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In non-surgical settings, covert stroke is more common than overt stroke and is associated with cognitive decline. Although overt stroke occurs in less than 1% of adults after non-cardiac surgery and is associated with substantial morbidity, we know little about perioperative covert stroke. Therefore, our primary aim was to investigate the relationship between perioperative covert stroke (ie, an acute brain infarct detected on an MRI after non-cardiac surgery in a patient with no clinical stroke symptoms) and cognitive decline 1 year after surgery. NeuroVISION was a prospective cohort study done in 12 academic centres in nine countries, in which we assessed patients aged 65 years or older who underwent inpatient, elective, non-cardiac surgery and had brain MRI after surgery. Two independent neuroradiology experts, masked to clinical data, assessed each MRI for acute brain infarction. Using multivariable regression, we explored the association between covert stroke and the primary outcome of cognitive decline, defined as a decrease of 2 points or more on the Montreal Cognitive Assessment from preoperative baseline to 1-year follow-up. Patients, health-care providers, and outcome adjudicators were masked to MRI results. Between March 24, 2014, and July 21, 2017, of 1114 participants recruited to the study, 78 (7%; 95% CI 6–9) had a perioperative covert stroke. Among the patients who completed the 1-year follow-up, cognitive decline 1 year after surgery occurred in 29 (42%) of 69 participants who had a perioperative covert stroke and in 274 (29%) of 932 participants who did not have a perioperative covert stroke (adjusted odds ratio 1·98, 95% CI 1·22–3·20, absolute risk increase 13%; p=0·0055). Covert stroke was also associated with an increased risk of perioperative delirium (hazard ratio [HR] 2·24, 95% CI 1·06–4·73, absolute risk increase 6%; p=0·030) and overt stroke or transient ischaemic attack at 1-year follow-up (HR 4·13, 1·14–14·99, absolute risk increase 3%; p=0·019). Perioperative covert stroke is associated with an increased risk of cognitive decline 1 year after non-cardiac surgery, and perioperative covert stroke occurred in one in 14 patients aged 65 years and older undergoing non-cardiac surgery. Research is needed to establish prevention and management strategies for perioperative covert stroke. Canadian Institutes of Health Research; The Ontario Strategy for Patient Oriented Research support unit; The Ontario Ministry of Health and Long-Term Care; Health and Medical Research Fund, Government of the Hong Kong Special Administrative Region, China; and The Neurological Foundation of New Zealand.

Literature regarding monitoring and consequences of distal limb ischemia due to femoral artery cannulation for Minimally Invasive Cardiac Surgery (MICS) remains limited. The primary objective was to determine its incidence, defined as a ≥ 15% difference in regional Oxygen Saturation (rSO 2 ) lasting ≥ four consecutive minutes between the cannulated and non-cannulated limb. The secondary objectives included: determination of distal limb ischemia, defined as a Tissue Oxygenation Index (TOI) < 50% in the cannulated limb, identification of predictors for distal limb ischemia, determination of a possible association of NIRS-diagnosed ischemia with acute kidney injury, and the need for vascular surgery up to six months after cardiac surgery. A prospective, observational cohort study with blinded rSO 2 -measurements to prevent intraoperative clinical decision-making. A single-center, community-hospital, clinical study. All consecutive patients ≥ 18 years old, and scheduled for predefined MICS. Patients underwent MICS with bilateral calf muscle rSO 2 -measurements conducted by Near-Infrared Spectroscopy (NIRS). In total 75/280 patients (26.79%) experienced distal limb ischemia according to the primary objective, while 18/280 patients (6.42%) experienced distal limb ischemia according to the secondary objective. Multivariate logistic regression showed younger age to be an independent predictor for distal limb ischemia ( p  = 0.003). None of the patients who suffered intraoperative ischemia required vascular surgery within the follow-up period. The incidence of NIRS-diagnosed ischemia varied from 6.4% to 26.8% depending on the used criteria. Short and long-term vascular sequelae, however, are limited and not intraoperative ischemia related. The added value of intraoperative distal limb NIRS monitoring for vascular reasons seems limited. Future research on femoral artery cannulation in MICS should shift focus to other outcome parameters such as acute kidney injury, postoperative pain or paresthesias.

Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO2) are frequently used during vascular and cardiac surgeries as a non-invasive means of assessing brain health; however, signal contamination from extracerebral tissues remains a concern. As an alternative, hyperspectral (hs)NIRS can be used to measure changes in the oxidation state of cytochrome c oxidase (ΔoxCCO), which provides greater sensitivity to the brain given its higher mitochondrial concentration versus the scalp. The purpose of this study was to evaluate the depth sensitivity of the oxCCO signal to changes occurring in the brain and extracerebral tissue components. The oxCCO assessment was conducted using multi-distance hsNIRS (source-detector separations = 1 and 3 cm), and metabolic changes were compared to changes in StO2. Ten participants were monitored using an in-house system combining hsNIRS and diffuse correlation spectroscopy (DCS). Data were acquired during carotid compression (CC) to reduce blood flow and hypercapnia to increase flow. Reducing blood flow by CC resulted in a significant decrease in oxCCO measured at rSD = 3 cm but not at 1 cm. In contrast, significant changes in StO2 were found at both distances. Hypercapnia caused significant increases in StO2 and oxCCO at rSD = 3 cm, but not at 1 cm. Extracerebral contamination resulted in elevated StO2 but not oxCCO after hypercapnia, which was significantly reduced by applying regression analysis. This study demonstrated that oxCCO was less sensitive to extracerebral signals than StO2.

In this clinical trial involving patients undergoing high-risk cardiac surgery, aprotinin was somewhat more effective than either aminocaproic acid or tranexamic acid in reducing massive perioperative bleeding but at the expense of a higher rate of death, mainly from cardiac causes. Aprotinin cannot be recommended to control blood loss in this clinical setting. In patients undergoing high-risk cardiac surgery, aprotinin was somewhat more effective than either aminocaproic acid or tranexamic acid in reducing massive perioperative bleeding but at the expense of a higher rate of death, mainly from cardiac causes. Every year an estimated 1 million to 1.25 million patients worldwide undergo cardiac surgery, including high-risk procedures such as repeat coronary-artery bypass grafting (CABG), valve replacements, and combined procedures. 1 High-risk procedures present an increased risk of death, massive bleeding, renal failure, and thrombotic complications, as compared with first-time isolated CABG. 2 – 4 Three antifibrinolytic agents have been used in cardiac surgery to minimize bleeding and reduce the need for transfusion: aprotinin, a naturally occurring serine protease inhibitor, and two lysine analogues, tranexamic acid and aminocaproic acid. 5 In clinical trials, all three drugs have been shown to be effective in reducing the . . .

Tissue oxygen saturation (StO2) is a noninvasive measure that reflects changes in tissue perfusion. Rapid response teams (RRTs) assess sick inpatients to determine need for intensive care unit (ICU) admission. This determination is subjective based on parameters such as systolic blood pressure, heart rate, and pulse oximetry. Our objective was to determine if parameters readily available at RRT bedside assessment (vital signs and StO2) can predict ICU admission and inhospital mortality. All inpatients assessed by RRT at a tertiary Canadian hospital were consecutively sampled for 3 months. After clinical assessment, the RRT physician (blinded to StO2) made the ultimate ICU admission decision. In 134 included patients, mean age was 65.5 ± 15.2 years, and 53% (n = 71) were males. There were 49 ICU admissions (36.6%) and 31 mortalities (23.1%). Two multivariable models significantly predicted ICU admission and inhospital mortality. The only independent predictor of ICU admission was pulse oximetry (adjusted odds ratio, 0.88; 95% confidence interval, 0.80-0.96; P = .007). Tissue oxygen saturation did not predict ICU admission but was the only independent predictor of mortality (adjusted odds ratio, 1.06; 95% confidence interval, 1.01-1.12; P = .04). Tissue oxygen saturation may identify critical illness in patients who would not traditionally meet ICU admission criteria and thus may identify patients who benefit from closer monitoring.

Introduction Microvascular reactivity is decreased in patients with septic shock; this is associated with worse clinical outcomes. The objectives of the present study were to investigate microvascular reactivity in cardiac surgery patients and to assess any association with clinical outcomes. Methods We retrospectively analyzed a prospectively collected registry. In total, 254 consecutive adult patients undergoing cardiac and thoracic aortic surgeries from January 2013 through May 2014 were analyzed. We performed a vascular occlusion test (VOT) by using near-infrared spectroscopy to measure microvascular reactivity. VOT was performed three times per patient: prior to the induction of anesthesia, at the end of surgery, and on postoperative day 1. The primary endpoint was a composite of major adverse complications, including death, myocardial infarction, acute kidney injury, acute respiratory distress syndrome, and persistent cardiogenic shock. Results VOT recovery slope decreased during the surgery. VOT recovery slope on postoperative day 1 was significantly lower in patients with composite complications than those without (3.1 ± 1.6 versus 4.0 ± 1.5 %/s, P = 0.001), although conventional hemodynamic values, such as cardiac output and blood pressure, did not differ between the groups. On multivariable regression and linear analyses, low VOT recovery slope on postoperative day 1 was associated with increases of composite complications (odds ratio 0.742; 95 % confidence interval (CI) 0.584 to 0.943; P = 0.015) and hospital length of stay (regression coefficient (B) −1.276; 95 % CI −2.440 to −0.112; P = 0.032). Conclusion Microvascular reactivity largely recovered on postoperative day 1 in the patients without composite complications, but this restoration was attenuated in patients with composite complications. Trial registration ClinicalTrials.gov NCT01713192 . Registered 22 October 2012.

Purpose Volatile anesthetics possess cardioprotective properties, but it is unknown if the cardioprotective effects extend equally to all members of the class. Although sevoflurane is a relatively newer anesthetic than isoflurane, its introduction into practice was not preceded by a head-to-head comparison with isoflurane in a trial focusing on clinically important outcomes. Our objective was to determine whether sevoflurane was non-inferior to isoflurane on a clinically important primary outcome in a heterogeneous group of adults undergoing cardiac surgery. Methods This was a pragmatic randomized non-inferiority comparative effectiveness clinical trial in 464 adults having coronary artery bypass graft and/or single valve surgery during November 2011 to March 2014. The intervention was maintenance of anesthesia with sevoflurane ( n = 231) or isoflurane ( n = 233) administered at a dose of 0.5-2.0 MAC throughout the entire operation. All caregivers were blinded except for the anesthesiologist and perfusionist. The primary outcome was a composite of intensive care unit (ICU) length of stay ≥ 48 hr and all-cause 30-day mortality. We hypothesized that sevoflurane would be non-inferior to isoflurane (non-inferiority margin < 10% based on an expected event rate of 25%). Secondary outcomes included prolonged ICU stay, 30- and 365-day all-cause mortality, inotrope or vasopressor usage, new-onset hemodialysis or atrial fibrillation, stroke, and readmission to the ICU. Results No losses to follow-up occurred. The primary outcome occurred in 25% of sevoflurane patients and 30% of isoflurane patients (absolute difference, −5.4%; one-sided 95% confidence interval, 1.4), thus non-inferiority was declared. Sevoflurane was not superior to isoflurane for the primary outcome ( P = 0.21) or for any secondary outcomes. Conclusion Sevoflurane is non-inferior to isoflurane on a composite outcome of prolonged ICU stay and all-cause 30-day mortality. Sevoflurane is not superior to isoflurane on any other of the clinically important outcomes. This trial was registered at clinicaltrials.gov; NCT01477151.

Purpose Deep tissue hypoxia has been hypothesized in the pathogenesis of complex regional pain syndrome type 1 (CRPS 1) for some patients. The purpose of this study was to determine if near-infrared spectroscopy (NIRS) could detect differences in deep tissue oxygen saturation (StO 2 ) and microcirculatory function in the hands of patients with CRPS 1. Methods Tissue oxygen saturation was evaluated at baseline and during an ischemia reperfusion challenge using vascular occlusion testing (VOT) in affected vs unaffected hands of patients with unilateral upper limb CRPS 1. A non-randomized experimental study design was used with baseline StO 2 as the primary outcome measure. Secondary outcome measures were occlusion and reperfusion slopes from VOT. Values were compared with the unaffected, contralateral hand and with the dominant and non-dominant hands of sex and age-matched volunteers. Correlations between values derived from NIRS and measures of pain and function from the Brief Pain Inventory (BPI) and the Disability of the Arm, Shoulder and Hand (DASH) questionnaires were explored. Results Independent of handedness, the baseline StO 2 of the affected hands of ten CRPS 1 patients was significantly lower than that of their unaffected hands (−5.8%; 95% confidence interval [CI] −10.6 to −1.0; P  = 0.02). The baseline StO 2 of affected CRPS 1 hands was also significantly lower than the non-dominant hands of ten volunteers (−7.3%; 95% CI −12.4 to −2.3; P  = 0.007). Differences in VOT occlusion and reperfusion slopes did not reveal changes that could be uniquely attributed to CRPS 1. No significant correlations were detected between values derived from VOT and values for pain and function obtained from BPI and DASH questionnaires for patients with CRPS 1. Conclusions Hands of patients affected by CRPS 1 of the upper limb showed significantly lower StO 2 compared with their unaffected contralateral hand as well as the hands of control subjects. This trial was registered at: ClinicalTrials.gov: NCT01586377.