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Biological phenotypes in patients with the acute respiratory distress syndrome (ARDS) have previously been described. We hypothesized that the trajectory of PaO 2 /F I O 2 ratio could be used to identify phenotypes of ARDS. We used a retrospective cohort analysis of an ARDS database to identify latent classes in the trajectory of PaO 2 /F I O 2 ratio over time. We included all adult patients admitted to an intensive care unit who met the Berlin criteria for ARDS over a 4-year period in tertiary adult intensive care units in Manitoba, Canada. Baseline demographics were collected along with the daily PaO 2 /F I O 2 ratio collected on admission and on days 1–7, 14 and 28. We used joint growth mixture modeling to test whether ARDS patients exhibit distinct phenotypes with respect to both longitudinal PaO 2 /F I O 2 ratio and survival. The resulting latent classes were compared on several demographic variables. In our study group of 209 patients, we found that four latent trajectory classes of PaO 2 /F I O 2 ratio was optimal. These four classes differed in their baseline PaO 2 /F I O 2 ratio and their trajectory of improvement during the 28 days of the study. Despite similar baseline characteristics the hazard for death for the classes differed over time. This difference was largely driven by withdrawal of life sustaining therapy in one of the classes. Latent classes were identified in the trajectory of the PaO 2 /F I O 2 ratio over time, suggesting the presence of different ARDS phenotypes. Future studies should confirm the existence of this finding and determine the cause of mortality differences between classes.

Background Research on the duration of infectivity of ICU patients with COVID-19 has been sparse. Tests based on Reverse Transcriptase polymerase chain reaction (RT-PCR) detect both live virus and non-infectious viral RNA. We aimed to determine the duration of infectiousness based on viral culture of nasopharyngeal samples of patients with COVID-19. Methods Prospective observational study in adult intensive care units with a diagnosis of COVID-19 Pneumonia. Patients had repeated nasopharyngeal sampling performed after day 10 of ICU admission. Culture positive rate (based on viral culture on Vero cells in a level 4 lab) and Cycle threshold from RT-PCR were measured. Results Nine patients of the 108 samples (8.3%, 95% CI 3.9–15.2%) grew live virus at a median of 13 days (interquartile range 11–19) after their initial positive test. 74.1% of patients were RT-PCR positive but culture negative, and the remaining (17.6%) were RT-PCR and culture negative. Cycle threshold showed excellent ability to predict the presence of live virus, with a Ct < 25 with an AUC of 0.90 (95% CI 0.83–0.97, p  < 0.001). The specificity of a Ct > 25 to predict negative viral culture was 100% (95% CI 70–100%). Conclusion 8.3% of our ICU patients with COVID-19 grew live virus at a median of 13 days post-initial positive RT-PCR test. Severity of illness, use of mechanical ventilation, and time between tests did not predict the presence of live virus. Cycle threshold of > 25 had the best ability to determine the lack of live virus in these patents.

Purpose Ebola virus disease (EVD) is a viral hemorrhagic fever that is highly transmissible and all too often rapidly fatal. Recent outbreaks in West Africa reveal that this infection has the potential to be transmitted worldwide. Anesthesiologists and intensivists, due to their training in the management of the critically ill, may be called upon to assist in the management of these patients. The focus of this brief review is on the epidemiology, pathogenesis, and management of patients with EVD. Source Review of the current literature. Principal findings Ebola virus disease causes severe diarrhea, electrolyte disturbances and other major end-organ dysfunction. Early aggressive resuscitation may reduce the mortality of this disease. There is presently no available vaccine nor cure, with experimental therapies having yielded limited success. Personal protective equipment (PPE) is necessary for all patient contact, and enhanced PPE is required for all aerosol-generating medical procedures. Conclusion Anesthesiologists and intensivists may be called upon to manage patients with EVD. It is important that these clinicians have an appreciation for the epidemiology and pathogenesis of this disease and for the proper utilization of PPE when treating these patients.

Introduction Goal-directed therapy (GDT) has been shown in numerous studies to decrease perioperative morbidity and mortality. The mechanism of benefit of GDT, however, has not been clearly elucidated. Targeted resuscitation of the vascular endothelium with GDT might alter the postoperative inflammatory response and be responsible for the decreased complications with this therapy. Methods This trial was registered at ClinicalTrials.gov as NCT01681251. Forty patients undergoing elective open repair of their abdominal aortic aneurysm, 18 years of age and older, were randomized to an interventional arm with GDT targeting stroke volume variation with an arterial pulse contour cardiac output monitor, or control, where fluid therapy was administered at the discretion of the attending anesthesiologist. We measured levels of several inflammatory cytokines (C-reactive protein, Pentraxin 3, suppressor of tumorgenicity--2, interleukin-1 receptor antagonist, and tumor necrosis factor receptor-III) preoperatively and at several postoperative time points to determine if there was a difference in inflammatory response. We also assessed each group for a composite of postoperative complications. Results Twenty patients were randomized to GDT and twenty were randomized to control. Length of stay was not different between groups. Intervention patients received less crystalloid and more colloid. At the end of the study, intervention patients had a higher cardiac index (3.4 ± 0.5 vs. 2.5 ± 0.7 l/minute per m 2 , p  < 0.01) and stroke volume index (50.1 ± 7.4 vs. 38.1 ± 9.8 ml/m 2 , p  < 0.01) than controls. There were significantly fewer complications in the intervention than control group (28 vs. 12, p  = 0.02). The length of hospital and ICU stay did not differ between groups. There was no difference in the levels of inflammatory cytokines between groups. Conclusions Despite being associated with fewer complications and improved hemodynamics, there was no difference in the inflammatory response of patients treated with GDT. This suggests that the clinical benefit of GDT occurs in spite of a similar inflammatory burden. Further work needs to be performed to delineate the mechanism of benefit of GDT. Trial registration ClinicalTrials.gov Identifier: NCT01681251 . Registered 18 May 2011.

Purpose The World Health Organization has proclaimed the current Ebola outbreak as a public health emergency. If an outbreak of Ebola should occur in Canada, anesthesiologists and anesthesia departments may be called upon to respond. The purpose of this review is to highlight and discuss potential ethical concepts that may be relevant to anesthesiologists. Source A thorough literature search was conducted using a variety of MEDLINE ® sources, and we used Stand on Guard for Thee. Ethical Considerations in Preparedness Planning for Pandemic Influenza, a report by The University of Toronto Joint Centre for Bioethics Pandemic Influenza Working Group, as the framework for our review. Principal findings Two groups of ethical concerns were identified. The first group relates to public health ethics, which analyzes the morality of public health interventions, and the second group relates to medical ethics, particularly to “the duty to care”. The Canadian Medical Association Code of Ethics is vague in the description of duties of physicians who may respond to high-risk contagious diseases. Conclusions Government, public health authorities, and anesthesia departments need to be prepared to respond to an outbreak of Ebola. Anesthesiologists have a skill that is suited to treat the complications of Ebola virus disease, and in case they are called for duty, anesthesiologists should be aware of the ethical concerns of treating a highly contagious communicable disease.

Background The mortality rate from septic shock has been declining. Cerebral hypoxia, measured non-invasively with cerebral oximetry, has been correlated with neurologic and non-neurologic sequelae. Whether cerebral desaturations occur in septic shock patients and what consequences these may have is untested. Methods Adult patients with septic shock had cerebral saturation monitoring initiated. The primary objective was to determine if the incidence and magnitude of cerebral desaturations in septic shock patients correlated with delirium. We also compared the incidence and magnitude of cerebral desaturations in patients with septic shock with patients undergoing high-risk non-cardiac surgical procedures, a group known to be at high risk for cerebral desaturations. Results Fifteen patients were enrolled. Twelve (80 %) patients had a decrease in SctO 2 below 65 %. Delirium was not associated with the area under the curve of an SctO 2 of 65 % ( p  = 0.84). Patients who died of septic shock had more significant decreases in SctO 2 than those who survived ( p  = 0.04). Decreased SctO 2 was more common in patients with septic shock and was of greater magnitude than those undergoing high-risk non-cardiac surgery. Conclusions Cerebral desaturations occur more commonly and are of a greater magnitude in septic shock patients compared with those undergoing high-risk non-cardiac surgery. There did not appear to be a relationship between the incidence or magnitude of decreases in SctO 2 and ICU delirium. Patients who died of septic shock had more significant decreases in SctO 2 than patients who survived.

Issue Title: Special Issue: Innovation in Perioperative Patient Safety / Numéro spécial : Innovations en sécurité périopératoire des patients

Purpose Cerebral desaturation occurs frequently in patients undergoing one-lung ventilation for thoracic surgery. The mechanism of this desaturation is unclear regarding its etiology. The objective of this study was to investigate whether or not decreases in cerebral oxygen saturation associated with one-lung ventilation were a consequence of decreased cardiac output. Methods A blinded observational study was conducted in 23 patients undergoing one-lung ventilation with thoracic surgery. Eighteen patients completed the study. Cerebral oxygen saturation was monitored using near-infrared spectroscopy (FORE-SIGHT ® monitor). Invasive blood pressure was monitored and hemodynamic variables were interrogated using the FloTrac ® system. Anesthesia was maintained with sevoflurane with a F i O 2 of 1.0. Post-hoc analysis involved a comparison between baseline and integrated changes in cerebral saturation, heart rate, stroke index, cardiac index, and stroke volume variability. Results All patients showed cerebral desaturation from a baseline of two-lung ventilation in the lateral decubitus position following institution of one-lung ventilation. The cardiac index was stable at these times, but with one-lung ventilation, the heart rate decreased and the stroke index increased to maintain a stable product. The integral of heart rate × time was inversely correlated with the integral of cerebral desaturation × time (linear regression analysis; P  = 0.02; (df) = 16)). Conclusions Cerebral oxygen desaturation was universal during one-lung ventilation in this study. There was no correlation between cerebral desaturation and cardiac output or other hemodynamic variables.

Introduction Obesity during pregnancy is associated with meta‐inflammation and an increased likelihood of clinical complications. Surgery results in intense, acute inflammatory responses in any individual. Because obese individuals exhibit constitutive inflammatory responses and high rates of Caesarian section, it is important to understand the impact of surgery in such populations. Whether more pronounced pro‐inflammatory cytokine responses and/or counterbalancing changes in anti‐inflammatory immune modulators occurs is unknown. Here we investigated innate immune capacity in vivo and in vitro in non‐obese, term‐pregnant controls versus healthy, term‐pregnant obese women (Class II, BMI 35–40). Methods Systemic in vivo induction of eleven pro‐ and anti‐inflammatory biomarkers and acute phase proteins was assessed in plasma immediately prior to and again following Caesarian section surgery. Independently, innate immune capacity was examined by stimulating freshly isolated PBMC in vitro with a panel of defined PRR‐ligands for TLR4, TLR8, TLR3, and RLR 24 h post‐surgery. Results The kinetics and magnitude of the in vivo inflammatory responses examined were indistinguishable in the two populations across the broad range of biomarkers examined, despite the fact that obese women had higher baseline inflammatory status. Deliberate in vitro stimulation with a range of PRR ligands also elicited pro‐ and anti‐inflammatory cytokine responses that were indistinguishable between control and obese mothers. Conclusions Acute in vivo innate immune responses to C‐section, as well as subsequent in vitro stimulation with a panel of microbial mimics, are not detectably altered in Class II obese women. The data argue that while Class II obesity is undesirable, it has minimal impact on the in vivo inflammatory response, or innate immunomodulatory capacity, in women selecting C‐section. Obese individuals exhibit constitutive inflammatory responses. Obese pregnant women have higher rates of C‐section utilization. Acute in vivo innate inflammatory responses to surgery, as well as subsequent cytokine responses following in vitro stimulation with a panel of microbial mimics, are indistinguishable in control and Class II obese women.