Showing papers in "Anesthesia & Analgesia in 1984"

Comparison of intramuscular and epidural morphine for postoperative analgesia in the grossly obese: influence on postoperative ambulation and pulmonary function.

Abstract: In a randomized double-blind study of thirty grossly obese patients undergoing gastroplasty for weight reduction, the effects of intramuscular and epidural morphine were compared as regards analgesia, ambulation, gastrointestinal motility, early and late pulmonary function, duration of hospitalization, and occurrence of deep vein thrombosis in the postoperative period. The patients were operated on under thoracic epidural block combined with light endotracheal anesthesia. A six-grade scale was devised to quantify postoperative mobilization. A radioactive isotope method using 99mTc -plasmin was employed to detect postoperative deep vein thrombosis. For 14 hr after the first analgesic injection, respiratory frequency was noted every 15 min and arterial blood gases were measured hourly. Peak expiratory flow was recorded daily until the patient was discharged from hospital. Spirometry was performed the day before and the day after surgery. Plasma concentrations of morphine were measured after both intramuscular and epidural administration. Both intramuscular and epidural morphine gave effective analgesia, but the average dose of intramuscular morphine was up to seven times greater than that required by the epidural route. A larger number of patients receiving epidural morphine postoperatively were able to sit, stand, or walk unassisted within 6, 12, and 24 hr, respectively. Being alert and more mobile as a result of superior postoperative analgesia from epidural morphine, patients in this group benefited more from vigorous physiotherapy routine, which resulted in fewer pulmonary complications. Furthermore, earlier postoperative recovery of peak expiratory flow and bowel function presumably contributed to a significantly shorter hospitalization in patients receiving epidural morphine. There was no evidence of prolonged respiratory depression in this high-risk category of patients. The 99mTc -plasmin tests revealed no significant difference between the two groups.

Regional blood flow during isoflurane and halothane anesthesia.

Abstract: Cardiac output distribution and regional blood flow in 18 dogs during isoflurane and halothane anesthesia were studied in dose-related fashion. Surgical preparation consisted of left thoracotomy and placement of catheters in the left atrium and aorta through a femoral artery. Regional blood flow was studied one week after surgical preparation using a microsphere technique at the three stages: awake, 1 MAC, and 2 MAC of inhalation anesthesia. At each stage of the experiment, two sets of microspheres (15- and 9-micron diameter), labeled with different isotopes, were used simultaneously. Both anesthetics increased cerebral blood flow, decreased blood flow through preportal area, and preserved renal blood flow. Isoflurane increased hepatic artery blood flow at both levels of anesthesia, while halothane preserved the flow during 1 MAC and decreased it at 2 MAC. Apparently, isoflurane provided better oxygenation to the liver than halothane. Myocardial blood flow was increased during isoflurane (despite decrease in blood pressure and cardiac output) and decreased during halothane anesthesia. Isoflurane appears to be a coronary vasodilator with potential beneficial (improvement in myocardial blood supply) as well as hazardous ("steal effect") effects on the heart.

Spinal anesthesia for surgery in the high-risk infant.

Abstract: Although Gray (1) in 1909 and others since then (2–5) have reported the use of spinal anesthesia in infants and children, spinal anesthesia is a technique that is only rarely used today in pediatric patients. Our experience since 1977, however, has confirmed that spinal anesthesia can indeed be a sa

Pulmonary aspiration--effects of volume and pH in the rat.

Abstract: To evaluate the effect of volume of aspirates with different pHs on mortality associated with pulmonary aspiration, hydrochloric acid solutions were injected into the tracheas of 336 Sprague-Dawley rats. The rats were divided randomly into 33 groups, were observed for 96 hr after aspiration, and were not resuscitated. Deaths were divided into two groups: early, less than 30 min after aspiration, and late, greater than 4 hr after aspiration. Late deaths, accounting for 22% of all fatalities, occurred exclusively in animals aspirating solutions with a pH less than 2.5. These late deaths indicated progressive lung damage as opposed to acute cardiorespiratory failure, which early deaths suggested. Low volume pulmonary aspirates (0.3 ml/kg) with extremely low pH (1.0) resulted in a high mortality rate (90%). Conversely, higher volume pulmonary aspirates (1.0-2.0 ml/kg) with a higher pH (greater than or equal to 1.8) resulted in a low mortality rate (14%). These data demonstrate an important interaction between pH and volume of aspirates: even low volumes have a high mortality rate if pH is very low, whereas if gastric fluid is effectively buffered, then much higher volumes than previously thought can be tolerated. This suggests that the routine use of nonparticulate antacids may be indicated in patients at risk from aspiration of stomach contents and should not be withheld because of concern of increasing gastric volume.

Hemodynamic effects of ketamine in children with congenital heart disease.

Abstract: Pulmonary and systemic vascular responses to ketamine (2 mg X kg-1, intravenously) were studied during cardiac catheterization in 20 children with congenital heart lesions. Pulmonary and systemic resistances (Rp, Rs), ratios between pulmonary and systemic flows (Qp/Qs), and left to right (L----R) and right to left shunts (R----L) were calculated before and after ketamine administration. Statistically significant (P less than 0.05) but clinically minor increases in heart rate (106.8 to 109.9 beats/min), mean pulmonary artery pressure (20.6 to 22.8 mm Hg), and Rp/Rs (0.12 to 0.14) were seen after ketamine. There were no significant changes in systemic arterial pressure, Rs, Qp/Qs, L----R, R----L, or arterial oxygen or carbon dioxide tensions. No patient had any major untoward effects from ketamine administration. It is concluded that the hemodynamic alterations after ketamine administration in children undergoing cardiac catheterization are small and do not alter the clinical status of the patients or the information obtained by cardiac catheterization.

Respiratory depression after epidural morphine--an experimental and clinical study.

Abstract: This study was comprised of an experimental part (20 volunteers) and a clinical part (10 surgical patients). In the experimental part, the effects of either 2-, 4-, or 10-mg doses of epidural morphine on ventilatory responses to a standardized CO2 challenge were studied in healthy volunteers. In the clinical part, ventilatory responses to CO2 were evaluated in patients receiving 4 mg of epidural morphine for pain relief after gall bladder surgery. Naloxone infusion was given to five volunteers to determine whether ventilatory changes due to epidural morphine could be prevented. Using a nonrebreathing method, end-tidal PCO2 (PETCO2) and minute ventilation (tidal volume X frequency) were measured before and 1, 5, 8, 13, and 22 hr after epidural morphine injection. Ventilation was stimulated by 4% CO2 in 21% O2 and 75% N2. In the experimental study, a dose-related depression of ventilatory drive was seen after epidural morphine. After 2- and 4-mg doses, increases in PETCO2 were present up to 5 hr after injection with a corresponding reduction in minute ventilation. Ten mg of epidural morphine was followed by a significant reduction in minute ventilation and an increase in PETCO2 that started 1 hr after injection, peaked at 5 hr, and then remained almost unchanged for the next 17 hr. PETCO2 was higher and remained elevated longer in surgical patients than in volunteers given the same amount of epidural morphine (4 mg).(ABSTRACT TRUNCATED AT 250 WORDS)

Laryngeal effects of prolonged intubation.

Abstract: Improved care for acute respiratory failure requires prolonged placement of an endotracheal tube. Whether a tracheotomy or a translaryngeal endotracheal tube is the better choice remains controversial. With the use of high-volume low-pressure cuffs, both routes of intubation have similar low rates of cuff-induced complications. Complications of the alternatives include problems that occur above the cuff, at the larynx during translaryngeal intubation, or the stoma in patients with a tracheotomy. The complications of tracheotomy are well-documented and will be touched on only briefly in this paper, which will review the consequences to the larynx of using translaryngeal intubation for prolonged maintenance of an airway. The issues to be considered are how and why injury to the larynx occurs, what immediate postextubation problems can be expected, and what long-term sequelae may occur.

Continuous epidural infusion of morphine for treatment of pain after thoracic surgery: a new technique.

Abstract: We evaluated postoperative pain relief and the incidence of side effects of three methods of thoracic epidural analgesia. Ninety patients, divided into three equal groups, received postoperative analgesia after thoracic surgery either as intermittent epidural injections of bupivacaine (25 mg/5 ml, 0.5% solution) as needed, or, intermittent epidural injections of morphine (5 mg/5 ml of normal saline, 0.1% solution) as needed, or continuous epidural infusion of morphine (0.1 mg, in 1 ml of normal saline) per hour supplemented with intravenous morphine (2 mg) upon request. Pain relief was evaluated by each patient on a pain scale visual analogue and by pain relief questionnaire for a period of 72 hr. Postoperative pain relief was achieved equally with these three methods of epidural analgesia in all patients with no significant difference between groups. Intermittent epidural injection of bupivacaine relieved pain for 4.9 ± 1.9 (SD) hr/injection and was associated with urinary retention in all patients, with numbness and weakness of the hands in 12 patients, and with severe hypotension in 7 patients. Intermittent epidural injection of morphine relieved pain for 5.8 ± 2.3 hr/injection and was associated with urinary retention in all patients, with pruritus in 12 patients, and with central narcosis and respiratory depression in 8 patients. Continuous epidural infusion of morphine with occasional intravenous morphine (2 mg) supplementation also effectively relieved postoperative pain and was associated with minimal systemic side effects. One patient complained of pruritus, and two patients developed urinary retention. Continuous epidural infusion of morphine at 0.1 mg/hr achieves effective and selective pain relief in the majority of patients after thoracic operations. Although this method of pain relief requires occasional supplementation with systemic narcotics, this technique avoids the major systemic side effects of both intermittent epidural injections of larger doses of morphine and those associated with epidural injection of bupivacaine.

Comparison of insulated and uninsulated needles for locating peripheral nerves with a peripheral nerve stimulator.

Abstract: This study was designed to compare the use of insulated and uninsulated needles with a peripheral nerve stimulator for locating a peripheral nerve in an anesthetized cat. The needles were mounted on a one-dimensional manipulator and both the saphenous and sciatic nerves were located. The tip of the insulated needle was consistently placed on the sciatic nerve. The tip of the uninsulated needle was placed 0.1-0.9 cm past the sciatic nerve. Injecting saline to assess the position of the tip of the needle relative to the sciatic nerve did not detect the needle being past the nerve. With the saphenous nerve preparation, both the needle and nerve were visible through the tissue. Using an insulated needle, the minimum current required to stimulate the nerve occurred when the tip of the needle touched the saphenous nerve. Using an uninsulated needle, the minimum current occurred when the tip was 0.1-0.8 cm past the nerve. The conclusion is that insulated needles more precisely locate the peripheral nerve than uninsulated needles.

The minimum anesthetic concentration of isoflurane in children.

Abstract: The minimum anesthetic concentration (MAC) of isoflurane was determined in five pediatric age groups. MAC was 1.6% in infants 0-1 month of age, 1.87% in those 1-6 months of age, 1.8% in those 6-12 months of age, 1.6% in those 1-3 yr of age, and 1.6% in children 3-5 yr of age. MAC in neonates was less than predicted.

Chronic neurological deficits and Nesacaine-CE--an effect of the anesthetic, 2-chloroprocaine, or the antioxidant, sodium bisulfite?

Abstract: Chronic neurological deficits have been described in patients after presumed accidental subarachnoid injection of 2-chloroprocaine-CE (Nesacaine-CE; N-CE) intended for epidural block. This study investigated the possible role of pure 2-chloroprocaine (2-CP) and sodium bisulfite, two components of Nesacaine-CE, in causing these complications when injected separately into the lumbar subarachnoid space of neurologically intact awake rabbits. Repeated 2-4-mg spinal anesthetic doses of pure 2-CP in lactated Ringer's solution did not produce chronic hindlimb paralysis even though accumulated doses reached 50 mg. However, 1.2-2.4 mg of sodium bisulfite, the antioxidant in N-CE added to prolong shelf-life, resulted in irreversible hindlimb paralysis in 12 out of 14 animals. This amount of bisulfite is contained in 12-24 mg of 2% N-CE. The demonstration that persistent paralysis resulted from low dosages of sodium bisulfite contained in commercially available 2-CP requires reevaluation of the suitability of this antioxidant for products prepared for intrathecal use.

Effects of diazepam premedication and epinephrine-containing local anesthetic on cardiovascular and plasma catecholamine responses to oral surgery.

Abstract: The effects of diazepam premedication and administration of an epinephrine-containing local anesthetic on plasma catecholamine levels and cardiovascular parameters were evaluated prior to and during a minor surgical procedure, the removal of impacted third molars. Significant elevations in circulating epinephrine levels (203% above control) and cardiac output (30%) were seen in unsedated patients after administration of lidocaine with epinephrine before surgery, while no changes were seen after lidocaine alone. Unsedated patients had increased norepinephrine (24%) and epinephrine (57%) levels during surgery. Diazepam premedication decreased norepinephrine levels 29% below preoperative levels, followed by an increase during surgery to preoperative levels. These results indicate that intraoral injections of epinephrine-containing local anesthetics result in increased circulating epinephrine levels that are associated with cardiovascular changes and that diazepam premedication decreases plasma norepinephrine levels and attenuates the sympathoadrenal response to surgical stress.

EEGs during high-dose fentanyl-, sufentanil-, or morphine-oxygen anesthesia.

Abstract: In 49 patients undergoing open-heart surgery we compared the electroencephalographic (EEG) effects of high-dose morphine, fentanyl, or sufentanil with O2, using two computerized analysis and display techniques: a period analysis (the Klein method) and an aperiodic analysis (the Neurometrics monitor). During fentanyl or sufentanil anesthesia, both techniques revealed a general decrease in frequency, shown by the aperiodic analysis primarily as a marked increase in the very low frequency range: an increase in the 1-Hz bin (TP1, in muv2) from 2.80 X 10(4) +/- 3.20 X 10(4) (SD) to 45.1 X 10(4) +/- 27.2 X 10(4) for fentanyl and from 3.11 X 10(4) +/- 2.83 X 10(4) to 52.8 X 10(4) for sufentanil. The cumulative percent power at 3 Hz (CP3) increased from 27.2 +/- 6.8 to 83.0 +/- 11.0 for fentanyl and from 22.7 +/- 5.2 to 85.1 +/- 10.4 for sufentanil, while the frequency at 90% cumulative percent power (F90, in Hz) decreased from 17.8 +/- 2.9 to 7.9 +/- 2.8 for fentanyl and 16.4 +/- 5.2 to 5.6 +/- 4.3 for sufentanil. The changes with morphine were less obvious, with some attenuation of high-frequency power shown by the Klein method, and an increase from 24.1 +/- 8.6 to 59.3 +/- 20.7 with CP3, but no change in TP1. Low-frequency power with the period analysis and TP1 with the aperiodic analysis decreased between laryngoscopy and the incisions with fentanyl and sufentanil.(ABSTRACT TRUNCATED AT 250 WORDS)

Fentanyl-and Sufentanil-oxygen-pancuronium Anesthesia for Cardiac Surgery in Infants

Abstract: The safety and efficacy of fentanyl-oxygen (50 and 75 micrograms/kg) and sufentanil-oxygen (5 and 10 micrograms/kg) were studied in 40 infants undergoing repair of complex heart defects. When fentanyl or sufentanil was given simultaneously with pancuronium, induction of anesthesia was rapid and smooth with only mild and clinically insignificant hemodynamic changes. Hemodynamic responses to tracheal intubation were completely blocked, whereas hemodynamic responses to surgical incision and sternotomy were partially and variably blocked. Except for somewhat more effective blocking of responses to surgical stimulation by sufentanil, the effects of both narcotics were similar. No significant differences in effects were found between the two dose levels of either drug. Transcutaneous oxygen tensions increased with induction, intubation, and surgical stimulation with both fentanyl and sufentanil, even in cyanotic patients with right to left shunts. Fentanyl- and sufentanil-oxygen-pancuronium anesthesia were both safe and effective for cardiac surgery in infants. This study raises the question of possible beneficial effects of high dose fentanyl and sufentanil in blunting stress responses in the pulmonary circulation, a critical aspect of anesthesia and intensive care in the infant and neonate.

Comparative cardiotoxicity of bupivacaine and lidocaine in the isolated perfused mammalian heart.

Abstract: This study was designed to compare the direct actions of bupivacaine and lidocaine on the isolated perfused guinea pig Langendorff heart preparation. Sixty min after mounting, either bupivacaine HCl (0.3 or 3 micrograms/ml) or lidocaine HCl (10 or 30 micrograms/ml) was added to the perfusate, and the effect (if any) was compared to untreated control values 30, 60, and 90 min later. Although the highest concentrations of both drugs invariably produced statistically significant reductions in heart rate, df/dt, coronary blood flow, and myocardial oxygen consumption (MVO2), these reductions were consistently greater after bupivacaine. Moreover, arrhythmias occurred in 6 of 12 preparations in those hearts exposed to 3 micrograms/ml of bupivacaine. Most often these arrhythmias consisted of heart block and bi- or trigeminy. Additional studies indicated that the reduction in coronary blood flow and MVO2 produced by 3 micrograms/ml of bupivacaine was a consequence of its direct negative inotropic and chronotropic action. Although the myocardial depression produced by bupivacaine and lidocaine could be reversed readily by substituting fresh perfusate, increasing the extracellular calcium concentration in stepwise increments did not augment the negative inotropic or chronotropic effect produced by 3 micrograms/ml of bupivacaine or 10 micrograms/ml of lidocaine. We conclude that 3 micrograms/ml of unbound bupivacaine is more cardiotoxic than 30 micrograms/ml of unbound lidocaine in this model.

Halothane and children: the first quarter century.

Abstract: For the past 25 years, halothane has been the primary anesthetic agent at Children's Hospital, Columbus, Ohio. To confirm our impression that adverse reactions to halothane are rarely a problem in children, we examined the records of 200,311 cases conducted with halothane from June 1, 1958, through May 31, 1983. Life-threatening complications due to side effects were identified in fifteen patients, and could be grouped into three areas: hepatitis (one), malignant hyperthermia (ten), and cardiac arrhythmias (four). No child died or sustained permanent sequelae. In eleven instances, other drugs (succinylcholine, atropine, cocaine, and epinephrine) possibly contributed to the adverse reactions.

Perioperative management of the patient with asthma.

Abstract: Physiopathologie: mecanique respiratoire, distribution de la ventilation et de la perfusion, reponses vasculaires pulmonaires a l'asthme. Medicaments utilises. Problemes specifiques: chirurgie d'urgence, grossesse, cardiopathie, chirurgie pediatrique

The pall ultipor breathing circuit filter--an efficient heat and moisture exchanger.

Abstract: The Pall bacterial filter was tested as a potential heat and moisture exchanger on a model patient, placed on a circle absorber system, and clinically. The laboratory study was conducted during mechanical ventilation at a V of 6 L/min with fresh gas inflows of 1, 3 and 6 L/min. The model patient introduced carbon dioxide into the circuitry at a rate of 200 ml/min. The resistance of the filter was tested before and after each experiment. With all fresh gas inflows , absolute humidity increased from around 19 mg H2O/L at the start of experimentation to about 27 mg H2O/L within 30 min. Maximum humidities reached were 28 +/- 0.7 mg H2O/L, 27.6 +/- 0.5 mg H2O/L, and 27.7 +/- 0.5 mg H2O/L within 3 hr, with fresh gas inflows of 1, 3, and 6 L/min, respectively. Variations in inspired humidity were also assessed at minute volumes of 4 and 5 L/min with fresh gas inflows of 6 and 3 L/min. Increases in percent dead space were negligible when the filter was inserted between the model patients (assumed to weigh between 70-40 kg) and the circuit. There was no statistically significant increase in pressure with gas flows of 50 L/min when the instrument was dry (0.02 +/- 0.001 cm H2O/L X min-1) or when it was wet (0.02 +/- 0.002 cm H2O/L X min-1). The clinical study was conducted on ten adult anesthetized patients breathing through the bacterial filter and ten controls. The loss of body temperature was 0.2 degrees C when the filter was used and 1.5 degrees C when the filter was not used. Arterial blood gas tensions were within normal limits when the bacterial filter was used as a humidifier.

Effects of fentanyl and morphine on intraoperative somatosensory cortical-evoked potentials.

Abstract: We compared the effects of morphine and fentanyl in the presence of 60% N2O on somatosensory cortical-evoked potentials (SCEP). Both drugs were administered by intravenous bolus (n = 12) and infusion (n = 20) techniques. SCEPs were recorded preoperatively and intraoperatively in 32 patients undergoing corrective surgery for scoliosis. Records were taken at the contralateral cerebral cortex by individual stimulation of the posterior tibial nerves at the ankle. Both drugs increased the latencies of the N1, P2, and N2 peaks and affected the peak-to-peak amplitudes of the primary complex. Intravenous bolus injections and continuous infusions of equianalgesic doses produced similar effects. The increase in N1 latency was significantly greater (morphine, P less than 0.05; fentanyl, P less than 0.01) with the bolus than with the infusion technique. The doses of morphine and fentanyl given by bolus injections were 1/3 times and 3 1/3 times greater than doses given by infusion. Changes in latency were more consistent than changes in amplitude. Both fentanyl and morphine increase latencies while affecting amplitudes unpredictably. Equianalgesic doses of fentanyl and morphine have similar effects on SCEP latencies. Low-dose continuous infusions of narcotics depress SCEPs less than intermittent bolus injections.

Pediatric fentanyl dosing based on pharmacokinetics during cardiac surgery.

Abstract: The pharmacokinetics of fentanyl (F) were studied in 10 children, age 5 months-4.5 yr (mean 19 months) undergoing cardiac surgery with cardiopulmonary bypass ( CPBP ). They suffered from transposition of the great arteries (6), tetralogy of Fallot (2), and atrio-ventricular (A-V) canal (2). Induction of anesthesia included a bolus of 50 micrograms X kg-1 X min-1 F followed by a continuous F infusion of either 0.15 micrograms X kg-1 X min-1 (4 patients) or 0.3 micrograms X kg-1 X min-1 (6 patients). The F infusion was discontinued when cardiopulmonary bypass was started, 81-141 min (mean 112 min) along with deep hypothermia. Blood was collected throughout surgery from an indwelling radial arterial catheter and plasma concentration of F was assayed by GLC. F plasma concentrations after 30 min were 2-3-fold higher than reported with the same regimen in adults. The calculated values for t1/2 alpha (12 +/- 9 min) (mean +/- SD), t1/2 beta (141 +/- 98 min) and total body clearance (12.8 +/- 7.3 ml X min-1 X kg-1) were similar to adult values. The significantly lower steady-state volume of distribution observed in children with intracardiac shunts (1385 +/- 875 ml X kg-1) compared to reported values for adults (3200-6000 ml X kg-1) explains the higher F plasma concentrations achieved in these children. Cardiopulmonary bypass produced a mean 70% (range, 56-89%) decrease in plasma F, significantly higher than would be expected from hemodilution alone. Studies of F disposition in the CPBP demonstrated that F is bound to the pump.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous infusion epidural analgesia in parturients receiving bupivacaine, chloroprocaine, or lidocaine--maternal, fetal, and neonatal effects.

Abstract: The effects of epidural analgesia for labor and delivery using a continuous infusion technique on fetal heart rate, uterine activity, maternal blood pressure, Apgar scores, neonatal acid-base status, and the Neurologic and Adaptive Capacity Scoring System were studied in 61 parturients. Group I (n = 23) received initial test and therapeutic doses of 2 and 6 ml of 0.5% bupivacaine followed by an infusion of 0.125% at a rate of 14 ml/hr. Group II (n = 19) received 2 and 6 ml of 2% chloroprocaine followed by an infusion of 0.75% at a rate of 27 ml/hr. Group III (n = 19) received 2 and 6 ml of 1.5% lidocaine followed by an infusion of 0.75% at a rate of 14 ml/hr. None of the three local anesthetics used had any significant effect on baseline fetal heart rate or uterine activity. In cases in which monitoring of fetal heart rate was both technically satisfactory and continuous, late and variable decelerations in fetal heart rate were seen in 10 of 17, 3 of 18, and 2 of 19 of the fetuses in groups I, II, and III, respectively. The incidence was significantly higher in group I than in groups II or III (P less than 0.05). Apgar scores and neonatal acid-base status were equally good in all three groups. Neurologic and adaptive capacity scores did not differ among the three groups of neonates, nor did any of the neonates in the three groups score lower than a control group of 19 neonates whose mothers did not receive any analgesia or medications for labor and delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasoconstrictors in spinal anesthesia with tetracaine--a comparison of epinephrine and phenylephrine.

Abstract: A randomized double-blind study was conducted in 50 orthopedic patients to determine the effect of epinephrine and phenylephrine on the anesthetic properties of intrathecally administered tetracaine. Two doses of each vasoconstrictor agent were studied: 0.2 mg of epinephrine, 0.3 mg of epinephrine, 1 mg of phenylephrine, and 2 mg of phenylephrine. The results show that both vasoconstrictor agents in the doses used significantly prolong duration of sensory anesthesia and motor blockade produced by the subarachnoid administration of tetracaine. At equipotent doses no differences existed between the ability of epinephrine and phenylephrine to prolong the duration of spinal anesthesia produced by tetracaine.

Comparison of four opioid analgesics as supplements to nitrous oxide anesthesia.

Abstract: The hemodynamic changes, plasma norepinephrine levels, pupil size, and rapidity of postoperative mental recovery were measured and compared in 72 patients randomly assigned in a double-blind manner to receive either morphine, meperidine, fentanyl, or sufentanil as supplements to nitrous oxide anesthesia. Meperidine, unlike the other opioids, which did not change heart rate, consistently increased it. Hemodynamic responses to laryngoscopy and intubation were suppressed by fentanyl and sufentanil, but not by morphine or meperidine. The sufentanil group was the only group in which median norepinephrine levels remained consistently below preinduction values. The frequency with which opioids had to be administered (doses/hr) was significantly less with sufentanil than with morphine and meperidine. Meperidine produced less constriction of the pupils than the other opioids and the duration of miosis was shorter. Fentanyl and sufentanil were associated with a more rapid return of mental function than morphine and meperidine. Meperidine caused deleterious effects on objective tests of psychomotor and cognitive skills that were not reflected by subjective evaluation of rate of recovery from anesthesia. The authors conclude that moderate doses of fentanyl and sufentanil are better supplements to nitrous oxide anesthesia than morphine or meperidine and that fentanyl and sufentanil are equally satisfactory. Subjective effects of the opioids correlated well with changes in pupil diameter.

Epidural buprenorphine--a double-blind study of postoperative analgesia and side effects.

Abstract: Epidural buprenorphine was investigated as a postoperative analgesic in a randomized double-blind study of 158 patients given epidural analgesia with mepivacaine or bupivacaine for orthopedic surgery of the lower extremity. At the end of surgery, patients were given either 0.15 mg of epidural buprenorphine (n = 38), 0.3 mg (n = 37) in 15-ml saline, or no further epidural injections (n = 47, control group) after 2% mepivacaine for intraoperative anesthesia. A fourth group (n = 36) received 0.3 mg of buprenorphine in 15-ml saline, after the intraoperative use of 0.5% bupivacaine. The patients rated postoperative pain. The need for additional analgesics as well as side effects were recorded. Analgesia after 0.15 mg buprenorphine was superior to that after no reinjection for 6 hr after surgery (P less than 0.05). Buprenorphine (0.3 mg) was superior both to no reinjection and to 0.15 mg of buprenorphine until the twelfth hour (P less than 0.05). Analgesia after bupivacaine followed by 0.3 mg of buprenorphine was not significantly different than analgesia seen after mepivacaine followed by 0.3 mg of buprenorphine. There was an increase of PaCO2 of 2-5 mm Hg between 1.5-3.5 hr after 0.3 mg of buprenorphine without any evidence for late respiratory depression. Other side effects, e.g., disturbances of micturition, pruritus, nausea, vomiting, fatigue, and headache, were comparably common in all groups. The epidural administration of 0.3 mg buprenorphine may be recommended for postoperative analgesia following orthopedic surgery of the lower extremity.

Comparison of fentanyl, sufentanil, and alfentanil anesthesia in patients undergoing valvular heart surgery.

Abstract: The hemodynamic responses to anesthesia and surgery were studied in three groups of 20 patients undergoing valve replacement surgery. Anesthesia was induced with either fentanyl (75 micrograms/kg), sufentanil (15 micrograms/kg), or alfentanil (125 micrograms/kg). Pancuronium (8 mg) was given for muscle relaxation and the lungs were ventilated with oxygen/air (FIO2 = 0.5). Additional fentanyl (25 micrograms/kg) or sufentanil (5 micrograms/kg) was given before skin incision. Patients receiving alfentanil were given a continuous infusion at a rate of 0.5 mg X kg-1 X hr-1. Only mean arterial blood pressure (MABP) and systemic vascular resistance (SVR) changed significantly in response to anesthesia or surgery. MABP decreased on average 24.5 mm Hg (P less than 0.01) after induction of anesthesia with sufentanil in patients with mitral valve disease. MABP and SVR increased significantly (P less than 0.01) in patients with aortic valve disease receiving fentanyl. There were no other statistically significant changes within the groups. Four patients (two in the sufentanil group and one from each of the other groups) developed transient hypotension during induction of anesthesia. It is concluded that all three opioids can provide satisfactory anesthesia for patients having valve replacement surgery.

Platelet Involvement in the Activated Coagulation Time of Heparinized Blood

Abstract: The activated coagulation time (ACT), commonly used during cardiopulmonary bypass (CPB), is assumed to measure only differences in heparin levels. Studies were undertaken to determine whether platelet activation/inhibition might also influence the test. When either the platelet inhibitor prostacyclin or the platelet activator adenosine diphosphate (ADP) was added to healthy donor blood containing 2 1U of heparin per ml, there was significant prolongation of the ACT (prostacyclin: mean prolongation, 60.6%; ADP: mean prolongation, 52.3%). In blood taken from the extracorporeal circuit of ten CPB cases, the prolongation with the platelet inhibitor carbacyclin, a prostacyclin analogue, was infinite. It is concluded that the ACT as used during CPB must be interpreted as a measure of both platelet procoagulant activity and heparin activity. Furthermore, this dual sensitivity, while fortuitous, is probably advantageous; patients with hyporeactive platelets will automatically receive less heparin.

Common bile duct pressure changes after fentanyl, morphine, meperidine, butorphanol, and naloxone.

Abstract: Five groups of 10 patients received thiamylal, enflurane, nitrous oxide-oxygen anesthesia for elective cholecystectomy. The common bile duct was intubated via the cystic duct with a 16-g plastic catheter, and the control intraductal pressure was measured. Patients then were given equi-analgesic doses of fentanyl, morphine, meperidine, butorphanol, or placebo intravenously, and the common bile duct pressure was recorded for 20 min. Fentanyl, morphine, and meperidine significantly increased pressure in the common duct (P less than 0.001). Butorphanol produced only insignificant changes. Naloxone given 20 min later significantly (P less than 0.001) decreased pressure in patients given fentanyl, morphine, and meperidine. Naloxone given without narcotics caused an increase in pressure that, although statistically significant (P less than 0.03), was clinically insignificant. In five additional patients anesthetized with thiamylal, nitrous oxide-oxygen and intermittent doses of fentanyl, common bile duct pressures were normal.

The effects of nitrous oxide on myocardial metabolism and hemodynamics during fentanyl or enflurane anesthesia in patients with coronary disease.

Abstract: Twenty patients about to have coronary artery bypass grafts were studied before and after 15 min of 50% nitrous oxide added to either fentanyl (75 micrograms/kg) or enflurane (0.5%) anesthesia. Arterial and central pressures and cardiac output were measured, plus coronary sinus blood flow and arterio-coronary sinus differences in oxygen, hemoglobin, and lactate contents. Fentanyl-N2O and enflurane-N2O both decreased systemic resistance, heart rate, cardiac output, and hence arterial pressure. Stroke work decreased significantly with little or no change in wedge pressure: ventricular function was impaired. Coronary flow and myocardial O2 consumption decreased with fentanyl-N2O. Oxygen extraction increased with enflurane-N2O, as did lactate contents of coronary sinus blood. Hemodynamic depression occurred from the combined effects of nitrous oxide and fentanyl or enflurane. The beta-blocked myocardia of nonstimulated coronary patients were becoming ischemic globally on 50% oxygen, after significant hypotension. From this and other evidence, we conclude that nitrous oxide may not be benign in patients with coronary arterial disease.

Hyperbaric bupivacaine for spinal anesthesia in cesarean section.

Abstract: The efficacy and safety of 0.5% hyperbaric bupivacaine (Sensorcaine, Astra) was evaluated in 22 patients undergoing elective cesarean section under spinal anesthesia. The dose varied from 7.5 to 10 mg, (depending on the patient's height) which was significantly lower than previously reported. Patients were placed in head-down tilt immediately after subarachnoid injection. The mean spread of analgesia was to T3, which was reached in 10-15 min. Regression was complete in 258 +/- 16 min. Complete motor paralysis of lower extremities occurred in only two patients. Complete recovery of motor function in all patients was evident in less than 2.5 h. All infants were vigorous at birth and there were no serious maternal complications. The incidence of hypotension was 4.5%, the lowest reported as a consequence of spinal anesthesia in this group of patients. A technique involving the use of reduced doses of hyperbaric bupivacaine (0.5%) in conjunction with head-down tilt appears to be useful for spinal anesthesia for cesarean section.