M. Salmenperä

Extubation criteria after weaning from intermittent mandatory ventilation and continuous positive airway pressure.

The “traditional” weaning criteria, arterial blood gases, and a number of other physiologic variables were measured in 47 patients to evaluate to what extent reduced ventilatory reserves or extrapulmonary organ dysfunction affect successful extubation. All patients had been weaned from continuous positive airway pressure (CPAP) and from mechanical ventilation according to the intermittent mandatory ventilation (IMV) method; at the time of study, all patients had compromised arterial oxygenation relieved by supplemental inspired oxygen.No significant difference between patients successfully extubated and those who required reintubation was found using the traditional weaning criteria or blood gases. On the other hand, patients who required reintubation had significantly lower urine volume (p < 0.01), lower respiratory quotient values (p < 0.05), and a higher incidence of positive blood culture (p < 0.05). These 3 variables also correlated best to the patients outcome after extubation.

Levosimendan Facilitates Weaning From Cardiopulmonary Bypass in Patients Undergoing Coronary Artery Bypass Grafting With Impaired Left Ventricular Function

BACKGROUNDnLevosimendan is a compound with vasodilatory and inotropic properties. Experimental data suggest effective reversal of stunning and cardioprotective properties.nnnMETHODSnThis prospective, randomized, placebo-controlled, double-blind study included 60 patients with 3-vessel coronary disease and left ventricular ejection fraction (LVEF) of less than 0.50. Levosimendan administration (12 microg/kg bolus, followed by an infusion of 0.2 microg/kg/min) was started immediately after induction anesthesia. Predefined strict hemodynamic criteria were used to assess the success of weaning. If weaning was not successful, CPB was reinstituted and an epinephrine infusion was started. If the second weaning attempt failed, intraaortic balloon pumping (IABP) was instituted.nnnRESULTSnThe groups had comparable demographics. The mean (standard deviation) preoperative LVEF was 0.36 (0.8) in both groups. The baseline cardiac index was 1.8 (0.3) L/min/m(2) in the levosimendan group and 1.9 (0.4) L/min/m(2) in the placebo group. The mean duration of CPB to primary weaning attempt was 104 (25) minutes in the levosimendan and 109 (22) minutes in the placebo group. Primary weaning was successful in 22 patients (73%) in the levosimendan group and in 10 (33%) in the placebo group (p = 0.002). The odds ratio for failure in primary weaning was 0.182 (95% confidence interval, 0.060 to 0.552). Four patients in the placebo group failed the second weaning and underwent IABP compared with none in the levosimendan group (p = 0.112).nnnCONCLUSIONSnLevosimendan significantly enhanced primary weaning from CPB compared with placebo in patients undergoing 3-vessel on-pump coronary artery bypass grafting. The need for additional inotropic or mechanical therapy was decreased.

Brain injury after adult cardiac surgery

Despite remarkable progress in surgical, cardiopulmonary bypass and anaesthetic techniques during the last three decades, brain damage remains an important complication of adult cardiac surgery. Effective brain protection strategies are already implemented today, but ongoing research is needed to meet the challenges faced in operating on increasingly old and disabled patients. The incidence of brain injury may be reduced by modifying the surgical procedure according to carotid duplex scanning and epiaortic echocardiography, by using techniques to reduce microembolization during cardiopulmonary bypass and by optimizing patient temperature during and after surgery. Increased knowledge will aid in choosing the best procedure or combination of procedures in each case to ensure that risks do not outweigh benefits.

Cardiovascular effects of pancuronium and vecuronium during high-dose fentanyl anesthesia.

To define the role of muscle relaxants in hemodynamic responses to high-dose (75 μg/kg) fentanyl anesthesia, we compared the circulatory effects of pancuronium (Pc) with those of vecuronium (Vc) in patients about to undergo coronary artery bypass surgery. The first measurements were made while the patients were awake. Thereafter the patients were anesthetized with fentanyl, intubated under succinylcholine relaxation and mechanically ventilated with a mixture of oxygen in air (Flo2 0.50). Ten minutes after completion of the fentanyl injection, the second set of measurements was made. Immediately thereafter, 0.1 mg/kg of either Pc (n = 10) or Vc (n = 10) was given, and no relaxant was administered to 10 control patients. Heart rate (HR) and cardiac index (CI), which had decreased significantly after fentanyl induction, decreased further after Vc, the latter decreases being significantly greater than the decreases in HR and CI observed in control patients. After Pc, HR and CI increased to control a wake levels; rate-pressure product also increased and stroke index decreased. Five of ten patients receiving Vc had a HR below 45 beats/min; HRs this low were not seen in patients given Pc. Neither Pc nor Vc affected systemic vascular resistance, but filling pressures of the heart decreased abruptly after both relax-ants. We conclude that if maintenance of preanesthetic hemodynamic status is the objective of anesthetic management of patients having coronary artery bypass surgery, Pc helps to achieve this objective during high-dose fentanyl anesthesia. On the other hand, many patients with limited coronary vascular reserve may well benefit from the negative chronotropic effect of Vc.

Hydroxyethyl starch as a prime for cardiopulmonary bypass: effects of two different solutions on haemostasis

Hydroxyethyl starch (HES) is efficacious as a volume expander in cardiac surgical patients, but it may impair the haemostatic mechanisms. However, this latter effect may be less conspicuous with low molecular weight (LMW) solutions than with high molecular weight (HMW) solutions. Therefore, LMW– and HMW–HES solutions were evaluated as priming solutions for cardiopulmonary bypass (CPB) with respect to their effect on haemostasis. Forty–five patients undergoing coronary bypass grafting were prospectively randomised to three groups and in a double–blind manner as their CPB prime either 20 ml kg‐1 LMW–HES (Mw 120 000), 20 ml kg‐1 HMW–HES (Mw 400000) or Ringers acetate 2000 ml. The final volume of the prime was completed to 2000 ml with Ringers acetate in the HES groups. Anaesthesia and CPB management were standardised. Plasma levels of von Willebrand factor antigen and factor VIII procoagulant activity were significantly more depressed after CPB in both HES–groups as compared with the crystalloid prime group. In addition, APTT was more prolonged and the maximal amplitude of thromboelastographic tracing was more decreased in the HES–groups. It is concluded that it may be advisable to avoid HES solutions in the CPB prime, especially in patients with an increased risk for bleeding after cardiac operations.

Serum Cystatin C in Elderly Cardiac Surgery Patients

BACKGROUNDnElderly cardiac surgery patients are more prone to develop postoperative acute kidney injury (AKI). The common clinical glomerular filtration marker, plasma creatinine, is considered to be inadequate to discover AKI in its early stage. The aim of this study was to determine if serum cystatin C can detect mild renal failure earlier than plasma creatinine.nnnMETHODSnFrom 110 cardiac surgery patients aged 70 or greater years, serum cystatin C and plasma creatinine samples were collected preoperatively and on postoperative days 1 to 5. Their urine output, creatinine, and estimated glomerular filtration rate were calculated and AKI was determined by the risk-injury-failure-loss-end-stage kidney disease criteria (RIFLE). The correlation of plasma creatinine and serum cystatin C to AKI was calculated.nnnRESULTSnAfter cardiac surgery, 62 of the 110 patients (56.4%) developed AKI according to the RIFLE classification. In this group, both serum cystatin C and plasma creatinine peaked on postoperative day 3. Cystatin C and creatinine correlated equally with AKI at different time points calculated with receiver operating characteristic curves. On postoperative day 1 the area under the curve (AUC) for creatinine was 0.66 (0.55 to 0.76) and for cystatin C 0.71 (0.61 to 0.81); Delta AUC 0.05 (0.01 to 0.12), p = 0.11. On postoperative day 2 the AUC for creatinine was 0.74 (0.64 to 0.83) and for cystatin was C 0.77 (0.68 to 0.86); Delta AUC -0.03 (-0.09 to 0.03), p = 0.32.nnnCONCLUSIONSnElderly cardiac surgery patients have a high incidence of AKI, as defined by the RIFLE criteria. After cardiac surgery serum cystatin C and plasma creatinine detected AKI similarly.

Myocardial metabolism on off-pump surgery; a randomized study of 50 cases.

OBJECTIVEnTo study the inflammatory reaction and myocardial metabolism in off-pump and on-pump coronary artery bypass patients.nnnDESIGNnFifty coronary artery bypass patients were randomized to off-pump or on-pump operations. Myocardial biopsies were taken to determine myocardial metabolism and inflammation (glutathione (GSH), superoxide dismutase (SOD) and myeloperoxidase (MP)) and plasma samples for indicators of oxidative stress (conjugated dienes (s-BDC), oxidative products of proteins (s-ox-Prot) and low-density lipoprotein (LDL)-total peroxyl radical trapping antioxidant potential (s-TRAP)).nnnRESULTSns-ox-Prot 10 min was 2.11 +/- 0.75 vs 2.69 +/- 0.60 (p = 0.014), s-TRAP 5 min was 861 +/- 180 vs 969 +/- 192 (p = 0.032) and s-TRAP 10 min 857 +/- 176 vs 985 +/- 166 (p = 0.011), GSH 10 min 0.55 +/- 0.19 vs 0.72 +/- 1.16 (p = 0.007) (off-pump vs on-pump). The monobasic (MB) fraction of the creatinine kinase 24 h after the operation was significantly lower in the off-pump group, 20.5 +/- 24.2 vs 61.8 +/- 84.6 (p = 0.023).nnnCONCLUSIONnGSH levels from the biopsies were increased in the perfusion group early in the reperfusion time showing that myocardial tissue was well protected and recovered more rapidly after cross-clamping than after the occlusion of the coronary arteries. However, release of creatinine kinase was lower in the off-pump group showing that cardiopulmonary bypass has more deleterious effects later after the operation.Objective --To study the inflammatory reaction and myocardial metabolism in off-pump and on-pump coronary artery bypass patients. Design --Fifty coronary artery bypass patients were randomized to off-pump or on-pump operations. Myocardial biopsies were taken to determine myocardial metabolism and inflammation (glutathione (GSH), superoxide dismutase (SOD) and myeloperoxidase (MP)) and plasma samples for indicators of oxidative stress (conjugated dienes (s-BDC), oxidative products of proteins (s-ox-Prot) and low-density lipoprotein (LDL)-total peroxyl radical trapping antioxidant potential (s-TRAP)). Results --s-ox-Prot 10 r min was 2.11 r - r 0.75 vs 2.69 r - 0.60 ( p r = r 0.014), s-TRAP 5 r min was 861 r - r 180 vs 969 r - r 192 ( p r = r 0.032) and s-TRAP 10 r min 857 r - r 176 vs 985 r - r 166 ( p r = r 0.011), GSH 10 r min 0.55 r - r 0.19 vs 0.72 r - r 1.16 ( p r = r 0.007) (off-pump vs on-pump). The monobasic (MB) fraction of the creatinine kinase 24 r h after the operation was significantly lower in the off-pump group, 20.5 r - r 24.2 vs 61.8 r - r 84.6 ( p r = r 0.023). Conclusion --GSH levels from the biopsies were increased in the perfusion group early in the reperfusion time showing that myocardial tissue was well protected and recovered more rapidly after cross-clamping than after the occlusion of the coronary arteries. However, release of creatinine kinase was lower in the off-pump group showing that cardiopulmonary bypass has more deleterious effects later after the operation.

The effects of aprotinin and tranexamic acid on thrombin generation and fibrinolytic response after cardiac surgery

Background:u2002 Thrombin formation during cardiac surgery could result in disordered hemostasis and thrombosis. The aim of the study was to examine the effects of aprotinin and tranexamic acid on thrombin generation and fibrinolytic activity in patients undergoing cardiac surgery.

On-site coagulation monitoring does not affect hemostatic outcome after cardiac surgery

Background: Rapid coagulation tests are now available for monitoring of bleeding patients after cardiac surgery. As inappropriate blood use in these patients may be due to lack of timely coagulation data, we studied the effect of an algorithm with on‐line coagulation monitoring on transfusions in these patients.

Biochemical Injury Markers and Mortality After Coronary Artery Bypass Grafting: A Systematic Review

The strength of the association between cardiac biomarker release and prognosis is uncertain. We performed a systematic literature search to find articles regarding these markers and death after coronary surgical interventions, and evaluated the results with meta-analytic methods. We found 23 articles concerning 29,483 patients that reported the MB fraction of creatine kinase (CK-MB) and troponin T and I. Heterogeneity of existing studies prevented the pooling of the results of troponin studies. The pooled data of the CK-MB studies suggest that after coronary artery bypass grafting, CK-MB release of more than five to eight times the upper limit of the reference range is associated with an increased risk of death during the next 40 months.