Anesthetic Management for Left Ventricular Assist Device Implantation Through Left Thoracotomy: Evaluation of On-Pump Versus Off-Pump.

BACKGROUND: Ventricular assist devices (VADs) are alternative approaches to medical treatment in patients with acute or chronic heart failure. The goal of this study was to compare an anesthetic approach in patients undergoing implantation of a VAD with (on-pump) or without (off-pump) cardiopulmonary bypass (CPB) through left thoracotomy. METHODS: A total of 32 patients were divided into 2 groups: on-pump (group 1) and off-pump (group 2). A standard anesthesia protocol was used in all patients. Baseline characteristics of the patients, intraoperative hemodynamic and respiratory variables, anesthetic agents and vasoactive drugs administered, the amount of blood products, extubation, length of hospital stay and intensive care unit stay, and postoperative complications were recorded. RESULTS: Patients' mean age was 54.7 ± 13.3 years (range, 18-74 years). Eighteen patients underwent surgery with CPB. Demographic data of the patients, preoperative characteristics, intraoperative use of blood products, intraoperative complications, and anesthetic drugs used were similar between groups (P > .05). The duration of surgery (219 ± 23 vs 273 ± 56 minutes) and anesthesia (274 ± 38 vs 323 ± 57 minutes) were shorter in group 2; there was no difference between the 2 groups in terms of mechanical ventilation time, length of stay in the intensive care unit, and length of hospital stay. There was no decrease in postoperative oxygen parameters and an increase in patient lactate levels with the use of CPB. The use of fresh frozen plasma and platelet suspension in the postoperative period was significantly higher in group 1 (P < .05). The rate of complications and mortality rate were comparable between the 2 groups (P > .05). CONCLUSIONS: Our study results show that the use of CPB during VAD implantation via left thoracotomy increases operation time and use of blood products, while causing no change in the rate of complications.

Anesthetic Management for Left Ventricular Assist Device Implantation Without Using Cardiopulmonary Bypass: Case Series.

PURPOSE: Ventricular assist devices are an alternative to medical treatment in patients with hemodynamic disturbances related to acute or chronic congestive heart failure. In this case series, we present our anesthesia management for implantation of left ventricular assist device (LVAD) with thoracotomy. METHOD: Sixteen patients with end-stage heart failure undergoing LVAD implantation via thoracotomy between November 2012 and August 2014 were analyzed prospectively. Preoperative characteristics, intraoperative hemodynamic and respiratory parameters, use of anesthetic and blood products, and durations of mechanical ventilation, hospital, and intensive care stays were recorded. RESULTS: Sixteen patients (mean age, 54.6 ± 13 years) were investigated. Single-lung ventilation was applied to 2 patients. Cardiopulmonary bypass (CPB) was required in 5 patients. Intraoperative ketamine, midazolam, fentanyl, and rocuronium requirements were 112 ± 63 mg, 5.5 ± 3.5 mg, 438 ± 187 µg, and 179 ± 49 mg, respectively. Requirements of fresh donor blood, fresh frozen plasma, and thrombocyte and erythrocyte suspension were 1.19 ± 1, 1 ± 0.8, 0.44 ± 0.5, and 0.25 ± 0.7 U, respectively. Durations of mechanical ventilation, intensive care unit, and hospital stay were 46 ± 53 hours, 8.2 ± 6.6 days, and 20.5 ± 11.6 days, respectively. Twelve patients were discharged from hospital with full recovery and 2 patients died; 2 patients are still receiving treatment in the hospital. CONCLUSION: A left thoracotomy approach can be used without CPB, because it reduces the incidences of pump complications and blood transfusion. In addition, this case series showed that the implantation of LVAD by thoracotomy can be implemented securely with single-lumen endotracheal tube without single-lung ventilation.

Anesthesia for cardiac transplantation: experience from a single center.

BACKGROUND: Cardiac transplantation has become the established therapeutic modality in patients with end-stage heart failure. This article presents our institution's clinical experience in the anesthetic management of patients who underwent cardiac transplantation between February 1998 and August 2012. METHODS: In our institution, 175 patients (136 males and 39 females) diagnosed as having end-stage heart failure have undergone cardiac transplantation between February 1998 and August 2012. A retrospective review performed on this series of patients sought to analyze elements of perioperative anesthetic care, including preoperative characteristics, general anesthia, and blood product usage. RESULTS: The patients were diagnosed as having either nonischemic cardiomyopathy (n = 128; 73%) or ischemic cardiomyopathy (n = 47; 27%). Seventy-three of them had undergone previous cardiac surgery. Invasive arterial, central venous, and pulmonary arterial pressures were monitored as well as intraoperative transesophageal echocardiography. Etomidate was used as the induction agent in 158/175 patients (average dose, 18.67 ± 1.91 mg). The average intraoperative fentanyl dose was 898.85 ± 211.65 µg. Anesthesia was maintained with either end-tidal 2%-4% sevoflurane (n = 132) or 4%-6% desflurane (n = 43). Dopamine, dobutamine, and epinephrine were used after weaning from cardiopulmonary bypass and continued upon exiting the operating room in 168, 159, and 143 patients, respectively. Inhaled nitric oxide (20-40 ppm) was used in 37 patients (21%). The total amount of perioperative blood, fresh frozen plasma, and thrombocyte suspension transfusions were 2.95 ± 2.05 (range, 1-15), 1.29 ± 0.97 (range, 0-6), and 1.23 ± 2.29 (range; 0-12) units, respectively. On average, patients were extubated 16 hours after arrival in the intensive care unit where they remained to day 6. A total of 67 patients (38%) died during the follow-up; infection and right ventricular failure were the most common causes. CONCLUSION: Anesthesia for cardiac transplantation requires an appreciation of heart failure pathophysiology, invasive monitoring, and skillful anesthetic and postoperative care.

Anesthesia for ventricular assist device placement: experience from a single center.

BACKGROUND: Circulatory support with ventricular assist systems has become a treatment alternative for patients with end-stage heart failure owing to the donor shortage. In this report, we have presented our institution's clinical experience in the anesthetic management of ventricular assist device (VAD) implantation. METHODS: Between April 2007 and August 2012, VAD implantation was performed in 84 adult patients with end-stage heart failure. The group included 75 male and 9 female patients of overall mean age, 47.6 ± 13.4 years. Our retrospective review analyzed elements of perioperative anesthetic care, including preoperative characteristics, general anesthetic care, and blood product usage. RESULTS: The indications for VAD implantation were dilated (n = 59; 70%) or ischemic cardiomyopathy (n = 25; 30%). An intra-aortic balloon pump had been placed in 16 patients. We monitored invasive arterial and central venous pressures as well as intraoperative transesophageal echocardiography. Etomidate was used as the induction agent in 79 of 84 patients (average dose, 18.75 ± 1.40 mg). Intraoperative fentanyl dose was 939.69 ± 212.44 µg. Anesthesia was maintained with sevoflurane (n = 55) or desflurane (n = 29). Dopamine, dobutamine, epinephrine, norepinephrine, and levosimendan were used in 74, 79, 60, 14, and 32 patients, respectively. Inhaled nitric oxide was administered to 38 subjects (45%). The amounts of perioperative blood, fresh frozen plasma, and thrombocyte suspension transfusions were 3.96 ± 2.78, 1.91 ± 1.21, 1.80 ± 2.48 u, respectively. On average, patients were extubated 13 hours after arrival in the intensive care unit and discharged therefrom on day 8. Thirty-one patients were successfully bridged to heart transplantation. While 27 patients (32%) died during the follow-up period, 26 are still living on VAD support. CONCLUSION: Among patients undergoing VAD implantation, the anesthesiologist should become familiar with the device and consider the severity of cardiac and other end-organ dysfunction.

Anesthesia for ventricular assist device placement in pediatric patients: experience from a single center.

BACKGROUND: The use of a ventricular assist device (VAD) as a bridge to heart transplantation in the pediatric population has evolved over the past decades This article presents our institution's clinical experience in the anesthetic management of pediatric patients with end-stage heart failure who underwent implantation of a VAD between June 2009 and August 2012. METHODS: Between February 2011 and August 2012, implantation of a VAD was performed in 10 children of mean age 8.6 years. This retrospective review analyzed their perioperative anesthetic care. RESULTS: All patients had end-stage heart failure due to dilated cardiomyopathy. We used invasive arterial and central venous pressure monitoring and intraoperative transesophageal echocardiography in conjunction with intravenous administration of either ketamine (1 mg/kg) and midazolam (n = 3) or thiopental (3-5 mg/kg; n = 7). The mean intraoperative fentanyl dose was 434 ± 264.27 µg. Anesthesia was maintained with sevoflurane. Dopamine, dobutamine, and epinephrine were infused in 8, 10, and 5 patients, respectively. Inhaled nitric oxide was administered to all patients. The amounts of perioperative blood, fresh frozen plasma, and thrombocyte suspension transfusions were be 2.3 ± 0.82 (range, 1-4), 1.6 ± 0.69 (range, 1-3), and 2.4 ± 1.42 (range, 0-4) units, respectively. On average, patients were extubated 23 hours after arrival in the intensive care unit and exited there on day 6. Six patients were successfully bridged to heart transplantation, 2 died during the follow-up, and 2 patients remain on VAD support. CONCLUSION: VAD is increasingly being used as a bridge to heart transplantation in the pediatric population. Anesthesiologists must be vigilant about the pathophysiology of heart failure, the operative procedure, and the implanted device.

Normal glucose enhances neuronal regeneration after lidocaine-induced injury.

BACKGROUND: Local anaesthetics exhibit direct neurotoxic effects on neurones. Numerous studies have investigated the factors that may reverse this neuropathology, but the effects of glucose conditions on neuronal regeneration after lidocaine-induced injury have not been examined by observing living neurones. The present study investigated the effects of different glucose conditions on neurite length, growth cone regeneration, and cell death in dorsal root ganglia (DRG) neurones after lidocaine-induced injury in vitro. METHODS: DRG explants were isolated from chick embryos at embryonic day 8 and cultured in media containing low, normal, or high glucose concentrations (10, 25, or 40 mM) for 24 h. Tissues were exposed to lidocaine 8 mM for 1 h, then rinsed and incubated for a further 24 h. Neurite length and growth cone collapse assays were performed to assess neuronal growth and regeneration. Lactate dehydrogenase (LDH) and caspase assays were also performed to detect neuronal cell death. RESULTS: Addition of lidocaine for 1 h resulted in >97% growth cone collapse and neurite destruction under all three glucose conditions. Two hours after rinsing out the lidocaine, significant reversal of growth cone collapse and neurite elongation was observed under all glucose conditions. Growth cone collapse was higher under low-glucose condition (P<0.05). High glucose negatively affected neurite length more than growth cone collapse. At 24 h, LDH release with both low- and high-glucose conditions was higher than with normal glucose (P<0.05). Low- and high-glucose conditions increased caspase 3/7 activation. CONCLUSIONS: Normal glucose is optimal for neuronal recovery after lidocaine-induced injury in vitro.

Ligasure vessel sealing system versus harmonic scalpel for sutureless nonanatomical pulmonary resections in a rabbit model. Which one is safer?

BACKGROUND: The safety and efficacy of the ligasure vessel sealing system (LVSS) and harmonic scalpel (HS) in sutureless nonanatomical lung resections were evaluated. METHODS: On twenty adult rabbit lungs, 1 x 1 cm wedge resections were performed under one-lung ventilation with both LVSS and HS. The air tightness and tissue damage caused by these different techniques were measured and compared. RESULTS: No statistically significant differences were found when the air tightness for both devices was compared after resection (p = 0.37). Tissue damage was obtained for LVSS, and the difference was statistically significant (p < 0.001). discussion: LVSS and HS can both be used for peripheral lung resections without any need of further intervention for securing the air tightness. LVSS was found safer by means of tissue damage when compared with HS in this experimental study.

The neuromuscular effects of 0.6 mg kg(-1) rocuronium in elderly and young adults with or without renal failure.

BACKGROUND AND OBJECTIVES: The elderly represent a wide and increasing patient population and significant numbers of elderly patients have chronic renal disease. This study aimed to investigate the neuromuscular effects of 0.6 mg kg(-1) rocuronium under propofol anaesthesia in young adults and elderly patients with or without renal failure. METHODS: The neuromuscular effects of rocuronium 0.6 mg kg(-1) under propofol anaesthesia were investigated in 40 patients with renal failure undergoing arteriovenous shunt surgery, of whom 20 were young adults (18-50 yr) and 20 were elderly (>65 yr) and in 40 patients with normal renal function undergoing peripheral venous surgery, of whom 20 were young adults and 20 were elderly. Neuromuscular transmission was monitored using acceleromyography. The times to recovery of the twitch (T1) to 25%, 50%, 75% and 90% and of the train-of-four ratio to 70%, and the recovery index were recorded. RESULTS: The times to recovery of the first twitch to 25%, 50%, 75% and 90% and train-of-four to 70% and recovery index were found to be prolonged in both young and elderly patients with renal failure compared to those with normal renal function (e.g. T1 25%: 58.4 +/- 20.2 and 80.1 +/- 23.7 min vs. 32.8 +/- 5.6 and 46.3 +/- 9.0 min, respectively) (P < 0.05). These parameters were also prolonged in the elderly when compared with young adults in both the renal failure and the non-renal failure groups. CONCLUSIONS: The neuromuscular effects of 0.6 mg kg(-1) rocuronium under propofol anaesthesia were markedly prolonged in young and elderly renal failure patients compared to patients with normal renal function, and also in elderly patients with normal renal function compared with young adults.

Infiltration of the sternotomy wound and the mediastinal tube sites with 0.25% levobupivacaine as adjunctive treatment for postoperative pain after cardiac surgery.

BACKGROUND AND OBJECTIVE: This study aimed to investigate the effect of 0.25% levobupivacaine infiltration of the sternotomy wound and the mediastinal tube sites on postoperative pain, morphine consumption and side-effects in patients undergoing cardiac surgery. METHODS: After obtaining Ethics Committee approval and informed consent,50 patients aged 18-65 yr, undergoing coronary artery bypass grafting, were included in this study. Anaesthesia was induced with 5 microg kg (-1) fentanyl, 0.3 mg kg (-1) etomidate, 1 mg kg (-1) lidocaine, 0.1 mg kg (-1) vecuronium and maintained with 1-2% sevoflurane, 50% oxygen in air and fentanyl. Patients were randomized into two groups before sternal wire placement: sternotomy and mediastinal tube sites were infiltrated with either 60 mL 0.25% levobupivacaine (infiltration group, n = 25) or 60 mL saline placebo (control group, n = 25). All patients received intravenous morphine patient-controlled analgesia (bolus dose: 2 mg, lock-out time: 15 min, 4 h limit: 20 mg) after extubation. Postoperative pain at rest and on coughing was assessed by a visual analogue scale (0-10). Pain scores,sedation scores (Ramsay scale), haemodynamic and respiratory parameters, arterial blood gases and morphine consumption were recorded. RESULTS: The times to extubation and visual analogue scale scores were similar between groups. Morphine consumption at 24 h was significantly lower in the infiltration group compared with the control group (29.5 +/- 5.1 vs. 42.8 +/- 4.7 mg, respectively, P < 0.05). The sedation scores were found to be significantly higher in the control group when compared with the infiltration group at 1, 2 and 4 h after extubation (P < 0.05), whereas sedation scores after 4 h were similar between groups. CONCLUSION: Infiltration of the median sternotomy incision and the mediastinal tube insertion sites with 0.25% levobupivacaine in addition to morphine patient-controlled analgesia was found to be effective in reducing postoperative morphine consumption when compared with morphine patient-controlled analgesia alone during the initial 24 h after cardiac surgery.

Comparison of the harmonic scalpel and the ultrasonic surgical aspirator in subsegmental lung resections: an experimental study.

BACKGROUND: In this study, we evaluated the effectiveness of two devices using ultrasonic energy for dissection of lung parenchyma in an experimental animal model by comparing the two methods with each other. METHODS: Twenty New Zealand rabbits were used. One-lung ventilation was obtained under direct vision and the left lung was collapsed. The rabbits were ventilated with pressure-controlled ventilation during the experiment, beginning with a pressure level of 10 cmH(2)O. After a 1 x 1-cm pulmonary wedge resection of part of the collapsed left lung using a harmonic scalpel (group A) or an ultrasonic surgical aspirator (group B), the left lung was inflated and the pressure level was increased by 5 cmH(2)O every five minutes. The pressure level which caused an air leak from the resection surface was recorded. The morphological damage to the lung parenchyma was evaluated under light microscopy. RESULTS: The mean value of airway pressure levels that resulted in an air leak from the resection surface was 32.5 +/- 9.2 cmH(2)O for group A and 24.5 +/- 2.9 cmH(2)O for group B, and the difference between the two groups was statistically significant. The mean level of coagulation necrosis was 558.6 +/- 380.8 microns (133 - 1064 microns) for group A. No tissue damage to pulmonary parenchyma was observed in group B. CONCLUSION: The harmonic scalpel can be safely used in peripheral lung resections without needing any other method to ensure hemostasis and air tightness. The ultrasonic surgical aspirator can be used for the dissection and resection of deeper lesions and preserves more lung tissue but requires additional interventions for control of the air leak from the resection surface.

The efficacy of intrathecal morphine in post-thoracotomy pain management.

This study compared the analgesic efficacy of intrathecal (IT) morphine plus IV patient-controlled analgesia (PCA) morphine with IV PCA morphine alone in 33 patients undergoing thoracotomy randomized to two groups: the IT morphine group (n=17) received 10 microg/kg morphine 1 h before the end of surgery, while the control group (n=16) did not. All patients had access to an IV PCA pump post-operatively that delivered 2 mg morphine boluses. Post-operative pain and sedation scores, respiratory and haemodynamic parameters, and morphine demand and delivery were assessed up to 48 h. Post-operative pain scores and morphine consumption were significantly reduced, while peak expiratory flow rates were significantly increased in the IT morphine group compared with controls. We concluded that IT morphine in addition to IV PCA established superior analgesia and maintained better respiratory function compared with IV PCA alone in post-thoracotomy patients.

Experimental use of N-butyl cyanoacrylate tissue adhesive on lung parenchyma after pulmonary resection.

BACKGROUND: The aim of this study was to investigate the effectiveness of N-butyl cyanoacrylate tissue adhesive for the prevention of air leak together with the morphological changes to lung parenchyma. METHODS: Twelve New Zealand rabbits were used. The rabbits were ventilated with pressure-controlled ventilation during the experiment, beginning with a pressure level of 10 cm H (2)O. After a 2 x 2-cm pulmonary wedge resection, the resection surface was sealed with N-butyl cyanoacrylate and the pressure level was increased every five minutes in 5-cm H (2)O increments. The pressure level which caused an air leak from the resection surface was recorded. The morphological damage to the lung parenchyma was evaluated under light microscopy. RESULTS: The mean value of the pressure levels that caused air leak was 43.3 +/- 8.8 cm H (2)O. No tissue damage to lung parenchyma was recorded after histopathological examination. CONCLUSION: N-butyl cyanoacrylate was effective in preventing air leak from the pulmonary resection surface even with high airway pressure levels. It could be used as an aid for pulmonary resection lines or to control the air leak from pulmonary parenchyma.

Alfa-fetoproteína como marcador de carcinoma hepatocelular / No disponible

No disponible

Circulatory arrest to protect transplant kidney in a patient with chronic type III dissection.

With broader indications for renal transplantation and improved allograft survival, it is anticipated that the problem of aortic disease in the post-transplant patient will be encountered with increasing frequency. We report a technique of protecting the transplant kidney from ischemic damage during distal aortic surgery. A 30-year-old renal transplant patient who had undergone an operation for ruptured chronic type III dissection 3 years previously underwent abdominal aortic aneurysm repair under hypothermic circulatory arrest. The patient recovered uneventfully and is presently doing well 1 year after the operation. Hypothermic circulatory arrest could be used in selected cases as a useful alternative for transplant kidney protection.

The side-effects of cardiopulmonary bypass on the lungs: changes in bronchoalveolar lavage fluids.

Although technical refinements have improved the safety of cardiac operations, postoperative dysfunction of lung and other organs occurs frequently after cardiopulmonary bypass (CPB). The aim of the present study was to search the aetiopathogenesis of pulmonary complications due to CBP. Ten patients with stable coronary artery disease, undergoing coronary artery bypass grafting (CABG) surgery, were included in the study. Forty bronchoalveolar lavage (BAL) fluid samplings were performed in the 10 patients. Samples were obtained at the following time periods: (1) preoperatively; (2) at the end of the first hour after anaesthetic induction; (3) at the conclusion of 30 min of crossclamp on CPB; and (4) at the conclusion of 20 h after the end of CPB, postoperatively. Cell contents of bronchoalveolar lavage fluid, alveolar macrophage viability, eosinophil cationic protein (ECP) levels and myeloperoxidase (MPO) concentrations were analysed in each bronchoalveolar lavage fluids. While the percentage of preoperative macrophages was 85.90% and the percentage of preoperative neutrophils was 2.40%, they were 77.00% and 11.30% in the postoperative samples, respectively. Mean alveolar macrophage viability was 96.20% preoperatively and 90.40% in the postoperative period. Preoperative eosinophil cationic protein mean concentration was < 2 microg/l and mean response value (RV) was 28.80. Preoperative mean myeloperoxidase concentration was 7.66 ng/ml. Postoperative eosinophil cationic protein mean response value was 63.40 and mean myeloperoxidase concentration was 59.25 ng/ml. There were significant differences between third and final samples with regard to both neutrophil percentages (p = 0.028) and MPO levels (p = 0.005). While the preoperative mean PaO2 value was 89.39 mmHg and mean SaO2 value was 97.12%, they were calculated in the postoperative arterial blood specimens of patients, without inhaling O2, as 65.31 mmHg and 93.84%. These changes between blood gas analyses reflect the impairment of the lungs (p = 0.009 and p = 0.007, respectively). Neither alveolar macrophage viability nor ECP levels changed significantly between consecutive periods. However, when the results of the first and fourth samples were compared, we saw the cumulative effects of CPB, in that alveolar macrophages lost their viability and ECP mean RVs rose. These changes were statistically significant (p = 0.027 and p = 0.013, respectively). However, postoperative ECP levels were not like those found in a patient with asthma. Also, changes between alveolar macrophage percentages (p = 0.028), between neutrophil percentages (p = 0.036) and between MPO concentrations (p = 0.005) were statistically significant. Again, changes in neutrophil percentages between first and final samples correlated with changes in MPO levels between same periods (r = 0.657, p = 0.039).

The protective effects of high dose ascorbic acid and diltiazem on myocardial ischaemia-reperfusion injury.

In this study, we aimed to compare the myocardial protective effects of high dose ascorbic acid with the effects obtained by adding diltiazem to high dose ascorbic acid. We studied 30 elective cardiac surgery patients prospectively. In ascorbic acid group (group AA), ascorbic acid was given after induction and just before aortic declamping, 50 mg.kg-1 each time. In ascorbic acid + diltiazem group (group AA + D), diltiazem was added to ascorbic acid (0.3 mg.kg-1, i.v. after induction and then 2 micrograms.kg-1 min-1 i.v. infusion until declamping). Group C was the control group. There was no significant difference between groups in terms of cardiac enzyme levels. After declamping, the arterial and coronary sinus malondialdehyde levels, measured as a marker of lipid peroxidation, were increased significantly in the group C while remained stable in the other two groups. Ventricular fibrillation (VF) after declamping was positive in 3, 1 and 6 patients in the groups AA, AA + D and C respectively. In this study, we observed the prevention of lipid peroxidation in the group AA and group AA + D. The only positive result obtained by addition of diltiazem to high dose ascorbic acid was the decrease in the frequency of VF after declamping. We concluded that the prevention of lipid peroxidation in the groups AA and AA + D provided no measurable protection over myocardial ischaemia-reperfusion injury.

Elderly coronary artery bypass graft patients with left ventricular dysfunction are hemodynamically stable after two different doses of rocuronium.

OBJECTIVE: To clarify the detailed hemodynamic responses to bolus administration of 2x 95% effective dose (ED95) and 3x ED95 of rocuronium in elderly patients with left ventricular dysfunction undergoing elective coronary artery bypass grafting (CABG). DESIGN: Prospective, randomized, clinical study. SETTING: University hospital. PARTICIPANTS: Twenty patients aged older than 65 who had coronary artery disease with left ventricular ejection fractions equal to or less than 40%. INTERVENTIONS: Using invasive cardiac monitoring, the detailed hemodynamic profile was obtained before and at 2, 4, 6, 8, and 10 minutes after the injection of rocuronium. MEASUREMENTS AND MAIN RESULTS: Minor changes in all the measured or derived hemodynamic variables within the two groups did not attain statistical significance. Except for a higher baseline and the subsequent mean arterial pressures in one group, there were neither statistically nor clinically significant differences between two different doses of rocuronium in any of the variables at any time. CONCLUSION: The results demonstrate that bolus administration of rocuronium (2x to 3x ED95) in combination with high-dose fentanyl provides sufficient cardiovascular stability among elderly CABG patients with left ventricular dysfunction. The cardiovascular profile of the two different bolus doses was similar. Rocuronium, in both doses, appears to be a suitable agent for muscle relaxation, especially for patients who require a high degree of cardiovascular stability.

The myoneural effects of propofol emulsion (Diprivan) on the nerve-muscle preparations of rats.

The potential effects of propofol emulsion (Diprivan) on the neuromuscular transmission and muscular contraction were studied using in vitro and in vivo nerve-muscle preparations of rats. The contractions of the isolated rat diaphragm elicited by either indirect or direct electrical stimulation were inhibited by propofol emulsion at threshold concentrations of 42 and 112 mumol l-1, respectively. Similarly, the gastrocnemius muscle contractions induced by either indirect or direct electrical stimulation in vivo were inhibited by propofol emulsion administration as a bolus injection of 2.5 mg kg-1 intravenously, followed by intravenous infusion of 150 micrograms kg-1 min-1 for 1 h into rats. The inhibitory effects of propofol in both preparations were greater with indirect rather than direct stimulation. Propofol emulsion was found to be capable of enhancing the paralysis of the indirectly stimulated rat diaphragm in vitro and gastrocnemius muscle in vivo induced by either pipecuronium or succinylcholine. The combination of propofol and pipecuronium led to a synergistic inhibition of the neuromuscular transmission, while the combination of propofol and succinylcholine led to additive inhibition. Pretreatment with propofol emulsion at these threshold concentrations markedly inhibited the stimulant effects of aminophylline and digoxin on the indirectly and directly induced diaphragmatic contractions. Also, the enhancement effects of aminophylline on the indirectly and directly and of digoxin on indirectly induced rat gastrocnemius muscle contractions were markedly inhibited by propofol emulsion administration to rats. Pretreatment with propofol emulsion at the threshold concentrations enhanced the inhibitory effects of verapamil on diaphragmatic contractions elicited either indirectly or directly and enhanced the inhibitory effect of adenosine on the contractions elicited indirectly. Similarly, the inhibitory effects of verapamil on the indirectly and directly and of adenosine on indirectly induced rat gastrocnemius muscle contractions were markedly potentiated by propofol emulsion administration to rats. In addition, doubling the concentration of calcium in the bathing fluid produced no change in the inhibitory effects of propofol emulsion on either indirectly or directly elicited diaphragmatic contractions, while doubling the concentration of external magnesium potentiated the propofol effects. Pretreatment with 4-aminopyridine suppressed the inhibitory effects of propofol emulsion on diaphragmatic contractions elicited either indirectly or directly. These results suggest that propofol acts presynaptically to inhibit the neuromuscular transmission and acts at the muscle membrane to inhibit the muscular contraction.