Postoperative Pain Management Strategies and Delirium After Transapical Aortic Valve Replacement: A Randomized Controlled Trial.

OBJECTIVE(S): This study was designed to compare 2 different perioperative analgesia strategies with respect to the incidence of postoperative delirium after a transapical approach for transcatheter aortic valve replacement (TAVR). The authors hypothesized that perioperative thoracic paravertebral analgesia with a local anesthetic would decrease opioid consumption and in turn reduce the incidence of postoperative delirium when compared with systemic opioid-based analgesia after a transapical TAVR procedure. DESIGN: Prospective, randomized controlled clinical trial. SETTING: Tertiary referral center, university hospital. PARTICIPANTS: The study comprised 44 patients undergoing a transapical TAVR procedure. Patients with a history of serious mental illness, delirium, and severe dementia and/or patients with contraindications to regional anesthesia were excluded. INTERVENTIONS: Patients were randomly assigned to either the paravertebral group (perioperative continuous thoracic paravertebral block with local anesthetic) or the patient-controlled analgesia group (systemically administered opioids) using a computer-generated randomization code in blocks of four patients. MEASUREMENTS AND MAIN RESULTS: Assessment of postoperative delirium was performed by trained research staff using the confusion assessment method for intensive care unit preoperatively and postoperatively every 12 hours or more often if needed according to the patient's condition during the first 7 postoperative days or until discharge. Pain was assessed with a 10 cm Visual Analog Scale pain score system during the 48 hours postoperatively. The sedation level was assessed using the Sedation Agitation Scale during the same period. Overall postoperative delirium was detected in 12/44 (27%) patients, with 7/22 (32%) in the patient-controlled analgesia and 5/22 (23%) in the paravertebral groups, respectively (p = 0.73). Both groups were similar with respect to demographic data, preoperative medications, and comorbidities. Paravertebral analgesia was associated with an opioid-sparing effect during surgery and during the 48-hour postoperative period. Sedation and pain scores were similar between the 2 groups. In addition, paravertebral analgesia was associated with earlier extubation times; however, the overall morbidity and mortality were similar between the 2 groups. CONCLUSIONS: Paravertebral analgesia in patients undergoing transapical TAVR procedures appears to have an opioid-sparing effect. However, it did not translate into a statistically significant decrease in the rate of postoperative delirium.

The influence of perioperative coagulation status on postoperative blood loss in complex cardiac surgery: a prospective observational study.

INTRODUCTION: Coagulopathy leading to excessive blood loss is a serious complication of cardiac surgery. In this prospective cohort study, we measured patients' coagulation status before and after cardiopulmonary bypass (CPB) and examined their relationships with postoperative blood loss. METHODS: Patients undergoing complex cardiac surgery with CPB who did not have preexisting coagulopathy were eligible. Detailed clinical and coagulation data were prospectively collected on all patients. Coagulation testing was performed before and after CPB, and included measures of thrombin generation, clotting factor consumption and dilution, clot stabilization, and fibrinolysis. The associations of variables with post-CPB blood loss (estimated loss from CPB to intensive care unit admission and 24-hour chest tube drainage) were assessed with the Spearman rank correlation test and multivariable linear regression. RESULTS: The median blood loss among the 101 study patients was 952 mL (interquartile range, 601-1553 mL). Variables independently associated with increasing blood loss were as follows: previous sternotomies (P = 0.01), lower pre-CPB prothrombin fragment F1 + 2 levels (measure of thrombin generation; P = 0.001), lower post-CPB platelet counts (P = 0.01), larger percent decrease in fibrinogen levels (P = 0.05), and higher post-CPB soluble fibrin monomer levels (measure of thrombin activity and clot stabilization; P < 0.0001) (model R(2) = 0.43). CONCLUSIONS: In complex cardiac surgery, blood loss is directly influenced by reduced pre-CPB thrombin generation rate, increased post-CPB consumption and dilution of clotting factors, as well as inadequate post-CPB clot stabilization. This information can aid in identifying patients at high risk for excessive blood loss and testing new interventions aimed at reducing the burden of this complication. The validity and generalizability of these findings need to be assessed by other studies.

The clinical utility of an index of global oxygenation for guiding red blood cell transfusion in cardiac surgery.

BACKGROUND: This observational study explored the potential utility of oxygen extraction ratio (O2ER) as an adjunct to the hemoglobin (Hb) concentration for guiding red blood cell (RBC) transfusion decisions after cardiac surgery with cardiopulmonary bypass (CPB). STUDY DESIGN AND METHODS: Hb and O2ER measures were obtained before as well as 15 and 120 minutes after RBC transfusion episodes (defined as 1-2 RBC units given in succession after CPB, within 24 hr. of surgery). Changes related to RBC transfusions among patients with normal (30%) and elevated(>30%) pretransfusion O2ERs were analyzed. RESULTS: Of the 176 patients enrolled, 74 received RBC transfusions. Of these, 50 had data available for 62 transfusion episodes. Pretransfusion episode O2ER values were elevated in 27 cases and normal in 35(56%) cases. Among those who received transfusion for low Hb concentration, 43 percent (27/62) had normal pretransfusion O2ER values. While the posttransfusion O2ER values did not change in patients with normal pretransfusion O2ER values, they did decrease inpatients with elevated pretransfusion O2ER values (% change [+/-SD] at 15 and 120 min after transfusion was -5.2 +/- 7.8 and -3.8 +/- 8.0%, respectively; p < 0.05). CONCLUSION: If a normal O2ER in anemic patients with no evidence of organ dysfunction indicates adequate tissue oxygen delivery, then our findings suggest that incorporating O2ER into the transfusion decision will substantially reduce post-cardiac surgery RBC transfusions by allowing us to safely avoid transfusing this group of patients. Future studies are needed to assess the validity of this conclusion.

N-acetylcysteine is associated with increased blood loss and blood product utilization during cardiac surgery.

OBJECTIVE: When used to prevent perioperative inflammation and ischemia-reperfusion injury, N-acetylcysteine may inadvertently impair hemostasis. We, therefore, performed a post hoc analysis of a recent randomized controlled trial in cardiac surgery to determine whether N-acetylcysteine was associated with increased blood loss and blood product transfusion. DESIGN: Blinded (patients, caregivers, outcome assessors) placebo-controlled parallel group randomized trial (www.ClinicalTrials.gov ID NCT00188630). SETTING: Tertiary care hospital in Toronto, Ontario, Canada (September 2003 to October 2005). PATIENTS: A total of 177 patients with preexisting moderate renal insufficiency (estimated glomerular filtration rate or=5 units of red blood cells within 24 hours of surgery was significantly higher with N-acetylcysteine (relative risk 1.85, 95% CI 1.06-3.21, p = 0.03; adjusted relative risk 2.09, 95% CI 1.24-3.83, p = 0.005). CONCLUSIONS: In patients who have preexisting moderate renal insufficiency and are undergoing cardiac surgery, N-acetylcysteine was associated with important effects on blood loss and blood product transfusion. Clinicians and researchers should, therefore, consider the potential for impaired hemostasis when using N-acetylcysteine in the perioperative setting. Further research is needed to elucidate mechanisms by which N-acetylcysteine may impair hemostasis, and the risk-benefit profile of N-acetylcysteine for perioperative organ protection.

The pharmacokinetic profile of recombinant human erythropoietin is unchanged in patients undergoing cardiac surgery.

BACKGROUND: In anticipation of future studies, we examined the pharmacokinetics profile of erythropoietin (EPO) in patients undergoing cardiac surgery. METHODS: Cardiac surgical patients were enrolled into one of six groups: four cardiopulmonary bypass (CPB) groups [placebo (n = 6), 250 IU/kg EPO (n = 3), 500 IU/kg EPO (n = 3), and 500 IU/kg EPO, two doses (n = 6)] and two off-pump coronary artery bypass (OPCAB) groups [placebo (n = 3) and 500 IU/kg EPO (n = 3)]. The EPO was administered prior to anesthesia and 10 min after CPB (if required). Blood samples for serum EPO were collected at baseline, 10 min after dosing, 5 min after sternotomy, during CPB or the equivalent for OPCAB (5, 15, 45, 60 min), and post-CPB (5, 15, 45, and 60 min, 6, 12 and 24 h, and daily until day 5). RESULTS: Endogenous EPO increased within 24 h of surgery in the placebo group and remained elevated. There was approximately a 40% decrease in serum EPO concentration at the initiation of CPB due to an increase in circulatory blood volume. There were no differences in apparent volume of distribution in the plasma (Vc) (42.2 +/- 9.9, 39.8 +/- 6.3, 42.3 +/- 14.0 mL/kg), clearance (CL) (4.63 +/- 1.14, 3.44 +/- 0.68, 4.27 +/- 0.52 mL h/kg), and t((1/2)) (16.4 +/- 8.0 16.9 +/- 10.6, 22.4 +/- 9.3 h) between the CPB treatment groups. The pharmacokinetic profile of EPO in the OPCAB group was similar to that for the CPB groups: Vc = 39.3 +/- 7.0 mL/kg, CL = 4.98 +/- 0.17 mL h/kg and t((1/2)) = 17.1 +/- 18.1 h. CONCLUSIONS: CPB had no apparent effect on the pharmacokinetics of EPO.

Off-pump coronary bypass surgery: risk of ischemic brain lesions in patients with atheromatous thoracic aorta.

PURPOSE: The purpose of this study was to determine if there is an association between the proximal thoracic aortic (ascending aorta and aortic arch) atheroma and ischemic brain lesions on diffusion-weighted magnetic resonance imaging (DW-MRI) after on-pump (ONCAB) and off-pump (OPCAB) coronary artery bypass surgery. METHODS: Patients who underwent ONCAB surgery (n = 13) and who had aortic atheroma > 2 mm were compared to a risk-adjusted prospective cohort of patients (n = 13) undergoing OPCAB surgery. Transesophageal echocardiography and epiaortic scanning were performed to assess the proximal thoracic aorta. Patients were evaluated for new ischemic brain lesions utilizing DW-MRI three to seven days after surgery. The NEECHAM confusion scale was used to evaluate patient consciousness. RESULTS: The groups were comparable with respect to demographic data, and prevalence of preoperative risk factors. The extent and severity of aortic atheroma was similar in the two groups. The average maximum height of atheroma was 5.0 +/- 2.0 mm in the OPCAB and 4.8 +/- 1.9 in the ONCAB groups, respectively. The prevalence of new ischemic brain lesions on DW-MRI was 0% in the OPCAB group and 61% in the ONCAB group (P = 0.001). Patients in the OPCAB group were less confused during the first two postoperative days. CONCLUSION: Patients with aortic atheroma > 2 mm may have a lower risk of new ischemic brain lesions as identified by DWMRI after OPCAB surgery. Patient stratification based upon aortic atheroma burden should be addressed in future trials designed to tailor treatment strategies to improve short- and long-term neurological outcomes in patients undergoing cardiac surgery.

Clinical outcomes in patients undergoing elective coronary artery bypass graft surgery with and without utilization of pulmonary artery catheter-generated data.

OBJECTIVE: The purpose of this study was to determine the frequency of pulmonary artery catheter (PAC) quantitative data requirements for modifying patient management during and after elective coronary artery bypass graft (CABG) surgery. DESIGN: A prospective observational clinical trial. SETTING: University tertiary referral center. PARTICIPANTS: Two hundred patients undergoing elective CABG surgery. INTERVENTIONS: Attending anesthesiologist and surgeon were blinded to PAC numeric values. These data could be revealed in the presence of at least 2 of the following criteria: (1) systolic blood pressure <90 mmHg, (2) central venous pressure >15 mmHg, (3) urine output <0.5 mL/kg/h, (4) pH <7.35/HCO(3) <18 mmol/L, (5) SaO(2) <95%/F(I)O(2) >80%, and (6) ST changes +/- 2 mm if the empiric treatment failed to restore normal hemodynamics within 10 minutes. All patients were classified into either blinded or unblinded PAC groups. MEASUREMENTS AND MAIN RESULTS: PAC data were unblinded in 46 (23%) patients. Preliminary diagnosis was confirmed in 28 (14%), and treatment was modified in 18 (9%) of these patients. Four (2%) patients were given additional fluid challenges, 10 (5%) patients received a combination of fluid challenges and inotropic support, 3 (1.5%) patients were started on vasoconstrictors, and 1 (0.5%) patient required insertion of an intra-aortic balloon pump. Patients in the unblinded PAC group had a higher prevalence of perioperative myocardial infarction, atrial fibrillation, and inotropic support; longer intubation times; and increased intensive care unit (ICU) and hospital lengths of stay. CONCLUSIONS: This study confirmed the contention that insertion of a PAC can be safely delayed until the clinical need arises either in the operating room or in the ICU after elective CABG surgery.

Acupressure wristbands for the prevention of postoperative nausea and vomiting in adults undergoing cardiac surgery.

OBJECTIVE: To determine whether the application of acupressure bands would lead to a reduction in postoperative nausea and vomiting after cardiac surgery. DESIGN: Prospective, randomized, double-blind clinical trial. SETTING: University-affiliated tertiary care teaching hospital. PARTICIPANTS: Adult patients undergoing cardiac surgery. INTERVENTIONS: One hundred fifty-two patients were enrolled to receive either acupressure treatment (n = 75) or placebo (n = 77). All patients had acupressure bands placed on both wrists before induction of anesthesia; those in the treatment group had a bead placed in contact with the P6 point on the forearm. MEASUREMENTS AND MAIN RESULTS: Patients were assessed for nausea, vomiting, and pain scores during the first 24 hours of the postoperative period. The incidences of nausea, vomiting, pain scores, and analgesic and antiemetic requirements were similar between the 2 groups. A subgroup analysis by gender implied that acupressure treatment may be effective only in female patients. CONCLUSION: Acupressure treatment did not lead to a reduction in nausea, vomiting, or antiemetic requirements in patients after cardiac surgery.