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PubMed2001

Effect of smoking on induction of anaesthesia with sevoflurane.

Inhalational induction with sevoflurane has been shown to be a viable alternative to intravenous induction; however, studies have focused mainly on healthy patients or volunteers. Airway complications in patients with potential airway irritability have not been studied. Sixty smokers undergoing general anaesthesia were randomly assigned to one of three groups: group 1, vital capacity breathing with 8% sevoflurane; group 2, tidal breathing with 8% sevoflurane; and group 3, tidal breathing with step-up of sevoflurane (sevoflurane concentration increased by increments of 2% every 10 s until 8%). Step-up induction was significantly slower to induce loss of consciousness than a vital capacity breath or tidal breathing at 8% (p < 0.05). Step-up induction produced more complications than tidal breathing at 8% (p = 0.05). All patients had acceptable induction of anaesthesia with no patient having an oxygen saturation below 96% at any time. Blood pressure and heart rate decreased gradually over time in all groups (p < 0.001), but there were no significant differences between groups. Patient satisfaction with the techniques was high with 59 of 60 patients willing to have the same technique again. Inhalational induction with sevoflurane can be used safely as an induction technique in smokers. In common with other patient groups, use of a high initial concentration reduces induction time without causing additional airway or cardiovascular complications.

Aged↗
PubMed2000

Safety of allergen-specific immunotherapy. Relation between dosage regimen, allergen extract, disease and systemic side-effects during induction treatment.

BACKGROUND: Allergen-specific immunotherapy is a well-documented treatment for allergic rhinitis, asthma, and allergy to Hymenoptera venoms. The drawbacks of injection immunotherapy are related to the risk of inducing systemic side-effects (especially during the induction phase), the time used to reach the maintenance dose, and the percentage of patients completing the induction phase). OBJECTIVE: To investigate the practicability and safety of three different patient-friendly induction regimens of clustered immunotherapy (several injections administered during each visit). METHODS: Since 1990, three different clustered induction regimens (regimen 1 = exclusively aqueous extracts; regimen 2 = a combination of aqueous and alum depot extracts; and regimen 3 = induction using exclusively alum depot extracts) have been investigated in 657 patients (10 369 injections). RESULTS: A total of 454 systemic (immediate and late) reactions were observed in 257 patients corresponding to 4.4% of the injections and 39.1% of the patients. Most of the systemic reactions were of little or no clinical importance (93% grade 1 and grade 2) and < 1% anaphylactic reactions. The 8-week induction regimen using exclusively alum depot extracts showed a statistical significant lower frequency and severity of systemic side-effects. Immunotherapy with cat and mite allergen extracts showed the highest frequency of severe side-effects, which may be related to these extracts being used predominantly in asthmatic patients. The lowest frequency of systemic side-effects was observed in patients allergic to Hymenoptera venoms and these patients furthermore showed the highest number of patients (97%) completing the induction phase. CONCLUSION: An 8-week clustered induction regimen using alum depot extract seems an acceptable compromise in relation to a reduction in the time used to reach maintenance dose and the risk of inducing clinically relevant systemic side-effects, and consequently imply a reduction in the costs of the treatment.

Allergens↗
PubMed2000

The epidemiology of labor induction: Arizona, 1997.

OBJECTIVE: This study was undertaken to describe labor induction risk factors and consequences among women with term singleton gestations with vertex presentation. STUDY DESIGN: Arizona births in 1997 (N = 65,607) were studied by means of stratified analysis and logistic regression. RESULTS: Labor induction occurred in 20.3% (n = 13,288). Labor induction risk factors were as follows: race or ethnicity (white non-Hispanic 25.3%; Hispanic, 13.9%; foreign-born Hispanic, 10.3%; and US-born Hispanic, 18.5%), education (<12 years, 14.1%; >12 years, 24.6%), payor (private insurance, 24.5%; Medicaid, 16.7%), hospital type (government controlled, 13.7%; investor owned, 30.5%). Race or ethnicity and hospital type remained important determinants of labor induction in the multivariate analysis. Relative risks of cesarean delivery with labor induction were as follows: nulliparous, 1.38; parous with no previous cesarean delivery, 1.00; and parous with previous cesarean delivery, 0.50. CONCLUSION: Large variations in labor induction were noted across maternal ethnicity and hospital type categories. Labor induction increased cesarean delivery rates among nulliparous women, whereas no increase was seen among parous women with no previous cesarean delivery. Labor induction was used less often among those with previous cesarean delivery; when it was used in this group, however, it was associated with a lower cesarean delivery rate.

Adult↗
PubMed2001

Temporal changes in rates and reasons for medical induction of term labor, 1980-1996.

OBJECTIVE: This study was undertaken to assess temporal changes in rates and reasons for medical induction of term labor. STUDY DESIGN: A retrospective medical record review was conducted on a population-based cohort of 1293 women with term deliveries. RESULTS: The rate of medical labor induction increased from 12.9% in 1980 to 25.8% in 1995. Stated indications also changed, with a 2-fold increase in induction for postdate gestation, a 23-fold increase in induction for macrosomia, a 15-fold increase in elective induction, and a 22-fold decline in induction for premature rupture of membranes. The average gestational age at delivery of postdate pregnancies declined from 41.9 weeks in 1980 to 41.0 weeks in 1995. By 1995, the average maternal length of stay and the percentage of cesarean deliveries were higher among women with induced labor at term than among those with spontaneous labor at term. CONCLUSION: Induction of term labor has almost doubled in prevalence during the past 15 years. The most common indications are elective induction and postdate pregnancy, often applied to gestations of 40 to 41 weeks' duration.

Adult↗
PubMed1999

Lightness induction revisited.

Lightness induction is the classical visual phenomenon whereby the lightness of an object is shown to depend on its immediate surround. Despite the long history of its study, lightness induction has not yet been coherently and satisfactorily explained in all its variety. The two main theories that compete to explain it descend (i) from H von Helmholtz, who believed that lightness induction originates from some central mechanisms that take into account the whole viewing situation, with particular stress upon the apparent illumination of the object; and (ii) E Hering who argued in favour of more peripheral sensory mechanisms based on local luminance contrast. The balance between these theories has recently been shifted towards Helmholtz's position by E H Adelson who has provided additional evidence that lightness induction depends on perceptual interpretation and, particularly, on apparent transparency. I challenge Adelson's conclusions by introducing modified versions of his tile pattern that use luminance gradients. In the first of these new demonstrations there is a strong lightness induction even though no apparent transparency is experienced. In the second there is a clear impression of transparent strips, yet no lightness induction is present. And the third shows that breaking up the Adelson tile pattern, while it affects neither the impression of transparency nor the type of grey-level junctions, makes the lightness-induction effect vanish. This implies that Adelson's illusion can be accounted for by neither local contrast, nor the apparent transparency, nor the type of grey-level junctions. Presented here is an alternative look at lightness induction as a phenomenon of the pictorial (as contrasted to natural) vision, which rests on the lightness-shadow invariance, much as Gregory's 'inappropriate constancy scaling' theory of geometrical illusions rests on the apparent size-distance invariance.

Contrast Sensitivity↗
PubMedDate not supplied

CCAAT/enhancer binding protein activation by PD98059 contributes to the inhibition of AhR-mediated 3-methylcholanthrene induction of CYP1A1.

2'-Amino-3'-methoxyflavone (PD98059), an MKK1 inhibitor, negatively regulates the induction of the CYP1A1 gene by polycyclic aromatic hydrocarbons. In view of the observations that PD98059 inhibits AhR-mediated CYP1A1 induction and has the capability to activate C/EBPbeta, the study investigated whether the inhibition by PD98059 of 3-MC induction of CYP1A1 results from C/EBP activation. 3-MC induction of the CYP1A1 and the CYP1A1 promoter-luciferase gene were inhibited by treatment of H4IIE cells with PD98059. PD98059 treatment inhibited 3-MC-induced AhR binding to the XRE, but increased protein binding to the CYP1A1 C/EBP binding site. PD98059 inhibited 3-MC induction of CYP1A1 in cells stably transfected with a dominant negative mutant of MKK1, indicating that PD98059 represses CYP1A1 induction by 3-MC irrespective of its MKK1 inhibition. The role of C/EBP activation by PD98059 in repressing CYP1A1 induction was supported by the observation that a dominant-negative mutant C/EBP abolished the ability of PD98059 to suppress 3-MC induction of CYP1A1.

Animals↗
PubMedDate not supplied

A modified acrosome induction test.

Many types of acrosome induction tests require special equipment and reagents that are not available to most clinicians; thus, simpler tests seem desirable. A modified acrosome induction test has been developed that uses basic reagents and a light microscope, which are available in most office settings. A hypoosmotic swelling test and a double stain (Bismark brown and rose Bengal) were combined to evaluate the viable acrosome reaction (AR) among 74 infertile men and 42 control men. The study included 34 infertile males without varicoceles, 20 with nonrepaired varicoceles and 20 with repaired varicoceles. On each test day, a specimen from a fertile donor was run as a control. The spontaneous acrosome reaction was recorded in semen before and after capacitation. The final % viable acrosome reaction equaled the capacitated value minus the spontaneous value for whole semen. The mean % viable AR among the control specimens was 16% with no values less than 10%. This mean value for controls was significantly greater than the mean % viable AR in each patient group. There were no overlaps in the 95% confidence intervals. When the study group was stratified according to normal acrosome induction tests or >10% viable AR, 30 patients had a normal test and 44 had abnormal tests. Six patients with varicoceles and an abnormal acrosome induction test had a varicocelectomy, and 2 (33%) converted their acrosome induction test to normal after at least 6 months of follow-up. Nine patients had in vitro fertilization (IVF), 3 had a poor result, and all had an abnormal acrosome induction test. Six had a good result with IVF and all 6 had a normal acrosome induction test. Thus, the acrosome induction test described in this report may be performed in any office laboratory to detect subtle male factor problems. The results may be helpful for planning IVF, intracytoplasmic sperm injection, or varicocele surgery for infertile men.

Acrosome↗
PubMed2005

The effect of vaginal pH on labor induction with vaginal misoprostol.

OBJECTIVE: To estimate the association of vaginal pH on the induction to vaginal delivery interval in labor induction with vaginal misoprostol. METHODS: Women presenting at term with intact membranes for labor induction were recruited. The pH of the vagina was measured during a digital examination of the cervix to determine the Bishop Score. Labor was induced with 25 microg of vaginal misoprostol placed every 6 h until spontaneous rupture of membranes or active labor occurred. The primary outcome was the induction to vaginal delivery interval in the lower pH (< 5) versus higher pH (> or = 5) group. Secondary outcomes assessed maternal and neonatal morbidities. Sample size calculated a priori estimated 120 subjects were required for a power of 95% and a 2-tailed a of 0.05. RESULTS: 120 women met inclusion criteria and had available pH data. There was no difference in the induction to vaginal delivery interval in the lower pH (1455 min) versus higher pH group (1295 minutes, Mean difference 160 [- 147,468] P = .30). No difference was observed for operative delivery rates or neonatal outcomes. CONCLUSION: The pH of the vagina may not affect the length of the induction to vaginal delivery interval in women undergoing labor induction with vaginal misoprostol. Further research is required to determine factors that may influence the efficacy of vaginal misoprostol when used for labor induction.

Administration, Intravaginal↗
PubMed1997

Inhalation induction with sevoflurane: a double-blind comparison with propofol.

We conducted a randomized, double-blind comparison of 8% sevoflurane and propofol as induction agents for day-case cystoscopy in 102 patients. All patients received an i.v. cannula and breathed oxygen 5 litre min-1. Anaesthesia was induced with propofol i.v. or inhalation of 8% sevoflurane and 10% Intralipid (as a placebo) i.v., delivered by a blinded observer. Anaesthesia was maintained in all patients with 2% sevoflurane via a face mask. Induction of anaesthesia with sevoflurane was significantly slower compared with propofol (mean 84 (SD 24) s vs 57 (11) s), but was associated with a lower incidence of apnoea (16% vs 65%) and a shorter time to establish spontaneous ventilation (94 (34) s vs 126 (79) s). Induction complications were uncommon in each group but the transition to maintenance was smoother with sevoflurane and was associated with less hypotension compared with propofol. Emergence from anaesthesia induced with sevoflurane occurred significantly earlier compared with propofol (5.2 (2.2) min vs 7.0 (3.2) min) and anaesthetic induction was also significantly cheaper with sevoflurane. According to a postoperative questionnaire, the majority of patients found both anaesthetic techniques acceptable. Nevertheless, significnatly more patients (14%) rated induction with sevoflurane as unpleasant compared with propofol (0) and significantly more patients (24%) would not choose sevoflurane induction compared with propofol (6%). This phenomenon may have been related to the particular patient population studied, however. Inhalation induction with 8% sevoflurane would appear to offer several objective advantages compared with induction with propofol in day-case patients, although a significant minority may dislike this technique.

Adult↗
PubMed2001

Comparison of pattern of breathing with other measures of induction of anaesthesia, using propofol, methohexital, and sevoflurane.

We assessed change of the pattern of breathing as a marker of induction of anaesthesia, using a method of maintaining spontaneous breathing throughout the induction period. We compared this index with a measure used clinically, the lash reflex, and measures used for drug investigations such as loss of grip of an object, cessation of finger tapping, and loss of arm tone. Ninety female patients (mean age 32 (17-63) yr, mean weight 63 (10) kg) were randomly allocated to induction of anaesthesia using propofol, methohexital, or sevoflurane. The i.v. agents were given by slow injection estimated to give an induction dose (for weight drop end point) in 90 s. Sevoflurane was given by progressively increasing the inhaled concentration to 8% so that induction should occur within 90-120 s. We measured time to change in breathing pattern, loss of voluntary finger tapping, loss of the lash reflex (tested at 15 s intervals), loss of postural tone in an outstretched arm, and loss of grip of a small metal cylinder held between finger and thumb. For methohexital and sevoflurane, the mean times for induction of anaesthesia occurred in the above order. With propofol, the lash reflex and tone were lost at the same time. The mean (SD) time to induction, by loss of arm tone was 64 (16) s for propofol, 83 (23) s for methohexital, and 94 (31) s for sevoflurane. The mean time to change in breathing pattern was 47 (20) s for propofol, 53 (14) s for methohexital, and 78 (29) s for sevoflurane. Although the time to achieve each end point was different, all the end points (except the lash reflex) appeared to provide similar measures of induction of anaesthesia. The pattern of breathing is an early sign of the onset of anaesthesia.

Adolescent↗
PubMed2003

Propofol and halothane versus sevoflurane in paediatric day-case surgery: induction and recovery characteristics.

BACKGROUND: The aim of this study was to compare the induction and recovery characteristics associated with propofol induction and halothane maintenance with sevoflurane anaesthesia in paediatric day surgery. METHODS: In total, 322 children were assigned randomly to i.v. propofol induction and halothane/nitrous oxide maintenance or sevoflurane/nitrous oxide alone. The patients' age, sex, and type of surgery were recorded, as were the times required for anaesthetic induction, maintenance, recovery and time to discharge home. Postoperative nausea and vomiting, and the incidence of adverse events during induction and recovery were also noted. RESULTS: No significant differences were detected in age, sex, type of surgery performed or intraoperative opioid administration. Excitatory movement was more common during induction with sevoflurane. The mean time required for induction with propofol was 3.1 min compared with 5 min in the sevoflurane group (P<0.001). The recovery time was shorter in the sevoflurane group compared with propofol/halothane (23.2 vs 26.4 min, P<0.002). The incidence of delirium in recovery was greater in the sevoflurane group (P<0.001). There was no difference between groups in the time spent on the postoperative ward before discharge home. On the postoperative ward the incidence of both nausea and vomiting was significantly higher in the sevoflurane group (P=0.034). Five children were admitted to hospital overnight, none for anaesthetic reasons. CONCLUSIONS: The increased incidence of adverse events during induction, postoperative nausea and vomiting and postoperative delirium in the sevoflurane group suggests that sevoflurane is not ideal as a sole agent for paediatric day case anaesthesia.

Adolescent↗
PubMed2002

The effect of a musical mood induction procedure on mood state-dependent word retrieval.

The purpose of this experiment was to replicate and expand upon an earlier study by Thaut and de l'Etoile (1993) by examining the effect of a musical mood induction procedure on mood state-dependent word retrieval. Participants (N = 45) completed a 2-day testing procedure. On day one, participants read a list of adjectives and wrote down an antonym for each one. On day two, participants recalled as many of the antonyms as possible. During the testing procedure, participants were placed in 1 of 4 conditions: (a) mood induction at encoding, (b) mood induction at recall, (c) no mood induction, and (d) mood induction at both encoding and recall. The mood induction procedure included 3 steps. Participants first assessed their current mood state using a visual analog scale. They then listened to music for 5 minutes, determined the mood of the piece while listening, and tried to match their mood to the music. Finally, participants again used the visual analog scale to indicate their mood. Results indicated that participants who received mood induction prior to both encoding and recall were able to retrieve significantly more words than participants who did not undergo any mood induction. The results are discussed in light of the associative network theory of memory and emotions and the treatment of mood disorders.

Affect↗
PubMed1993

Mutation induction by UV light in retroviral hprt cDNA integrated at various chromosomal positions in repair-deficient hamster cells.

Mutation induction by UV irradiation was studied in a retroviral vector integrated in one copy per cell at various chromosomal positions. As a mutational target, hamster hprt cDNA was present on the retroviral vector. To minimize the influence of repair we used repair-deficient hamster cells, V-H1 and UV5, as a recipient for the vector. There is no major influence of chromosomal position on UV-induced mutation frequency and spectrum because no statistically significant difference between mutation induction in retroviral cDNA copies integrated at different chromosomal sites was observed. However, a major difference was found in mutation induction between the endogenous hamster hprt gene and the retroviral cDNA copies. Most noticeable was the absence in the cDNA of the strong strand bias for mutation induction, which was reported for the endogenous hprt gene. Our results with the hprt cDNA exclude as a general phenomenon a difference in mutation induction for leading and lagging strand DNA replication, which was proposed as an explanation for this strand bias in the endogenous gene. The similarity of mutation induction in the different retroviral cDNA copies, all directly surrounded by the same DNA sequence elements, together with the marked difference between the mutation induction in the endogenous gene and the cDNA copies may point to an important role of chromatin structure in mutation induction.

Animals↗
PubMed1977

Induction of ornithine decarboxylase in cultured mouse L cells. II. Effects of additions of amino acids and serum.

Induction of ornithine decarboxylase [EC 4.1.1.17] (ODC) in mouse L cells by components of the culture medium was investigated. It was found that further addition of amino acid mixture, but not of calf serum, to confluent cells of 5 day culture induced ODC and that this induction was accelerated by actinactinomycin D. In salt solution, addition of either amino acids or serum alone did not cause full induction, but addition of both together did. This induction, in contrast, was inhibited by actinomycin D. Induction by insulin, but not by cyclic AMP, was enhanced by a higher concentration of amino acids. These results can be explained by supposing that in non-growing cells there is stable RNA which is involved in ODC induction, possibly mRNA of ODC, and that the observed induction is caused by inhibition of enzyme degradation and accelerated translation, while in growing cells this RNA is unstable and ODC induction is controlled at the level of transcription.

Amino Acids↗
PubMed1998

Induction of the stress response with prostaglandin A1 increases I-kappaBalpha gene expression.

I-kappaBalpha is an intracellular protein that functions as a primary inhibitor of the proinflammatory transcription factor NF-kappaB. Induction of the stress response with heat shock was previously demonstrated to induce I-kappaBalpha gene expression. Because the stress response can also be induced by nonthermal stimuli, we determined whether induction of the stress response with prostaglandin A1 (PGA1) would induce I-kappaBalpha gene expression. Treatment of human bronchial epithelium (BEAS-2B cells) with PGA1 induced nuclear translocation of heat shock factor 1, thus confirming that PGA1 induces the stress response in BEAS-2B cells. Induction of the stress response with PGA1 increased I-kappaBalpha mRNA expression in a time-dependent manner and increased I-kappaBalpha peptide expression. Transient transfection assays involving a human I-kappaBalpha promoter-luciferase reporter construct demonstrated that induction of the stress response with PGA1 activated the I-kappaBalpha promoter. Induction of the stress response with PGA1 and concomitant induction of I-kappaBalpha were associated with inhibition of TNF-alpha-mediated secretion of interleukin 8 and with inhibition of TNF-alpha-mediated nuclear translocation and activation of NF-kappaB. These data demonstrate that induction of the stress response, by a nonthermal stimulus, increases I-kappaBalpha gene expression by a mechanism involving activation of the I-kappaBalpha promoter. Coupled with previous data demonstrating heat shock-mediated induction of I-kappaBalpha gene expression, these data suggest that I-kappaBalpha may be considered to be one of the stress proteins. The functional consequences of stress response-mediated I-kappaBalpha gene expression may involve attenuation of cellular proinflammatory responses.

Cell Line, Transformed↗
PubMed1999

Distress during the induction of anesthesia and postoperative behavioral outcomes.

UNLABELLED: We determined whether children who are extremely anxious during the induction of anesthesia are more at risk of developing postoperative negative behavioral changes compared with children who appear calm during the induction process. Children (n = 91) aged 1-7 yr scheduled for general anesthesia and elective outpatient surgery were recruited. Using validated measures of preoperative anxiety and postoperative behaviors, children were evaluated during the induction of general anesthesia and on Postoperative Days 1, 2, 3, 7, and 14. Using a multivariate logistic regression model, in which the dependent variable was the presence or absence of postoperative negative behavioral changes and the independent variables included several potential predictors, we demonstrated that anxiety of the child, time after surgery, and type of surgical procedure were predictors for postoperative maladaptive behavior. The frequency of negative postoperative behavioral changes decreased with time after surgery, and the frequency of negative postoperative behavioral changes increased when the child exhibited increased anxiety during the induction of anesthesia. Finally, we found a significant correlation (r) of 0.42 (P = 0.004) between the anxiety of the child during induction and the excitement score on arrival to the postanesthesia care unit. We conclude that children who are anxious during the induction of anesthesia have an increased likelihood of developing postoperative negative behavioral changes. We recommend that anesthesiologists advise parents of children who are anxious during the induction of anesthesia of the increased likelihood that their children will develop postoperative negative behavioral changes such as nightmares, separation anxiety, and aggression toward authority. IMPLICATIONS: Anesthesiologists who care for children who are anxious during the induction of anesthesia should inform parents that these children have an increased likelihood of developing postoperative negative behavioral changes.

Anesthesia↗
PubMed2000

Nimodipine premedication and induction dose of propofol.

UNLABELLED: Antagonists at the L-type voltage sensitive calcium channel (L-VSCC) potentiate anesthetic potency in experimental models, suggesting that it may be a target site for IV anesthetics. Nimodipine is a 1, 4-dihydro- pyridine antagonist of L-VSCC which crosses the blood-brain barrier. We tested the hypothesis that premedication with oral nimodipine in healthy patients would reduce the induction dose of propofol, independently of its effects on the cerebral circulation. Sixty ASA physical status I or II patients (18-60 yr), undergoing knee arthroscopy or minor urological surgery, were randomized to receive either nimodipine 60 mg or placebo, orally 1-2 h before induction. Noninvasive mean blood pressure, heart rate, and time-averaged mean velocity in the middle cerebral artery by using transcranial Doppler ultrasonography were obtained before and 5 min after the induction of anesthesia. Propofol 1% was administered by an infusion pump at a rate of 10 mL/min. Both groups of patients had a reduction in mean blood pressure after the induction (P < 0.01), but there were no significant differences between the groups. The induction dose of propofol was 2.19 mg/kg (95% confidence interval [CI]: 1.97-2.42) in the nimodipine group, compared with 2.16 mg/kg (95% CI 1.98-2.34) in the control group, P = 0.8. Time-averaged mean velocity remained unchanged after the induction of anesthesia in both patients receiving nimodipine premedication (51% CI 43-59 cm/s to 52% CI 46-58 cm/s, P = 0.6) and those receiving placebo (50% CI 43-58 cm/s to 53% CI 45-59 cm/s, P = 0.3). Premedication with oral nimodipine 60 mg does not reduce the induction dose of propofol compared with placebo, casting doubt on the hypothesis that propofol has an anesthetic action at L-VSCC. IMPLICATIONS: Premedication with oral nimodipine 60 mg does not reduce the induction dose of propofol compared with placebo, casting doubt on the hypothesis that propofol has an anesthetic action at L-type voltage sensitive calcium channels.

Adolescent↗
PubMed2001

Induction of anesthesia with ketamine reduces the magnitude of redistribution hypothermia.

UNLABELLED: Hypothermia after induction of general anesthesia results largely from core-to-peripheral redistribution of body heat. Both central inhibition of tonic thermoregulatory vasoconstriction in arteriovenous shunts and anesthetic-induced arteriolar and venous dilation contribute to this redistribution. Ketamine, unique among anesthetics, increases peripheral arteriolar resistance; in contrast, propofol causes profound venodilation that other anesthetics do not. We therefore tested the hypothesis that induction of anesthesia with ketamine causes less core hypothermia than induction with propofol. Twenty patients undergoing elective surgery were randomly assigned to anesthetic induction with either 1.5 mg/kg ketamine (n = 10) or 2.5 mg/kg propofol (n = 10). Anesthesia in both groups was subsequently maintained with sevoflurane and 60% nitrous oxide in oxygen. Forearm minus finger, skin-temperature gradients <0 degrees C were considered indicative of significant arteriovenous shunt vasodilation. Ketamine did not cause vasodilation just after induction, whereas propofol rapidly induced vasodilation. Core temperatures in the patients given ketamine remained significantly greater than those in the patients induced with propofol. These data suggest that maintaining vasoconstriction during induction of anesthesia reduces the magnitude of redistribution hypothermia. IMPLICATIONS: Core hypothermia during the first hour of anesthesia was less after induction of anesthesia with ketamine than propofol. Maintaining arteriovenous shunt vasoconstriction during induction of anesthesia reduces the magnitude of redistribution hypothermia.

Adult↗