Wash-in and wash-out curves of sevoflurane and isoflurane in morbidly obese patients.

BACKGROUND: The aim of this prospective, randomized study is to compare sevoflurane and isoflurane pharmacokinetics in morbidly obese patients. METHODS: With Ethical Committee approval and written informed consent, 14 obese patients (BMI >35 kg/m2), ASA physical status II, undergoing laparoscopic, silicone-adjustable gastric banding were randomly allocated to receive either sevoflurane (n=7) or isoflurane (n=7) as main anesthetic agents. General anesthesia was induced with 1 mg x kg-1 fentanyl, 6 mg x kg-1 sodium thiopental, and 1 mg x kg-1 succinylcholine followed by 0.4 mg kg-1 x h-1 atracurium bromide (doses were referred to ideal body weight). Intermittent positive pressure ventilation (IPPV) was applied using a Servo-900C ventilator with a nonrebreathing circuit and a 15 l x min-1 fresh gas flow (tidal volume: of 10 ml x kg-1; respiratory rate: 12 breaths/min; inspiratory to expiratory time ratio of 1:2) using an oxygen/air mixture (FiO2=50%), while supplemental boluses of thiopental or fentanyl were given as indicated in order to maintain blood pressure and heart rate values within +/-20% from baseline. After adequate placement of tracheal tube and stabilization of the ventilation parameters, 2% sevoflurane or 1.2% isoflurane was given for 30 min via a nonrebreathing circuit. End-tidal samples were collected at 1, 5, 10, 15, 20, 25 and 30 min, and measured using a calibrated infrared gas analyzer. General anesthesia was then maintained with the same inhalational agents, while supplemental fentanyl was given as indicated. After the last skin suture the inhalational agents were suspended, and the end tidal samples were collected at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 min. Then the lungs were manually ventilated until extubation. RESULTS: No differences in age, gender and body mass index were reported between the two groups. Surgical procedure required 91+/-13 in the sevoflurane group and 83+/-32 min in the isoflurane group. The FA/FI ratio was higher in the sevoflurane group from the 5th to the 30th min. Also the washout curve was faster in the sevoflurane group during the observation period; however, the observed differences were statistically significant only 30 and 60 sec after discontinuation of the inhalational agents. CONCLUSIONS: The results of this prospective, randomized study confirmed that sevoflurane provides more rapid wash-in and wash-out curves than isoflurane also in the morbid obese patient.

Randomized comparison of isoflurane and sevoflurane for laparoscopic gastric banding in morbidly obese patients.

STUDY OBJECTIVE: To compare the efficacy and recovery profile of sevoflurane and isoflurane as the main anesthetics for morbidly obese patients. DESIGN: Randomized, blinded study. SETTING: Inpatients. PATIENTS: 30 ASA physical status II and III obese patients [body mass index (BMI) > 35 kg/m(2)] undergoing laparoscopic gastric banding for morbid obesity. INTERVENTIONS: After standard intravenous induction of general anesthesia and tracheal intubation, anesthesia was maintained with either sevoflurane or isoflurane as the main anesthetics. The end-tidal concentrations of the volatile drugs were adjusted to maintain systolic arterial blood pressure within +/-20% from baseline values. When the surgeon started the skin suture, the end-tidal concentration of the inhalational drug was reduced to 0.5 minimum alveolar concentration in both groups. At the last skin suture, the inhalational drug was discontinued and the vaporizator was removed to allow blinded evaluation of the emergence times. MEASUREMENTS AND MAIN RESULTS: No differences in anesthetic exposure, hemodynamic parameters, incidence of untoward events, or postoperative pain relief were reported between the two groups. Extubation, emergence, and response times were shorter after sevoflurane [6 min (3-15 min), 8 min (5-18 min), and 12 (6-25 min)] than isoflurane [10 min (6-26 min), 14 min (6-21 min), and 21 min (14-41 min)] (p = 0.001, p = 0.03, and p = 0.0005, respectively). The median time for postanesthesia care unit discharge was 15 minutes (25th-75th percentiles: 10-18 min) after sevoflurane and 27 minutes (25th-75th percentiles: 20-30 min) after isoflurane (p = 0.0005). CONCLUSIONS: Sevoflurane provides a safe and effective intraoperative control of cardiovascular homeostasis in morbidly obese patients undergoing laparoscopic gastric banding, with the advantage of a faster recovery and earlier discharge from the postanesthesia care unit than isoflurane.

0.2% ropivacaine with or without fentanyl for patient-controlled epidural analgesia after major abdominal surgery: a double-blind study.

STUDY OBJECTIVE: To evaluate the effects of adding low concentration of fentanyl to 0.2% ropivacaine when providing patient-controlled epidural analgesia (PCEA) outside the Post-Anesthesia Care Unit. DESIGN: Prospective, randomized, double-blind study. SETTING: Inpatients at a University Department of Anesthesia. PATIENTS: 32 ASA physical status I, II, and III patients, who were scheduled for elective major abdominal surgery, including bowel resection, hepatic resection, and pancreaticoduodenectomy. INTERVENTIONS: Patients received standard general/epidural anesthesia. After surgery patients were randomly allocated in a double-blind fashion to receive PCEA with either 0.2% ropivacaine (n = 16) or 0.2% ropivacaine/2 microg/mL fentanyl (n = 16) [background infusion ranging between 4 and 6 mL/hr, with 1.5-mL incremental doses and a 20-min lock-out time]. Dynamic pain during coughing, sedation, pulse oxymetry, hemodynamic variables, and motor block were evaluated at 1, 6, 12, 24, and 48 hours after the end of surgery by a blinded observer. Occurrence of untoward events, including nausea, vomiting, pruritus, need for supplemental oxygen (for SpO(2) < 90%), and respiratory complications, as well as total consumption of PCEA solution and incremental doses given to the patient were also recorded. MEASUREMENTS AND MAIN RESULTS: No differences in pain relief, motor block, degree of sedation, recovery of gastrointestinal motility, and other side effects were observed between the two groups. Patients receiving 0.2% ropivacaine alone requested far more incremental doses (23 doses [0-60] vs. 5 doses [0-25]) (p = 0.006) and needed far more analgesic solution (230 mL [140-282] vs. 204 [130-228]) (p = 0.003) than patients receiving the ropivacaine/fentanyl mixture. Peripheral oxygen saturation was lower at 12, 24, and 48 hours during ropivacaine/fentanyl infusion than in patients receiving ropivacaine alone (12 h: 91% +/- 2% vs. 95% +/- 2%, p < 0.006; 24 h: 93% +/- 1% vs. 96% +/- 2%, p = 0.003; 48 h: 92% +/- 1.8% vs. 96% +/- 1%, p = 0.004). CONCLUSIONS: A thoracic epidural infusion of 0.2% ropivacaine, with or without fentanyl, provided effective pain relief in most patients with a very low degree of motor blockade. Adding 2 microg/ml fentanyl to 0.2% ropivacaine reduced total consumption of local anesthetic solution and need for incremental doses, but did not provide clinically relevant advantages in quality of pain relief and incidence of motor block, leading to a significant decrease in peripheral SpO(2), lasting up to 48 hours after surgery.

Effects of pneumoperitoneum and reverse Trendelenburg position on cardiopulmonary function in morbidly obese patients receiving laparoscopic gastric banding.

We prospectively evaluated the effects of pneumoperitoneum and reverse Trendelenburg position on cardiopulmonary function in 20 ASA physical status II-III morbidly obese patients (body mass index > 35 kg m(-2)) undergoing laparoscopic gastric banding. After general anaesthesia was induced, patients' lungs were ventilated using intermittent positive pressure ventilation (at measurement times, the following parameters were used: tidal volume 12 mL kg(-1) ideal body weight, respiratory rate of 12 bpm, an inspiratory to expiratory time ratio of 1:2). Haemodynamic variables, blood gas parameters, and lung/chest compliance were recorded: in the supine position, after induction of general anaesthesia (T0, baseline) and induction of pneumoperitoneum (T1); after placing the patient in a 25 degree reverse Trendelenburg position (T2); during the surgical time (T3); before deflating the abdomen (T4); after pneumoperitoneum resolution (T5), and before the end of anaesthesia, with the patient supine (T6). The PaO2, PaO2/FiO2 ratio, and lung/chest compliance decreased during the study. After the pneumoperitoneum had been resolved, lung/chest compliance but not oxygenation parameters returned to baseline values. The arterial to end-tidal CO2 tension difference progressively increased from 0.38+/-0.3 kPa (2.85+/-2.25 mmHg) (T0) to 0.63+/-0.3 kPa (4.73+/-2.25 mmHg) (T6). In morbidly obese patients, undergoing laparoscopic gastric banding, a CO2 pneumoperitoneum markedly affected gas exchange and lung/chest compliance, while positioning the patient in a 25 degree reverse Trendelenburg position had no beneficial effects.

Clinical comparison of either small doses of fentanyl or remifentanil for blunting cardiovascular changes induced by tracheal intubation.

BACKGROUND: To compare in a prospective, randomized study the effects on cardiovascular changes after tracheal intubation produced by small doses of either remifentanil or fentanyl. METHODS: With Ethical Committee approval, after intravenous midazolam premedication (0.05 mg.kg-1), 30 normotensive, ASA physical status I-II patients, without cardiovascular or respiratory diseases, and with a Mallampati score < 2, were randomly allocated to receive an intravenous bolus of either 3 micrograms.kg-1 fentanyl (n = 15) or 1 microgram.kg-1 remifentanil (n = 15) infused over 60 sec and followed by a 0.15 microgram.kg-1.min-1 continuous intravenous infusion. General anesthesia was then induced with propofol (2 mg.kg-1), followed by atracurium besilate (0.5 mg.kg-1) to facilitate tracheal intubation. Following intubation, the lungs were ventilated mechanically using a 60% nitrous oxide in oxygen mixture with a 1% inspired fraction of sevoflurane. Arterial blood pressure and heart rate were recorded before anesthesia induction (baseline), one minute after induction of anesthesia, immediately after tracheal intubation and every minute for the first five minutes after intubation. RESULTS: Systolic arterial blood pressure values were significantly higher in the Fentanyl than in the Remifentanil group patients from 2 to 5 min after tracheal intubation (p < 0.01), while no differences were observed between the two groups in either diastolic arterial blood pressure or heart rate values. Four patients in the Remifentanil group (26%) but only one patient in the Fentanyl group (7%) showed systolic blood pressure values < 90 mmHg during the study period (p = not significant); however, the observed decreases in systolic arterial blood pressure values were transient and did not require treatment for any subject. CONCLUSION: We conclude that in healthy normotensive patients, the control of cardiovascular responses to tracheal intubation obtained with a 1 microgram.kg-1 loading dose of remifentanil is more effective than that provided by a 3 micrograms.kg-1 bolus of fentanyl, with the advantage of no risks for postoperative respiratory depression.

An analysis of the diagnostic contribution of double-radiocompound renography.

The diagnostic contribution of double-radiocompound renography was tested by applying discriminant analysis to the data obtained in one group of normal subjects and in some groups of selected pathological cases which included glomerulonephritis, pyelonephritis, and hypertension. The results obtained confirm the reliability of the test and give evidence of its usefulness in diagnostic clinical work.

[Comparison of the diagnostic efficacy of various in vitro tests for the study of thyroid performance (author's transl)]. / Valutazione comparativa della efficacia diagnostica di alcuni test in vitro per lo studio della funzionalità tiroidea

Discriminating analysis was employed in an evaluation of the diagnostic efficacy of individual in vitro tests of thyroid performance (T3 resin uptake, T4, FTI, ETR) and PB131I determination, and their combinations, when used for the differentiation of euthyroid, Basedow hyperthyroid, hyperfunctioning autonomous adenoma, and hypothyroid cases. The results are discussed with reference to optimization of the data: radiation dose ratio.