Preoperative and perioperative use of levosimendan in cardiac surgery: European expert opinion.

In cardiac surgery, postoperative low cardiac output has been shown to correlate with increased rates of organ failure and mortality. Catecholamines have been the standard therapy for many years, although they carry substantial risk for adverse cardiac and systemic effects, and have been reported to be associated with increased mortality. On the other hand, the calcium sensitiser and potassium channel opener levosimendan has been shown to improve cardiac function with no imbalance in oxygen consumption, and to have protective effects in other organs. Numerous clinical trials have indicated favourable cardiac and non-cardiac effects of preoperative and perioperative administration of levosimendan. A panel of 27 experts from 18 countries has now reviewed the literature on the use of levosimendan in on-pump and off-pump coronary artery bypass grafting and in heart valve surgery. This panel discussed the published evidence in these various settings, and agreed to vote on a set of questions related to the cardioprotective effects of levosimendan when administered preoperatively, with the purpose of reaching a consensus on which patients could benefit from the preoperative use of levosimendan and in which kind of procedures, and at which doses and timing should levosimendan be administered. Here, we present a systematic review of the literature to report on the completed and ongoing studies on levosimendan, including the newly commenced LEVO-CTS phase III study (NCT02025621), and on the consensus reached on the recommendations proposed for the use of preoperative levosimendan.

Blood transfusion after cardiac surgery: is it the patient or the transfusion that carries the risk?

BACKGROUND: The transfusion of red blood cells (RBCs) after cardiac surgery has been associated with increased long-term mortality. This study reexamines this hypothesis by including pre-operative hemoglobin (Hb) levels and renal function in the analysis. METHODS: A retrospective single-center study was performed including 5261 coronary artery bypass grafting (CABG) patients in a Cox proportional hazard survival analysis. Patients with more than eight RBC transfusions, early death (7 days), and emergent cases were excluded. Patients were followed for 7.5 years. Previously known risk factors were entered into the analysis together with pre-operative Hb and estimated glomerular filtration rate (eGFR). In addition, subgroups were formed based on the patients' pre-operative renal function and Hb levels. RESULTS: When classical risk factors were entered into the analysis, transfusion of RBCs was associated with reduced long-term survival. When pre-operative eGFR and Hb was entered into the analysis, however, transfusion of RBCs did not affect survival significantly. In the subgroups, transfusion of RBCs did not have any effect on long-term survival. CONCLUSIONS: When pre-operative Hb levels and renal function are taken into account, moderate transfusions of RBC after CABG surgery do not seem to be associated with reduced long-term survival.

Levosimendan cardioprotection in acutely beta-1 adrenergic receptor blocked open chest pigs.

BACKGROUND: Levosimendan and volatile anesthetics have myocardial pre-conditioning effects. beta-1 adrenergic receptor antagonists may inhibit the protective effect of volatile anesthetics. No information exists as to whether this also applies to the pre-conditioning effect of levosimendan. We therefore investigated whether levosimendan added to metoprolol would demonstrate a cardioprotective effect. METHODS: Three groups of anesthetized open chest pigs underwent 30 min of myocardial ischemia and 90 min of reperfusion by temporary occlusion of the largest side branch from the circumflex artery or the left anterior descending artery. One group (CTRL) served as a control, in another group (BETA), a metoprolol-loading dose was intravenously injected 30 min before ischemia, and in a third group (BETA+L), a levosimendan infusion was added to metoprolol. Myocardial tissue concentrations of glucose, glycerol, and lactate/pyruvate ratio as the primary end-points were investigated with microdialysis in ischemic and non-ischemic tissues. RESULTS: At the end of the ischemic period, statistically significant differences were only found between CTRL and BETA+L in the ischemic myocardium, with a lower lactate/pyruvate ratio, lower glycerol, and higher glucose concentrations in BETA+L as compared with CTRL. There were no differences in non-ischemic myocardium. From 10 to 90 min of reperfusion, no more differences were found between groups. CONCLUSION: The cardioprotective effect of levosimendan on ischemic metabolism with a reduction in the myocardial lactate/pyruvate ratio, less glycerol accumulation, and better preserved glucose concentration does not seem to be prevented by beta-1 adrenergic receptor antagonism with metoprolol.

Levosimendan cardioprotection reduces the metabolic response during temporary regional coronary occlusion in an open chest pig model.

BACKGROUND: Inotropic and myocardial anti-ischemic effects have been demonstrated with levosimendan. The comparison of levosimendan started before an ischemia-reperfusion event as compared with levosimendan started during ischemia has not been studied. METHODS: In anesthetized pigs, a major branch of the circumflex artery was completely occluded for 30 min and then reperfused. The metabolism in the ischemic myocardium and in non-ischemic control myocardium was studied with microdialysis concomitantly with monitoring of global hemodynamics and coronary artery flow in the chosen artery. In the protection group (PRO, n= 6), a levosimendan infusion was started 30 min before coronary artery occlusion, and in the treatment group (TRE, n= 6), a levosimendan infusion was started 10 min after the coronary artery occlusion with a loading dose of 13.3 microg/kg followed by an infusion of 0.67 microg/kg/min. A two-way repeated measures ANOVA completed with Bonferroni's multiple comparison procedure was applied to the data. A P < 0.05 was considered significant. RESULTS: During the ischemic period, the cardiac output and contractility (dp/dt(max)) were higher in the PRO as compared with the TRE and the systemic vascular resistance was lower. The myocardial microdialysate glucose concentration in the ischemic area during ischemia was higher in the PRO as compared with the TRE, and the lactate/pyruvate ratio and the lactate concentration were lower. The differences in the metabolites persisted into the first 10 min of reperfusion. No differences were found for the non-ischemic areas. CONCLUSION: Levosimendan used throughout myocardial ischemia-reperfusion might have a cardioprotective affect on the response to myocardial ischemia as compared with levosimendan started during the ischemia.

Myocardial glycerol release, arrhythmias and hemodynamic instability during regional ischemia-reperfusion in an open chest pig model.

BACKGROUND: To develop cardioprotection against peri-operative myocardial ischemia-reperfusion injury, we need animal models where the local metabolism and blood flow are studied concomitantly with the global circulatory consequences during regional coronary occlusion. METHODS: In six anesthetized domestic pigs, the largest branch of the circumflex artery was occluded for 30 min. Microdialysate was sampled from the ischemic and non-ischemic myocardium along with continuous measurements of local coronary artery flow, global hemodynamics and registration of arrhythmias, from baseline through to 30 min of ischemia and 180 min of reperfusion. RESULTS: During ischemia, the microdialysate glucose concentration decreased, the glycerol concentration increased and the lactate/pyruvate ratio increased significantly. For glycerol, there was a further increase at reperfusion. During ischemia, cardiac output was unchanged; however, during reperfusion there was a significant drop lasting for several minutes, longer than the period in which an increased number of arrhythmias were registered. CONCLUSION: The present study demonstrates deranged circulation and arrhythmias corresponding to ischemic metabolism after regional myocardial ischemia and reperfusion. Reperfusion induced more pronounced circulatory changes than the actual ischemia. A substantial increase in myocardial glycerol release seems to be a marker of ischemic metabolism and may prove to be an indicator of reperfusion injury.

Transplantation of lungs from a non-heart-beating donor.

BACKGROUND: In animals, we have previously done successful lung transplantations using organs from non-heart-beating donors. We have also developed an ex-vivo system of assessing the function of such organs before transplantation. The next stage was to try the technique in human beings. Bearing in mind the sensitive ethical issues involved, our first aim was to find out what procedures would be acceptable, and to use the results to guide a clinical lung transplantation from a non-heart-beating donor. METHODS: The ethical acceptability of the study was gauged from the results of a broad information programme directed at the general public in Sweden, and from discussions with professionals including doctors, nurses, hospital chaplains, and judges. The donor was a patient dying of acute myocardial infarction in a cardiac intensive-care unit after failed cardiopulmonary resuscitation. The next of kin gave permission to cool the lungs within the intact body, and intrapleural cooling was started 65 min after death. Blood samples were sent for virological testing and cross matching. The next of kin then had time to be alone with the deceased. After 3 h, the body was transported to the operating theatre and the heart-lung block removed. The lungs were assessed ex vivo, and the body was transported to the pathology department for necropsy. RESULTS: No contraindications to transplantation were found, and the right lung was transplanted successfully into a 54-year-old woman with chronic obstructive pulmonary disease. The donor lung showed excellent function only 5 min after reperfusion and ventilation, and during the first 5 months of follow-up, the function of the transplanted lung has been good. INTERPRETATION: About half the deaths in Sweden are caused by cardiac and cerebrovascular disease. This group could be a potential source of lung donors. When all hospitals and ambulance personnel in Sweden have received training in non-heart-beating lung donation, we hope that there will be enough donor lungs of good quality for all patients needing a lung transplant.

Acupuncture for lower back and pelvic pain in late pregnancy: a retrospective report on 167 consecutive cases.

Adverse and analgesic effects of acupuncture during the second and third trimesters of pregnancy were studied retrospectively in an observational study including 167 consecutive patients with lower back pain, pelvic pain, or both. In each patient acupuncture was given on at least two different occasions by three manual stimulations of two or more acupuncture or tender points, mainly LR-3 and LI-4 together with local tender points, at 15-min intervals. Possible adverse and analgesic effects were assessed by the midwife responsible for the acupuncture given in each patient. There were no abortions and no influence on the delivery course of the infants, but transient premature labor was observed during the fourth stimulation carried out in the 15th gestational week in one woman. Other possible adverse effects, like transient dizziness or tiredness, were reported in 35 patients (21%). Analgesia, as assessed by midwives involved, was good or excellent in 72% of patients. Acupuncture seems to be safe and effective for pain relief in lower back pain, pelvic pain, or both during the second and third trimesters of pregnancy. Nevertheless, prospective randomized studies are needed to confirm these findings.

Effects of dopamine in lung-transplanted pigs at 32 degrees C.

BACKGROUND: We have used hypothermia successfully in patients with acute respiratory failure after lung transplantation. However, we have observed that dopamine may cause a substantial decrease in mean arterial pressure (MAP) in hypothermic subjects. Furthermore, a dopamine-induced increase in pulmonary vascular resistance (PVR) has been reported in the literature, and this could aggravate the increase in PVR which is often seen both in the early postoperative phase after lung transplantation, and during hypothermia. We thus hypothesized that dopamine would decrease MAP and increase PVR in hypothermic lung-transplanted subjects. METHODS: Left single lung transplantation combined with right pneumonectomy was performed in 6 pigs anesthetized with ketamine and midazolam and muscle relaxed with pancuronium. After an observation period of 24 h, the effect of dopamine infused at 5 and 12 microg x kg(-1) x min(-1) was studied in normothermia (38 degrees C) and after cooling by cold-water immersion to 32 degrees C. RESULTS: Systemic vascular resistance index (SVRI) increased and cardiac index (CI) decreased in hypothermia. Dopamine decreased SVRI and increased CI, both in normothermia and at 32 degrees C. MAP decreased during infusion of dopamine in hypothermia. Dopamine had no effect on the pulmonary vascular resistance index (PVRI). CONCLUSION: The results suggest that dopamine may be used to increase cardiac output after lung transplantation in moderate hypothermia as well as in normothermia, but one should be aware that dopamine may cause a substantial decrease in blood pressure, depending on the prevailing hemodynamic conditions at the start of its administration.

Acupuncture for pain relief during childbirth.

BACKGROUND: There are few studies on acupuncture in childbirth despite the generally established analgesic effect of acupuncture treatment. METHODS: The analgesic effect of acupuncture during childbirth was assessed by comparing the need for other pain treatments (epidural analgesia using bupivacaine, pudendal nerve block, intramuscular meperidine, nitrous oxide/oxygen, intracutaneous sterile water injections) in 90 women given acupuncture (acupuncture group) with that in 90 women not given acupuncture (control group). RESULTS: 52 women (58%) in the acupuncture group and 13 (14%) in the control group managed their deliveries without further pain treatment (p < 0.001). The groups were similar with respect to age, pariety, duration of delivery, use of oxytocine and incidence of Caesarean section. Acupuncture treatment was found to have no major side effects, and 85 women (94%) given acupuncture reported that they would reconsider acupuncture in future deliveries. CONCLUSION: Acupuncture reduces the need for other methods of analgesia in childbirth.

Contradictory effects of dopamine at 32 degrees C in pigs anesthetized with ketamine.

BACKGROUND: In critically ill patients who were surface cooled to 33 +/- 2 degrees C, we have observed that dopamine sometimes causes a substantial decrease in blood pressure. The present study was designed to compare the effects of dopamine in normothermia to those seen after surface cooling to 32 degrees C. METHODS: Seven pigs with a mean body weight of 21 kg were anesthetized with ketamine and muscle relaxation was induced with pancuronium. They were mechanically ventilated and given dopamine infusions (5 and 12 micrograms.kg-1.min-1)in normothermia and after surface cooling by cold water immersion to a central blood temperature of 32.0 degrees C (range 31.6-32.6 degrees C). RESULTS: In normothermia, dopamine at a dose of 5 micrograms.kg-1.min-1 increased mean arterial blood pressure (MAP) by 16% (P < 0.01) and cardiac output (CO) by 9% (P = 0.051); at 12 micrograms.kg-1.min-1 dopamine increased MAP by 26% (P < 0.01) and CO by 18% (P < 0.01). In hypothermia, MAP and CO did not change at an administration rate of 5 micrograms.kg-1.min-1; at 12 micrograms.kg-1.min-1 CO was unchanged but MAP was significantly reduced by 15% (P < 0.01). CONCLUSION: Dopamine increased CO and MAP in normothermia but not at 32 degrees C, where there was even a significant reduction of MAP in this porcine model.

Regional cerebral blood flow (SPECT) during anaesthesia with isoflurane and nitrous oxide in humans.

Nitrous oxide and isoflurane have different effects on absolute cerebral blood flow (CBF) and regional distribution of CBF in humans. In this study we examined the effects of isoflurane in combination with nitrous oxide on CBF. We studied 10 patients (two groups of five patients, ASA I) anaesthetized with 50% nitrous oxide and either 0.5 or 1.0 MAC of isoflurane during normocapnia (PaCO2 5.7 kPa) using two-dimensional CBF measurement (CBFxenon) (i.v. 133xenon washout technique) and a three-dimensional method for measurement of regional CBF (rCBF) distribution with SPECT (single photon emission computer-aided tomography with 99mTc- HMPAO). The results were compared with 1.0 MAC of isoflurane from a previous study performed in exactly the same way as the present investigation. During normocapnia, anaesthesia with 50% nitrous oxide and 0.5 MAC of isoflurane resulted in a mean CBFxenon of 45 (SEM 5) ISI units. Increasing the isoflurane concentration to 1.0 MAC had no significant effect on mean CBFxenon (53 (5) ISI units). Both flow values were significantly (P = 0.01) higher than the CBFxenon value obtained when 1 MAC of isoflurane was administered alone (33 (3) ISI units). There were no significant differences in rCBF distribution regardless of whether or not isoflurane was given alone or together with nitrous oxide at 0.5 or 1 MAC. In all situations there were higher relative flows in subcortical regions (thalamus and basal ganglia, 10%) and in the pons (7-10% above average). rCBF in the cerebellum was approximately 10% greater than average. In summary, we have found that mean CBF was greater with combined nitrous oxide and isoflurane anaesthesia than previously found with isoflurane alone; however, relative flow distribution was similar.

Cardiac changes in stroke patients and controls evaluated with transoesophageal echocardiography.

In stroke patients several cardiac changes associated with embolism can be detected with transoesophageal echocardiography. Potential major cardiac embolic sources (e.g. atrial fibrillation, thrombi of left ventricle/atrium, vegetation, myxoma, dilated cardiomyopathy) have a causal relationship to embolism. Other changes with no certain causal relationship are regarded as potential minor cardiac embolic sources (e.g. atrial septal aneurysm, patent foramen ovale, mitral annular calcification, mitral valve prolapse, protruding atheroma of the aorta). We compared the prevalences of major and minor potential cardiac embolic sources in a stroke population with that in controls. One hundred and twenty-one patients with first-ever stroke were compared with 68 randomly selected controls. All subjects underwent magnetic resonance imaging of the brain, carotid ultrasound and transthoracic/transoesophageal echocardiography. The patients were slightly older (mean age 70.7 +/- 10.3 years) than the controls (65.5 +/- 15.5 years) (p < 0.05). Potential major cardiac embolic sources were found in 27% of the patients and in 4% of the controls (p < 0.001). The most common major potential embolic source was atrial fibrillation, detected in 22/121 patients. Fifteen of these also had spontaneous echocontrast in the left atrium. Eleven left atrial thrombi were found (four of these patients had atrial fibrillation and seven had sinus rhythm). A history of heart disease was more common in patients with a potential major cardiac embolic source or a carotid artery stenosis (77%) than in those patients without (44%) (p < 0.01). After excluding subjects with a major potential cardiac embolic source and/or carotid artery stenosis, no differences in the prevalence of minor potential cardiac embolic sources were found between patients (55%) and control subjects (47%) (p = NS). Even when subjects without a major potential cardiac embolic source or a carotid artery stenosis were categorized into three age groups (35-54, 55-74 and > 74 years) the prevalence of potential minor cardiac embolic sources did not differ between patients and controls. To conclude, major potential cardiac embolic sources are more common in an older population with first-ever stroke than in a comparable control group. However, potential minor cardiac embolic sources did not differ in prevalence in the patients compared with controls. Certain changes (e.g. atrial septal aneurysm) might have a potential embolic role in younger stroke patients but in our study no difference was found between older stroke patients and controls.

Side localization of parathyroid adenomas by simplified intraoperative venous sampling for parathyroid hormone.

Side localization of parathyroid adenomas was performed by venous sampling for intact parathyroid hormone (PTH) in 20 consecutive patients with primary hyperparathyroidism (pHPT) after induction of anesthesia. The results were thus available during surgery. Nineteen of the patients had solitary parathyroid adenoma, and one had hyperplasia. There was no complication to the procedure. A lateralizing PTH gradient for a parathyroid adenoma was obtained in 13 patients. At surgery 12 of them (92%) were proved correct; that is, the adenoma was localized on the same side. Thus the technique correctly lateralized the adenoma in 12 of 19 patients (63%). We therefore conclude that the method of intraoperative venous sampling for intact PTH is safe, and the predictive value of a lateralizing gradient is high. It could therefore be used as an adjunct to surgical skill and noninvasive localization procedures in selected cases, for instance in patients with prior neck surgery and hypercalcemic crisis.

Distribution of cerebral blood flow during anesthesia with isoflurane or halothane in humans.

BACKGROUND: Halothane and isoflurane have been shown to induce disparate effects on different brain structures in animals. In humans, various methods for measuring cerebral blood flow (CBF) have produced results compatible with a redistribution of CBF toward deep brain structures during isoflurane anesthesia in humans. This study was undertaken to examine the effects of halothane and isoflurance on the distribution of CBF. METHODS: Twenty ASA physical status patients (four groups, five in each) anesthetized with either isoflurane or halothane (1 MAC) during normo- or hypocapnia (PaCO2 5.6 or 4.2 kPa (42 or 32 mmHg)) were investigated with a two-dimensional CBF measurement (CBFxenon, intravenous 133xenon washout technique) and a three-dimensional method for measurement of the regional CBF (rCBF) distribution with single photon emission computer-aided tomography (SPECT; 99mTc-HMPAO). In the presentation of SPECT data, the mean CBF of the brain was defined as 100%, and all relative flow values are related to this value. RESULTS: The mean CBFxenon level was significantly influenced by the PaCO2 as well as by the anesthetic used. At normocapnia, patients anesthetized with halothane had a mean CBFxenon of 40 +/- 3 (SE) ISI units. With isoflurane, the flow was significantly (P < 0.01, 33 +/- 3 ISI units) less than with halothane. Hypocapnia decreased mean CBFxenon (P < 0.0001) during both anesthetics (halothane 24 +/- 3, isoflurane 13 +/- 2 ISI units). The effects on CBFxenon, between the anesthetics, differed significantly (P < 0.01) also during hypocapnia. There were significant differences in rCBF distribution measured between the two anesthetics (P < 0.05). During isoflurane anesthesia, there was a relative increase in flow values in subcortical regions (thalamus and basal ganglia) to 10-15%, and in pons to 7-10% above average. Halothane, in contrast, induced the highest relative flow levels in the occipital lobes, which increased by approximately 10% above average. The rCBF level was increased approximately 10% in cerebellum with both anesthetics. Changes in PaCO2 did not alter the rCBF distribution significantly. CONCLUSIONS: There is a difference in the human rCBF distribution between halothane and isoflurane with higher relative flows in subcortical regions during isoflurane anesthesia. However, despite this redistribution, isoflurane anesthesia resulted in a lower mean CBFxenon than did anesthesia with halothane.

Effects of nitrous oxide on human regional cerebral blood flow and isolated pial arteries.

BACKGROUND: Results from previous studies on the effect of nitrous oxide (N2O) on the cerebral circulation are conflicting. Early reports claim N2O to have no effect whereas recent findings demonstrate a cerebral cortical vasodilatation during N2O inhalation, but the regional cerebral blood flow (CBF) in the subcortical structures is unknown. METHODS: Regional CBF was measured three-dimensionally with single photon emission computer-aided tomography after injection of xenon 133 in 8 spontaneously breathing men (mean age 29.6 yr) during normocapnia and hypocapnia with and without inhalation of 50% N2O. 8 isolated human pial arterial segments were mounted in organ baths. The segments were contracted with prostaglandin F2 alpha and subjected to 30% oxygen and 5.6% carbon dioxide in nitrogen or N2O. RESULTS: Normocapnic young men had a global CBF of 55 +/- 4 ml.100 g-1.min-1. Decreasing end-tidal CO2 tension by 1.3 kPa (9.3 mmHg) reduced CBF uniformly, with a decrease in global CBF to 45 +/- 2 ml.100 g-1.min-1 (P < 0.0001). During normocapnia, inhalation of 50% N2O increased mean CBF to 67 +/- 7 ml.100 g-1.min-1 (P < 0.0001). Inhalation of 50% N2O during hypocapnia increased mean CBF to 63 +/- 5 ml.100 g-1.min-1 (P < 0.0001). During N2O inhalation there was no significant difference in mean CBF between normo- and hypocapnia. However, during hypocapnia, but not during normocapnia, N2O inhalation significantly changed the distribution of regional CBF (P < 0.0001). Compared with hypocapnia without N2O, flow increased through the frontal (143%), parietal (140%) and temporal (133%) regions as well as through insula (151%), basal ganglia (145%) and thalamus (133%). In isolated human pial arteries, addition of N2O changed neither basal tension, nor the contraction elicited by prostaglandin F2 alpha. CONCLUSIONS: Inhalation of 50% N2O increased global CBF mainly by augmenting flow in frontal brain structures. In contrast, changes in carbon dioxide without N2O affected CBF uniformly in the brain. The uneven change in distribution of the CBF when N2O was added during hypocapnia, the reduced carbon dioxide response, and the lack of effect of N2O on isolated human pial arteries suggest that N2O may increase metabolism in selected brain areas.

Cerebral blood flow during carotid endarterectomy determined by three dimensional SPECT measurement; relation to preoperative risk assessment.

Cross-clamping of the carotid artery during carotid endarterectomy implies a risk of developing an ischaemic insult. To evaluate the effects of carotid artery occlusion on cerebral blood flow (CBF), both hemispheric and regional CBF (rCBF) were investigated using intravenously (i.v.) administered 133Xenon with 3 min clearance recording time for two-dimensionally (hemispheric CBF) and 99m-technetium-hexamethylpropylene amine oxime (99mTC-HMPAO) for three-dimensionally single photon emission computed tomography (SPECT) measurements (rCBF). Thirteen patients scheduled to undergo carotid endarterectomy anaesthetised with fentanyl/isoflurane participated in the study. Preoperative evaluation included investigation of rCBF with SPECT in all participants. Two intraoperative 133Xe CBF measurements were performed in each patient, before and after occlusion of the carotid artery. The preoperative rCBF measurement constituted the reference, for technical reasons, for the intraoperative investigations of rCBF during cross-clamping, which was completed immediately after the hemispheric measurements. The increase in preoperative risk evaluation as described by Sundt et al. and modified by Cho et al. corresponded excellently to a decrease in hemispheric CBF due to cross-clamping. A significant decrease in rCBF (p < 0.005) was present between patients with high and low preoperative risk score for the region of the middle cerebral artery. In this region, a correlation between decrease in rCBF and corresponding decrease in hemispheric CBF was also present. The present study demonstrates that the vascular regions of the ipsilateral middle cerebral artery are the most vulnerable vascular area during cross-clamping in individuals with high preoperative risk score.(ABSTRACT TRUNCATED AT 250 WORDS)

Surgery for primary hyperparathyroidism performed under local anaesthesia.

Patients with primary hyperparathyroidism are often elderly with cardiovascular disease and in some an operation might be hazardous owing to anaesthetic complications. A technique for operation for primary hyperparathyroidism under local anaesthesia is described. The method uses a unilateral approach. Seventeen consecutive patients operated on under local anaesthesia were compared with a group of 15 patients undergoing surgery under general anaesthesia. Normocalcaemia was achieved in 14 patients in each group. There was no difference in the extent of pain or the overall well-being between the two groups as determined by a visual analogue scale. Patients receiving local anaesthesia, however, experienced significantly less nausea after operation (P < 0.01). There was more fluctuation in blood pressure and heart rate in the general anaesthesia group compared with the other group. Surgery for primary hyperparathyroidism can be performed safely under local anaesthesia, and could be offered to patients if general anaesthesia were not suitable or involved an increased perioperative risk. It should not be recommended for routine use in patients who are fit for general anaesthesia.

Effects of nitrous oxide on cerebral haemodynamics and metabolism during isoflurane anaesthesia in man.

Seven normoventilated and five hyperventilated healthy adults undergoing cholecystectomy and anaesthetized with methohexitone, fentanyl and pancuronium were studied with measurement of cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and quantified electroencephalography (EEG) under two sets of conditions: 1) 1.7% end-tidal concentration of isoflurane in air/oxygen; 2) 0.85% end-tidal concentration of isoflurane in nitrous oxide (N2O)/oxygen. The object was to study the effects of N2O during isoflurane anaesthesia on cerebral circulation, metabolism and neuroelectric activity. N2O in the anaesthetic gas mixture caused a 43% (P less than 0.05) increase in CBF during normocarbic conditions but no significant change during hypocapnia. CMRO2 was not significantly altered by N2O. EEG demonstrated an activated pattern with decreased low frequency activity and increased high frequency activity. The results confirm that N2O is a potent cerebral vasodilator in man, although the mechanisms underlying the effects on CBF are still unclear.

Cardiopulmonary perfusion and cerebral blood flow in bilateral carotid artery disease.

The fear of cerebral complications after cardiopulmonary bypass in patients with heart disease and severe carotid artery disease has led many authors to suggest combined approaches in these patients. The pathogenetic mechanism for stroke is based partly on the stenotic narrowing of the carotid artery. A diameter reduction of 75% is frequently considered hemodynamically significant and indicative of an increased risk for neurological morbidity. We studied the cerebral blood flow in 7 patients undergoing coronary artery bypass grafting who also had severe bilateral carotid disease. The results were compared with the results in 17 patients without carotid disease who had bypass grafting. The cerebral blood flow was measured by xenon 133 washout technique before, during, and after cardiopulmonary bypass with moderate hypothermia. Acid-base regulation was according to the alpha-stat theory, and blood pressure was kept greater than 50 mm Hg. The cerebral blood flow levels (mL.100g-1.min-1) before, during, and after cardiopulmonary bypass in the study group (30 +/- 11, 31 +/- 8, 47 +/- 20) (mean +/- standard deviation) were almost identical to those in the control group (30 +/- 11, 28 +/- 8, 47 +/- 12). The cerebral blood flow levels for the left and right hemispheres in the group with carotid disease were comparable and within normal ranges. In 2 patients, slight differences were noted between hemispheres, and this finding may indicate an increased risk for ischemia. These patients, however, did not show any signs of postoperative deficit. The flow limitations of critical carotid stenoses do not seem to imply a risk for cerebral hypoperfusion if cardiopulmonary perfusion is performed in a controlled manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous transcranial Doppler sonography and cerebral blood flow measurements of cerebrovascular CO2-reactivity in patients with aneurysmal subarachnoid haemorrhage.

Transcranial Doppler sonography (TCD) flow velocities and cerebral blood flow (CBF) measurements were evaluated in 14 patients who had suffered a major aneurysmal subarachnoid hemorrhage (SAH). Cerebrovascular reactivity to hypocapnia was evaluated simultaneously by the two methods. The measurements were performed under general anaesthesia preoperatively, within 72 hours after the bleed, during normocapnia and hypocapnia. There was poor correlation between absolute values of hemispheric CBF and corresponding TCD mean flow velocity. Controlled hyperventilation was associated with a significant decrease in CBF as well as TCD flow velocity (p less than 0.001). In terms of reactivity indices the correlation between the two methods was poor and not significant (r = 0.33, p = 0.09). The principal differences between the methods are discussed as well as the application of TCD in the evaluation of cerebrovascular reactivity.