Incidence of postoperative cognitive dysfunction after general or spinal anaesthesia for extracorporeal shock wave lithotripsy.

BACKGROUND: Since general anaesthesia invariably accompanies surgery, the contribution of each to the development of postoperative cognitive dysfunction (POCD) has been difficult to identify. METHODS: A prospective randomized controlled trial was undertaken in elderly patients undergoing extracorporeal shock wave lithotripsy (ESWL). Between 2005 and 2011, 2706 individuals were screened to recruit 100 eligible patients. Patients were randomly assigned to receive general or spinal anaesthesia alone. A battery of eight neuropsychological tests was administered before operation and at 7 days and 3 months after operation. The reliable change index was used to calculate the incidence of POCD. Intention-to-treat analysis was used to compare rates of POCD. RESULTS: Futility analysis led to stopping of the trial after recruitment of 100 patients. Fifty patients were randomly assigned to general anaesthesia, and 48 patients to spinal anaesthesia without sedation or postoperative opioids. At 3 months, POCD was detected in 6.8% [95% confidence interval (CI): 1.4-18.7%] of patients in the general anaesthesia group and 19.6% (95% CI: 9.4-33.9%) in the spinal group (P=0.07). At 7 days after operation, the incidence of POCD was 4.1% (95% CI: 0.5-14%) in the general anaesthesia group and 11.9% (95% CI: 4.0-26.6%) in the spinal group (P=0.16). CONCLUSIONS: We found no significant difference in the rates of POCD when comparing general anaesthesia with spinal anaesthesia, suggesting that the surgical or procedural process itself may contribute to the development of POCD. CLINICAL TRIAL REGISTRATION: Australian Clinical Trials Registry number ACTRN12605000150640.

Defining intra-operative hypotension--a pilot comparison of blood pressure during sleep and general anaesthesia.

The scientific justification for particular values of intra-operative hypotension is poorly substantiated. To provide a rationale for appropriate values we recorded blood pressure measurements at home for 24 h using an automated non-invasive ambulatory blood pressure measurement device. These blood pressures were compared with blood pressure measured before and during general anaesthesia in 18 subjects undergoing elective day surgery. We confirmed that a pre-operative reading taken upon admission to hospital is significantly elevated compared to a usual daytime blood pressure in the same patient. The median (IQR [range]) increases in systolic and mean arterial pressures were 10 (2-15 [-5 to 59]) mmHg, p = 0.003 and 10 (5-14 [-5 to 35]) mmHg, p = 0.002, respectively. When using this admission blood pressure measurement as a 'baseline', systolic and mean arterial pressures decreased during sleep by 41 (30-46 [6-83]) mmHg and 34 (26-36 [6-58]) mmHg, respectively (p = 0.001). This decreased even further intra-operatively: systolic blood pressure by 49 (36-64 [15-96]) mmHg and mean arterial pressure by 36 (26-46 [8-66]) mmHg (p = 0.001).

Postoperative cognitive dysfunction after sevoflurane or propofol general anaesthesia in combination with spinal anaesthesia for hip arthroplasty.

It is unknown if the type of general anaesthetic used for maintenance of anaesthesia affects the incidence of postoperative cognitive dysfunction (POCD). The aim of this study was to compare the incidence of POCD in patients administered either sevoflurane or propofol for maintenance of anaesthesia during total hip replacement surgery. Following administration of a spinal anaesthetic, patients received either sevoflurane (n=121) or propofol (n=171) at the discretion of the anaesthetist for maintenance of general anaesthesia to maintain the processed electroencephalogram (bispectral index, BIS) under 60. POCD was assessed postoperatively at day 7, three months, and 12 months using a neurocognitive test battery. There was no statistically significant difference between the incidence of POCD at any timepoint with sevoflurane compared to propofol. The mean BIS was significantly lower in the sevoflurane group than in the propofol group (mean BIS 44.3 [standard deviation, SD 7.5] in the sevoflurane group versus 53.7 [SD 8.1] in the propofol group, P=0.0001). However, there was no statistically significant association between intraoperative BIS level and the incidence of POCD at any timepoint. Our results suggest that the incidence of POCD is not strongly influenced by the type of anaesthesia used in elderly patients.

Early extubation following coronary artery bypass surgery: a prospective randomized controlled trial. The Fast Track Cardiac Care Team.

STUDY OBJECTIVES: To determine the safety of early extubation (EE) after coronary artery surgery. DESIGN: Prospective randomized controlled trial. SETTING: The cardiac surgery operating room and ICU of a university-affiliated teaching hospital. PATIENTS: One hundred eligible patients presenting for elective coronary artery surgery. INTERVENTIONS: Patients randomized to the EE group were administered a reduced dose of fentanyl (15 microg/kg) and an anesthetic compatible with EE, while patients randomized to the conventional extubation (CE) group were given fentanyl (50 microg/kg). MEASUREMENTS AND RESULTS: The time to extubation in the EE group (median, 240 min; range, 30 to 930 min) was significantly less than the CE group (median, 420 min; range, 125 to 1,140 min) (p<0.01). Twenty patients were withdrawn from the study according to protocol guidelines. There were no cases of reintubation or complications attributable to EE. CONCLUSIONS: By using an appropriate anesthetic technique and postoperative management, EE can be achieved following coronary artery bypass surgery without major complications.

Enhanced potency of intravenous, but not intrathecal, morphine and morphine-6-glucuronide after burn trauma.

We examined the analgesic effect of morphine (M) and its metabolite morphine-6-glucuronide (M6G) in a rat model of acute thermal trauma. M or M6G were given by intrathecal (IT) or intravenous (i.v.) routes after brief burn or sham burn delivered during inhalational anesthesia. In the sham group, M6G was significantly less potent than M when given i.v., yet tended to be more potent than M when given IT. For both drugs, thermal injury increased i.v. potency, yet decreased (for M) or displayed a trend to decrease (for M6G) It potency. The increased potency seen with i.v. but not IT opioid administration may reflect pharmacokinetic (e.g., diminished clearance) and/or pharmacodynamic responses (e.g., activation of peripheral opioid receptors) after thermal injury.

Fentanyl-induced muscle rigidity as affected by pretreatment with amantadine hydrochloride.

STUDY OBJECTIVE: To determine whether the degree of muscle rigidity in humans caused by the administration of high-dose fentanyl is affected by pretreatment with amantadine hydrochloride, a drug that stimulates the release of dopamine in the basal ganglia. DESIGN: Randomized, observer-blinded comparison of regimes. SETTING: Inpatient surgery at a university-affiliated teaching hospital. PATIENTS: Sixteen patients scheduled for elective surgery in whom the administration of high-dose fentanyl was felt to be appropriate. INTERVENTIONS: Eight patients in the control group were given diazepam 5 mg orally 1 hour prior to induction of anesthesia. Eight patients in an experimental group were given the same dose of diazepam and also were treated with amantadine 1 g orally in divided doses over a period of 25 hours prior to their scheduled surgery. At the time of surgery, all patients were given fentanyl 50 micrograms/kg intravenously at a rate of 1 mg/min and were clinically evaluated for the degree of muscle rigidity of the chest wall, abdomen, and extremities. MEASUREMENTS AND MAIN RESULTS: A single observer, blinded to the technique, evaluated and recorded the degree of muscle rigidity present in the chest wall, abdomen, and upper extremities immediately after administration of the fentanyl and 3 minutes later. The observer was the same individual in all instances. In no case did the muscle rigidity compromise our ability to adequately oxygenate the patient. CONCLUSIONS: Muscle rigidity associated with the administration of high-dose fentanyl is not attenuated by prior administration of amantadine in the dose range studied.

The effects of thiopental sodium on fentanyl-induced muscle rigidity in a human model.

STUDY OBJECTIVE: To describe a safe human model in which to study the treatment of fentanyl-induced muscle rigidity and report on the efficacy of thiopental sodium for this purpose. DESIGN: Randomized, observer-blinded comparison of regimens. SETTING: Inpatient surgery at a university-affiliated teaching hospital. PATIENTS: Thirty patients scheduled for elective surgery in whom the administration of high-dose fentanyl was felt to be appropriate and who experienced severe muscle rigidity in the chest, abdomen, and upper extremities after the fentanyl was administered. INTERVENTIONS: One arm was isolated from circulation with a blood pressure (BP) cuff inflated to 100 mmHg above systolic blood pressure (SBP), after which fentanyl 25 to 50 micrograms/kg was administered intravenously (IV) at a rate of 1 mg/min in the contralateral arm. If severe muscle rigidity became apparent in three muscle groups (the chest, abdomen, and arms), patients were either (1) observed for 3.5 minutes without further intervention, (2) given thiopental sodium 1.5 mg/kg IV, followed 120 seconds later by succinylcholine 1 mg/kg IV, or (3) given succinylcholine 1 mg/kg IV, followed 120 seconds later by thiopental sodium 1.5 mg/kg IV. MEASUREMENTS AND MAIN RESULTS: A single observer, blinded to the technique, evaluated and recorded the degree of muscle rigidity present in the chest wall, abdomen, and upper extremities (one isolated from the circulation by a tourniquet) 90 seconds and 3.5 minutes after the onset of muscle rigidity in the control group and 90 seconds after the administration of either thiopental sodium or succinylcholine in the two experimental groups. The observer was the same individual in all instances. The muscle rigidity associated with the administration of high-dose fentanyl was clinically attenuated by the administration of thiopental sodium, especially in the extremities. Succinylcholine was more effective than thiopental sodium in producing muscle flaccidity in all muscle groups not isolated by a tourniquet. In no case did the muscle rigidity compromise our ability to oxygenate the patient adequately. CONCLUSIONS: Thiopental sodium does blunt the degree of muscle rigidity induced by high-dose fentanyl, though not as effectively as does succinylcholine. One can safely isolate an extremity prior to the administration of high-dose fentanyl and a muscle relaxant, intubate the trachea, and ventilate a patient, while retaining the ability to study the effect of centrally acting drugs on fentanyl-induced rigidity in the isolated extremity.

EEG monitoring using aperiodic analysis during carotid and open heart surgery.

The Cerebral Electrical Activity (CEA) was monitored by Lifescan in 38 patients undergoing carotid surgery under general or regional anaesthesia and another 20 patients during cardiopulmonary bypass undergoing open heart surgery. This monitor uses aperiodic analysis to process the electroencephalogram. Abrupt changes in CEA were observed when blood flow was disrupted due to surgical intervention or administration of thiopentone. Gradual changes in CEA were due to anaesthesia or hypothermia. In one patient a long period of depressed CEA did not result in a neurological deficit and in another patient a neurological event was undetected by the monitor.

Review of transcranial Doppler ultrasound to detect microemboli during orthopedic surgery.

Transcranial Doppler ultrasonography has been used to detect microemboli in the middle cerebral artery during orthopedic surgery. We conducted a comprehensive systematic literature review of transcranial Doppler ultrasonography in orthopedic surgery to evaluate its status in this setting. Fourteen studies were selected for qualitative analysis. The highest number of patients studied was 45; emboli were detected in all studies, occurring in 20%-100% of patients. Most embolic counts were below 10, but some high counts were noted. No study reported all the technical parameters of the transcranial Doppler ultrasonography. All studies assessed neurologic status, and 6 studies evaluated cognitive function postoperatively. No study identified an association between postoperative cognitive function and embolic count. Six studies sought the presence of right-to-left shunts.

Concurrent intracardiac metastasis in a patient with intestinal perforation.

The administration of anaesthesia to subjects with intracardiac lesions poses the potential for cardiac complications. Cardiac metastases should be identified in susceptible cases and transthoracic echocardiography performed to elucidate the nature of the cardiac lesions. We describe a case of an intracardiac metastasis in a 65-year-old subject with a small bowel tumour leading to intestinal perforation and presenting for surgical treatment. Oncological assessment of the situation, in conjunction with the anaesthetic risks, led to abandonment of surgery and palliative treatment.

Cognitive function in patients undergoing coronary angiography.

OBJECTIVE: To measure cognition in patients before and after coronary angiography. DESIGN: Prospective observational cohort study. SETTING: University teaching hospital. PATIENTS: 56 patients presenting for elective coronary angiography. MAIN OUTCOME MEASURES: Computerised cognitive test battery administered before coronary angiography, before discharge from hospital and 7 days after discharge. A matched healthy control group was used as a comparator. RESULTS: When analysed by group, coronary angiography patients performed worse than matched controls at each time point. When the cognitive change was examined for each individual, of the 48 patients tested at discharge, 19 (39.6%) were classified as having a new cognitive dysfunction, and of 49 patients tested at day 7, six (12.2%) were classified as having a new cognitive dysfunction. CONCLUSIONS: The results confirm that cognitive function is decreased in patients who have cardiovascular disease. Furthermore, coronary angiography may exacerbate this impaired cognition in some patients.

A prospective observational study of the effect of night duty on the cognitive function of anaesthetic registrars.

The issue of fatigue in hospital medical staff represents a potential health and safety risk to both staff and patients, and is receiving worldwide interest. We aimed to characterize the cognitive performance of anaesthetic registrars before and after a series of night shifts. We enrolled nine full-time anaesthetic trainees in an Australian adult tertiary-referral hospital. We conducted a cross-over observational study which tested cognitive performance in participants before and after seven consecutive night shifts and compared this with performance before and after seven consecutive day shifts. Cognitive function was measured using a computerized assessment tool. Participants completed a mean of 62.5% of the requested testing (seven participants completed 87%). There was no significant change in performance before or after any day shift, nor at the commencement of each night shift. There was near perfect accuracy in performance in all tests at all times. There was a statistically significant deterioration in speed of performance for detection and identification tasks at the end of night shift as the week progressed. Anaesthetic registrars demonstrate a significant decline in cognitive performance after a series of night shifts.

The sensitivity and specificity of three common statistical rules for the classification of post-operative cognitive dysfunction following coronary artery bypass graft surgery.

BACKGROUND: The application of statistical rules to determine post-operative cognitive dysfunction (POCD) has varied, and partially explains the wide range of reported incidences of POCD in the literature. The current study assessed the sensitivity and specificity of three commonly used statistical rules in a sample of coronary artery bypass graft (CABG) patients and healthy non-surgical controls. METHODS: Two hundred and four CABG patients [mean age, 68.8 years; standard deviation (SD), 7.0 years] completed neuropsychological assessment pre-operatively (baseline) and 1 week and 3 months post-operatively. Ninety age- and gender-matched non-surgical controls (mean age, 67.8 years; SD, 7.9 years) completed the same tasks at the same time points. POCD was determined in each group using three rules: the 1SD decline on two or more tasks; the 20% decline on 20% of tasks rule; and a modified reliable change index. RESULTS: The modified reliable change index demonstrated the greatest combination of sensitivity and specificity. The 20% decline on 20% of tasks rule detected the largest incidence of impairment in the CABG group, but showed large incidences of false positive classifications in the control group. The 1SD rule detected the lowest incidence of POCD in the CABG group, but detected a larger incidence of impairment in the control group. CONCLUSIONS: The use of the modified reliable change index is recommended, given the sensitivity to change it displayed and the low rates of false positive classification in the control sample. The use of control groups in future research is also recommended.

Effect of intravenous clonidine on the dose of thiopental required to induce anesthesia.

A randomized, double-blind, controlled trial was conducted to investigate the influence of intravenous clonidine on thiopental dose requirements when used for induction of anesthesia and associated hemodynamic effects. Sixty ASA physical status I or II patients were randomly allocated to one of three treatment groups: normal saline solution (control, n = 20); clonidine (2.5 micrograms/kg, n = 20); or clonidine (5 micrograms/kg, n = 20). The test drug was administered 15 min before induction of anesthesia with intravenous thiopental. The dose of thiopental to produce loss of lash reflex was recorded as well as mean arterial blood pressure and heart rate at 3-min intervals up to induction of anesthesia and then at 1-min intervals for 5 min. Significant decreases in thiopental dose were observed in both groups receiving clonidine compared with the control group, but there was no significant difference between clonidine groups. With dosage calculated according to total body mass, the control group required 5.50 +/- 1.15 mg/kg (mean +/- SD) of thiopental, whereas those who received 2.5 micrograms/kg of clonidine required 4.15 +/- 1.46 mg/kg of thiopental (a reduction of 25%), and those who received 5.0 micrograms/kg of clonidine required 3.48 +/- 1.06 mg/kg of thiopental (a reduction of 37%). When thiopental dose was adjusted for lean body mass, similar reductions were obtained. Clonidine, in both doses, produced more sedation than control, and the 2.5-mg/kg dose produced less sedation than the larger dose. Mean arterial blood pressure was lower in the groups receiving clonidine. There were no significant differences in heart rate among the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidural fentanyl reduces the shivering threshold during epidural lidocaine anesthesia.

UNLABELLED: Epidural local anesthetics and IV opioids both decrease the core temperature that triggers shivering. However, the effect of epidural opioids on shivering thresholds has not been assessed. In this study, we tested the hypothesis that adding epidural fentanyl to epidural lidocaine decreases the shivering threshold compared with epidural lidocaine alone. Fourteen healthy male patients undergoing extracorporeal shockwave lithotripsy under epidural anesthesia were randomly assigned to receive either epidural lidocaine or epidural lidocaine plus epidural fentanyl. Ice-cold lactated Ringer's solution was given IV before epidural blockade, and the core temperature that triggers shivering was established. Then epidural anesthesia was induced, and the shivering threshold was established again after lithotripsy. Results were analyzed using paired or unpaired t-tests. Reduction in the shivering threshold by epidural anesthesia was significantly greater when fentanyl was added to lidocaine than when lidocaine was used alone (mean +/- SD: -0.6+/-0.4 degrees C versus -0.1+/-0.4 degrees C; P < 0.02). We conclude that patients are at increased risk of hypothermia when fentanyl is added to epidural lidocaine. IMPLICATIONS: Fentanyl is often added to lidocaine to improve the quality of epidural blockade and to reduce side effects. However, this study shows that patients are at increased risk of hypothermia when fentanyl is added to lidocaine.

Anaesthesia for extracorporeal shockwave lithotripsy at the Victorian Lithotripsy Service--the first 300 patients.

A prospective survey was undertaken of the anaesthesia for the first 300 patients at the Victorian Lithotripsy Service. The majority (71.7%) were not hospitalised on site, including four quadriplegics and two ASA grade IV patients. Two hundred and eighty-three (94.3%) patients received continuous lumbar epidural anaesthesia, sixteen (5.3%) received general anaesthesia and one received a spinal anaesthetic. Eighty-two patients (27.3%) underwent ancillary procedures at the time of extracorporeal shockwave lithotripsy. The most common intraoperative complications were hypotension (72 patients, 25.4%) and shivering (39 patients, 13.8%). Arrhythmias occurred in nine (3%) patients. There was a 90% patient follow-up rate and the most common postoperative complication was backache (101 patients, 37.4%). The problems of anaesthesia for extracorporeal shockwave lithotripsy are discussed. Epidural anaesthesia offers a number of advantages for this procedure and proved very suitable for the majority of patients.

Epidural opioids as anaesthesia for extracorporeal shock wave lithotripsy in two patients with cardiac disease.

Two patients with cardiac disease underwent Extracorporeal Shock Wave Lithotripsy (ESWL) in the Dornier HM3 machine. In order to minimize cardiovascular changes, epidural opioids (fentanyl 100 micrograms in 10 ml saline was used in one patient and meperidine 50 mg in 10 ml saline in the other patient) were used as an alternative to either general anaesthesia or epidural local anaesthesia. Both patients displayed haemodynamic stability, remained pain-free and experienced no complications. Epidural opioids proved a suitable form of anaesthesia for ESWL in these patients.

A double-blind assessment of segmental sensory changes with epidural fentanyl versus epidural saline in patients undergoing extracorporeal shock-wave lithotripsy.

Segmental changes to pin prick and cold stimuli were tested in a double-blind manner in pain-free patients scheduled for extracorporeal shockwave lithotripsy (ESWL). Fifty patients were randomly allocated to receive either epidural fentanyl (100 micrograms in 10 ml normal saline) or 10 ml epidural normal saline. In a further 25 patients an epidural catheter was inserted but no solution injected. In contrast to this latter group, epidural fentanyl and normal saline both produced segmental sensory changes. There were no significant differences between fentanyl and normal saline groups in the number of patients reporting sensory changes to pin prick, rate of onset of these changes, or segmental level. For cold stimuli, more patients in the fentanyl group than in the normal saline group reported a change (16 vs. 8; P = 0.02) but the segmental level was similar. The effect of normal saline as a diluent in epidurally administered opioids may be of clinical importance.

Comparison of the processed electroencephalogram and awake neurological assessment during carotid endarterectomy.

A processed electroencephalogram (EEG) produced by the Lifescan monitor (Neurometrics), was compared to awake neurological assessment for detecting cerebral ischaemia in seventy patients undergoing carotid endarterectomy under cervical plexus block. Of the six patients demonstrating neurological signs on cross-clamping the carotid, five displayed simultaneous EEG changes, four being detected during surgery, and one being detected after reviewing the EEG postoperatively. Another four patients displayed EEG changes indicative of ischaemia but unassociated with neurological signs. A further patient displayed contralateral intraoperative EEG changes. Hypotension resulted in one EEG change and two cases were associated with technical difficulties with the monitor. The presence of false negatives, possible false positives, technical errors and subjective interpretation associated with the processed EEG make it less reliable than awake neurological assessment for the detection of cerebral ischaemia.

The use of aperiodic analysis of the EEG during carotid artery surgery.

A new processed EEG machine, the Lifescan, which uses aperiodic analysis, was used to monitor cerebral activity prospectively in twenty-one patients undergoing carotid artery surgery under general anaesthesia. The machine was easy to apply, use and read. Volatile agents caused a bilateral decrease in high frequency activity. Unilateral changes consistent with cerebral ischaemia at the time of carotid cross-clamping were also seen. One such prolonged change was not associated with neurological deficit. A further patient awoke with neurological deficit without displaying Lifescan evidence of ischaemia. The machine requires further assessment.