

Prospective, randomized study.

SETTING

Operating room of a university-affiliated hospital.

PATIENTS

36 ASA physical status I and II patients without cerebrovascular disease, hypertension, or diabetes mellitus, undergoing an elective abdominal surgery.

INTERVENTIONS

Patients were randomly allocated to one of three groups (nicardipine-, nitroglycerin-, or prostaglandin E1-induced hypotension group; 12 in each group). Anesthesia was induced and maintained with a bolus dose, followed by a continuous infusion of propofol (6.7 +/- 1.5 mg/kg/hr) and fentanyl (1.68 +/- 0.4 micrograms/kg/hr). Deliberate hypotension of mean arterial pressure 55 to 60 mmHg was induced and maintained with a bolus dose, followed by a continuous infusion of nicardipine (6.80 +/- 0.75 micrograms/kg/min), nitroglycerin (3.20 +/- 1.10 micrograms/kg/min), or prostaglandin E1 (0.103 +/- 0.052 microgram/kg/min).

MEASUREMENTS AND MAIN RESULTS

Time-averaged mean red blood cell velocity in the right middle cerebral artery (Vmca) at PaCO2 ranging from 25 to 50 mmHg was measured with transcranial Doppler ultrasonography. A minimum of six simultaneous measurements of Vmca and PaCO2 were obtained during baseline and deliberate hypotension in each patient. Absolute slope between Vmca and PaCO2 during baseline and deliberate hypotension was determined individually by linear regression analysis. Absolute slope was treated as the variable, because it yielded a significant close correlation coefficient (r > 0.95; p < 0.05). Comparisons between baseline and deliberate hypotension were made by analysis of variance for repeated measures. Mean absolute slope was significantly reduced from 1.88 +/- 0.57 cm/sec/mmHg (mean +/- SD) to 1.21 +/- 0.46 in the nicardipine group (p < 0.05), from 1.75 +/- 0.69 to 1.35 +/- 0.47 in the nitroglycerin group (p < 0.05), and from 1.95 +/- 0.89 to 1.33 +/- 0.70 (p < 0.05) in the prostaglandin E1 group, respectively.

CONCLUSION

Nicardipine-, nitroglycerin-, and prostaglandin E1-induced hypotension attenuate the human cerebrovascular CO2 reactivity during propofol-fentanyl anesthesia.

Detecting alveolar epithelial injury following volatile anesthetics by (99m)Tc DTPA radioaerosol inhalation lung scan

BACKGROUND

Many volatile anesthetics have long been thought to affect alveolar epithelial permeability.

OBJECTIVE

The purpose of this study was to examine the acute effects of volatile anesthetics on the permeability of the alveolocapillary barrier to (99m)Tc DTPA.

METHODS

Twenty-seven patients (24 females, 3 males, age 29-73 years) undergoing operation were enrolled in this study and grouped according to the type of anesthesia received. Group 1 patients were administered 1% halothane. Group 2 patients were given 1.5% isoflurane. Intravenous anesthesia without volatile anesthetics were used for group 3 patients. Before and after anesthesia, (99m)Tc DTPA radioaerosol inhalation lung scans were performed to detect alveolar epithelial injury due to volatile anesthetics. The negative slope of the regression line was designated as the (99m)Tc DTPA pulmonary clearance rate and was expressed in terms of percentage decrease in radioactivity per minute.

RESULTS

In group 1, the (99m)Tc DTPA clearance rates were 1.26 +/- 0.34 and 1.29 +/- 0.38 before and after anesthesia, respectively. The difference was not significant (p > 0.05). In group 2, the rates were 0.76 +/- 0.20 and 1.10 +/- 0. 37, before and after anesthesia, respectively. The difference was significant (p < 0.05). In group 3, the clearance rates were 1.07 +/- 0.38 and 1.21 +/- 0.48, before and after anesthesia, respectively. The difference was not significant.

CONCLUSIONS

Following isoflurane administration, the more rapid pulmonary clearance of (99m)Tc DTPA indicates that isoflurane increases the permeability of the alveolo-capillary barrier.

Opioid rotation for cancer pain: rationale and clinical aspects

BACKGROUND

Some patients with cancer pain may develop uncontrolled adverse effects, including generalized myoclonus, delirium, nausea and emesis, or severe sedation before achieving adequate analgesia during opioid dose titration. Sequential therapeutic trials should be considered to determine the most favorable drug.

METHODS

Recent literature was taken into account when reviewing the rationale and potential of opioid rotation.

RESULTS

When aggressive attempts to prevent adverse effects fail, drug rotation should be considered, because sequential therapeutic trials can be useful in identifying the most favorable drug. Different mechanisms, including receptor activity, the asymmetry in cross-tolerance among different opioids, different opioid efficacies, and accumulation of toxic metabolites can explain the differences in analgesic or adverse effect responses among opioids in a clinical setting.

CONCLUSIONS

When pain is relieved inadequately by opioid analgesics given in a dose that causes intolerable side effects despite routine measures to control them, treatment with the same opioid by an alternative route or with an alternative opioid administered by the same route should be considered. Opioid rotation may be useful in opening the therapeutic window and for establishing a more advantageous analgesia/toxicity relationship. By substituting opioids and using lower doses than expected according to the equivalency conversion tables, it is possible in the majority of cases to reduce or relieve the symptoms of opioid toxicity in those patients who were highly tolerant to previous opioids while improving analgesia and, as a consequence, the opioid responsiveness.

Hemodynamic response to tracheal intubation after vital capacity rapid inhalation induction (VCRII) with different concentrations of sevoflurane

STUDY OBJECTIVE

To evaluate the blood pressure (BP) and heart rate (HR) response to tracheal intubation after vital capacity rapid inhalation induction (VCRII) with four concentrations of sevoflurane followed by nitrous oxide (N2O) 50% and sevoflurane in concentrations administered by clinical judgment.

DESIGN

Prospective, randomized study.

SETTING

University teaching hospital.

PATIENTS

60 unpremedicated, ASA physical status I and II adult patients undergoing surgery with general anesthesia.

INTERVENTIONS

After fentanyl 3 micrograms/kg, VCRII was accomplished with four concentrations of sevoflurane in O2: Group 1 (n = 15): sevoflurane 3%; Group 2 (n = 15): sevoflurane 4%; Group 3 (n = 15): sevoflurane 5%; and Group 4 (n = 15): sevoflurane 6%. At loss of consciousness, rocuronium 0.6 mg/kg was given, and intubation was performed 90 seconds later. Thereafter, anesthesia continued with N2O 50% and sevoflurane.

MEASUREMENTS AND MAIN RESULTS

BP and HR measurements were made at the ward (baseline), at loss of consciousness, and just prior to, and each minute after, tracheal intubation during a 5-minute period. The hemodynamic profile among groups was similar, with a slight hypertensive and tachycardic response to intubation.

CONCLUSION

VCRII with sevoflurane 3% to 6% following fentanyl 3 micrograms/kg can be considered for blunting the hemodynamic response to tracheal intubation in healthy patients.

Isoflurane, nitrous oxide, and fentanyl pharmacodynamic interactions in surgical patients as measured by effects on median power frequency

STUDY OBJECTIVE

To identify and quantify the simultaneous interactions of isoflurane, nitrous oxide (N2O), and fentanyl during surgical procedures. The slowing of the EEG to a median power frequency of 2 Hz to 3 Hz was chosen as the measure of pharmacodynamic drug effect.

DESIGN

Prospective, randomized, open label.

SETTING

Operating room of a university hospital.

PATIENTS

65 ASA physical status I and II patients undergoing gynecological laparatomies.

INTERVENTIONS

25 patients received no fentanyl. 20 patients received a loading dose of 100 micrograms fentanyl and a continuous infusion of 70 micrograms.h-1 fentanyl. Calculated effect compartment concentrations were 0.7 ng.ml-1 between the first and second hours after induction of anesthesia. Another 20 patients received a loading dose of 200 micrograms fentanyl and a continuous infusion of 150 micrograms.h-1 fentanyl; the respective effect compartment concentrations were 1.5 ng.ml-1. N2O was randomly administered in concentrations of 0, 20, 40, and 60 vol%; in the group that did not receive fentanyl, we additionally investigated 75 vol% N2O. Each patient received two different N2O concentrations, with each combination of N2O and fentanyl finally applied to ten patients. Isoflurane vaporizer settings were chosen so that the median power frequency was held between 2 Hz and 3 Hz. The type and degree of interaction among the three anesthetic drugs was analyzed based on a generalized isobole approach.

MEASUREMENTS AND MAIN RESULTS

The interaction of isoflurane, N2O, and fentanyl is compatible with additivity. A model with regard to the relative potencies and age dependency is given by: [formula: see text] with C0,iso = 1.30 vol%, C0,N2O = 177 vol%, C0,fen = 10.6 ng.ml-1, and a = -0.0031 yr-1. where conc. = end-tidal or effect compartment concentrations.

CONCLUSION

The potency of N2O and fentanyl to substitute isoflurane in maintaining a median power frequency of 2 Hz to 3 Hz during surgery is less than anticipated from minimum alveolar concentration studies.

[Total intravenous anesthesia with propofol, fentanyl and clopheline in young children with occlusive hydrocephalus during ventriculoperitoneal shunting]

Total intravenous anesthesia with propofol, fentanyl, and clonidine was used in infants aged under 1 year operated on for occlusive hydrocephalus. The course of anesthesia in 18 patients with the hypertensive hydrocephalus syndrome is analyzed. Four of these patients with an extremely grave premorbid history and body weight of 1-3 kg were operated on before the age of 2 months. Propofol can be used in infants aged under 1 year, including physiologically immature small-for-date infants. Clonidine, an alpha 2-adrenoagonist, used in older neurosurgical patients and adults for stabilizing cerebral perfusion pressure, is allowed in infants, too. The authors analyze the time course of central hemodynamics during anesthesia with propofol, fentanyl, and clonidine and anesthesia by other drugs (combined anesthesia with ketamine and opioid analgesics, neuroleptanalgesia).

Opioid consumption in Spain--the significance of a regulatory measure

OBJECTIVE

To investigate the impact of new regulatory measures on opioid consumption in Spain during the period 1985-1998.

METHODS

A search in the ECOM (Especialidades Consumo de Medicamentos) database of the Ministry of Health was made for the 1985-1998 period. This database contains information about drug preparations prescribed in primary care in the National Health System in Spain.

RESULTS

Since 1985-1998, the overall opioid consumption has increased tenfold, from 94.7 DDD (defined daily dose) per million inhabitants per day to more than 1000 DDD. For the five drugs that require a special prescription form (morphine, methadone, pethidine, tilidine and fentanyl), the consumption has increased 13.5-fold.

CONCLUSION

A huge increase in opioid consumption has occurred. In this increase, changes in supply and, to a lesser extent, regulatory measures have played an important role.

Subcutaneous administration of fentanyl and midazolam to prevent withdrawal after prolonged sedation in children

OBJECTIVE

To determine the efficacy of switching to subcutaneous fentanyl with or without midazolam to prevent withdrawal after prolonged sedation in children in the pediatric intensive care unit (PICU).

DESIGN

Retrospective review of hospital records.

SETTING

Tertiary care center, PICU.

PATIENTS

The cohort for the study included patients who had received subcutaneous fentanyl with or without midazolam to prevent withdrawal after prolonged sedation in the PICU.

MEASUREMENTS AND MAIN RESULTS

Subcutaneous fentanyl with or without midazolam was administered to nine patients ranging in age from 3 to 7 yrs (mean, 4.4 +/- 1.8 yrs) and ranging in weight from 11 to 31 kg (mean, 20.1 +/- 6.8 kg). All patients required prolonged administration of fentanyl with or without midazolam during mechanical ventilation for respiratory failure. The starting infusion rate for subcutaneous fentanyl varied from 5 to 9 microg/kg/hr (mean, 7.1 +/- 1.4 microg/kg/hr). Four patients also received subcutaneous midazolam at a rate of 0.15 to 0.3 mg/kg/hr (mean, 0.24 mg/kg/hr). Subcutaneous access was maintained for 3-7 days (mean, 5.7 +/- 1.4 days) in the nine patients. No problems with the subcutaneous access were noted during treatment. The fentanyl infusion was decreased by 1 microg/kg/hr every 12-24 hrs and the midazolam infusion was decreased by 0.05 mg/kg/hr every 12-24 hrs. No patient demonstrated signs of symptoms of moderate to severe withdrawal.

CONCLUSION

The subcutaneous route provides an effective alternative to intravenous administration. It allows for gradual weaning from sedative/analgesic agents after prolonged sedation while eliminating the need to maintain intravenous access.

Continuous paravertebral extrapleural infusion for post-thoracotomy pain management

BACKGROUND

Continuous thoracic epidural analgesia is considered by many the gold standard for post-thoracotomy pain control but is associated with its own complications. In this study we compare continuous paravertebral extrapleural to epidural infusion for post-thoracotomy pain control.

METHODS

In a prospective fashion, 50 patients were randomized to receive either paravertebral or epidural infusion for post-thoracotomy pain control. The anesthesia department placed epidurals, and the operative surgeon placed unilateral paravertebral catheters. Patients were evaluated for analgesic efficacy and postoperative complications.

RESULTS

We found that both methods of analgesia provide adequate postoperative pain control. Epidural infusion demonstrated an improved efficacy early in the postoperative course but provided statistically similar analgesia to paravertebral by postoperative day 2. Neither group demonstrated a greater number of pain-related complications. Narcotic-induced complications such as pruritus, nausea/vomiting, and postural hypotension/mental status changes/respiratory depression were seen with statistically similar frequency in both epidural and paravertebral arms. Urinary retention, however, was noted to be significantly more frequent in patients with epidural catheters. Drug toxicity was not observed with either epidural or paravertebral infusion.

CONCLUSIONS

We recommend continuous paravertebral infusion as an improved method of post-thoracotomy analgesia that can be placed and managed by the surgeon.

Combined spinal-epidural analgesia in the management of labouring parturients with mitral stenosis

We report the use of combined spinal-epidural analgesia during labour in three parturients with moderately severe mitral stenosis. In each case, rapid analgesia was achieved using intrathecal fentanyl 25 micrograms without major haemodynamic changes. Maintenance analgesia was then established gradually using a dilute epidural infusion of bupivacaine 0.1% and fentanyl 0.0002%, with the avoidance of large or rapid boluses of local anaesthetic. Supplementary analgesia in the latter stages of labour was provided using slow epidural boluses of fentanyl, with or without a low concentration of bupivacaine, which was sufficient to allow controlled instrumental deliveries. We conclude that combined spinal-epidural analgesia is a useful technique for providing analgesia and maintaining haemodynamic stability in parturients with mitral stenosis.

Hemodynamic responses induced by dopamine and dobutamine in anesthetized patients premedicated with clonidine

To test the hypothesis that the pharmacological effects of dopamine (DOA) and dobutamine (DOB) are altered when there is inhibition of the release of norepinephrine from nerve endings, we examined the hemodynamic responses to DOA and DOB in anesthetized patients premedicated with oral clonidine. Seventy adult patients were assigned to one of two groups (oral premedication with clonidine 5 microg/kg or no premedication). After the induction of general anesthesia, heart rate and systemic blood pressure (BP) were measured for 10 min after each of five IV infusions (3 and 5 microg x kg(-1) x min(-1) of DOA; 0.5, 1, and 3 microg x kg(-1) x min(-1) of DOB) in a randomized, double-blind manner. In patients given clonidine, the mean BP increases induced by DOA 5 microg x kg(-1) x min(-1) were significantly attenuated (P < 0.01), whereas the mean BP increases induced by DOB-0.5, 1, or 3 microg x kg(-l) x min(-1) were significantly enhanced (P < 0.01 or 0.05). The heart rate responses to DOA and DOB did not differ between patients with or without clonidine. Premedication with clonidine alters the effects on BP to both DOA and DOB. When small doses of DOA or DOB are used in clonidine-premedicated patients, differences of pharmacological profiles need to be considered for perioperative management.

IMPLICATIONS

Our randomized, double-blind study suggests that premedication with clonidine may enhance the effect on blood pressure response to a small dose of dobutamine (direct-acting) and attenuate that to a small dose of dopamine (mixed direct-and indirect-acting) in patients anesthetized with fentanyl and nitrous oxide.

Comparison of intra-articular fentanyl and intra-articular bupivacaine for post-operative pain relief after knee arthroscopy

A randomized double-blinded study consisting of 107 patients was conducted to compare the effect on post-operative pain relief of intra-articular fentanyl and intra-articular bupivacaine after knee arthroscopy. The results showed that intra-articular bupivacaine produced superior analgesia in the immediate post-operative period. At 2 h post-operatively, the intra-articular bupivacaine group had a mean pain score of 2.0 (standard deviation 2.1, P < 0.05) compared with the intra-articular fentanyl group which had a mean pain score of 3.2 (standard deviation 2.3, P < 0.05). After 2 h post-operatively, intra-articular bupivacaine and intra-articular fentanyl had a similar effect on pain scores. The mean pain score 18 h post-operatively was 2.7 for the intra-articular bupivacaine group (standard deviation 2.2, P value 0.6) compared with the intra-articular fentanyl group which had a mean pain score of 2.8 (standard deviation 1.9, P value 0.6).

The relative potency of oral transmucosal fentanyl citrate compared with intravenous morphine in the treatment of moderate to severe postoperative pain

Pharmacokinetic studies have shown that oral transmucosal absorption of fentanyl is relatively rapid compared with gastrointestinal absorption, and it results in increased bioavailability. We designed this study to establish the relative potency of oral transmucosal fentanyl citrate (OTFC) compared with i.v. morphine in 133 postoperative patients. The morning after surgery, patients randomly received one dose of either OTFC (200 or 800 microg) and a placebo i.v. injection or i.v. morphine (2 or 10 mg) and an oral transmucosal placebo unit. Pain intensity, pain relief, time to meaningful pain relief, and time to remedication were recorded. Median time to onset of relief was approximately 5 min for all groups. Over the first hour, little difference among treatment groups was seen for pain intensity and pain relief. By 2 h after study drug administration, 800 microg of OTFC and 10 mg of i.v. morphine generally produced similar analgesia, which was better than the smaller doses. Duration of analgesia with the larger doses (800 microg of OTFC and 10 mg of morphine) was similar and longer that produced by the smaller doses. The larger doses of OTFC and morphine produced better and more sustained analgesia than 200 microg of OTFC or 2 mg of morphine.

IMPLICATIONS

The relative potency of oral transmucosal fentanyl citrate (OTFC) to i.v. morphine was 8-14:1. In this postoperative setting, OTFC produced rapid pain relief similar to that produced by i.v. morphine. The larger doses of OTFC (800 microg) and morphine (10 mg) produced better and more sustained analgesia than 200 microg of OTFC or 2 mg of morphine.