Large bolus dose vs. continuous infusion of cisatracurium during hypothermic cardiopulmonary bypass surgery

BACKGROUND AND OBJECTIVE: We investigated whether a high bolus dose of cisatracurium (8x ED95) given at induction can provide muscle relaxation for the major part of a cardiac procedure with hypothermic cardiopulmonary bypass, avoid important postoperative residual curarization and cause no waste of product. METHODS: Twenty patients were randomly assigned either to Group 1 (n = 10) or Group 2 (n = 10). Those in Group 1 were given cisatracurium in a high bolus dose (0.4 mg kg(-1)). Those in Group 2 received cisatracurium 0.1 mg kg(-1) at induction followed after 30 min by a continuous infusion of cisatracurium. As an escape medication in case of patient movement, a bolus dose of cisatracurium 0.03 mg kg(-1) was given. RESULTS: In Group 1 (large cisatracurium bolus dose), the clinical duration of effect (until T1/T0 = 25%) was 110 min. Six of 10 patients in Group 1 required additional boluses of cisatracurium intraoperatively. Four of these six had received an additional bolus near the end of surgery and had a train-of-four (TOF) ratio = 0 at the end. The other four patients in Group 1 had a final TOF ratio >0.9. In Group 2 (continuous cisatracurium infusion), only two patients had a TOF ratio >0.9 at the end of surgery, no patient moved and none received additional boluses. The total amount of cisatracurium used in the bolus and infusion Groups was 34.5 +/- 7.8 and 21.3 +/- 5.7 mg, respectively (P = 0.0004). CONCLUSIONS: For continued neuromuscular block during hypothermic cardiac surgery, a high bolus dose of cisatracurium appears to be safe, although it is not an alternative to a continuous infusion, as its neuromuscular blockade does not cover the intraoperative period and a high incidence of movements occurs. In the patients who received a high bolus dose of cisatracurium, postoperative residual curarization appeared after additional boluses had been given. The consumption of cisatracurium by high bolus was significantly greater than with continuous infusion.     

Renal dose dopamine in open heart surgery. Does it protect renal tubular function?

BACKGROUND: This prospective, randomized study assessed the effect of dopamine on renal tubular function in patients who had coronary artery bypass grafting. METHODS: Two groups of patients with normal preoperative renal function were randomly divided into a dopamine group (n=11), who received dopamine in a dose of 2 mg/kg x min, and a control group (n=11), who received no treatment. Dopamine infusion was initiated 24 hours before the operation and was continued for 48 hours postoperatively. Measurements of renal function obtained 2 days before the operation were considered preoperative and were repeated on the 1st, 3rd, and 7th postoperative days. Urinary excretion of b2-Microglobulin (b2-M), considered a sensitive means for diagnosing proximal tubular damage, was measured during the early (day 3) and late (day 7) postoperative period. RESULTS: There were no significant differences respect to the clearances of creatinine, osmotic, and free-water in the dopamine group compared with the control group (p>0.05). Urine microalbumin levels significantly increased on postoperative day 3 in both groups. During the early postoperative period, excretion of urine b2-M was significantly greater in the dopamine group than in the control group (p<0.05). CONCLUSIONS: Consequently, in patients with normal preoperative renal and cardiac function scheduled for elective coronary artery bypass grafting, renal dose dopamine infusion alone may not provide sufficient protection on tubular function and increases renal tubular injury during the early postoperative period.     

Patterns of severe pancreatic injury following cardiopulmonary bypass.

Severe pancreatic complications following cardiac surgery are rare, but 14 patients with severe pancreatitis have been encountered since 1971. Six of these developed acute fulminating pancreatitis following cardiac surgery and each of these died within 21 days following operation. Seven patients had less severe pancreatitis, resulting in pancreatic abscess formation and five in this group expired. One patient developed a pancreatic pseudocyst following mild acute pancreatitis and expired 4 months later. Although the etiologic mechanisms are unclear, possible factors include: prolonged cardiopulmonary bypass, "the low cardiac output syndrome," and inadequately treated or unrecognized postoperative pancreatitis. The diagnosis is based on physical examination, upper gastrointestinal series, and the abdominal CT scan. Despite aggressive surgical therapy, pancreatitis following cardiopulmonary bypass is an extremely serious condition.     

Ketamine infusion reduces narcotic requirements following gastric bypass surgery: a randomized controlled trial

BackgroundAs the obesity epidemic worsens, anesthesiologists should expect to see more obese patients presenting for surgical procedures. Opioids cause respiratory depression, which has caused complications in patients with obstructive sleep apnea. Opioids can also cause nausea, prolonging the time that patients spend in the postanesthesia care unit. Ketamine is a potential analgesic alternative that may have advantages to narcotics in the bariatric population.ObjectivesTo determine whether an intraoperative ketamine infusion would reduce postoperative narcotic use in patients during the first 48 hours after laparoscopic gastric bypass.SettingMajor academic medical center.MethodsThere were 54 participating patients. The intervention group (n = 27) was randomized to receive 100 μg of fentanyl with anesthesia induction, then a 20-mg bolus of ketamine, followed by a 5 μg/kg/min intraoperative ketamine infusion starting after anesthesia induction and ending after wound closure commenced. The control group (narcotic only, n = 27) also received 100 μg of fentanyl at anesthesia induction and intraoperative boluses of fentanyl at the discretion of the anesthesia team, with .3 mg of hydromorphone administered approximately 45 minutes before the completion of surgery.ResultsAt 24 hours, the mean morphine-equivalent units (MEUs) were 12.7 (standard deviation [SD], 9.9; 95% confidence interval [CI], 8.8–16.6) for the ketamine group (n = 28) and 16.5 (SD, 9.8; 95% CI, 12.6–20.4) for the control group (n = 28). At 48 hours, the MEUs were 16.7 (SD, 12.0; 95% CI, 11.9–21.4) for the ketamine group and 22.7 (SD, 14.9; 95% CI, 16.8–28.6) for the control group. Cumulative MEUs for 24 hours (P = .039) and 48 hours (P = .058) postoperatively were lower in the ketamine group compared with the narcotic-only (control) group, although the difference at 48 hours did not reach statistical significance. Compared with the narcotic-only group, the ketamine group used 26% fewer MEUs after 24 hours and 31% fewer MEUs after 48 hours. This difference can mostly be attributed to group differences during the first 6 hours after surgery.ConclusionsKetamine successfully reduced the amount of opioids required to control bariatric patients’ pain at 24 hours postoperatively, but not over the 48-hour postoperative period.     

L-arginine reduces tubular cell injury in acute post-ischaemic renal failure.

BACKGROUND: The pathophysiology of renal ischaemia, resulting in tubular cell injury and leading to acute renal failure (ARF), remains unclear. An ever-increasing number of investigations focus on a possible role of nitric oxide (NO) in regulating circulation during ARF. In this context, we investigated the influence of chronic stimulation or inhibition of NO synthesis, or both, on haemodynamic parameters, histology and plasma renin activity (PRA) after ischaemia-reperfusion injury of rat kidneys. METHODS: Experiments were performed on adult, male Wistar rats. Before induction of ARF, a group of animals was treated with a NO synthesis inhibitor (L-NAME) and another group was treated with a precursor of NO synthesis (L-arginine). The animals received those substances for 4 weeks. Control groups received the same amount of tap water for 4 or 8 weeks and were divided into groups with ARF (4 weeks--ARF group and 8 weeks ARF group) and a sham-operated group. Another group of rats was treated first with L-NAME and then with L-arginine in their drinking water, for 4 weeks for each of these two substances. All parameters were evaluated 24 h after the induction of ischaemic ARF or the sham operation. RESULTS: Our results show that such long-term stimulation of NO release by L-arginine improved renal haemodynamics in the ischaemic form of ARF. Renal blood flow (RBF) increased by 96% in the L-arginine-treated rats with ARF compared with the group with ARF alone. Inhibition of NO synthesis worsens renal haemodynamics after ARF. However, this aggravation can be reversed by L-arginine. The rate of water reabsorption was reduced in all groups with ARF, but this reduction was least in the group treated with L-arginine. The rate of Na+ reabsorption was reduced in all groups 24 h after renal ischaemia, but a significant decrease was observed after the inhibition of NO synthesis. Histological examination of the kidney specimens showed that morphological changes were least in the rats treated with L-arginine, when compared with all other groups with ARF. Nevertheless, the lesions were most prominent in the L-NAME+ARF group. In this group, the areas of corticomedullar necrosis were more widespread in comparison with other groups, especially the L-arginine group where only swelling of the proximal tubular cells was observed. Treatment with L-NAME was not accompanied by any significant alteration in the plasma concentration of angiotensin I (ANG I), while in the group treated with L-arginine ANG I had a tendency to decrease. CONCLUSIONS: Acute post-ischaemic renal failure may be alleviated by administering the NO substrate (L-arginine). NO acts cytoprotectively on tubular epithelial cells in ischaemia--reperfusion injury of rat kidney. Evidence of this comes from both histopathological findings and increased tubular water and sodium reabsorption. However, inhibition of NO synthesis (provoked by L-NAME) worsens renal haemodynamics and aggravates morphological changes after ARF. These aggravations can, however, be reversed by L-arginine.     

Abdominal complications following cardiopulmonary bypass in open-heart surgery

Open-heart surgery was performed on 1686 adult patients between 1980 and 1984, with a mortality rate due to abdominal complications of 0.6%. Every operation involved the use of cardiopulmonary bypass (CPB). Abdominal complications occurred in 1.6%, with an overall mortality rate of 36%. The most frequent complication was gastrointestinal (Gl) bleeding (61%). The mortality of the patients who bled from the Gl tract was 53%. Other complications encountered were gastroduodenal ulcer, colitis, ileus, subphrenic abscess and intraperitoneal bleeding. Prolonged CPB and low output syndrome preceded multiple organ failure, which occurred in 39% of those who had abdominal complications and in 59% of those who bled. Gl bleeding after CPB did not correlate with a previous history of gastric ulcer. Reoperation because of cardiac tamponade or excessive chest tube drainage was a factor predisposing to Gl bleeding. The mortality and abdominal complication rates were significantly higher in valve surgery than in coronary revascularization.     

多巴胺对病人体外循环期间肾血流的影响

目的 评价小剂量多巴胺对病人体外循环(CPB)期间肾血流的影响.方法 择期体外循环下行心血管手术病人60例,年龄21～64岁,随机分为2组(n=30):生理盐水对照组(C组)和多巴胺组(D组).麻醉诱导后气管插管,机械通气,分别于首次灌注心脏停搏液后5 min(给药前)及颈内静脉输注多巴胺2/μg·kg-1·min-120min时(给药后)采用经食管超声测定左侧肾动脉内径及血流速度,计算左肾血流量和肾动脉阻力.结果 与C组比较,D组给药后肾动脉血流速度及血流量增加,肾动脉阻力下降(P<0.05),肾动脉内径差异无统计学意义(P0.05).结论 CPB中静脉输注小剂量多巴胺可增加肾大血流量.     

Effects of prostacyclin infusion on renal function during cardiopulmonary bypass

Infusion of prostacyclin inhibits platelet activation during cardiopulmonary bypass (CPB) but also results in systemic arterial hypotension. Therefore, the effects of CPB and prostacyclin on renal function were studied in 36 male patients undergoing aortocoronary bypass. Nineteen patients (Group 1) received prostacyclin, 50 ng per kilogram of body weight per minute, during CPB, and 17 patients (Group 2) served as controls. There was pronounced hypotension in Group 1 only. Urine production during CPB averaged 88 +/- 140 ml and 2,306 +/- 1,112 ml in Groups 1 and 2, respectively. No patient had renal failure. Glomerular filtration rate (GFR), as measured by clearance of chromium 51-labeled ethylenediaminetetraacetic acid, was increased in Group 1 from 86 +/- 14 to 99 +/- 22 ml/1.73 m2/min (p less than 0.05) the day after operation, but remained unchanged in Group 2 (81 +/- 15 to 82 +/- 21 ml/1.73 m2/min). The increased GFR in Group 1 can be regarded as an expected adaptation to the change in body fluids after CPB. Therefore, the unchanged GFR in Group 2 must be regarded as caused by insufficient adaptation or impaired renal function. Proximal tubular function was evaluated by determination of beta 2-microglobulin in urine. In both groups, urinary beta 2-microglobulin and the ratio of urinary beta 2-microglobulin to urinary creatinine were increased the day after operation. The hypotension in Group 1 did not exacerbate the damage to tubular function.     

The association of lowest hematocrit during cardiopulmonary bypass with acute renal injury after coronary artery bypass surgery

BACKGROUND: Acute renal injury is a common serious complication of cardiac surgery. Moderate hemodilution is thought to reduce the risk of kidney injury but the current practice of extreme hemodilution (target hematocrit 22% to 24%) during cardiopulmonary bypass (CPB) has been linked to adverse outcomes after cardiac surgery. Therefore we tested the hypothesis that lowest hematocrit during CPB is independently associated with acute renal injury after cardiac surgery. METHODS: Demographic, perioperative, and laboratory data were gathered for 1,404 primary elective coronary bypass surgery patients. Preoperative and daily postoperative creatinine values were measured until hospital discharge per institutional protocol. Stepwise multivariable linear regression analysis was performed to determine whether lowest hematocrit during CPB was independently associated with peak fractional change in creatinine (defined as the difference between the preoperative and peak postoperative creatinine represented as a percentage of the preoperative value). A p value of less than 0.05 was considered significant. RESULTS: Multivariable analyses including preoperative hematocrit and other perioperative variables revealed that lowest hematocrit during CPB demonstrated a significant interaction with body weight and was highly associated with peak fractional change in serum creatinine (parameter estimate [PE] = 4.5; p = 0.008) and also with highest postoperative creatinine value (PE = 0.06; p = 0.004). Although other renal risk factors were significant covariates in both models, TM50 (an index of hypotension during CPB) was notably absent. CONCLUSIONS: These results add to concerns that current CPB management guidelines accepting extreme hemodilution may contribute to postoperative acute renal and other organ injury after cardiac surgery.     

Occipital alopecia following cardiopulmonary bypass.

Postoperative alopecia is a minor complication of surgery but a cosmetic disaster to the patient. Over a 3 year period, 60 cases of occipital alopecia were discovered in patients following open-heart surgery and 5 cases on other surgical services. In contrast to previous reports, 29 patients had alopecia one year later, presumed to be permanent. Extensive operations, with prolonged recovery and elective overnight mechanical ventilation, were common to all. Retrospective analysis and prospective studies clearly demonstrated that localized scalp pressure was the cause of the alopecia and that the duration of pressure determined the extent of the damage. Moving the patient's head at regular intervals during operation and recovery eliminated the alopecia. The type of head rest used did not modify the development of alopecia. Electrical injury and the use of heparin, hypothermia, electrocautery, or hypotension were eliminated as possible causes. Conclusive evidence correlating periperative events with the formation of pressure sores in man has not been previously reported.     

Myocardial function following cardiopulmonary bypass.

Twenty-one patients have been studied in the 48 h after valve replacement to determine the possible contribution of abnormalities of left ventricular myocardial blood flow and oxygen consumption to the impaired cardiac performance which is sometimes evident in such patients. In the 14 patients making an uneventful recovery (Group A) the mean values for blood flow and oxygen consumption were both higher than in resting man, while the arterio-coronary sinus oxygen content difference was narrowed, with a high coronary sinus oxygen tension. Five patients had a low cardiac output (Group B) and had similar levels of blood flow and oxygen consumption to Group A, while the coronary sinus oxygen content and tension were reduced. When the heart rate was increased by pacing (Group C) myocardial oxygen consumption increased but coronary blood flow failed to rise, while the arterio-coronary sinus oxygen content difference widened slightly. It is concluded that the low postoperative cardiac output is not due to low coronary blood flow or myocardial oxygen supply, but these patients have a limited ability to increase their already high coronary blood flow. Therefore any increase in oxygen demand may be met by the potentially detrimental mechanism of widening the arterio-coronary sinus difference, with lower coronary sinus and tissue oxygen tension.     

Cardiac surgery with cardiopulmonary bypass in patients with chronic renal failure.

OBJECTIVE: Renal failure is known to increase the morbidity and mortality in patients undergoing cardiac surgery. The results of heart surgery in patients with non-dialysis-dependent, mild renal insufficiency are not clear. METHODS: One hundred nineteen adult patients with chronic renal failure underwent cardiac surgery. Group I consisted of 93 patients who had creatinine levels between 1.6 and 2.5 mg/dL but who were not supported by dialysis. Group II consisted of 18 patients with creatinine levels higher than 2.5 mg/dL who were not supported by dialysis. Group III consisted of 8 patients with end-stage renal disease who were receiving hemodialysis. RESULTS: The hospital mortality rates were 11.8%, 33.0%, and 12.5%, respectively. Morbidity was 21.5%, 44.4%, and 75.0%, respectively, in groups I, II, and III. Postoperative hemodialysis was needed in 2 (2.15%) patients from group I and 6 (33%) patients from group II. On multivariable logistic regression analysis, risk factors for mortality were preoperative creatinine level more than 2.5 mg/dL, angina class III-IV, emergency operation, excessive mediastinal hemorrhage, postoperative pulmonary insufficiency, low cardiac output, and rhythm disturbances. Risk factors for morbidity were preoperative creatinine level more than 2.5 mg/dL and postoperative dialysis. CONCLUSIONS: Chronic renal failure increases the mortality and morbidity in patients undergoing cardiac surgery. Renal insufficiency with creatinine levels higher than 2.5 mg/dL increases the risk of postoperative dialysis and prolongs the length of hospital stay. Careful preoperative management and intraoperative techniques, such as avoiding low perfusion pressure and using low-dose dopamine, may be useful for a good operative outcome.