Dexmedetomidine versus Propofol Sedation Reduces Delirium after Cardiac Surgery: A Randomized Controlled Trial.

BACKGROUND: Postoperative delirium (POD) is a serious complication after cardiac surgery. Use of dexmedetomidine to prevent delirium is controversial. The authors hypothesized that dexmedetomidine sedation after cardiac surgery would reduce the incidence of POD. METHODS: After institutional ethics review board approval, and informed consent, a single-blinded, prospective, randomized controlled trial was conducted in patients 60 yr or older undergoing cardiac surgery. Patients with a history of serious mental illness, delirium, and severe dementia were excluded. Upon admission to intensive care unit (ICU), patients received either dexmedetomidine (0.4 µg/kg bolus followed by 0.2 to 0.7 µg kg h infusion) or propofol (25 to 50 µg kg min infusion) according to a computer-generated randomization code in blocks of four. Assessment of delirium was performed with confusion assessment method for ICU or confusion assessment method after discharge from ICU at 12-h intervals during the 5 postoperative days. Primary outcome was the incidence of POD. RESULTS: POD was present in 16 of 91 (17.5%) and 29 of 92 (31.5%) patients in dexmedetomidine and propofol groups, respectively (odds ratio, 0.46; 95% CI, 0.23 to 0.92; P = 0.028). Median onset of POD was on postoperative day 2 (1 to 4 days) versus 1 (1 to 4 days), P = 0.027, and duration of POD 2 days (1 to 4 days) versus 3 days (1 to 5 days), P = 0.04, in dexmedetomidine and propofol groups, respectively. CONCLUSIONS: When compared with propofol, dexmedetomidine sedation reduced incidence, delayed onset, and shortened duration of POD in elderly patients after cardiac surgery. The absolute risk reduction for POD was 14%, with a number needed to treat of 7.1.

The interaction of carbon dioxide and hypoxia in the control of cerebral blood flow.

Both hypoxia and carbon dioxide increase cerebral blood flow (CBF), and their effective interaction is currently thought to be additive. Our objective was to test this hypothesis. Eight healthy subjects breathed a series of progressively hypoxic gases at three levels of carbon dioxide. Middle cerebral artery velocity, as an index of CBF; partial pressures of carbon dioxide and oxygen and concentration of oxygen in arterial blood; and mean arterial blood pressure were monitored. The product of middle cerebral artery velocity and arterial concentration of oxygen was used as an index of cerebral oxygen delivery. Two-way repeated measures analyses of variance (rmANOVA) found a significant interaction of carbon dioxide and hypoxia factors for both CBF and cerebral oxygen delivery. Regression models using sigmoidal dependence on carbon dioxide and a rectangular hyperbolic dependence on hypoxia were fitted to the data to illustrate this interaction. We concluded that carbon dioxide and hypoxia act synergistically in their control of CBF so that the delivery of oxygen to the brain is enhanced during hypoxic hypercapnia and, although reduced during normoxic hypocapnia, can be restored to normal levels with progressive hypoxia.

Early benefit of preserved cognitive function is not sustained at one-year after cardiac surgery: a longitudinal follow-up of the randomized controlled trial.

PURPOSE: Recently, we showed that processing of shed blood with a continuous-flow cell saver during cardiopulmonary bypass resulted in a clinically significant reduction in postoperative cognitive decline (POCD) six weeks after coronary artery bypass graft (CABG) surgery. The current study examined if the early benefit of reduced POCD was sustained in the same patient population at one-year follow-up. METHODS: One hundred seventy patients (cell saver group, n = 84; controls, n = 86) underwent neuropsychological testing at baseline and one year after surgery. The raw scores for each test were converted to Z-scores, and a combined Z-score of ten main variables was then calculated for each study group. RESULTS: Postoperative cognitive decline was present in 16 of 84 (19%) patients in the cell saver group (95% confidence interval [CI], 10.8 to 27.2) vs 15 of 86 (17.4%) patients in the control group (95% CI, 9.6 to 25.2) (P = 0.786). Six of the 15 patients in the control group with POCD at six weeks had the impairment at one year and five did not; four were lost to follow-up. Three of the six cell saver patients with POCD at six weeks still had impairment at one year, two did not, and one was not tested. Thirteen (15.4%) and nine (10.5%) patients in the cell saver and control groups, respectively, developed new POCD which was not evident at the six-week follow-up. CONCLUSIONS: The short-term preservation of cognitive function in elderly patients using the cell saver management strategy did not translate into a long-term benefit one year after CABG surgery. The presence of progressing cerebrovascular disease may be responsible for the long-term cognitive decline.

Rapid elimination of CO through the lungs: coming full circle 100 years on.

At the start of the 20th century, CO poisoning was treated by administering a combination of CO(2) and O(2) (carbogen) to stimulate ventilation. This treatment was reported to be highly effective, even reversing the deep coma of severe CO poisoning before patients arrived at the hospital. The efficacy of carbogen in treating CO poisoning was initially attributed to the absorption of CO(2); however, it was eventually realized that the increase in pulmonary ventilation was the predominant factor accelerating clearance of CO from the blood. The inhaled CO(2) in the carbogen stimulated ventilation but prevented hypocapnia and the resulting reductions in cerebral blood flow. By then, however, carbogen treatment for CO poisoning had been abandoned in favour of hyperbaric O(2). Now, a half-century later, there is accumulating evidence that hyperbaric O(2) is not efficacious, most probably because of delays in initiating treatment. We now also know that increases in pulmonary ventilation with O(2)-enriched gas can clear CO from the blood as fast, or very nearly as fast, as hyperbaric O(2). Compared with hyperbaric O(2), the technology for accelerating pulmonary clearance of CO with hyperoxic gas is not only portable and inexpensive, but also may be far more effective because treatment can be initiated sooner. In addition, the technology can be distributed more widely, especially in developing countries where the prevalence of CO poisoning is highest. Finally, early pulmonary CO clearance does not delay or preclude any other treatment, including subsequent treatment with hyperbaric O(2).

Isocapnic hyperpnoea shortens postanesthetic care unit stay after isoflurane anesthesia.

BACKGROUND: We conducted a prospective controlled clinical trial of the effect of isocapnic hyperpnoea (IH) on the times-to-recovery milestones in the operating room (OR) and postanesthetic care unit (PACU) after 1.5 to 3 hours of isoflurane anesthesia. METHODS: Thirty ASA grade I-III patients undergoing elective gynecological surgery were randomized at the end of surgery to either IH or the conventional recovery (control). Six patients with duration of anesthesia of <90 minutes were excluded from the analysis. The anesthesia protocol included propofol, fentanyl, morphine, rocuronium, and isoflurane in air/O(2). Unpaired t tests and analyses of variance were used to test for differences in times-to-recovery indicators between the two groups. RESULTS: The durations of anesthesia in IH and control groups were 140.8 + or - 32.7 and 142 + or - 55.6 minutes, respectively (P = 0.99). The time to extubation was much shorter in the IH group than in the control group (6.6 + or - 1.6 (SD) vs. 13. 6 + or - 3.9 minutes, respectively; P < 0.01). The IH group also had shorter times to eye opening (5.8 + or - 1.3 vs. 13.7 + or - 4.5 minutes; P < 0.01), eligibility for leaving the OR (8.0 + or - 1.7 vs. 17.4 + or - 6.1 minutes; P < 0.01), and eligibility for PACU discharge (74.0 + or - 16.5 vs. 94.5 + or - 14.7 minutes; P < 0.01). There were no differences in other indicators of recovery. CONCLUSION: IH accelerates recovery after 1.5 to 3 hours of isoflurane anesthesia and shortens OR and PACU stay.

Accelerated ethanol elimination via the lungs.

Ethanol poisoning is endemic the world over. Morbidity and mortality depend on blood ethanol levels which in turn depend on the balance between its rates of absorption and clearance. Clearance of ethanol is mostly at a constant rate via enzymatic metabolism. We hypothesized that isocapnic hyperpnea (IH), previously shown to be effective in acceleration of clearance of vapour anesthetics and carbon monoxide, would also accelerate the clearance of ethanol. In this proof-of-concept pilot study, five healthy male subjects were brought to a mildly elevated blood ethanol concentration (~ 0.1%) and ethanol clearance monitored during normal ventilation and IH on different days. IH increased elimination rate of ethanol in proportion to blood levels, increasing the elimination rate more than three-fold. Increased veno-arterial ethanol concentration differences during IH verified the efficacy of ethanol clearance via the lung. These data indicate that IH is a nonpharmacologic means to accelerate the elimination of ethanol by superimposing first order elimination kinetics on underlying zero order liver metabolism. Such kinetics may prove useful in treating acute severe ethanol intoxication.

Preoperative use of statins is associated with reduced early delirium rates after cardiac surgery.

BACKGROUND: Delirium is an acute deterioration of brain function characterized by fluctuating consciousness and an inability to maintain attention. Use of statins has been shown to decrease morbidity and mortality after major surgical procedures. The objective of this study was to determine an association between preoperative administration of statins and postoperative delirium in a large prospective cohort of patients undergoing cardiac surgery with cardiopulmonary bypass. METHODS: After Institutional Review Board approval, data were prospectively collected on consecutive patients undergoing cardiac surgery with cardiopulmonary bypass from April 2005 to June 2006 in an academic hospital. All patients were screened for delirium during their hospitalization using the Confusion Assessment Method in the intensive care unit. Multivariable logistic regression analysis was used to identify independent perioperative predictors of delirium after cardiac surgery. Statins were tested for a potential protective effect. RESULTS: Of the 1,059 patients analyzed, 122 patients (11.5%) had delirium at any time during their cardiovascular intensive care unit stay. Administration of statins had a protective effect, reducing the odds of delirium by 46%. Independent predictors of postoperative delirium included older age, preoperative depression, preoperative renal dysfunction, complex cardiac surgery, perioperative intraaortic balloon pump support, and massive blood transfusion. The model was reliable (Hosmer-Lemeshow test, P = 0.3) and discriminative (area under receiver operating characteristic curve = 0.77). CONCLUSIONS: Preoperative administration of statins is associated with the reduced risk of postoperative delirium after cardiac surgery with cardiopulmonary bypass.

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.

Non-invasive prospective targeting of arterial P(CO2) in subjects at rest.

Accurate measurements of arterial P(CO(2)) (P(a,CO(2))) currently require blood sampling because the end-tidal P(CO(2)) (P(ET,CO(2))) of the expired gas often does not accurately reflect the mean alveolar P(CO(2)) and P(a,CO(2)). Differences between P(ET,CO(2)) and P(a,CO(2)) result from regional inhomogeneities in perfusion and gas exchange. We hypothesized that breathing via a sequential gas delivery circuit would reduce these inhomogeneities sufficiently to allow accurate prediction of P(a,CO(2)) from P(ET,CO(2)). We tested this hypothesis in five healthy middle-aged men by comparing their P(ET,CO(2)) values with P(a,CO(2)) values at various combinations of P(ET,CO(2)) (between 35 and 50 mmHg), P(O(2)) (between 70 and 300 mmHg), and breathing frequencies (f; between 6 and 24 breaths min(-1)). Once each individual was in a steady state, P(a,CO(2)) was collected in duplicate by consecutive blood samples to assess its repeatability. The difference between P(ET,CO(2)) and average P(a,CO(2)) was 0.5 +/- 1.7 mmHg (P = 0.53; 95% CI -2.8, 3.8 mmHg) whereas the mean difference between the two measurements of P(a,CO(2)) was -0.1 +/- 1.6 mmHg (95% CI -3.7, 2.6 mmHg). Repeated measures ANOVAs revealed no significant differences between P(ET,CO(2)) and P(a,CO(2)) over the ranges of P(O(2)), f and target P(ET,CO(2)). We conclude that when breathing via a sequential gas delivery circuit, P(ET,CO(2)) provides as accurate a measurement of P(a,CO(2)) as the actual analysis of arterial blood.

Continuous-flow cell saver reduces cognitive decline in elderly patients after coronary bypass surgery.

BACKGROUND: Cerebral microembolization during cardiopulmonary bypass may lead to cognitive decline after cardiac surgery. Transfusion of the unprocessed shed blood (major source of lipid microparticulates) into the patient during cardiopulmonary bypass is common practice to reduce blood loss and blood transfusion. Processing of shed blood with cell saver before transfusion may limit cerebral microembolization and reduce cognitive decline after surgery. METHODS AND RESULTS: A total of 226 elderly patients were randomly allocated to either cell saver or control groups. Anesthesia and surgical management were standardized. Epiaortic scanning of the proximal thoracic aorta was performed in all patients. Transcranial Doppler was used to measure cerebral embolic rates. Standardized neuropsychological testing was conducted 1 week before and 6 weeks after surgery. The raw scores for each test were converted to Z scores, and then a combined Z score of 10 main variables was calculated for both study groups. The primary analysis was based on dichotomous composite cognitive outcome with a 1-SD rule. Cognitive dysfunction was present in 6% (95% confidence interval, 1.3% to 10.7%) of patients in the cell saver group and 15% (95% confidence interval, 8% to 22%) of patients in the control group 6 weeks after surgery (P=0.038). The severity of aortic atheroma and cerebral embolic count were similar between the 2 groups. CONCLUSIONS: The present report demonstrates that processing of shed blood with cell saver results in clinically significant reduction in postoperative cognitive dysfunction after cardiac surgery. These findings emphasize the clinical importance of lipid embolization in contributing to postoperative cognitive decline in patients exposed to cardiopulmonary bypass.

Epiaortic scanning modifies planned intraoperative surgical management but not cerebral embolic load during coronary artery bypass surgery.

BACKGROUND: Patients with aortic atheroma are at increased risk for neurological injury after coronary artery bypass graft (CABG) surgery. We sought to determine the role of epiaortic ultrasound scanning for reducing cerebral embolic load, and whether its use leads to changes of planned intraoperative surgical management in patients undergoing CABG surgery. METHODS: Patients >70-yr-of-age scheduled for CABG surgery were prospectively randomized to either an epiaortic scanning (EAS) group (aortic manipulation guided by epiaortic ultrasound) or a control group (manual aortic palpation without EAS). All patients received a comprehensive transesophageal echocardiographic examination. Transcranial Doppler (TCD) was used to monitor the middle cerebral arteries for emboli continuously from 2 min before aortic cannulation to 2 min after aortic decannulation. Neurological assessment was performed with the National Institute of Health stroke scale before surgery and at hospital discharge. The NEECHAM confusion scale was used for assessment and monitoring of patient global cognitive function on each day after surgery until hospital discharge. RESULTS: Intraoperative surgical management was changed in 16 of 55 (29%) patients in the EAS group and in 7 of 58 (12%) patients in the control group (P = 0.025). These changes included adjustments of the ascending aorta cannulation site for cardiopulmonary bypass (CPB), the avoidance of aortic cross-clamping by using ventricular fibrillatory arrest during surgery, or by conversion to off-pump surgery. During surgery, 7 of 58 (12%) patients in the control group crossed over to the EAS group based on the results of manual aortic palpation. The median [range] TCD detected cerebral embolic count did not differ between the EAS and control groups during aortic manipulations (EAS, 11.5 [1-516] vs control, 22.0 [1-160], P = 0.91) or during CPB (EAS, 42.0 [4-516] vs control, 63.0 [5-758], P = 0.46). The NEECHAM confusion scores and National Institute of Health stroke scale scores were similar between the two groups. CONCLUSIONS: These results show that the use of EAS led to modifications in intraoperative surgical management in almost one-third of patients undergoing CABG surgery. The use of EAS did not lead to a reduced number of TCD-detected cerebral emboli before or during CPB.

Hyperbaric oxygen therapy for spinal cord ischaemia after complex aortic repair - a retrospective review.

BACKGROUND: Complex aortic repair (CAR) carries high rates of debilitating postoperative complications, including spinal cord injury. The rate of spinal cord deficits post-CAR is approximately 10%, with permanent paraplegia in 2.9% and paraparesis in 2.4% of patients. Treatment options are limited. Rescue therapies include optimization of spinal cord perfusion and oxygen delivery by mean arterial pressure augmentation (> 90 mm Hg), cerebrospinal fluid drainage, and preservation of adequate haemoglobin concentration (> 100 g L⁻¹). Hyperbaric oxygen therapy (HBOT) has been described in several case reports as part of the multimodal treatment for spinal cord ischemia. HBOT has been used in our centre as adjunct rescue treatment for patients with spinal cord injury post-CAR that were refractory to traditional medical management, and we aimed to retrospectively review these cases. METHODS: After Research Ethics Board approval, we performed a retrospective review of all post-CAR patients who developed spinal cord injury with severe motor deficit and were treated with HBOT at our institution since 2013. RESULTS: Seven patients with spinal cord injury after CAR were treated with HBOT in addition to traditional rescue therapies. Five patients showed varying degrees of recovery, with two displaying full recovery. One developed oxygen-induced seizure, medically treated. No other HBOT-related complications were noted. CONCLUSIONS: Our retrospective study shows a potential benefit of hyperbaric oxygen therapy on neurological outcome in patients who developed spinal cord injury after CAR. Prospective research is needed to understand the role, efficacy, benefits and risks of HBOT in this setting.

Relationship between hyperbaric oxygen therapy and quality of life in participants with chronic diabetic foot ulcers: data from a randomized controlled trial.

AIMS: To investigate the effect of hyperbaric oxygen therapy on health-related quality of life (HRQoL) in participants with diabetes and chronic foot ulcers. METHODS: Using data from a randomized controlled trial, we included 103 participants (49 in hyperbaric oxygen therapy group and 54 in sham group) for analyses. The primary outcome was HRQoL as measured by the EQ-5D-3L instrument, while secondary outcomes included quality of life evaluated by the Short Form 36 (SF-36) and Diabetic Foot Ulcers Scale-Short Form (DFS-SF). We used the analysis of covariance to assess whether the EQ-5D index values in hyperbaric oxygen therapy group differed from the sham group. Logistic regression was used to assess the relationship between hyperbaric oxygen therapy and the responses of 'problems' for the EQ-5D health states. RESULTS: No significant differences in EQ-5D index values were found between the hyperbaric oxygen therapy and sham groups: 0.01 (95% CI -0.25, 0.28; p = 0.93) at week 12; 0.07 (95% CI -0.21, 0.34; p = 0.64) at week 6. Hyperbaric oxygen therapy was found to be associated with fewer participants reporting 'problems' in mobility (OR 0.24, 95% CI 0.07, 0.85 at week 12) and pain or discomfort (OR 0.20, 95% CI 0.07, 0.61 at week 6; OR 0.32, 95% CI 0.11, 0.97 at week 12), compared with the sham group. No significant differences in SF-36 or DFS-SF were observed. CONCLUSIONS: No significant effect of hyperbaric oxygen therapy on HRQoL measured by EQ-5D index value was found in this study. Due to the potential insufficient power to assess statistical difference, more large-scale research is needed to further evaluate the effect of hyperbaric oxygen therapy on HRQoL in participants with chronic diabetic foot ulcers.

Modified N95 mask delivers high inspired oxygen concentrations while effectively filtering aerosolized microparticles.

STUDY OBJECTIVE: In a pandemic, hypoxic patients will require an effective oxygen (O2) delivery mask that protects them from inhaling aerosolized particles produced by others, as well as protecting the health care provider from exposure from the patient. We modified an existing N95 mask to optimize O2 supplementation while maintaining respiratory isolation. METHODS: An N95 mask was modified to deliver O2 by inserting a plastic manifold consisting of a 1-way inspiratory valve, an O2 inlet and a gas reservoir. In a prospective repeated-measures study, we studied 10 healthy volunteers in each of 3 phases, investigating (1) the fractional inspiratory concentrations of O2 (F(I)O2) delivered by the N95 O2 mask, the Hi-Ox80 O2 mask, and the nonrebreathing mask during resting ventilation and hyperventilation, each at 3 O2 flow rates; (2) the ability of the N95 mask, the N95 O2 mask, and the nonrebreathing mask to filter microparticles from ambient air; and (3) to contain microparticles generated inside the mask. RESULTS: The F(I)O2s (median [range]) delivered by the Hi-Ox80 O2 mask, the N95 O2 mask, and the nonrebreathing mask during resting ventilation, at 8 L/minute O2 flow, were 0.90 (0.79 to 0.96), 0.68 (0.60 to 0.85), and 0.59 (0.52 to 0.68), respectively. During hyperventilation, the FiO2s of all 3 masks were clinically equivalent. The N95 O2 mask, but not the nonrebreathing mask, provided the same efficiency of filtration of internal and external particles as the original N95, regardless of O2 flow into the mask. CONCLUSION: An N95 mask can be modified to administer a clinically equivalent FiO2 to a nonrebreathing mask while maintaining its filtration and isolation capabilities.

Hyperbaric Oxygen Therapy Does Not Reduce Indications for Amputation in Patients With Diabetes With Nonhealing Ulcers of the Lower Limb: A Prospective, Double-Blind, Randomized Controlled Clinical Trial.

OBJECTIVE: Hyperbaric oxygen therapy (HBOT) is used for the treatment of chronic diabetic foot ulcers (DFUs). The controlled evidence for the efficacy of this treatment is limited. The goal of this study was to assess the efficacy of HBOT in reducing the need for major amputation and improving wound healing in patients with diabetes and chronic DFUs. RESEARCH DESIGN AND METHODS: Patients with diabetes and foot lesions (Wagner grade 2-4) of at least 4 weeks' duration participated in this study. In addition to comprehensive wound care, participants were randomly assigned to receive 30 daily sessions of 90 min of HBOT (breathing oxygen at 244 kPa) or sham (breathing air at 125 kPa). Patients, physicians, and researchers were blinded to group assignment. At 12 weeks postrandomization, the primary outcome was freedom from meeting the criteria for amputation as assessed by a vascular surgeon. Secondary outcomes were measures of wound healing. RESULTS: One hundred fifty-seven patients were assessed for eligibility, with 107 randomly assigned and 103 available for end point adjudication. Criteria for major amputation were met in 13 of 54 patients in the sham group and 11 of 49 in the HBOT group (odds ratio 0.91 [95% CI 0.37, 2.28], P = 0.846). Twelve (22%) patients in the sham group and 10 (20%) in the HBOT group were healed (0.90 [0.35, 2.31], P = 0.823). All other indices of wound healing were also not statistically significantly different between groups. CONCLUSIONS: HBOT does not offer an additional advantage to comprehensive wound care in reducing the indication for amputation or facilitating wound healing in patients with chronic DFUs.

Tranexamic acid and early saphenous vein graft patency in conventional coronary artery bypass graft surgery: a prospective randomized controlled clinical trial.

OBJECTIVE: Use of antifibrinolytic agents reduces the risk of bleeding and decreases the need for blood product use in patients undergoing cardiac surgery. The purpose of this study was to determine whether perioperative use of tranexamic acid decreases the rate of saphenous vein graft patency in the early postoperative period after conventional coronary artery bypass grafting surgery. METHODS: A total of 312 patients scheduled for elective coronary artery bypass grafting surgery with cardiopulmonary bypass were randomized to receive either tranexamic acid 100 mg/kg (n = 147) or placebo (n = 165) in a double-blinded fashion before the initiation of cardiopulmonary bypass. Saphenous vein graft patency was assessed with magnetic resonance imaging 5 to 30 days after surgery. RESULTS: Both groups were comparable with respect to baseline demographic data and surgical characteristics. A total of 237 (76%) patients underwent magnetic resonance imaging assessment. A total of 297 saphenous vein grafts were performed and 253 (85.2%; 95% confidence interval, 83.5%-86.9%) were seen in the tranexamic acid group, and 265 saphenous vein grafts were performed and 231 (87.2%; 95% confidence interval, 85.5%-88.9%) were seen in the placebo group (P = .4969). The blood loss and blood product transfusion rates in the tranexamic acid group were significantly lower than in the placebo group. There was no difference between groups with respect to postoperative morbidity and mortality. CONCLUSIONS: The administration of tranexamic acid before cardiopulmonary bypass did not seem to compromise early venous graft patency rates but reduced perioperative blood product transfusion rates. Consequently, tranexamic acid could be advocated for routine use in patients undergoing conventional coronary artery bypass grafting surgery.

Regional anesthesia in cardiac surgery: a friend or a foe?

Escalating costs and change in the profile of patients presenting for cardiac surgery requires modification of perioperative management strategies. Regional anesthesia has played an integral part of many fast-track anesthesia protocols across North America and Europe. This review suggests that for patients undergoing coronary artery bypass graft surgery, the risk-to-benefit ratio is in favor of epidural and spinal anesthesia, provided there are no specific contraindications and the guidelines for the use of regional techniques in cardiac surgery are followed. Patients managed with regional techniques seem to benefit from superior postoperative analgesia, shorter postoperative ventilation, reduced incidence of supraventricular arrhythmia, and lower rates of perioperative myocardial infarction. The results of this analysis suggest that for each episode of neurologic complication, 20 myocardial infarctions and 76 episodes of atrial fibrillation would be prevented, thus, we would consider the regional anesthesia and analgesia to be an effective strategy that improves perioperative morbidity. However, other treatment modalities such as the addition of calcium channel blockers, aspirin, and beating heart surgery, are also suggested to be beneficial in cardiac surgical patients and may impose less risk than the use of regional techniques. We believe that the results presented in this review are encouraging enough to permit continued investigation. A prospective, randomized, controlled multicenter trial needs to be adequately powered to answer important clinical questions and allow for a long-term follow-up.

Mild to moderate atheromatous disease of the thoracic aorta and new ischemic brain lesions after conventional coronary artery bypass graft surgery.

BACKGROUND AND PURPOSE: The presence of new ischemic brain infarcts, detected by diffusion-weighted magnetic resonance imaging (DW-MRI), have been reported in considerable number of patients after cardiac surgery. We sought to determine the role of proximal thoracic aortic atheroma in predicting embolic events and new ischemic brain lesions in patients undergoing conventional coronary revascularization surgery. METHODS: Transesophageal echocardiography and epiaortic scanning was performed to assess the severity of aortic atherosclerosis in the ascending aorta and the aortic arch. Patients were allocated to either low-risk group, (intimal thickness < or =2mm), or high-risk group (intimal thickness >2mm). Transcranial Doppler was used to monitor the middle cerebral artery. DW-MRI was performed 3-7 days after surgery. The NEECHAM Confusion Scale was used for assessment and monitoring patient consciousness level. RESULTS: Patients in the high-risk group were considerably older; 71+/-6 (n=38) versus 67+/-6 (n=72) years, P=0.004 and were more likely to have impaired left ventricular function. Confusion was present in 6 (16%) patients in the high-risk group and 5 (7%) patients in the low-risk group. Patients in the high-risk group had a three-fold increase in median embolic count, 223.5 versus 70.0, P=0.0003. DW-MRI detected brain lesions were only present in patients from high-risk group, 61.5 versus 0%, P<0.0001. There was significant correlation between the NEECHAM scores and embolic count in the high-risk group; r=0.63, P<0.001. CONCLUSIONS: The findings of this investigation suggest that mild to moderate atheromatous disease of the ascending aorta and the aortic arch (intimal thickness >2mm) is a major contributor to ischemic brain injury after cardiac surgery.

Rates of carbon monoxide elimination in males and females.

The purpose of this study was to verify the previously reported shorter half-time of elimination (t½) of carbon monoxide (CO) in females compared to males. Seventeen healthy subjects (nine men) completed three sessions each, on separate days. For each session, subjects were exposed to CO to raise the carboxyhemoglobin percentage (COHb) to ~10%; then breathed in random order, either (a) 100% O2 at poikilocapnia (no CO2 added), or (b) hyperoxia while maintaining normocapnia using sequential gas delivery, or (c) voluntary hyperpnea at~4x the resting minute ventilation. We measured minute ventilation, hemoglobin concentration [Hb] and COHb at 5 min intervals. The half-time of reduction of COHb (t½) was calculated from serial blood samples. The total hemoglobin mass (HbTOT) was calculated from [Hb] and estimated blood volume from a nomogram based on gender, height, and weight. The t½ in the females was consistently shorter than in males in all protocols. This relationship was sustained even after controlling for alveolar ventilation (P < 0.05), with the largest differences in t½ between the genders occurring at low alveolar ventilation rates. However, when t½ was further normalized for HbTOT, there was no significant difference in t½ between genders at alveolar ventilation rates between 4 and 40 L/min (P = 0.24). We conclude that alveolar ventilation and HbTOT are sufficient to account for a major difference in CO clearance between genders under resting (nonexercising) conditions.