Summary

Background and objective: The haemodynamic effects of acute pulmonary hypertension can be largely attributed to ventricular interdependence during diastole. However, there is evidence that the two ventricles also interact during systole. The aim of the present study was to examine the effects of acute pulmonary hypertension on both components of left ventricular systole, i.e. contraction and relaxation, using load-independent indices. Methods: Ten pigs were instrumented with biventricular conductance catheters, a pulmonary artery flow probe and a high-fidelity pulmonary pressure catheter. Haemodynamic measurements were performed in baseline conditions and during stable pulmonary vasoconstriction induced by the thromboxane analogue U46619. Contractility was quantified using the end-systolic pressure–volume and preload recruitable stroke work relationships. The τ-end-systolic pressure relationship was used to assess load-dependency of relaxation. Results: Acute pulmonary hypertension caused a decrease in the slope of the left ventricular preload recruitable stroke work relationship (from 6.64 ± 1.7 to 5.19 ± 1.9, mean ± SD; P < 0.05), a rightward shift of the end-systolic pressure–volume relationship (P < 0.05), and an increase in the slope of the τ-end-systolic pressure relationship (from −0.15 ± 0.5 to 0.35 ± 0.17; P < 0.05). The diastolic chamber stiffness constant of both ventricles increased during pulmonary hypertension (P < 0.05). Conclusions: In the present model, acute pulmonary hypertension impairs left ventricular contractile function and relaxing properties. The present study provides additional evidence that, besides the well-known diastolic ventricular cross talk, systolic ventricular interaction may play a significant role in the haemodynamic consequences of acute pulmonary hypertension.

Summary

AstraZeneca (the manufacturer of Diprivan™) presents its review of the history of the so-called ‘propofol infusion syndrome’, highlighting the difficulties in analysing the incomplete information available. Theories as to its causality are presented and discussed; these include mitochondrial toxicity, mitochondrial defects, impaired tissue oxygenation and carbohydrate deficiency. A review of published and confidential safety data is presented and discussed; it concludes that the major risk factors for its development appear to be poor oxygen delivery, sepsis, serious cerebral injury and high propofol dosage. In some reports an increasing lipaemia was noted and was likely to be due to a failure of hepatic lipid regulation, possibly related to poor oxygenation and/or possibly a lack of glucose. In some cases an increasing lipaemia was the first indication of impending ‘propofol infusion syndrome’ onset and it should not be viewed as a benign sign. The lipaemia can lead to sequestration of propofol into the lipid phase, leading to lowered free propofol levels and apparent insensitivity to propofol. In conclusion AstraZeneca advocates good haemodynamic and oxygen delivery management, adequate glucose provision, adherence to recommended propofol dosing regimes together with active management of lipaemias to both prevent and treat ‘propofol infusion syndrome’.

Summary

Subarachnoid haemorrhage due to rupture of cerebral aneurysms is a multisystem disease. Treatment of the condition in the past has relied on craniotomy and clipping of the aneurysm to prevent a recurrent haemorrhage. There is now emerging evidence to suggest that endovascular treatment of cerebral aneurysms may reduce the morbidity associated with open surgery. The anaesthetic management of interventional neuroradiology also creates new challenges due to the novel approach to treatment. Anaesthetists need to be familiar with this procedure and the management of potential complications. This review provides an overview such considerations.

Summary

Background and objective: The aromatic alcohol most closely resembling the aromatic tail of lidocaine is 2,6-dimethylphenol. This agent is as potent as lidocaine in blocking voltage-operated sodium channels. The aim of this study was to show the effect of halogenation in the para-position on the potency of this compound to block voltage-operated sodium channels. Methods: Insertion of the halogen chloride into the para-position of the molecule 2,6-dimethylphenol yielded 2,6-dimethyl-4-chlorophenol. Block of sodium currents by this compound was studied using heterologously expressed voltage-operated rat neuronal (rat IIa) sodium channels. Results: 2,6-dimethyl-4-chlorophenol reversibly suppressed depolarization-induced whole-cell sodium inward currents. The ECR50 for block of resting channels at a hyperpolarized holding potential (−150 mV) was 127 μmol, the Hill coefficient nH 1.7. Membrane depolarization inducing either fast or slow-inactivation strongly increased the blocking potency. This is an important feature of a local-anaesthetic-like action. The estimated half-maximum effect concentration for the fast-inactivated channel state ECI50 was 28 μmol, the Hill coefficient nH 3.8. When 20–30% of channels were slow-inactivated using long (2.5 s) prepulses, followed by a 10 ms repolarization period to allow recovery from fast inactivation, the IC50 at −100 mV holding potential was reduced to 53 μmol. Conclusion: These results, which show that 2,6-dimethyl-4-chlorophenol blocks voltage-operated sodium channels in a lidocaine-like manner while having a several fold higher potency than the non-halogenated parent compound, highlight a potentially meaningful principle of increasing the sodium channel blocking potency of phenol derivatives.

Summary

Background and objective: To assess the knowledge, beliefs and attitudes of anaesthesia providers on the patients' possible intraoperative visual experiences during cataract surgery under local anaesthesia. Methods: Anaesthesia providers from the Ophthalmic Anaesthesia Society (USA); British Ophthalmic Anaesthesia Society (UK); Alexandra Hospital, National University Hospital, Tan Tock Seng Hospital, Singapore General Hospital and Changi General Hospital (Singapore) were surveyed using a structured questionnaire. Results: A total of 146 anaesthesiologists (81.6%), 10 ophthalmologists (5.6%) and 23 nurse anaesthetists (12.8%) responded to the survey. Most respondents believed that patients would experience light perception and many also felt that patients might encounter other visual sensations such as movements, flashes, colours, surgical instruments, hands/fingers and the surgeon during the surgery. A significantly higher proportion of anaesthesia providers with previous experience of monitoring patients under topical anaesthesia believed that patients might experience the various visual sensations compared to those who have not previously monitored. For both topical and regional anaesthesia, anaesthesia providers who routinely counsel their patients are (1) more likely to believe that preoperative counselling helps or (2) were previously told by patients that they could see intraoperatively and/or that they were frightened by their visual sensations. These findings were statistically significant. Conclusions: The majority of anaesthesia providers in the USA, UK and Singapore are aware that patients may experience a variety of visual sensations during cataract surgery under regional or topical anaesthesia. Those who have previously managed patients undergoing cataract surgery under topical anaesthesia are more likely to believe this compared to those who have not.

Summary

Background and objective: To determine the minimal oxygen delivery and pump flow that can maintain systemic oxygen uptake during normothermic (37°C) pulsatile and non-pulsatile cardiopulmonary bypass in dogs. Methods: Eighteen anaesthetized dogs were randomly assigned to receive either non-pulsatile (Group C; n = 9) or pulsatile bypass flow (Group P; n = 9). Oxygen delivery was reduced by a progressive decrease in pump flow, while arterial oxygen content was maintained constant. In each animal, critical oxygen delivery was determined from plots of oxygen uptake vs. oxygen delivery and from plots of blood lactate vs. oxygen delivery using a least sum of squares technique. Critical pump flow was determined from plots of lactate vs. pump flow. Results: At the critical point, oxygen delivery obtained from oxygen uptake was 7.7 ± 1.1 mL min−1 kg−1 in Group C and 6.8 ± 1.8 mL min−1 kg−1 in Group P (n.s.). These values were similar to those obtained from lactate measurements (Group C: 7.8 ± 1.6 mL min−1 kg−1; Group P: 7.6 ± 2.0 mL min−1 kg−1). Critical pump flows determined from lactate measurements were 55.6 ± 13.8 mL min−1 kg−1 in Group C and 60.8 ± 13.9 mL min−1 kg−1 in Group P (n.s.). Conclusions: Oxygen delivery values greater than 7–8 mL min−1 kg−1 were required to maintain oxygen uptake during normothermic cardiopulmonary bypass with either pulsatile or non-pulsatile blood flow. Elevation of blood lactate levels during bypass helps to identify inadequate tissue oxygen delivery related to insufficient pump flow.

Summary

Background and objective: The glutamate-nitric oxide-cyclic guanosine monophosphate pathway has been identified as a potential target for anaesthetic agents. However, mice deficient in neuronal nitric oxide synthase have a similar susceptibility to volatile anaesthetic agents to wild-type mice and are not affected by non-isoform selective inhibitors. We hypothesized that the neuronal nitric oxide synthase selective inhibitor, 7-nitroindazole, would also reduce the propofol requirements in wild-type mice but would have no effect in neuronal nitric oxide synthase knockout mice. Methods: We determined the time to loss of righting reflex, time to painful stimulus and time to regaining the righting reflex in neuronal nitric oxide synthase knockout and wild-type mice following the intraperitoneal injection of propofol in untreated, 7-nitroindazole and vehicle only treated animals (n = 6 per group). Propofol (200 mg kg−1) resulted in loss of righting reflex in the untreated and vehicle only groups but was lethal in 7-nitroindazole pre-treated mice, requiring a reduced dose of propofol (100 mg kg−1). Results: 7-nitroindazole pre-treatment significantly reduced the loss of righting reflex (P < 0.001) in both wild-type and knockout mice when compared to untreated and vehicle only pre-treated animals, but had no effect on time to painful stimulus or regaining of the righting reflex. 7-nitroindazole reduced the propofol requirements in knockout mice to the same extent as in wild-type animals. Conclusions: Propofol exerts its anaesthetic effects at least partially via the glutamate-nitric oxide-cyclic guanosine monophosphate pathway. The neuronal nitric oxide synthase knockout mice are sensitive to neuronal nitric oxide synthase selective inhibition suggesting that compensatory pathways in neuronal nitric oxide synthase knockout mice exist.

Summary

Background and objective: Following strabismus surgery, immediate postoperative ophthalmic evaluation may be desired. Thus, an anaesthetic technique allowing rapid recovery of ocular motility is required. Saccadic eye movements is a biophysical monitor of ocular motility and may be used to assess recovery from anaesthesia. The aim of this study is to compare the time to the recovery of saccadic eye movements in patients, following one of two anaesthetic techniques: Propofol–remifentanil-based anaesthesia vs. sevoflurane–fentanyl-based anaesthesia. Methods: Fifty adult patients undergoing strabismus surgery were randomly assigned to one of two groups: patients in Group R received induction and maintenance of anaesthesia with propofol and remifentanil, while patients in Group S received induction of anaesthesia with propofol and fentanyl and maintenance of anaesthesia with sevoflurane. Recovery from anaesthesia was measured from the time all anaesthetics were turned off and was assessed every 2 min. Recovery time was attained when patients were able to generate brisk saccadic eye movements. At recovery time, the ophthalmic evaluation was started. Results: The mean recovery time of saccadic eye movements was significantly shorter in the Group R when compared to the Group S (12.1 ± 4.3 min vs. 21.5 ± 4.7 min, respectively, P < 0.0001). More patients in Group S experienced nausea and vomiting postoperatively as compared to Group R (9/25 vs. 2/25, respectively, P = 0.037). Conclusions: Propofol–remifentanil-based anaesthesia may be a useful technique in strabismus surgery when immediate postoperative ophthalmic evaluation is desired. When compared to sevoflurane maintenance of anaesthesia, it allows for a more rapid recovery from anaesthesia as judged by recovery of saccadic eye movements and a decreased incidence of postoperative nausea and vomiting.

Summary

Background and objective: High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome. Methods: Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5–1.0 μg kg−1 min−1) or propofol/sufentanil (30–40 ng kg−1 min−1) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group. Results: Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05). Conclusions: Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

Summary

Closed circuit anaesthesia was described decades ago but did not achieve wide popularity among anaesthesiologists mainly because reliable control of inspiratory gas concentrations was not possible. Recent innovations including fast gas analysers, electronically controlled dosage systems and algorithms for feedback control have made possible the development of sophisticated closed circuit ventilators designed for routine clinical practice. The main advantages comprise economic use of medical gases and volatile anaesthetics, reduction of anaesthetic gas loss into the atmosphere, improved airway acclimatization as well as estimations of oxygen consumption. This article reviews historical aspects, recent developments as well as advantages and limitations of closed system anaesthesia.

Summary

Background and objective: To investigate the effects of intra-aortic balloon pump therapy on parameters of global and regional oxygenation in patients undergoing cardiac surgery. Methods: As part of a large surveillance study in cardiac surgery patients (n = 266) we retrospectively analyzed the course of 28 patients requiring intra-aortic balloon pump therapy. Patients were grouped according to the time point of pump insertion (during weaning from cardiopulmonary bypass: group early intra-aortic balloon pumping (n = 17); after admission to the intensive care unit: group late intra-aortic balloon pumping (n = 9). Haemodynamic and tonometric variables, arterial lactate, and use of catecholamines were measured hourly. Measurements and results: Cardiac index increased in both groups after intra-aortic balloon pump insertion (2.2 ± 0.5 baseline; 3.4 ± 0.8 L min−1 m−2 4 h later (group early intra-aortic balloon pumping); 2.8 ± 0.5 baseline, 3.6 ± L min−1 m−2 4 h later (group later intra-aortic balloon pumping), each P < 0.05), there were no differences between groups. Arterial lactate values increased in group later intra-aortic balloon pumping after pump insertion to a maximum 2 h later (8.4 ± 6.1 mmol L−1 baseline; 12.7 ± 7.4 mmol L−1, P < 0.05), and decreased continuously afterwards. The difference of arterial and gastric CO2 showed a sharp decrease after pump insertion in group later intra-aortic balloon pumping (26.4 ± 9.8 baseline; 7.0 ± 11.1 mmHg, P < 0.05). There were no differences between groups. Epinephrine doses were higher in group later intra-aortic balloon pumping (P < 0.05). Conclusions: Intra-aortic balloon pump therapy improved global and regional splanchnic oxygenation in cardiac surgery patients with low-cardiac-output syndrome. Gastro-intestinal tonometry could provide additional information concerning tissue oxygenation. Patients with later intra-aortic balloon pump insertion needed more catecholamine therapy to achieve similar haemodynamic values.

Summary

Background and objective: Sedation is commonly required by critically ill patients and inadequate sedation may be hazardous. Traditionally, subjective scales have been used for monitoring sedation. Bispectral index has been proposed, although its utility in the intensive care unit is debated. Our aim was to evaluate the depth of sedation in intubated surgical critically ill patients by means of two sedation scales (Ramsay and Observer's Assessment of Alertness and Sedation) and bispectral index. Methods: Sedation was assessed prospectively in 50 postoperative intubated patients requiring at least 24 h of sedation (35 propofol, 15 midazolam/fentanyl), every 8 h for a 24 -h period. The bispectral index value recorded was the mean value obtained during a 10-min observation period, whenever the quality signal index was above 75% and the electromyographic signal was below 25%. Results: Most of the patients (78%) were oversedated (bispectral index < 60). The three sedation scores (global data) correlated significantly (P < 0.001). This correlation was lost in the midazolam group in which the patients were also significantly more sedated than the propofol group (P = 0.001). The correlation between the bispectral index and the scales in the midazolam group reappeared when the measurements with a Ramsay = 6 or an Observer's Assessment of Alertness and Sedation = 1 were excluded. Conclusions: Sedation should be monitored routinely in intensive care units. The Ramsay and the Observer's Assessment of Alertness and Sedation scales showed equal efficacy. Bispectral index might prove useful for discriminating between deeper levels of sedation.

Summary

Background and objective: Inhalation anaesthetics given only during post-ischaemic reperfusion have some protective effect against reperfusion injury in the heart. Adenosine triphosphate-regulated mitochondrial potassium channels have been shown to be an important mediator of cardioprotection. Thus, we investigated whether 5-hydroxydecanoate, a putative mitochondrial potassium channel blocker, prevents the cardioprotective effect of volatile anaesthetics. Methods: Forty rats were randomly allocated to four groups of equal size: control group, 5-hydroxydecanoate group, 5-hydroxydecanoate + sevoflurane group and 5-hydroxydecanoate + isoflurane group. Seven minutes after the start of perfusion, normal saline (control group) or 5-hydroxydecanoate (the other groups) was administered. Ten minutes after the start of perfusion, the heart was rendered globally ischaemic for 10 min. One minute before the end of the ischaemic period, 2.7% sevoflurane or 1.4% isoflurane were administered in the 5-hydroxydecanoate + sevoflurane or 5-hydroxydecanoate + isoflurane groups respectively. The heart was reperfused for 10 min. Results: Adenosine triphosphate content at the end of reperfusion in the 5-hydroxydecanoate + sevoflurane group was significantly lower (P < 0.05) than those in the control and the 5-hydroxydecanoate + isoflurane groups (19.9 ± 8.7, 28.1 ± 3.4 and 30.4 ± 2.3 μmol g−1, respectively). In addition, the combination of inhalation anaesthetics and 5-hydroxydecanoate decreased the ratios of recovered hearts from ischaemia (5-hydroxydecanoate + sevoflurane group: 40%, 5-hydroxydecanoate + isoflurane group 50%). Conclusion: 5-hydroxydecanoate alone caused no significant changes in haemodynamics and myocardial metabolism. However, the combination of 5-hydroxydecanoate and volatile anaesthetics impaired the recovery from ischaemia. Although animal data cannot be extrapolated to human beings, we suggest that more attention be paid to patients on sulphonylurea drugs, which inhibit potassium channels, when they are anaesthetized with volatile anaesthetics.

Summary

Background and objective: Sub-Tenon's block is usually delivered by the infero-nasal (IN) approach, but occasionally this may not be possible. The infero-temporal (IT) approach has been described, but data is not available on its efficacy. Methods: One hundred patients undergoing cataract extraction were randomized to receive an IN or IT sub-Tenon's injection of lidocaine 2% with hyaluronidase 15 IU mL−1. Akinesia was assessed using the Brahma scale at 0, 2, 4, 6 and 8 min. Injection, intraoperative and postoperative pain scores (verbal analogue score, 0–10) were noted, along with the incidence of sub-conjunctival haemorrhage and chemosis. Results: There were no differences in patient characteristics data, or mean volume of administered local anaesthetic solution (3.3 (SD = 0.4) mL). There were no significant differences between groups in terms of onset of akinesia. Mean akinesia scores at 2, 4, 6 and 8 min were 2.7, 1.1, 0.4 and 0.2 for Group IN, compared to 2.2, 0.9, 0.8 and 0.3 for Group IT. Chemosis occurred in 14 patients in Group IN, compared to 22 in Group IT (P = 0.21).A sub-conjunctival haemorrhage was noted in 14 patients in Group IN and 19 patients in Group IT (P = 0.52). No patients required supplementary injections. Mean pain scores for the injection, intraoperatively and postoperatively were 0.9, 0 and 0 for Group IN, compared to 1.1, 0 and 0 for group IT. The surgeons scored all the blocks as ‘good’ except for one patient in each group. Conclusions: The IT approach provides an equally rapid onset of block, without a significant increase in complications.

Summary

Background: The aim of this prospective, randomized, blinded study was to compare analgesic efficacy of continuous paravertebral and epidural analgesia for post-thoracotomy pain. Methods: Forty-two ASA physical status II–III patients undergoing lung resection surgery were randomly allocated to receive post-thoracotomy analgesia with either a thoracic epidural (group EPI, n = 21) or paravertebral (group PVB, n = 21) infusion of 0.2% ropivacaine (infusion rate: 5–10 mL h−1). The degree of pain at rest and during coughing, haemodynamic variables and blood gas analysis were recorded every 12 h for the first 48 h. Results: The area under the curve of the visual analogue pain score during coughing over time was 192 (60–444) cm h−1 in group EPI and 228 (72–456) cm h−1 in group PVB (P = 0.29). Rescue morphine analgesia was required in four patients of group EPI (19%) and five patients of group PVB (23%) (P = 0.99). The PaO2/FiO2 ratio reduced significantly from baseline values in both groups without between-group differences. The median (range) percentage reduction of systolic arterial pressure from baseline was −9 (0 to −9)% in group PVB and −17 (0 to −38)% in group EPI (P = 0.02); while clinically relevant hypotension (systolic arterial pressure decrease >30% of baseline) was observed in four patients of group EPI only (19%) (P = 0.04). Patient satisfaction with the analgesia technique was 8.5 (8–9.8) cm in group EPI and 9 (7.5–10) cm in group PVB (P = 0.65). Conclusions: Continuous thoracic paravertebral analgesia is as effective as epidural blockade in controlling post-thoracotomy pain, but is associated with less haemodynamic effects.

Summary

Background and objective: Acute renal failure is a serious complication of cardiac surgery. We studied the long-term survival and quality of life of patients requiring renal replacement therapy after cardiac surgery, since they represent a heavy burden on hospital resources and their outcome has never been adequately evaluated. Methods: Out of 7846 consecutive cardiac surgical patients, 126 (1.6%) required postoperative renal replacement therapy: their preoperative status and hospital course was compared with patients who had no need of postoperative renal replacement therapy. A multivariate analysis identified predictors of renal replacement therapy. Long-term survival and quality of life was collected in patients who had renal replacement therapy and in case-matched controls. Results: Hospital mortality in the study group was 84/126 (66.7%) vs. 118/7720 (1.5%) in the control population (P < 0.001). Patients who underwent renal replacement therapy and were discharged from the hospital (42 patients) had a reasonable long-term outcome: at 42 ± 23 months, 30 out of 42 patients were alive, with only 3 patients complaining of limitations in daily activities. Predictors of in-hospital renal replacement therapy were: emergency surgery, preoperative renal impairment, intra-aortic balloon pumping, reoperation for bleeding, previous cardiac surgery, female gender, low ejection fraction, bleeding >1000 mL, chronic obstructive pulmonary disease and age. Conclusions: This study confirms that the in-hospital mortality of patients requiring renal replacement therapy is high and shows a low long-term mortality with reasonable quality of life in patients discharged from hospital alive.

Summary

Background and objective: Combined (local and general) anaesthesia or Balanced (intravenous analgesics and inhalational hypnotics) anaesthesia are commonly used in paediatrics. The authors have investigated the influence of both types of anaesthesia on the requirements of sevoflurane to maintain an adequate level of hypnosis as measured by Bispectral index (at around 50) monitoring in paediatric orthopaedic patients. Methods: Twenty-six orthopaedic surgery patients aged 2–15 yr were randomized to receive, during general sevoflurane anaesthesia, 5 μg kg−1 of intravenous fentanyl (Balanced anaesthesia group) or 1 mL kg−1 of caudal-epidural bupivacaine 0.25% (Combined anaesthesia group). The end-tidal sevoflurane concentration was adjusted every 5 min in order to maintain Bispectral index values at around 50. Results: Patients showed very similar Bispectral index values (P > 0.05) in both the Combined and the Balanced groups before anaesthesia (96.7 ± 2.7 vs. 96.9 ± 1.8), after induction (48.5 ± 2.9 vs. 49.8 ± 3.6) and after administration of analgesia (50.9 ± 3.8 vs. 50.3 ± 4.3). The sevoflurane end-tidal concentration requirements were similar in both the Combined and Balanced groups before administration of analgesia (2.1 ± 0.2 vs. 2.1 ± 0.4, P = 0.9415), but lower end-tidal concentrations were required by the Combined group than by the Balanced group (0.81 ± 0.4 vs. 1.5 ± 0.5, P < 0.0001) in the first 20 min after administration of analgesia. Conclusion: Combined anaesthesia with epidural bupivacaine maintains the same Bispectral index values as Balanced anaesthesia during orthopaedic surgery in children without fentanyl and with a lower sevoflurane requirement.

Summary

Background and objective: Cardiopulmonary bypass is known to induce postoperative coagulopathy including fibrinolysis. We have evaluated the effect of the topical use of tranexamic acid in the pericardial cavity on postoperative bleeding following open heart surgery. Methods: One hundred patients, scheduled for elective open heart surgery, were included in this double-blind, prospective, randomized, controlled study. They were allocated to a treatment group (Group I), or placebo group (Group II). Patients with coagulopathies, renal failure, re-do surgery, or recent anti-platelet treatment were excluded. In Group I, tranexamic acid (2 g in 100 mL of saline solution) was poured into the pericardial cavity before sternal closure. Placebo patients received 100 mL of saline. Postoperative blood loss, need for transfusion of blood products and the rate of re-sternotomy for bleeding were documented. Results: During the first postoperative 24 h, cumulative blood loss was significantly higher in Group II compared to Group I (1208 ± 121 mL vs. 733 ± 93 mL, respectively) (P < 0.001). More blood transfusions were administered to Group II patients (4.54 ± 1.4 units) as compared to Group I patients (2.64 ± 1.5 units) (P < 0.01). Conclusion: Topical application of tranexamic acid in patients undergoing primary open heart surgery led to a significant reduction of both postoperative mediastinal bleeding, and rate of re-exploration for haemostasis.

Summary

Background: The suggested induction dose of methohexital for electroconvulsive therapy (ECT) varies widely influencing efficacy of ECT and safety of anaesthesia. Bispectral index (BIS), a monitor of consciousness, may be useful to assure adequate hypnosis with optimized methohexital dose. Methods: Patients with medically resistant major depression (ICD10), scheduled for multiple ECT's, were studied. Depth of anaesthesia was BIS controlled. ECT was not performed until BIS dropped below 50. Initially anaesthesia was induced with methohexital 1.0 mg kg−1, and stepwise reduced by 0.1 mg kg−1 during consecutive treatments. If BIS did not drop below 50, the methohexital was supplemented by further boluses of 0.5 mg kg−1, until the desired level of hypnosis was reached. The adequacy of the anaesthetic recommendation for methohexital (1.0–1.5 mg kg−1) as well as the psychiatric recommendation (0.75–1 mg kg−1) was investigated. Results: One-hundred and nine ECT's in 14 patients were studied. The recommended anaesthetic dose (1.0–1.5 mg kg−1) was inadequate in 40% of the treatments, with 12% exceeding 1.5 mg kg−1, and 28% below 1.0 mg kg−1. Psychiatric recommendation (0.75–1.0 mg kg−1) was inadequate in 49%, with 39% exceeding 1.0 mg kg−1 and 10% undershooting at 0.75 mg kg−1. Conclusions: Methohexital for ECT showed a great variability, exceeding as well as undershooting the dosage recommendations widely. BIS monitoring may be useful to secure adequate hypnosis during muscle relaxation and treatment and may optimize ECT efficacy.

Summary

Background and objective: We conducted this study in order to evaluate the potential myotoxic effects of ropivacaine after single injection in rats and the time-course of the possible damage. Methods: One hundred and twenty-eight male Wistar rats were allocated to four different groups. The first three groups received intramuscular injections with ropivacaine 0.75%, ropivacaine 0.5% and normal saline, respectively, into the right tibialis anterior muscle. The fourth group received needle puncture without injection. Eight rats from each group were sacrificed 2, 4, 7 and 30 days after injection. Samples were blindly examined under light microscope for evidence of myotoxicity, scored as 0 = no damage to 3 = myonecrosis and statistically analysed. Samples obtained 7 days after injection were also examined under transmission electron microscope. Results: Ropivacaine 0.75% and ropivacaine 0.5% caused extensive destruction to muscles fibres, compared to saline or needle on days 2, 4 and 7. Statistically significant differences were found in muscle damage by drug injections among all groups except for saline vs. needle groups. Thirty days after injections all sample appearances had returned to normal. Conclusions: Ropivacaine after single intramuscular injection caused reversible muscle damage in a dose-dependent manner.