Preoperative Values In Groups Research Articles

English

BACKGROUND Music is an inexpensive, easily available anxiolytic known to mankind since ages. Cataract extraction surgery is one of the widely performed surgeries under local anaesthesia. India is a developing country where limited resources are spent over health infrastructure which has to cater to a large population. In our study we have tried to utilize the anxietolytic effect of music in combating the anxiety and stress patients suffer during surgery. METHODS In this prospective, interventional study, 300 patients diagnosed with senile cataract were selected. The sample size was decided taking into consideration various prevalence studies. The patients were consequently recruited for the study considering the inclusion and exclusion criteria. Patients were divided into three groups - one undergoing phacoemulsification surgery under topical anaesthesia and two groups undergoing phacoemulsification surgery under local anaesthesia by the same surgeon in a same operating room. Two groups including the one where topical anaesthesia was used were made to listen to ‘Classical Sitar Music’ whereas one group was not made to listen to music. Blood pressure and heart rates were measured before and after surgery and compared in all patients. RESULTS Blood pressure and heart rates were statistically significantly normalized (lowered) post-operatively when compared to their pre-operative values in groups which were made to listen to music. There was a marked decrease in the anxiety levels in patients who were operated under topical anaesthesia when compared to those operated under local anaesthesia. CONCLUSIONS Music can be widely used in decreasing anxiety levels in patients undergoing cataract extraction surgery thereby improving the post-operative prognosis in patients in a cost-effective way. KEY WORDS Phacoemulsification Surgery, Classical Sitar Music, Peri-Bulbar Block, Topical Anaesthesia, Anxiety, Blood Pressure, Pulse Rate

Comparison of nasal functional outcomes of let down rhinoplasty and open technical rhinoplasty using spreader graft.

This study aimed to compare open technique rhinoplasty with spreader graft and Let Down rhinoplasty using Nasal Symptom Obstruction Evaluation (NOSE), Sinonasal Outcome Test-22 (SNOT-22), and Visual Analog Scale (VAS). A total of 50 patients were included in the study. Patients with a hump greater than 4mm and mild septal deviation participated in the study. The patients were divided into two groups. Group 1 consisted of 26 patients who underwent Let Down rhinoplasty, while Group 2 consisted of 24 patients who underwent open rhinoplasty with spreader graft. NOSE, SNOT-22, and VAS scales were completed by both groups preoperatively and postoperatively. There was no significant difference between the groups in terms of age and gender. Postoperative values of scales were significantly lower than preoperative values in Group 1 (p < 0.001). In Group 2, postoperative values were significantly lower than preoperative values (p < 0.001). There was no significant difference between the two groups according to NOSE, SNOT-22 and VAS scores. According to the comparison of scale scores, both Let Down rhinoplasty and open technique rhinoplasty using spreader graft improved nasal functional results such as nasal obstruction.

Changes in Lung Function Parameters after Total Intravenous Anaesthesia and Balanced Anaesthesia with Desflurane: A Prospective Randomised Study.

ObjectiveFollowing anaesthesia, there is a decrease in pulmonary function. Unlike volatile anaesthetics, propofol decreases the upper airway tone, and total intravenous anaesthesia (TIVA) with propofol may decrease coughing on emergence. Coughing may reduce postoperative atelectasis. Thus, TIVA may lead to greater decreases in lung function postoperatively as compared to balanced anaesthesia with desflurane.MethodsSixty patients of either sex, aged 18–60 years and American Society of Anaesthesiologists (ASA) status I/II, who were to undergo mastoid surgery, were randomly allocated to Group B and Group T. Anaesthesia was maintained with desflurane, nitrous oxide and oxygen in Group B, and with TIVA in Group T. Pulmonary function tests (PFT) were done preoperatively, and 1, 3 and 24 hours postoperatively.ResultsDemographic data and preoperative PFT were comparable in both groups. One hour after surgery, there was a greater decrease in FEV1 and peak expiratory flow rate (PEFR) in Group T (p=0.044 and 0.042, respectively). Three hours postoperatively, the decrease in MEFR and PEFR was again greater in Group T (p=0.005 and 0.008, respectively), while the MEFR recovered to preoperative values in Group B. By 24 hours, the forced vital capacity (FVC), MEFR and PEFR recovered to preoperative values in Group T, while FVC remained reduced in Group B (p=0.006).ConclusionBoth anaesthetic techniques cause a postoperative impairment in the lung function, but while TIVA causes a greater reduction in PFT in the early postoperative period, recovery is also earlier. On the other hand, balanced anaesthesia with desflurane was associated with a greater reduction in PFT at 24 hours.

A randomized single-blinded, parallel-arm group feasibility trial evaluating role of pectoral nerve block on serum vascular endothelial growth factor levels in patients undergoing unilateral modified radical mastectomy.

Metastatic breast cancer cells carry adult and neonatal variants of NaV1.5 voltage-gated activated Na+ channels involved in cell invasion. We hypothesize that instilling lignocaine near the surgical field to anesthetize the pectoral nerves for analgesia will decrease angiogenesis by blocking voltage-gated activated Na+ channels. Twenty patients undergoing unilateral modified radical mastectomy were randomized in a single-blinded, parallel-arm group feasibility pilot study in two groups. In Group I a catheter was placed between the pectoralis major and minor muscle under direct vision before skin closure. Ten milliliters of 2% lignocaine was given as an initial bolus followed by 10 mL of 2% lignocaine every 8 hours up to 24 hours. Group II did not receive any regional block. Primary measure outcomes were pre and postoperative changes in levels of vascular endothelial growth factor. Secondary outcomes were postoperative pain scores and total rescue analgesia used. Nine patients in each group were analyzed. Baseline demographic data of all females were similar with respect to age, body mass, height and duration of anesthesia. Postoperative mean serum levels of vascular endothelial growth factor were decreased by 46.60% from baseline in Group I, while were increased by 84.27% as compared to preoperative values in Group II. Postoperative average pain scores were less in Group I. Postoperative rescue analgesia in 24 hours in Group I was lower than that in Group II. There was no postoperative adverse event related to catheter or lignocaine administration at given doses. Instilling lignocaine to block pectoral nerves provides better postoperative analgesia and decreases a marker of angiogenesis. The study protocol was approved by the Institutional Ethical Committee of the Tertiary Centre (All India Institute of Medical Sciences Rishikesh India) (No. AIIMS/IEC/19/1002) on August 9, 2019, and the larger expansion trial was prospectively registered on Clinical Trial Registry India (No. CTRI/2020/01/022784) on January 15, 2020.

Arthroscopic Fragment Resection for Capitellar Osteochondritis Dissecans in Adolescent Athletes: 5- to 12-Year Follow-up.

Background:Capitellar osteochondritis dissecans (OCD) in skeletally immature athletes has often been seen in baseball players and gymnasts. The choice of surgical procedure for unstable lesions in skeletally immature athletes remains controversial.Purpose:To investigate functional outcomes and radiographic changes in the midterm to long-term postoperative period after arthroscopic (AS) resection for small to large capitellar OCD lesions in skeletally immature athletes.Study Design:Case series; Level of evidence, 4.Methods:A total of 38 elbows in 38 patients (33 boys, 5 girls; mean age, 14 years [range, 13-15 years]) with skeletally immature elbows underwent AS resection for capitellar OCD. Patients were observed for at least 5 years (mean, 8 years [range, 5-12 years]). Elbows with a lesion width that did not exceed one-half of the radial head diameter were assigned to group 1 (n = 17 elbows), and larger lesions were assigned to group 2 (n = 21 elbows). Functional scores, patient satisfaction, range of motion (ROM), and osteoarthritis (OA) grades were evaluated between the groups.Results:All patients returned to sports activity. Functional scores at the final follow-up were not significantly different between the groups. Patient satisfaction scores were significantly higher in group 1 than in group 2. There was significant improvement in flexion ROM at the final follow-up compared with preoperative values in group 1 (P = .017), and there was a significant between-group difference (group 1: 141°; group 2: 133°; P = .002). Extension ROM showed significant improvement in both groups (group 1: from –8° to 3°; group 2: from –17° to –1°; P < .001 for both). Group 1 tended to have better extension than group 2, but the difference was not significant. There were no elbows with severe OA in either group, but the OA grade progressed in 5 elbows (29%) in group 1 and 9 elbows (43%) in group 2, and this rate of OA progression was statistically significant between groups (P = .005).Conclusion:Both functional outcomes and radiological findings after AS fragment resection were excellent in elbows with small lesions. Although overall outcomes were acceptable in elbows with larger lesions, flexion ROM and patient satisfaction scores were significantly inferior to those in elbows with smaller lesions.

Conchal contractility after inferior turbinate hypertrophy treatment:A prospective, randomized clinical trial

ObjectiveThe aim of this study is to evaluate the effects of these two methods (Nasal corticosteroids (NCS) and radiofrequency (RF) application) on conchal contractility utilizing objective rhinologic measurement parameters. Methods82 patients were presented with the complaint of nasal obstruction and diagnosed with inferior turbinate hypertrophy and were included in the study. Patients in Group 1 received NCS for 12weeks. Patients in Group 2 were administered RF to their inferior turbinates. Acoustic rhinometry and rhinomanometry tests with and without decongestant were performed. ResultsIn the evaluation of the contractility difference of rhinometry parameters, there was not a significant difference among pre and postoperative acoustic rhinometric parameters in Group 1. Whereas in Group 2, postoperative contractility difference was significantly decreased compared to preoperative values.In the evaluation of the contractility difference of rhinomanometric parameters, no significant difference was found between pre and postoperative values in Group 1. However, postoperative contractility difference was significantly decreased compared to preoperative values in Group 2 in terms. ConclusionBecause the RF procedure produces fibrosis in the vascular tissues, inferior turbinates do not have a shrinking response to decongestant administration. Administration of NCS administration maintains the contractility function compared to RF application.

Comparison of Size 2 LMA-ProSeal™ and LMA-Supreme™ in Spontaneously Breathing Children: a Randomised Clinical Trial.

The aim of this study was to compare size 2 Laryngeal Mask Airway ProSeal and size 2 Laryngeal Mask Airway Supreme in spontaneously breathing children undergoing lower abdominal elective surgery of <1 hour duration. Randomized clinical trial. Sixty children aged 1-7 years, weighing 10-20 kg, ASA I physical status were randomly allocated to the Laryngeal Mask Airway ProSeal and Laryngeal Mask Airway Supreme. There were no differences in demographic variables, ease of gastric tube placement, ease of insertion and ventilation, number of insertion attempts, hemodynamic changes on insertion, postoperative complications and bloodstaining between the groups. Gastric insufflation was detected and gastric tube was placed in all patients except one in LMA Supreme. Postoperative cuff volumes were comparable with the preoperative values in group itself. Oropharyngeal leak pressures were higher in Laryngeal Mask Airway ProSeal (24.6±5.5 vs 21.3±4.2, respectively; p<0.01). As a result Laryngeal Mask Airway ProSeal and Laryngeal Mask Airway Supreme can safely be used in spontaneously breathing pediatric population undergoing lower abdominal elective surgery.

Effect Analysis of 1-Year Posttransplant Body Mass Index on Chronic Allograft Nephropathy in Renal Recipients

Objective We sought to evaluate the effects of body mass index (BMI) at 1 year after transplantation on chronic allograft nephropathy (CAN). Methods We grouped 564 kidney transplanted patients between June 1997 and March 2005 according to BMI at 1 year after transplantation: group I showed a BMI more than 18.5 and less than or equal to 25 (normal weight); group II, BMI greater than 25 and less than or equal to 30 (overweight); and group III, BMI greater than 30 (obese). We retrospectively studied all patients. All donors were living donors, none of whom were prisoners. Results One-year posttransplant BMI was greater than preoperative values in groups II and III ( P < .05 and P < .01 respectively). The CAN incidences among the three groups were 34.9% (128/367), 38.4% (48/125), and 43.1% (31/72), respectively (group I vs III; P < .05). With the increase in 1-year posttransplant BMI the rates of hypertension, diabetes mellitus, and hyperlipidemia increased, but there was no difference in acute rejection episodes among the three groups. Multivariate analysis revealed BMI at the first postoperative year to show a significant influence on CAN. Conclusions One-year BMI after kidney transplantation has a strong association with CAN. Thus diet control, exercise, and decreased immunosuppressive agent exposure may control BMI and decrease the incidence of CAN.

Ketamine versus propofol for strabismus surgery in children

To compare the effects of intravenous infusion of ketamine and propofol anesthesia in children undergoing strabismus surgery. Sixty pediatric patients aged 4-11 years were enrolled for the study. Patients in Group K were infused ketamine 1-3 mg/kg/hr (n = 30) and patients in Group P were infused with propofol 6-9 mg/kg/hr (n = 30). After giving fentanyl 1 mug/kg and rocuronium bromide 0.5 mg/kg, patients were intubated. The consumption of anesthetics (P = 0.0001) and antiemetics (P = 0.004), the incidence of oculocardiac reflex (P = 0.02) in Group K were significantly lower than in Group P. The recovery time (P = 0.008), postoperative agitation score (P = 0.005), Face Pain Scale (P = 0.001), Ramsay Sedation Score (P = 0.01) during awakening and at postoperative 30th min (P = 0.02) in Group K were significantly lower than in Group P. The postoperative agitation score during awakening was significantly lower than the preoperative values in Group K (P = 0.0001). The infusion of ketamine is more advantageous than the infusion of propofol in children for use in strabismus surgery.

Comparison of dexmedetomidine and midazolam for monitored anesthesia care combined with tramadol via patient-controlled analgesia in endoscopic nasal surgery: A prospective, randomized, double-blind, clinical study

Abstract. Monitored anesthesia care (MAC) may be applied for septoplasty or endoscopic sinus surgery in which an adequate sedation and analgesia without respiratory depression are desired for comfort of both the patient and the surgeon. Several combinations with different agents have been used for this purpose in these patients. However, analgesic properties for these agents have not been reported. The aim of this study was to investigate the analgesic and sedative effects of dexmedetomidine or midazolam infusion combined with tramadol that was used via patient-controlled analgesia (PCA), and to document the effects of these drugs on early cognitive functions. This prospective, randomized, double-blind, clinical study enrolled patients undergoing septoplasty or endoscopic sinus surgery at the Abant Izzet Baysal University Hospital, Bolu, Turkey, between February and September 2006. Patients were randomly allocated in a 1:1 ratio into 1 of 2 groups: the dexmedetomidine group (group D) patients received IV dexmedetomidine 1 μg/kg for 10 minutes followed by continuous infusion of 0.5 μg/kg · h(-1); and the midazolam group (group M) patients were administered a loading dose of IV midazolam 40 μg/kg for 10 minutes followed by infusion at the rate of 50 μg/kg · h(-1). A 1-minute bolus dose of IV tramadol (1.5 mg/kg) was administered in both groups 10 minutes after the administration of the primary drug, and continued via infusion using a PCA device. After baseline measurements, systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), heart rate (HR), oxygen saturation, and rate of respiration were recorded after the loading dose of study drug, after the bolus tramadol dose, at 10-minute intervals during the operation, and twice in the recovery rooms; 5 minutes after arrival and 5 minutes before discharge. Verbal rating score (VRS) and Ramsay sedation score were determined at baseline (after surgery was started), every 10 minutes thereafter until the end of the operation, and 2 times during recovery. All patients were assessed with the Wechsler Memory Scale-Revised at baseline (preoperatively) and 4 hours after the operation. Seventy patients were enrolled in the study and randomly assigned to 1 of 2 groups: group D (sex, male/female, 23/12; mean [SEM] age, 32.53 [2.07] years; mean [SEM] weight, 73.03 [2.41] kg) or group M (sex, male/female, 21/14; mean [SEM] age, 34.43 [1.83] years; mean [SEM] weight, 67.90 [2.32] kg). All hemodynamic parameters (SAP, DAP, MAP, HR) were significantly higher in group M compared with group D from the onset of the surgery to discharge time (P < 0.05). Pain and sedation scores were similar in both groups, but the amount of PCA-administered rescue tramadol was significantly higher in group M (P = 0.001). A higher, though not statistically significant, prevalence of adverse events (ie, hypotension, bradycardia, and perioperative nausea and vomiting) were observed in group D. Postoperative logical verbal memory and digit span values were significantly higher in group D when compared with group M (P < 0.05). Postoperative digit span and visual reproduction scores were significantly higher than preoperative values in group D (P < 0.05). Postoperative personality functioning scores were significantly higher than preoperative values in group M (P < 0.05). Based on VRS, Ramsay sedation scores, and surgeon and anesthesiologist satisfaction scores, dexmedetomidine or midazolam combined with tramadol PCA provided adequate analgesia and sedation in these adult patients undergoing septoplasty or endoscopic sinus surgery with MAC. A significantly larger amount of rescue tramadol was used by group M, suggesting that a better analgesic effect was achieved with dexmedetomidine.

Comparison of dexmedetomidine and midazolam for monitored anesthesia care combined with tramadol via patient-controlled analgesia in endoscopic nasal surgery: A prospective, randomized, double-blind, clinical study

Abstract Monitored anesthesia care (MAC) may be applied for septoplasty or endoscopic sinus surgery in which an adequate sedation and analgesia without respiratory depression are desired for comfort of both the patient and the surgeon. Several combinations with different agents have been used for this purpose in these patients. However, analgesic properties for these agents have not been reported. The aim of this study was to investigate the analgesic and sedative effects of dexmedetomidine or midazolam infusion combined with tramadol that was used via patient-controlled analgesia (PCA), and to document the effects of these drugs on early cognitive functions. This prospective, randomized, double-blind, clinical study enrolled patients undergoing septoplasty or endoscopic sinus surgery at the Abant Izzet Baysal University Hospital, Bolu, Turkey, between February and September 2006. Patients were randomly allocated in a 1:1 ratio into 1 of 2 groups: the dexmedetomidine group (group D) patients received IV dexmedetomidine 1 μg/kg for 10 minutes followed by continuous infusion of 0.5 μg/kg · h−1; and the midazolam group (group M) patients were administered a loading dose of IV midazolam 40 μg/kg for 10 minutes followed by infusion at the rate of 50 μg/kg · h−1. A 1-minute bolus dose of IV tramadol (1.5 mg/kg) was administered in both groups 10 minutes after the administration of the primary drug, and continued via infusion using a PCA device. After baseline measurements, systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), heart rate (HR), oxygen saturation, and rate of respiration were recorded after the loading dose of study drug, after the bolus tramadol dose, at 10-minute intervals during the operation, and twice in the recovery rooms; 5 minutes after arrival and 5 minutes before discharge. Verbal rating score (VRS) and Ramsay sedation score were determined at baseline (after surgery was started), every 10 minutes thereafter until the end of the operation, and 2 times during recovery. All patients were assessed with the Wechsler Memory Scale-Revised at baseline (preoperatively) and 4 hours after the operation. Seventy patients were enrolled in the study and randomly assigned to 1 of 2 groups: group D (sex, male/female, 23/12; mean [SEM] age, 32.53 [2.07] years; mean [SEM] weight, 73.03 [2.41] kg) or group M (sex, male/female, 21/14; mean [SEM] age, 34.43 [1.83] years; mean [SEM] weight, 67.90 [2.32] kg). All hemodynamic parameters (SAP, DAP, MAP, HR) were significantly higher in group M compared with group D from the onset of the surgery to discharge time (P < 0.05). Pain and sedation scores were similar in both groups, but the amount of PCA-administered rescue tramadol was significantly higher in group M (P = 0.001). A higher, though not statistically significant, prevalence of adverse events (ie, hypotension, bradycardia, and perioperative nausea and vomiting) were observed in group D. Postoperative logical verbal memory and digit span values were significantly higher in group D when compared with group M (P < 0.05). Postoperative digit span and visual reproduction scores were significantly higher than preoperative values in group D (P < 0.05). Postoperative personality functioning scores were significantly higher than preoperative values in group M (P < 0.05). Based on VRS, Ramsay sedation scores, and surgeon and anesthesiologist satisfaction scores, dexmedetomidine or midazolam combined with tramadol PCA provided adequate analgesia and sedation in these adult patients undergoing septoplasty or endoscopic sinus surgery with MAC. A significantly larger amount of rescue tramadol was used by group M, suggesting that a better analgesic effect was achieved with dexmedetomidine.

Endogenous nitric oxide production and atrial natriuretic peptide biological activity in infants undergoing cardiac operations.

To examine whether preoperative heart failure and cardiac surgery influence nitric oxide production and atrial natriuretic peptide (ANP) biological activity in infants and whether nitric oxide and ANP participate in the control of postoperative pulmonary vascular tone. Prospective, clinical study. Tertiary pediatric cardiac intensive care unit in a referral cardiosurgical center. Nineteen infants (median age 4 months) undergoing cardiac surgery: 13 infants with ventricular or atrioventricular septal defect associated with heart failure and pulmonary hypertension (group 1); and six infants with tetralogy of Fallot, without heart failure (group 2). Blood samples obtained from indwelling catheters or bypass circuit outlets. Nitrite and nitrate blood concentrations (as a marker for nitric oxide synthesis) and the molar ratio of cyclic guanosine 3',5'-monophosphate (cGMP) to ANP (as a marker for ANP biological activity) were determined before, during, and up to 24 hrs after cardiopulmonary bypass (CPB). In group 1 patients, these biological parameters were related to postoperative pulmonary arterial pressure. Preoperative nitrite and nitrate concentrations were higher in group 1 patients than in group 2 patients (p < .02), and this difference persisted during CPB. Nitrite and nitrate concentrations 24 hrs postoperatively were lower than preoperative values in group 1 patients (p < .05) and were unchanged in group 2 patients. An inverse correlation was observed postoperatively between nitrite and nitrate concentrations and systolic pulmonary arterial pressure (r2 = 0.4, p < .05). Group 1 patients had a lower preoperative cGMP/ANP ratio than group 2 patients (p < .05), despite higher ANP levels (p < .005). The cGMP/ANP ratio decreased during CPB in both groups (p < .0001), and in group 2 patients, cGMP and ANP values remained below preoperative values < or = 24 hrs postoperatively. A correlation was observed between ANP levels and systolic pulmonary arterial pressure 2 and 4 hrs postoperatively (r2 = .4, p < .05, respectively), but no correlation was observed between ANP biological activity and postoperative pulmonary arterial pressure. Infants with heart failure and pulmonary hypertension have increased nitric oxide synthesis and decreased ANP biological activity; both phenomena may be involved in the pathophysiology of this clinical condition. CPB has no detectable effect on nitric oxide production but does decrease ANP biological activity. In patients with preoperative heart failure and pulmonary hypertension, endogenous nitric oxide appears to play a role in the control of postoperative pulmonary vascular tone.

The Impact of Iatrogenic Urothelial Trauma on Urinary Levels of Transforming Growth Factor-Alpha

Growth factors are important regulators of epithelial cell biology. We postulated that iatrogenic bladder manipulations may alter urinary growth factor levels and thereby influence both normal and neoplastic urothelium. Using a rat model we studied the effects of various types of urothelial injury, corresponding to bladder catheterization, cystoscopy, fulguration, and chronic indwelling catheterization (Groups, B, C, D, and E respectively) on levels of urinary transforming growth factor-alpha (uTGFa). Urine samples collected circa the time of transurethral bladder manipulation were analyzed for protein, creatinine (Cr), and TGFa. Results in experimental groups were compared to control values (group A). Peak concentrations of uTGFa uniformly occurred on the day of surgery and represented 176%, 196%, 726%, 461% and 916% increases relative to pre-operative values in groups A, B, C, D and E respectively. Total uTGFa (nM/mg. Cr) was maximal on experimental day 0 in groups A, B, C, D and day 2 in group E (102%, 114%, 227%, 290% and 976% change from baseline respectively). Compared to control, levels of uTFGFa were significantly elevated on day 0 in the fulguration group, and day 0 and 2 in the chronic catheterization animals (p <.05). Nonsignificant elevations of uTGFa relative to control were based in all groups through day 7. The chronic catheterization levels remained significantly elevated, compared to control, over the duration of the study (ANOVA, p <.05). Urinary protein levels correlated with the severity of the injury and showed a strong positive correlation with uTGFa (p =.0001). This study demonstrated a clear impact of iatrogenic urothelial trauma on urinary levels of TGFa.

A Randomized Prospective Controlled Study of the Metabolism and Hepatotoxicity of Halothane in Humans

In a randomized prospective controlled study in humans, the metabolism and hepatic effects of a single administration of halothane were compared with enflurane and meperidine. Pre- and postoperative antipyrine pharmacokinetics, intraoperative indocyanine green clearance, liver histology, and postoperative liver function tests were determined in 24 patients undergoing abdominal surgery who were randomly allocated to receive either halothane (0.5%, group I), enflurane (0.8%, group II), or meperidine (group III) as a supplement to a common basal anesthetic regimen consisting of thiopental, nitrous oxide/oxygen/muscle relaxant. In addition, end-tidal concentrations of the volatile reductive metabolites of halothane, chlorodifluoroethylene (CDF), and chlorotrifluoroethane (CTF) were determined in group I patients and serum and urinary inorganic fluoride were determined in both group I and II patients. Indocyanine green clearance was measured before anesthesia (stage I), during basal anesthesia (stage II), in the presence of surgical stimuli (stage III), and after introduction of the selected anesthetic agent (stage IV). CDF and CTF were detectable within 20 min of the start of halothane anesthesia in every patient receiving halothane. Peak serum fluoride concentrations occurred at 2 and 24 hr in the enflurane and halothane groups, respectively, whereas urinary fluoride excretion was elevated postanesthesia in the enflurane group only. There was no difference between the pre- and postoperative disposition of antipyrine in group II or III, but after anesthesia, antipyrine clearance was significantly decreased (P less than 0.02) and plasma half-life increased (P less than 0.05) in group I patients (halothane). Concentrations of serum alanine aminotransferase (ALT) and bilirubin were significantly elevated (P less than 0.5) postoperatively in groups I and II but unchanged from preoperative values in group III patients. Three of the 24 liver biopsies taken at the end of stage IV showed several foci of acute liver cell necrosis; of these, two patients were from group I and one from group II. There were no significant differences in liver cell morphology (P greater than 0.5) in biopsies taken at the end of stage IV compared with biopsies at the end of stage III, from groups I and II. The results of this study show that reductive metabolism of halothane occurs routinely in patients undergoing halothane anesthesia under conditions of normoxia. This may be the cause of the changes in antipyrine clearance after halothane anesthesia.