Tsuyoshi Satsumae

Preoperative small-dose ketamine prevented tourniquet-induced arterial pressure increase in orthopedic patients under general anesthesia

The mechanism of tourniquet-induced arterial pressure increase is not known. We investigated the effect of preoperative ketamine on tourniquet-induced arterial pressure and heart rate changes in 85 patients undergoing knee surgery with a tourniquet under general anesthesia. Patients were randomly assigned into three groups; Large Ketamine (n = 28; ketamine 1.0 mg/kg), Small Ketamine (n = 28; ketamine 0.25 mg/kg), and Control (n = 29; normal saline) groups. Anesthesia was maintained with 1.5%–2.5% sevoflurane and 66% N2O in oxygen with endotracheal intubation. Ketamine or normal saline was given in a double-blinded fashion before skin incision and tourniquet inflation. Arterial pressure and heart rate were recorded every 10 min until 60 min after the start of tourniquet inflation and again after deflation. Arterial pressure and heart rate were compared among the three groups by using repeated-measures analysis of variance. In the Large and Small Ketamine groups, arterial pressure was not significantly changed, but in the Control group arterial pressure was significantly increased 40, 50, and 60 min after the start of tourniquet inflation (P < 0.05). Development of more than a 30% increase in systolic arterial pressure during tourniquet inflation was more frequent in the Control group than the other groups. The results show that preoperative IV ketamine, 0.25 mg/kg or more, significantly prevented tourniquet-induced systemic arterial pressure increase in patients under general anesthesia.

Convulsions after ropivacaine 300 mg for brachial plexus block

A healthy 18-yr-old male (weight 60 kg, height 167 cm), with a history of febrile convulsions in childhood, developed a grand mal convulsion 10 min after the second of two injections of ropivacaine 150 mg, both given incrementally 15 min apart (total 300 mg), for combined axillary/interscalene brachial plexus block. Treatment was with oxygen, lung ventilation, and i.v. midazolam, and the patient made a complete recovery. Arterial plasma ropivacaine concentration 2 min after the onset of convulsions was only 2.13 mg litre(-1), suggesting that this patient was particularly susceptible to local anaesthetic toxicity. Whether sub-clinical EEG changes identified after operation were related to this sensitivity cannot be determined, but review illustrates wide variation in both the dose and the plasma concentration of local anaesthetics associated with systemic toxicity. The UK recommended dose of ropivacaine for brachial plexus block is 225-300 mg according to stature.

Longer-term diabetic patients have a more frequent incidence of nosocomial infections after elective gastrectomy

UNLABELLED Diabetes mellitus (DM) is one of the risk factors for the development of postoperative nosocomial infections in surgical patients. We conducted this retrospective study to elucidate the perioperative risk factors for postoperative nosocomial infections in diabetic patients undergoing elective gastrectomy. Chart review was performed on diabetic and nondiabetic patients undergoing elective gastrectomy for gastric malignancy from January 1992 through April 1999. Fourteen of the 83 diabetic patients, and 23 of the 284 nondiabetic patients developed postoperative nosocomial infections. Statistical comparisons of multiple variables were made between patients with and without postoperative nosocomial infections. In diabetic patients, univariate analysis showed that longer-term DM (especially longer than 10 yr) was associated with a significantly increased risk for postoperative nosocomial infections. Multiple logistic regression analysis showed that DM lasting longer than 10 yr was an independent risk factor for postoperative nosocomial infections (odds ratio, 6.8; 95% confidence interval, 1.7 to 27.1). In nondiabetic patients, similar analysis showed that age was an independent risk factor for postoperative nosocomial infections. We conclude that patients with longer-term DM had a significantly greater incidence of postoperative nosocomial infections after elective gastrectomy. IMPLICATIONS Postoperative nosocomial infection is one of the major problems in diabetic patients. This study demonstrated that postoperative nosocomial infections were more common in patients undergoing elective gastrectomy if they had diabetes mellitus longer than 10 yr.

Effects of fentanyl infusion on tracheal intubation and emergence agitation in preschool children anaesthetized with sevoflurane

BACKGROUND Sevoflurane can be used as a sole agent for intubation in children, but studies have suggested that it is associated with emergence agitation. Fentanyl infusions can be used both to facilitate intubation and decrease emergence agitation. We investigated the effects of fentanyl on conditions at intubation and on emergence from sevoflurane anaesthesia without confounding nitrous oxide or premedication. METHODS IRB approval and informed consent were obtained. Subjects comprised 150 ASA physical status I or II (age, 2-6 yr). Anaesthesia was induced with sevoflurane in oxygen and maintained using a predetermined concentration of sevoflurane. Subjects were randomly allocated to receive one of three doses of fentanyl: vehicle only (control group), a bolus dose of 1 microg kg(-1) followed by a continuous infusion of 0.5 microg kg(-1) h(-1) (F1 group), or a bolus dose of 2 microg kg(-1) followed by a continuous infusion of 1 microg kg(-1) h(-1) (F2 group). Sevoflurane minimum alveolar concentration for tracheal intubation (MAC(TI)) and emergence agitation score were assessed. RESULTS MAC(TI) values were 2.49%, 1.61%, and 1.16% in control, F1, and F2 groups, respectively (P<0.05). Agitation scores were 11.5, 7.0, and 2.6 in control, F1, and F2 groups, respectively (P<0.05). CONCLUSIONS Fentanyl infusion consisting of a bolus dose of 2 microg kg(-1) followed by a continuous infusion of 1 microg kg(-1) h(-1) facilitates tracheal intubation and smooth emergence in children anaesthetized using sevoflurane. CLINICAL TRIAL REGISTRATION this study was started in 2000 and was finished in 2008. We had no registration number. IRB approval was obtained.

Minimum alveolar concentrations of sevoflurane for maintaining bispectral index below 50 in children

Objective:  To determine minimum alveolar concentration (MAC) of sevoflurane for maintaining bispectral index (BIS) below 50 (MACBIS50) in children.

Arteriovenous differences in PCO2 and cardiac output during CPR in the dog

Using 14 mongrel dogs, we investigated the correlation between arteriovenous differences of PCO2 (AVD-CO2) and cardiac output (CO) during CPR. Ventricular fibrillation was induced by an electrical current and the respirator was stopped for 5 min. Cardiopulmonary resuscitation (CPR) was performed during the next 10 min and CO was measured with simultaneous arterial and venous blood gas analysis. CO was measured 26 times during CPR. The animals were divided into two groups according to the values of CO during CPR: low-CO group (CO < 0.3 l/min) and high-CO group (CO > or = 0.3 l/min). AVD-CO2 in the low CO group was 39.8 +/- 5.7 mmHg and that of the high group was 27.4 +/- 14.8 mmHg (mean +/- S.D., P < 0.05). In conclusion, AVD-CO2 showed an inverse result with the degree of CO during CPR.

The effect of propofol infusion on minimum alveolar concentration of sevoflurane for smooth tracheal intubation

AbstractPurpose. This study was conducted to determine the effect of propofol infusion on the minimum alveolar concentration necessary for smooth tracheal intubation (MACEI) of sevoflurane. Methods. Sixty-nine patients, American Society of Anesthesiologists (ASA) status I, aged 30–49 years, were randomly assigned to one of three groups according to the agents used for tracheal intubation (n = 23 for each group): the SP group, in whom the intubation was attempted under sevoflurane plus propofol infusion; the S group, tracheal intubation under sevoflurane alone; and the P group, tracheal intubation under propofol infusion alone. Anesthesia was induced with propofol 2.5 mg·kg−1 i.v. bolus. Prior to the tracheal intubation attempt, propofol infusion, 10 mg·kg−1·h−1, was given for 15 min in the SP and P groups, and sevoflurane equilibration was established in the SP and S groups. All tracheal intubation attempts were made 15 min after anesthetic induction. The end-tidal sevoflurane concentration at which tracheal intubation was attempted was predetermined by the up-and-down method (with 0.5% as a step size). MACEI was determined using a logistic regression test. Results. The MACEI of sevoflurane was 1.73% in the SP group, and 2.99% in the S group. Laryngoscopy was not possible in the P group patients. Conclusion. Propofol infusion reduced sevoflurane MACEI. This finding suggests that propofol would be an excellent adjuvant to use with sevoflurane for tracheal intubation.

The relationship between age and minimum alveolar concentration of sevoflurane for maintaining bispectral index below 50 in children.

We evaluated the minimum alveolar concentration of sevoflurane required to maintain the bispectral index below 50 in children. We studied 55 children, divided into 1‐year‐old, 2‐ to 4‐year‐old and 5‐ to 9‐year‐old groups and used Dixons up‐and‐down method and probit analysis. In the 1‐year‐old group, the bispectral index values remained above 50, with the end‐tidal sevoflurane concentration reaching 4.0% or higher. The minimum alveolar concentration of sevoflurane for maintaining the bispectral index below 50 was significantly higher in the 2‐ to 4‐year‐old group (2.33%, 95% CI 2.25–2.57) than in the 5‐ to 9‐year‐old group (2.10%, 95% CI 1.94–2.25; p = 0.005). We conclude that assessing the depth of anaesthesia using bispectral index is unreliable in children aged < 2 years anaesthetised with sevoflurane.

Hemodynamic effects of oral clonidine premedication in lumbar epidural anesthesia

Clonidine, an α2-adrenergic agonist, has a potent sympatholytic effect and augments the pressor effect of ephedrine during general anesthesia. We evaluated whether oral clonidine premedication would alter the hemodynamic changes and enhance the pressor response to intravenous ephedrine during epidural anesthesia in 35 adult patients. They were randomly administered either premedication with clonidine approximately 5 μg·kg−1 po (n=17) or no clonidine medication (n=18). After establishment of epidural anesthesia, the hemodynamic response to ephedrine iv was measured in the awake state at 1-min intervals for 10 min. Then, the same hemodynamic measurement was repeated in the asleep state induced with midazolam iv. There were no differences in blood pressure (BP) and heart rate values between groups during the onset of epidural anesthesia, except that BP before epidural anesthesia was lower in the clonidine group than the control group (P<0.05). The magnitude and duration of pressor responses to ephedrine were comparable between groups in awake and asleep states. In conclusion oral clonidine premedication 5 μg·kg−1 alters neither the hemodynamic changes nor the pressor response to intravenous ephedrine during epidural anesthesia.