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Biomedical subjects

H Obara

Publications and source records attributed to H Obara.

At least 145 records · Page 8Linked to original sources
PubMed1993

Efficacy of oral clonidine premedication in children.

BACKGROUND: Clonidine, an alpha 2-adrenoceptor agonist, has been shown to be effective as a preanesthetic medication in adults. The current study was designed to investigate the efficacy of two doses of oral clonidine as a premedicant preceding oral atropine in children. METHODS: In a prospective, randomized, double-blind, controlled clinical trial, 105 children, aged 4-12 yr, undergoing elective ophthalmologic surgery received 0.4 mg/kg diazepam, 2 micrograms/kg clonidine, or 4 micrograms/kg clonidine orally. These agents mixed with apple juice were administered 105 min before the estimated time of induction of anesthesia, and were followed by treatment with 0.03 mg/kg oral atropine 60 min before anesthesia. A blinded observer noted the children's level of sedation, quality of separation from parents, and degree of acceptance of mask application during inhalation of nitrous oxide used for establishment of venous access. Anesthesia was induced with 5 mg/kg thiamylal, and tracheal intubation was facilitated with 0.2 mg/kg vecuronium. Hemodynamic changes after tracheal intubation were compared among the three groups. RESULTS: Clonidine produced significant sedation, and the effect was dose related. Clonidine, 4 micrograms/kg, provided better quality of separation and acceptance of mask than the two other regimens. This dose of clonidine attenuated the increases in blood pressure and heart rate after tracheal intubation. No clinically significant perioperative hypotension or bradycardia was observed. CONCLUSIONS: These data indicate that, even in pediatric surgery, the combination of 4 micrograms/kg and 0.03 mg/kg oral clonidine is an effective premedication. However, the safety and optimal dose of clonidine in this setting remain to be determined.

Administration, Oral↗
PubMed1993

Attenuation of the pressor response to tracheal intubation with oral nitrendipine.

The effect of nitrendipine on the cardiovascular responses to tracheal intubation was studied in a placebo-controlled, randomised, double-blind trial. Thirty patients (ASA physical status 1) undergoing elective surgery received either 5 or 10 mg nitrendipine, or a placebo orally 3 h before induction of anaesthesia (n = 10 for each group). Anaesthesia was induced with sodium thiopentone 5 mg/kg i.v. and tracheal intubation was facilitated with vecuronium 0.2 mg/kg i.v. Patients receiving the placebo showed a significant increase in the mean arterial pressure and the rate-pressure product in response to tracheal intubation. These increases following intubation were reduced in nitrendipine-treated patients compared with the placebo group (P < 0.05). Oral administration of nitrendipine (5 or 10 mg, 3 h before induction of anaesthesia) was able to attenuate the hypertensive response to tracheal intubation in ASA 1 patients under light anaesthesia. We propose this pharmacological technique with supplementary doses of opioids and/or benzodiazepines for the management of patients with hypertension or coronary artery disease.

Administration, Oral↗
PubMed1993

Effects of 2-, 4- and 12-hour fasting intervals on preoperative gastric fluid pH and volume, and plasma glucose and lipid homeostasis in children.

We evaluated 105 randomly-selected unpremedicated children aged 1-14 years to determine the effects of a 2-, 4- and 12-h preoperative fasting interval on the preoperative gastric fluid pH and volume, and plasma glucose and lipid homeostasis. Each child undergoing elective surgery ingested a large volume (approximately 10 ml/kg b.w.) of apple juice and then fasted for 2, 4 or 12 h before the estimated induction of anaesthesia. After induction of anaesthesia, gastric fluid was aspirated through a large-bore, multiorifice orogastric tube. Plasma concentrations of glucose, total ketone bodies, non-esterified fatty acid (NEFA), triglycerides, and cortisol were measured at the time of induction to evaluate the fasting interval effects on preoperative plasma glucose and lipid homeostasis. There were no significant differences between the three groups in either gastric fluid volume or pH. In addition, there were no significant differences between the groups with respect to the proportion with a pH < 2.5 and volume > 0.4 ml/kg b.w. Neither plasma concentrations of glucose, triglycerides, nor cortisol at the time of anaesthetic induction differed between the three groups. Both 4 and 12 h nil per os (NPO) caused an increase in lipolysis, which was presumably a compensatory mechanism to maintain normoglycaemia. The plasma NEFA and total ketone bodies concentrations were therefore significantly higher in these two fasting intervals than in 2 h NPO. These data suggest that a 2-h NPO, after a large volume of ingested apple juice, may offer additional benefits by preventing an increase in lipolysis during the fasting interval without either increasing the volume of gastric fluid or decreasing the gastric pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Attenuation of the cardiovascular and catecholamine responses to tracheal intubation with oral guanabenz.

We conducted a randomized, placebo-controlled, and double-blind study to evaluate the efficacy of oral guanabenz, an alpha 2-adrenergic agonist, in attenuating the cardiovascular and catecholamine responses to laryngoscopy and tracheal intubation in 30 normotensive (ASA physical status 1) patients undergoing elective surgery. They were allocated to one of three groups (n = 10 for each): placebo, 4 mg, or 6 mg of guanabenz groups. These tablets were administered 2 h before the induction of anesthesia. Anesthesia was induced with thiopental 5.0 mg/kg intravenously (IV), and tracheal intubation was facilitated by the administration of vecuronium, 0.2 mg/kg IV. During anesthesia, ventilation was assisted or controlled with 1% enflurane and 50% nitrous oxide in oxygen. Laryngoscopy lasting 30 s was attempted 2 min after the administration of thiopental and vecuronium. Patients receiving placebo showed a significant increase in mean arterial blood pressure, heart rate, and plasma catecholamine concentrations in response to tracheal intubation. These changes were significantly smaller in patients receiving either dose of guanabenz (P < 0.05). Oral administration of guanabenz before induction of anesthesia is a simple and effective method for attenuating the pressor and tachycardic responses to laryngoscopy and tracheal intubation with the drug acting at least partly via inhibition of the increases in plasma catecholamines concentrations.

Administration, Oral↗
PubMed1993

Selective intrabronchial instillation of surfactant in a patient with pneumonia: a preliminary report.

The efficacy of treatment with exogenous surfactant has been reported in children with respiratory failure due to severe pneumonia. Its effect in adults with similar features has not been established. We therefore administered 240 mg of surfactant to a 71 year old man, who had developed right lower lobe pneumonia and hypoxaemia following abdominal aortic surgery. After this treatment, the patient's oxygenation, evaluated by arterial oxygen tension/fraction of inspired oxygen (PaO2/FIO2) ratio during artificial ventilation, gradually improved, and ventilator settings could be reduced whilst maintaining PaO2 at the appropriate level. Although the precise mechanism by which surfactant improves respiratory failure due to pneumonia is unclear, administration of the drug may have overcome a quantitative deficiency of endogenous surfactant attributable to the antagonistic effect of pulmonary exudates and reduced production following damage to type II pneumocytes. The present case provides an indirect suggestion of a possible causal relationship between the improvement of oxygenation and administration of surfactant in adult respiratory failure caused by pneumonia.

Aged↗
PubMed1992

Effect of verapamil on the cardiovascular responses to tracheal intubation.

We have studied the efficacy of verapamil in attenuating the cardiovascular responses to tracheal intubation in three groups of ASA grade I patients given verapamil 0.05 mg kg-1 or 0.1 mg kg-1 or saline 45 s before the start of laryngoscopy. Anaesthesia was induced with thiopentone 5 mg kg-1 i.v. and tracheal intubation was facilitated with vecuronium 0.2 mg kg-1. During anaesthesia, ventilation was assisted or controlled with 1% enflurane and 50% nitrous oxide in oxygen. In patients who received saline, there was a significant increase in mean arterial pressure and rate-pressure product associated with tracheal intubation. The increases were significantly less in verapamil-treated patients compared with those in the control group, although verapamil failed to prevent tachycardia caused by laryngoscopy and intubation.

Adult↗
PubMed1992

Perioperative complement activation in neonates under halothane or fentanyl anaesthesia.

We investigated perioperative changes in complement activation in 18 neonates undergoing elective abdominal surgery with or without thoracotomy by measuring plasma concentrations of C3a and C5a, and leucocyte counts in peripheral blood. The 18 neonates, ranging in age from 1 to 17 days, were randomly divided into two groups according to type of anaesthetic procedures; the "halothane group" consisted of nine neonates in whom general anaesthesia was maintained with halothane and nitrous oxide (N2O) in oxygen, while the "fentanyl group" consisted of nine neonates in whom general anaesthesia was maintained with fentanyl and N2O in oxygen. Plasma C3a and C5a concentrations were higher in the fentanyl group than in the halothane group during the perioperative period. We have demonstrated that abdominal surgical trauma caused complement activation even in neonates undergoing the fentanyl rather than the halothane anaesthesia. Further studies are required to elucidate the precise mechanisms and the clinical implication of perioperative complement activation in neonates.

Abdomen↗
PubMed1992

Effects of mexiletine on the haemodynamic responses to tracheal intubation.

The efficacy of intravenous mexiletine in attenuating the cardiovascular responses to laryngoscopy and tracheal intubation was studied in 30 normotensive patients undergoing elective surgery. The patients were randomly allocated to one of three treatment groups: saline (n = 10); 2 mg/kg mexiletine (n = 10); and 3 mg/kg mexiletine (n = 10). The placebo/mexiletine was administered immediately before induction of anaesthesia using 5 mg/kg thiopentone and tracheal intubation was facilitated with 0.2 mg/kg vecuronium; laryngoscopy lasting 30 s was attempted 2 min after induction of anaesthesia. All groups showed a significant (P less than 0.05) increase in mean arterial pressure and heart rate associated with tracheal intubation. The increase in mean arterial pressure was significantly (P less than 0.05) smaller in patients receiving 3 mg/kg mexiletine compared with those receiving either saline or 2 mg/kg mexiletine. There was no significant attenuation in heart rate in either of the mexiletine treatment groups compared with the saline group. It is concluded that 3 mg/kg mexiletine given intravenously provides a simple and effective method for attenuating the pressor response to laryngoscopy and tracheal intubation.

Adult↗