Dynamic-energy-budget-driven fruiting-body formation in myxobacteria.

We develop an interacting particle model to simulate the life cycle of myxobacteria, which consists of two main stages--the swarming stage and the development (fruiting body formation) stage. As experiments have shown that the phase transition from swarming to development stage is triggered by starvation, we incorporate into the simulation a system of ordinary differential equations (ODEs) called the dynamic energy budget, which controls the uptake and use of energy by individuals. This inclusion successfully automates the phase transition in our simulation. Only one parameter, namely, the food density, controls the entire simulation of the life cycle.

Quality of life 12 months after coronary artery bypass graft surgery.

OBJECTIVE: The primary purpose of this study was to assess the relationship between preoperative risk factors, postoperative chronic pain, sleep, and gender on perceptions of quality of life (QoL) in a sample of 123 coronary artery bypass graft (CABG) surgery patients 12 months after surgery. A secondary purpose was to determine whether there is concordance between spousal and patient reporting of QoL after CABG surgery. DESIGN: A cross-sectional comparative study. SETTING: The study setting included patients living in the community, who had had CABG surgery 12 months earlier at The Alfred hospital, a major metropolitan public acute care center, in Melbourne, Australia. PARTICIPANTS: Study participants were 123 adult patients (mean age = 64 years) who had undergone CABG surgery and had participated in a recent clinical trial. These patients were followed up to 12 months. The patient's spouse or next of kin (NoK) was asked questions about their perception of change in the patient's QoL. INSTRUMENTS: Results were assessed using The Medical Outcome Study Short Form-36 (SF-36) questionnaire and additional questions given at 12 months after CABG surgery. The Cleveland Clinic Clinical Severity Score (CSS) was used preoperatively as a tool to predict QoL outcome. RESULTS: Significant improvements in QoL, as measured by the SF-36, were seen in physical functioning (P <.0001), bodily pain (P =.024), social functioning (P =.011), and role limitations resulting from emotional status (P =.003). Other significant associations (P =.002) were found between poor QoL and patients who reported severe pain or poor quality sleep. Low-risk patients, as identified by the preoperative CSS, were more likely to have improved QoL at 12 months. Alteration in QoL was reported equally by patients and their spouses or NoK. Short-term memory impairment was reported by 41% of spouses or NoK. CONCLUSIONS: CABG surgery results in improved QoL for the majority of patients with extensive coronary artery disease. Nevertheless, some patients continue to have severe pain, sleep disturbances, and altered relationship with their spouse or NoK 12 months after surgery.

Patient satisfaction after anaesthesia and surgery: results of a prospective survey of 10,811 patients.

Patient satisfaction after anaesthesia is an important outcome of hospital care. We analysed our anaesthetic database to identify potentially modifiable factors associated with dissatisfaction. At the time of analysis, our database contained information on 10,811 in-patients interviewed on the first day after operation. The major subjective outcome measure was patient satisfaction. We also measured other predetermined outcomes, such as nausea, vomiting, pain and complications. The overall level of satisfaction was high (96.8%); 246 (2.3%) patients were 'somewhat dissatisfied' and 97 (0.9%) were 'dissatisfied' with their anaesthetic care. After adjustment for patient and surgical factors, there was a strong relation between patient dissatisfaction and: (i) intraoperative awareness (odds ratio (OR) 54.9, 95% confidence intervals (CI) 15.7-191); (ii) moderate or severe postoperative pain (OR 3.94, 95% CI 3.16-4.91); (iii) severe nausea and vomiting (OR 4.09, 95% CI 3.18-5.25); and (iv) any other postoperative complications (OR 2.04, 95% CI 1.61-2.56). Several factors associated with dissatisfaction may be preventable or better treated.

Comparison of 0.5% ropivacaine and 0.5% bupivacaine in lumbar epidural anaesthesia for lower limb orthopaedic surgery.

The purpose of this study was to compare the epidural use of 0.5% ropivacaine and 0.5% bupivacaine in patients undergoing lower limb orthopaedic surgery. In a double-blind, randomized, multi-centre study involving 67 patients, thirty-two patients received 20 ml of 0.5% ropivacaine and 35 patients received 20 ml of 0.5% bupivacaine at the L2,3 or L3,4 interspace. Parameters measured were the onset time, duration and spread of sensory block, the onset time, duration and degree of motor block, the quality of anaesthesia and the heart rate and blood pressure profile during block onset. Four patients (3 ropivacaine, 1 bupivacaine) were excluded from the study due to technical failure of the block. The onset and duration of analgesia at the T10 dermatome (median, interquartile range) was 10 (5-15) minutes and 3.5 (2.7-4.3) hours respectively for ropivacaine, and was 10 (6-15) minutes and 3.4 (2.5-3.8) hours respectively for bupivacaine. Maximum block height (median, range) was T6 (T2-T12) for ropivacaine and T6 (C7-T10) for bupivacaine. Nine patients receiving ropivacaine and eight patients receiving bupivacaine developed no apparent motor block. The incidence of complete motor block (Bromage grade 3) was low in both groups, being 4/27 for ropivacaine and 6/34 for bupivacaine. In the ropivacaine group, motor and sensory block were judged to be satisfactory in 78% of patients. In the bupivacaine group, motor and sensory block were judged to be satisfactory in 71% and 62% of patients respectively. Cardiovascular changes were similar in both groups. No statistical differences were found between the two groups regarding any of the study parameters.

Postoperative nausea and vomiting. Propofol or thiopentone: does choice of induction agent affect outcome?

Postoperative nausea and vomiting (PONV) has many causes, including anaesthetic drugs. Choice of induction agent may affect the incidence of PONV, though the evidence is conflicting. We have analysed our database of outcome after surgery. Data on 4173 patients were analysed using multivariate logistic regression, with an overall incidence of PONV 21.3%. Propofol, when compared to thiopentone for induction of anaesthesia, resulted in an 18% reduction in PONV (OR = 0.82, P = 0.03). The likely postoperative benefits of propofol may outweigh concerns about its additional cost.

Continuous extradural infusion of ropivacaine for prevention of postoperative pain after major orthopaedic surgery.

We studied 151 patients undergoing total hip or knee arthroplasty, or cruciate ligament reconstruction in a multicentre study in Australia and New Zealand. Patients were openly allocated randomly to one of five treatment groups or to a control group. General anaesthesia was induced after introduction of extradural block with 0.5% ropivacaine. After surgery, patients received an extradural infusion of 0.2% ropivacaine at 6, 8, 10, 12 or 14 ml h-1 or received no postoperative extradural infusion (control group). All patients had access to i.v. PCA morphine for supplementary analgesia. Morphine consumption was lower in all treatment groups compared with the control group, decreasing with increasing ropivacaine infusion rate. Median VAS scores were lower in all ropivacaine infusion groups compared with the control group for the first 10 h of the study; however by the end of the study, VAS scores were similar in all groups. The higher ropivacaine infusion rates caused a slower convergence of spread of the initial sensory block and a higher degree of motor block. The overall incidence of side effects was similar, with the exception of a higher incidence of urinary retention and hypotension in the groups receiving the higher rates of ropivacaine. The quality of treatment scores were similar for all treatment groups (Br. J. Anaesth. 1996; 76: 606-610).

Double-blind, randomized trial of cessation of smoking after audiotape suggestion during anaesthesia.

We studied the use of intraoperative tape suggestion to improve the rate of cessation of smoking in 363 smokers who wanted to stop smoking. They were allocated randomly to hear a taped message encouraging them to stop smoking or to a blank tape, played during general anaesthesia. Overall 56 patients (15.4%, 95% confidence interval (CI) 11.7-19.1%) had claimed to have stopped smoking at 2 months and 29 patients (8.0%, 95% CI 5.9-10.1%) were confirmed to have stopped smoking at 6 months. There was no significant difference between the groups at either 2 or 6 months (risk ratios 1.06 and 1.09, respectively, P = 0.78). A preoperative:postoperative ratio of a visual analogue scale measuring the patient's motivation to stop smoking was not significantly different (control group 1.13 vs message group 1.10, P = 0.55). This study does not support the hypothesis that intraoperative tape suggestion can change smoking behaviour.