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H F Nicodemus

Publications and source records attributed to H F Nicodemus.

15 recordsLinked to original sources
PubMed1996

Vomiting and recovery after outpatient tonsillectomy and adenoidectomy in children. Comparison of four anesthetic techniques using nitrous oxide with halothane or propofol.

BACKGROUND: The authors' purpose in this study was to compare prospectively four different anesthetic induction and maintenance techniques using nitrous oxide with halothane and/or propofol for vomiting and recovery after outpatient tonsillectomy and adenoidectomy procedures in children. METHODS: Eighty unpremedicated children, aged 3-10 yr, were assigned randomly to four groups: group H/H, 0.5-2% halothane induction/halothane maintenance; group P/P, 3-5 mg.kg-1 propofol induction and 0.1-0.3 mg.kg-1.min-1 propofol maintenance; group H/P, 0.1-0.3 mg.kg-1.min-1 halothane induction/propofol maintenance; and group P/H, 3-5 mg.kg-1 propofol induction and 0.5-2% halothane maintenance. Nitrous oxide (67%) and oxygen (33%) were administered in all the groups. Other treatments and procedures were standardized intra- and postoperatively. Results of postoperative vomiting and recovery were analyzed in the first 6 h and beyond 6 h. RESULTS: Logistic regression showed that vomiting occurred 3.5 times as often when halothane was used for maintenance of anesthesia (groups H/H and P/H) compared with the use of propofol (groups P/P and H/P; Odds Ratio 3.5; 95% confidence interval 1.3 and 9.4, respectively; P = 0.012). A significant association between vomiting ( < 6 h: yes/no) and discharge times ( > 6 h: yes/no) (Odd's Ratio = 3.6; 95% confidence interval: 1.02, 12.4, respectively) (P = 0.046) was shown. However, no significant differences among the groups in the incidence of vomiting beyond 6 h, recurrent vomiting, or hospital discharge times were shown. CONCLUSIONS: After tonsillectomy and adenoidectomy procedures, despite reduced postoperative vomiting with use of propofol rather than halothane, along with nitrous oxide for anesthetic maintenance, the authors found no differences in "true" endpoints such as unplanned admissions or discharge times. Among the groups, the main factor that delayed hospital discharge beyond 6 h was vomiting within the first 6 h.

Adenoidectomy↗
PubMed1994

The pharmacokinetics of propofol in children using three different data analysis approaches.

BACKGROUND: Accurate dosing of propofol in children requires accurate knowledge of propofol pharmacokinetics in this population. Improvement in pharmacokinetic accuracy may depend on the incorporation of individual patient factors into the pharmacokinetic model or the use of population approaches to estimating the pharmacokinetic parameters. We investigated whether incorporating individual subject covariates (e.g., age, weight, and gender) into the pharmacokinetic model improved the accuracy. We also investigated whether the use of a mixed-effects population model (e.g., the computer program NONMEM) improved the accuracy of the pharmacokinetic model beyond the accuracy obtained with models estimated using two simple approaches. METHODS: We studied 53 healthy, unpremedicated children (28 boys and 25 girls) ranging from 3 to 11 yr of age. Twenty children only received an initial loading dose of 3 mg/kg intravenous propofol. In the remaining 33 children, an initial intravenous propofol dose of 3.5 mg/kg was followed by a propofol maintenance infusion. Six hundred fifty-eight venous plasma samples were gathered and assayed for propofol concentrations. Three different regression techniques were used to analyze the pharmacokinetics: the "standard two-stage" approach, the "naive pooled-data" approach, and the nonlinear mixed-effects modeling approach (as implemented in NONMEM). In both the pooled-data and mixed-effects approaches, individual covariates (age, weight, height, body surface area, and gender) were added to the model to examine whether they improved the quality of the fit. Accuracy of the model was measured by the ability of the model to describe the observed concentrations. RESULTS: The pharmacokinetics of propofol in children were best described by a three-compartment pharmacokinetic model. There were no appreciable differences among the pharmacokinetics estimated using the two-stage, pooled-data, and mixed-effects approaches. Weight was a significant covariate, and the weight-proportional model was supported by all three regression approaches. The pharmacokinetic parameters of the weight-proportional pharmacokinetic model (pooled-data approach) were: central compartment (V1) = 0.52 1 x kg-1; rapid-distribution compartment (V2) = 1.01 x kg-1; slow-distribution compartment (V3) = 8.2 1 x kg-1; metabolic clearance (Cl1) = 34 ml.kg-1 x min-1; rapid-distribution clearance (Cl2) = 58 ml.kg-1 x min-1; and slow-distribution clearance (Cl3) = 26 ml.kg-1 x min-1. The inclusion of age as an additional covariate of V2 statistically improved the model, but the actual improvement in the fit was small. CONCLUSIONS: The pharmacokinetics of propofol in children are well described by a standard three-compartment pharmacokinetic model. Weight-adjusting the volumes and clearances significantly improved the accuracy of the pharmacokinetics. Adjusting the pharmacokinetics for inclusion of additional patient covariates or using a mixed-effects model did not further improve the ability of the pharmacokinetic parameters to describe the observations.

Child↗
PubMed1991

Intrathecal morphine does not reduce minimum alveolar concentration of halothane in humans: results of a double-blind study.

The effect of intrathecal morphine on the minimum alveolar concentration (MAC) of halothane was investigated in 22 patients undergoing elective abdominal surgery. The patients were randomly assigned to the control (CTRL) or intrathecal morphine sulfate (ITMS)-treated groups. Approximately 2.5 h before induction of anesthesia with halothane, the ITMS-treated group received 15 micrograms/kg preservative-free ITMS (Duramorph; Elkins-Sinn, Cherry Hill, NJ) while in the right lateral decubitus position. The CTRL group was treated in an identical fashion except that, after placement of the introducer needle, actual dural puncture was omitted. After inhalational induction with halothane as the sole anesthetic agent, the patients' responses to surgical incision were recorded. MAC was determined with the modified up-down method of Dixon and verified with probit analysis. MAC (+/- SE) after ITMS was 0.76 +/- 0.06, compared with a CTRL MAC of 0.78 +/- 0.15 (not significant). Under the conditions of this study, the MAC of halothane in humans was not significantly affected by ITMS.

Adult↗
PubMed1991

Bilateral infraorbital block with 0.5% bupivacaine as post-operative analgesia following cheiloplasty in children.

Various studies have shown that bupivacaine nerve blocks provide prolonged post-operative analgesia. We studied the efficacy of a 0.5% bupivacaine infraorbital nerve block as post-operative analgesia in a random, prospective, double blind manner in children undergoing cleft lip repair. Following the induction of anesthesia with ketamine 2-4 mg/kg im, 60 patients, aged 2-13 years, ASA I and II were equally divided: Group A received 1-1.5 ml bupivacaine, 0.5% with 1:200,000 epinephrine; Group B received 1-1.5 ml saline injected into the vicinity of the infraorbital foramina. In every patient, the surgeon infiltrated the lip with 4-7 ml of 1% lidocaine with 1:100,000 epinephrine for both anesthesia and hemostasis. Post-operative evaluations were completed after 4, 8, and 12 to 24 hours and were based on a visual analogue scale for pain. Similarly, the nurses and the parents also evaluated post-operative discomfort using specific criteria. All the observers were kept unaware of the solutions used for the block. The results showed that Group A was pain free for a mean duration of 19.4 +/- 5.06 (SD) hours in contrast to 11.7 +/- 6.19 hours for Group B, (p less than 0.001). Group A required no other analgesic whereas a total of 17 patients in Group B required analgesic medication starting at four hours post-operatively, (p less than 0.001). Both the nurses and the parents confirmed that those who received infraorbital block were more comfortable than those who did not. One-way analysis of variance indicates that the mean scores for both groups differs significantly at all levels of comparison, (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Bupivacaine↗
PubMed1981

Hemodynamic effects of inotropes during hypothermia and rapid rewarming.

The hemodynamic effects of propranolol, lidocaine, and dopamine were studied in anesthetized, mechanically ventilated dogs, cooled to 25 degrees C with a venovenous shunt through a heat exchanger. After 1 h at 25 degrees C, the shunt was converted to an arteriovenous shunt which remained functional until the study was completed. Before rewarming, the authors treated each group of 8 dogs with intravenous doses of the drugs: group 1: 10 ml saline as control; group 2: propranolol 0.3 mg/kg; group 3: 50 mg lidocaine initially, followed with continuous infusion of 40-50 microgram/kg.min; group 4: dopamine infusion at 12 microgram/kg.min; and group 5: lidocaine as in group 3 and dopamine as in group 4. For the dopamine-treated groups, 2 min of infusion was allowed; in all other groups, 5 min elapsed after injection before the hemodynamic data were recorded. The hemodynamic data were collected at esophageal temperatures of 25, 30, and 37 degrees C. The findings were: (1) hypothermia impaired cardiovascular function; (2) lidocaine and propranolol had minimal hemodynamic effects during hypothermia; lidocaine was physiologically more desirable than propranolol; (3) dopamine, alone or combined with lidocaine, reversed the cardiovascular depression from hypothermia; the improvement was equivalent to rewarming by as much as 5 degrees C; and (4) at the completion of rewarming, cardiovascular recovery was more complete with dopamine/lidocaine-treated animals compared to untreated and propranolol-treated animals. Based on these findings, these inotropes appear to be safe adjuncts to resuscitation during hypothermia.

Animals↗
PubMed1981

Failure of naloxone or physostigmine to reverse nitrogen anesthesia in guinea pigs.

Stress as well as anesthesia has been reported to stimulate endorphin release. The possibility that the stress of compression at 1 atm/min or nitrogen anesthesia, or both, might release endorphins was tested in guinea pigs with the use of naloxone--a narcotic antagonist, and physostigmine--a cholinesterase inhibitor. The animals received i.p. equal volumes of either drugs or the placebo just before compression to 32 ATA (oxygen less than or equal to 1 ATA). The pressure at loss of righting reflex was compared. Nitrogen anesthesia occurred at mean pressures ranging from 26.9 to 27.8 ATA, with no statistical differences demonstrated in all groups. It is concluded that 1) neither naloxone nor physostigmine reversed nitrogen narcosis and 2) stress of compression or nitrogen narcosis, or both, failed to show effects attributable to increased endorphin release.

Anesthesia↗
PubMed1980

Dose-responses of guinea pigs to diazepam at recompression depths.

Dose-responses to diazepam were studied in guinea pigs at the recompression pressures used for the treatment of gas embolism and decompression sickness. The conditions and the doses were randomly assigned. Sufficient exposure to 6 ATA air, 3 ATA oxygen, or 1 ATA air was allowed in the hyperbaric chamber before diazepam was administered intravenously. Loss of righting reflex and its return were the end points for sleep and awakening, respectively. The data were analyzed with a mathematical model for dose-response and duration of effect. Results were: (1) in 1 ATA air, widely varying doses induced sleep of long duration; (2) in 6 ATA air, sleep was induced with small doses; and (3) in 3 ATA oxygen, sleep was induced with large doses. The duration of sleep under hyperbaric conditions was shorter than at sea level pressure. The null hypothesis, which assumed similar dose-responses and durations of sleep under these three conditions, was rejected. The dose and duration of diazepam's effect during recompression apparently depend on the pressure and the gas composition used.

Animals↗
PubMed1979

Ketamine and thiopental sleep responses in guinea pigs in hyperbaric helium-oxygen.

One-hundred twenty three guinea pigs, randomly divided into four groups, were exposed to the following normoxic environments: Group I, 1 atmosphere absolute (ATA) air; Group II, 1 ATA helium-oxygen (heliox); Group III, 20 ATA heliox; and Group IV, 31 ATA heliox. Each group was divided into five subgroups; each subgroup received a different and graduated intravenous dose of ketamine in one of these environments. An additional 172 guinea pigs were exposed either to 1 ATA air or 31 ATA heliox and given thiopental. The duration of sleep, determined by failure of the animals to right themselves, was then used to construct dose-response curves for the two drugs in the hyperbaric environments. Results demonstrated less pressure antagonism of anesthesia with ketamine than with thiopental. For both drugs, pressure not only increased the dose required to induce sleep but also decreased the duration of sleep, when it occurred, by as much as 50% compared to effects of the same doses at surface pressure.

Anesthesia↗