First Measurement of the g Factor in the Chiral Band: The Case of the

The g factor of the 56 ns half-life isomeric state in ^{128}Cs has been measured using the time-differential perturbed angular distribution method. This state is the bandhead of the positive-parity chiral rotational band, which emerges when an unpaired proton, an unpaired neutron hole, and an even-even core are coupled such that their angular momentum vectors are aplanar (chiral configuration). g-factor measurements can give important information on the relative orientation of the three angular momentum vectors. The measured g factor g=+0.59(1) shows that there is an important contribution of the core rotation in the total angular momentum of the isomeric state. Moreover, a quantitative theoretical analysis supports the conclusion that the three angular momentum vectors lie almost in one plane, which suggests that the chiral configuration in ^{128}Cs demonstrated in previous works by characteristic patterns of electromagnetic transitions appears only above some value of the total nuclear spin.

Anaesthesia and postoperative pain management for bilateral lung volume reduction surgery.

Bilateral lung volume reduction surgery was introduced into Australia in 1995 for treatment of selected patients with emphysema. We present our experience of the anaesthetic management of our first 55 cases and describe factors associated with outcome. There were four postoperative deaths (7%). Mean (SD) total operation time was 231 (72) minutes. Median intensive care unit (ICU) stay was 26 hours. There was a significant improvement in postoperative lung function (FEV1, VC, 6-minute walk test, all P < 0.001). Eight patients (15%) required reintubation for respiratory failure; three of these patients subsequently died. With multivariate analysis, total operation time was the only significant predictor of length of ICU stay R2 = 0.25, P = 0.001), which itself was the only significant predictor of hospital stay duration (R2 = 0.36, P < 0.001).

Continuous arterial blood gas monitoring during bilateral sequential lung transplantation.

OBJECTIVE: To determine the accuracy and clinical utility of a continuous arterial blood gas (ABG) monitor during lung transplantation. DESIGN: Prospective, observational cohort study. SETTING: University hospital. PARTICIPANTS: Eleven patients undergoing bilateral sequential lung transplantation (BSLTx). INTERVENTIONS: Repeated ABG sampling. MEASUREMENTS AND MAIN RESULTS: Agreement was measured by the bias (limits of agreement): pH, 0.006 (-0.10 to 0.10); PaO2, -22 mmHg (-130 to 86 mmHg); and PaCO2, -1.6 mmHg (-13.4 to 10.2 mmHg). Sensitivity and specificity of the Paratrend 7 (Biomedical Sensors, Ltd, Malvern, PA) PaO2 measurements (to detect PaO2 < 100 mmHg) were 84.6% and 97.6%, respectively. CONCLUSION: Continuous ABG monitoring with the Paratrend 7 shows sufficiently good agreement with laboratory blood gas analysis during BSLTx and thus is a convenient alternative to intermittent laboratory blood gas measurement. Because of the potential for significant (and sometimes rapid) acid-base disturbances, continuous ABG monitoring may have a role during most lung transplantation procedures.

Clonidine and cardiac surgery: haemodynamic and metabolic effects, myocardial ischaemia and recovery.

Clonidine may have beneficial effects in patients undergoing major surgery. We enrolled 156 patients having elective CABG surgery in a double-blind, randomized trial. Patients were randomized to receive either two doses of placebo (Group PP) or clonidine 5 micrograms/kg (Group CC). Perioperative measurements included haemodynamics, anaesthetic and analgesic drug usage, creatinine clearance, cortisol excretion, recovery times and quality of life (SF-36) after surgery. Overall, there was no significant difference with time to tracheal extubation (median [10-90 centile]): CC 7.1 (3.4-18) h vs PP 8.0 (4.3-17) h, P = 0.70; but there was a higher proportion of patients extubated within four hours: CC 20% vs. PP 8%, P = 0.038. Clonidine resulted in a number of significant (P < 0.05) haemodynamic changes, particularly pre-CPB: less tachycardia and hypertension, more bradycardia and hypotension. Clonidine was associated with a significant (P < 0.05) reduction in anaesthetic drug usage, higher creatinine clearance, lower cortisol excretion and improvement in some aspects of quality of life. This study lends support to consideration of clonidine therapy in patients undergoing CABG surgery.

Early hemodynamic effects of left atrial administration of epinephrine after cardiac transplantation.

We studied the hemodynamic effects of left atrial (LA) administration of epinephrine in 10 patients after cardiac transplantation, using a prospective, randomized, double-blind, cross-over design. After allograft implantation, a LA catheter was inserted and epinephrine infusion commenced at 100 ng.kg-1.min-1. Each trial period consisted of 20 min, with the LA and right atrial (RA) lines switched over between each period; hemodynamic measurements were taken after each time period. Whether epinephrine was administered via the RA or LA did not significantly alter hemodynamics (RA versus LA): mean (SD) arterial blood pressure 67 (7.5) vs 64 (9.5) mm Hg (P = 0.16), mean pulmonary artery pressure 22 (4.0) vs 21 (9.4) mm Hg (P = 0.67), cardiac index 3.2 (1.1) vs 3.2 (1.1) L.min-1.m-2 (P = 0.83), pulmonary vascular resistance index 308 (157) vs 345 (157) dynes.s.cm-5/m-2 (P = 0.30) or right ventricular ejection fraction 35% (11%) vs 32% (9.8%) (P = 0.23). Arterial epinephrine plasma levels were similar (P = 0.16). There was no significant pulmonary extraction of measured catecholamines. We observed no hemodynamic benefit of LA epinephrine administration. It may be that the cardiac transplantation population reacts differently compared with other cardiac surgical patients (possibly because pulmonary extraction of catecholamines is reduced). Because we did not observe a hemodynamic advantage in patients immediately after cardiac transplantation, we would not recommend the use of LA epinephrine at the dose studied.

Anesthesia for bilateral sequential lung transplantation: experience of 64 cases.

OBJECTIVES: To review the experience of anesthesia for bilateral sequential lung transplantation (BSLTx) and describe factors associated with outcome. DESIGN: Case series. SETTING: University hospital. PARTICIPANTS: Sixty-four adult patients undergoing BSLTx. INTERVENTIONS: Descriptive and inferential statistical analysis. MEASUREMENTS AND MAIN RESULTS: Details of anesthetic technique, patient, and perioperative characteristics are presented. Mean (SD) lung allograft ischemic times were 320 (81) minutes for the first lung and 446 (93) minutes for the second lung. Mean (SD) duration of surgery was 8.5(2) hours, and median time to extubation was 28 hours. There was a reduction in the use of cardiopulmonary bypass, from 10 of 19 (53%) in 1992 to 1993 to 10 of 45 (22%) in 1994 to 1996, p = 0.016. There was an association between time to extubation and duration of surgery (Spearman rank correlation, p = 0.33, p = 0.008), but no association with intraoperative fluid administration (p = 0.18, p = 0.16), or inotrope requirements (p = 0.06, p = 0.65). Predictors of in-hospital mortality were preoperative renal impairment (p = 0.034), early reoperation (p = 0.005), and delay in extubation (p = 0.013); and for 12-month mortality was patient age (p = 0.01). The actuarial survival rates were 90%, 73%, and 58% at 30 days, 1 year, and 2 years, respectively. CONCLUSIONS: Anesthesia for BSLTx is a most challenging procedure, for which maintenance of tissue oxygenation and right ventricular perfusion are essential. Recent advances include use of inhaled nitric oxide, ventilator management that reduces dynamic hyperinflation, and permissive hypercapnia. Analysis of outcome from a large case series such as this enables the anesthesiologist to be more aware of the important features of anesthesia for BSLTx, as well as identify potential areas of improvement.

Hemodynamic effects, myocardial ischemia, and timing of tracheal extubation with propofol-based anesthesia for cardiac surgery.

Recent interest in earlier tracheal extubation after coronary artery bypass graft (CABG) surgery has focused attention on the potential benefits of a propofol-based technique. We randomized 124 patients (34 with poor ventricular function) undergoing CABG surgery to receive either a propofol-based (5 mg.kg-1.h-1 prior to sternotomy, 3 mg.kg-1. h-1 thereafter; n = 58) or enflurane-based (0.2%-1.0%, n = 66) anesthetic. Induction of anesthesia consisted of fentanyl 15 micrograms/kg and midazolam 0.05 mg/kg intravenously in both groups. The enflurane group received an additional bolus of fentanyl 5 micrograms/kg prior to sternotomy and fentanyl 10 micrograms/kg with midazolam 0.1 mg/kg at commencement of cardiopulmonary bypass (CPB). Patients receiving propofol were extubated earlier (median 9.1 h versus 12.3 h, P = 0.006), although there was no difference in time to intensive care unit (ICU) discharge (both 22 h, P = 0.54). Both groups had similar hemodynamic changes throughout (all P > 0.10), as well as metaraminol (P = 0.49) and inotrope requirements (P > 0.10), intraoperative myocardial ischemia (P = 0.12) and perioperative myocardial infarction (P = 0.50). The results of this trial suggest that a propofol-based anesthetic, when compared to an enflurane-based anesthetic requiring additional dosing of fentanyl and midazolam for CPB, can lead to a significant reduction in time to extubation after CABG surgery, without adverse hemodynamic effects, increased risk of myocardial ischemia or infarction.

The association among gastric mucosal pH, endotoxemia, and low systemic vascular resistance after cardiopulmonary bypass.

OBJECTIVE: Previously, it was found that a number of patients suffer a "low systemic vascular resistance syndrome" after cardiopulmonary bypass, and this was hypothesized to be secondary to endotoxemia, resulting from intestinal ischemia during bypass. DESIGN: Prospective cohort. SETTING: University teaching hospital. PARTICIPANTS: Thirty-two patients undergoing cardiac surgery. INTERVENTIONS: A number of variables relating to adequacy of tissue perfusion were measured at seven time periods perioperatively: cardiac output, systemic vascular resistance, oxygen delivery and consumption, oxygen extraction ratio, gastric mucosal pH, serum lactate, and endotoxin levels. MEASUREMENTS AND MAIN RESULTS: Investigators could not find any association between systemic vascular resistance and mucosal pH or endotoxin levels after bypass. There were significant changes in oxygen flux and extraction ratio (p < 0.001) as well as serum lactate (p < 0.001). There was no significant change in endotoxin levels or mucosal pH. The systemic vascular resistance at 6 hours postbypass could be predicted from the vascular resistance reading at 1 hour postbypass by a regression equation. A significant correlation between systemic vascular resistance and mixed venous oxygen was found at 4 and 6 hours postbypass (p < 0.01) as well as with oxygen extraction (p < 0.01). There was a negative correlation between mucosal pH and serum lactate, particularly at 6 hours postbypass (p < 0.01). There was no correlation between mucosal pH and endotoxin levels, oxygen flux, or cardiac output. CONCLUSIONS: The investigators therefore could not find any evidence that intestinal ischemia during bypass, as measured by gastric mucosal pH, predisposes to endotoxemia, or low systemic vascular resistance after cardiac surgery.

Comparison of patient-controlled analgesia and nurse-controlled infusion analgesia after cardiac surgery.

A randomized, controlled clinical trial was conducted on 72 patients undergoing elective cardiac surgery to compare patient-controlled analgesia (PCA) to nurse-titrated infusion of morphine. Pain and nausea scores were assessed at 5, 20, 32 and 44 hours after cardiopulmonary bypass. Serum cortisol estimations were performed at 24 and 48 hours, and morphine consumption was measured at 0-24 and 24-48 hours. There was no difference between pain scores (P = 0.72), nausea scores (P = 0.52), serum cortisol at 24 and 48 hours (P = 0.32 and P = 0.34), and morphine consumption at 0-24 and 24-48 hours (P = 0.16 and P = 0.12). There was also no difference in the time to tracheal extubation (P = 0.79) and discharge from ICU (P = 0.64). There was a significant association between pain and serum cortisol at 48 hours (P = 0.023). This study also found a tenfold difference in the amount of morphine used (range = 11 to 108 mg), with no significant association with patient age or sex. We could find no significant benefit from the routine use of PCA in cardiac surgical patients.

ACE-inhibitors, calcium antagonists and low systemic vascular resistance following cardiopulmonary bypass. A case-control study.

OBJECTIVE: To investigate whether the syndrome of low systemic vascular resistance (SVR) following cardiac surgery and cardiopulmonary bypass (CPB) is more common in patients taking angiotensin-converting enzyme inhibitors (ACE-inhibitors) or calcium antagonists. DESIGN: A case-control study, with cases ("low SVR syndrome") identified from intensive care unit observation charts. These cases were each matched to two controls identified from the same group of charts during the same time period. Exposure (ACE-inhibitors or calcium antagonists) was determined in a blinded fashion from the patient's medical record. SETTING: Cardiothoracic surgical unit in a teaching hospital. PARTICIPANTS: We identified 42 cases of low SVR syndrome; these were matched to 84 controls. RESULTS: There was no association between therapy with ACE-inhibitors and the low SVR syndrome following CPB (odds ratio [OR], 1.33; 95% confidence interval [CI], 0.53-3.34), nor with calcium antagonists (OR, 0.49; 95% CI, 0.21-1.13). The incidence of the low SVR syndrome was 7.4%. Patients who develop the low SVR syndrome are more likely to be treated with noradrenaline, adrenaline and dopamine, and spend more time in the cardiothoracic intensive care unit. CONCLUSION: The "low SVR syndrome" following CPB is not associated with preoperative therapy with ACE-inhibitors or calcium antagonists.