Mean platelet volume and cardiac-surgery-associated acute kidney injury: a retrospective study.

PURPOSE: Increased mean platelet volume (MPV) may indicate platelet activation, platelet aggregation, and a resulting prothrombotic state. Such changes in the postoperative period have been associated with organ injury and adverse outcomes. We hypothesized that changes in MPV after cardiac surgery are associated with both a higher risk of acute kidney injury (AKI) and mortality. METHODS: In this retrospective study, we evaluated consecutive patients undergoing adult cardiac surgery patients between 12 December 2011 and 5 June 2018. The change in MPV was derived by calculating the difference between the baseline MPV before surgery and the average postoperative MPV just prior to the occurrence of AKI. We defined postoperative AKI according to Kidney Disease: Improving Global Outcomes Clinical Practice Guideline for Acute Kidney Injury as either a ≥ 50% increase in serum creatinine in the first ten postoperative days, or an increase of ≥ 0.3 mg·dL-1 during any 48-hr window across the ten-day postoperative period. Multivariable logistic regression analysis was used to examine the association between MPV change and postoperative AKI and mortality. RESULTS: Of the 4,204 patients studied, 1,373 (32.7%) developed postoperative AKI, including 83 (2.0%) and 38 (0.9%) who developed stages II and III AKI, respectively. Compared with patients who had an increase in median postoperative MPV of 0.2 femtolitre (fL), those with an increase of 0.8 fL had an 80% increase in the odds of developing AKI (adjusted odds ratio [aOR], 1.80; 95% confidence interval [CI],1.36 to 2.38; P < 0.001) and were almost twice as likely to progress to a higher severity AKI (aOR, 1.66; 95% CI, 1.28 to 2.16; P < 0.001). Change in MPV was not associated with mortality (aOR,1.32; 95% CI, 0.92 to 1.89; P = 0.14). CONCLUSION: Increased MPV change in the postoperative period was associated with both increased risk and severity of AKI, but not mortality.

RéSUMé: OBJECTIF: Un volume plaquettaire moyen (VPM) augmenté peut être indicatif d'une activation plaquettaire, d'une agrégation plaquettaire, et de l'état prothrombotique qui en résulte. De tels changements en période postopératoire ont été associés à des lésions aux organes et à des devenirs défavorables. Nous avons émis l'hypothèse que des changements du VPM après une chirurgie cardiaque seraient associés à un risque plus élevé d'insuffisance rénale aiguë et de mortalité. MéTHODE: Dans cette étude rétrospective, nous avons évalué des patients adultes consécutifs subissant une chirurgie cardiaque entre le 12 décembre 2011 et le 5 juin 2018. Le changement de VPM a été dérivé en calculant la différence entre le VPM de base avant la chirurgie et le VPM postopératoire moyen juste avant la survenue de l'IRA. Nous avons défini une IRA postopératoire sur la base des Directives Kidney Disease: Improving Global Outcomes Clinical Practice Guideline for Acute Kidney Injury (Les maladies rénales: Guide d'exercice clinique pour améliorer les devenirs globaux pour l'insuffisance rénale aiguë) en tant qu'une augmentation ≥ 50 % de la créatine sérique au cours des dix premiers jours postopératoires, ou une augmentation de ≥ 0,3 mg·dL−1 pendant toute fenêtre de 48 h au cours des dix premiers jours postopératoires. Une analyse multivariée de régression logistique a été utilisée pour examiner l'association entre le changement de VPM et l'IRA postopératoire et la mortalité. RéSULTATS: Parmi les 4204 patients à l'étude, 1373 (32,7 %) ont souffert d'IRA postopératoire, y compris 83 (2,0 %) et 38 (0,9 %) qui ont développé des IRA de stade II et III, respectivement. Par rapport aux patients ayant manifesté une augmentation du VPM postopératoire médian de 0,2 femtolitre (fL), ceux affichant une augmentation de 0,8 fL ont démontré une augmentation de 80 % de la probabilité d'IRA (rapport de cotes ajusté [RCA], 1,80; intervalle de confiance [IC] 95 %, 1,36 à 2,38; P < 0,001) et couraient un risque pratiquement deux fois plus élevé de voir leur IRA progresser à un stade plus grave (RCA, 1,66; IC 95 %, 1,28 à 2,16; P < 0,001). Les changements de VPM n'étaient pas associés à la mortalité (RCA, 1,32; IC 95 %, 0,92 à 1,89; P = 0,14). CONCLUSION: Une augmentation accrue du VPM en période postopératoire a été associée à un risque et une gravité accrus d'IRA, mais pas à la mortalité.

Glymphatic System Function in Relation to Anesthesia and Sleep States.

The brain is one of the most metabolically active organs in the body. The brain's high energy demand associated with wakefulness persists during rapid eye movement sleep, and even during non-rapid eye movement sleep, cerebral oxygen consumption is only reduced by 20%. The active bioenergetic state parallels metabolic waste production at a higher rate than in other organs, and the lack of lymphatic vasculature in brain parenchyma is therefore a conundrum. A common assumption has been that with a tight blood-brain barrier restricting solute and fluid movements, a lymphatic system is superfluous in the central nervous system. Cerebrospinal fluid (CSF) flow has long been thought to facilitate central nervous system tissue "detoxification" in place of lymphatics. Nonetheless, while CSF production and transport have been studied for decades, the exact processes involved in toxic waste clearance remain poorly understood. Over the past 5 years, emerging data have begun to shed new light on these processes in the form of the "glymphatic system," a novel brain-wide perivascular transit passageway dedicated to CSF transport and metabolic waste drainage from the brain. Here, we review the key anatomical components and operational drivers of the brain's glymphatic system, with a focus on its unique functional dependence on the state of arousal and anesthetic regimens. We also discuss evidence for why clinical exploration of this novel system may in the future provide valuable insight into new strategies for preventing delirium and cognitive dysfunction in perioperative and critical care settings.

Sodium-glucose cotransporter-2 inhibitors: an overview and perioperative implications.

PURPOSE OF REVIEW: Sodium-glucose cotransporter 2 (SGLT-2) inhibitors are a relatively new class of drugs used in the management of diabetes mellitus. This review will highlight key pharmacologic characteristics of this class of drugs; discuss their potential role in management of patients with cardiac disease; and raise several perioperative concerns for anesthesiologists caring for patients on SGLT-2 inhibitors. RECENT FINDINGS: Recent trials have shown a strong mortality benefit in diabetic patients on SGLT 2 inhibitors especially in patients with a high cardiovascular burden. In addition, there is a reduction in HbA1c levels, blood pressure, weight and readmissions secondary to heart failure in this patient population. However, these drugs have been also associated with an increased incidence of adverse events, such as euglycemic ketoacidosis, urinary tract infections, acute kidney injury and limb amputations. SUMMARY: SGLT 2 inhibitors are being increasingly prescribed secondary to their significant salutatory effect in patients with type II diabetes mellitus. Although there are no perioperative consensus guidelines for management of patients on SGLT2 inhibitors, they should be discontinued at least 24-48 h prior to major surgeries. Their overall management in the perioperative period should be carried out on a case-to-case basis using a multidisciplinary approach.

Elevated Pulse Pressure, Intraoperative Hemodynamic Perturbations, and Acute Kidney Injury After Coronary Artery Bypass Grafting Surgery.

OBJECTIVE: To explore whether baseline pulse pressure (PP) confers an increased risk for acute kidney injury (AKI) independent of intraoperative hypotension or hypertension in patients who undergo coronary artery bypass grafting (CABG) surgery. DESIGN: Retrospective study. SETTING: Single academic center. PARTICIPANTS: 5,808 patients who underwent CABG surgery. MEASUREMENTS AND MAIN RESULTS: Baseline arterial blood pressure was defined as the mean of the first 5 measurements recorded by the automated record keeping system before anesthesia was induced. Weighted duration of intraoperative hypotension and hypertension were defined as the area (min × mmHg) below a mean arterial pressure of 55 mmHg and above a mean arterial pressure of 100 mmHg. Multivariable logistic and proportional odds regression analyses were performed to determine whether baseline PP and weighted duration of intraoperative hypotension and hypertension were independently associated with postoperative AKI. Of the 5,808 patients, PP was <40 mmHg in 90 (1.6%), 40-to-80 mmHg in 2,463 (42.4 %), and >80 mmHg in 3,255 (56%) patients. The incidence of AKI was 57.7%, which included 7.4% (249 patients) and 2.8% (93 patients) who experienced stages 2 and 3 AKI, respectively. In the risk-adjusted analyses, baseline PP was associated with higher odds for postoperative AKI (odds ratio for every 20 mmHg increase in PP, 1.15; 95% confidence interval 1.10-1.21; p < 0.0001) and a higher severity of postoperative AKI (proportional odds ratio, 1.13; 95% confidence interval 1.03-1.24; p = 0.0098). There was no evidence that weighted duration of intraoperative hypotension or hypertension was associated with postoperative AKI or that either interacted with the association of baseline PP with AKI. CONCLUSIONS: Baseline PP was significantly associated with postoperative AKI after CABG surgery, independent of weighted duration of intraoperative hypotension or hypertension.

Hospitalization costs and resource allocation in cholecystectomy with use of intravenous versus oral acetaminophen.

OBJECTIVE: To evaluate intravenous (IV) acetaminophen (APAP) vs oral APAP use as adjunctive analgesics in cholecystectomy patients by comparing associated hospital length of stay (LOS), hospital costs, opioid use, and rates of nausea/vomiting, respiratory depression, and bowel obstruction. METHODS: We conducted a retrospective analysis of the Premier Database (January 2012 to September 2015) including cholecystectomy patients who received either IV APAP or oral APAP. Differences in LOS, hospitalization costs, mean daily morphine equivalent dose (MED), and potential opioid-related adverse events were estimated. Multivariable logistic regression was performed for the binary outcomes and instrumental variable regressions, using the quarterly rate of IV APAP use for all hospitalizations by hospital as the instrument in two-stage least squares regressions for continuous outcomes. Models were adjusted for patient demographics, clinical risk factors, and hospital characteristics. RESULTS: Among 61,017 cholecystectomy patients, 31,133 (51%) received IV APAP. Subjects averaged 51 and 57 years of age, respectively, in the IV and oral APAP cohorts. In the adjusted models, IV APAP was associated with 0.42 days shorter LOS (95% CI = -0.58 to -0.27; p < .0001), $1,045 lower hospitalization costs (95% CI = -$1,521 to -$569; p < .0001), 2 mg lower average daily MED (95% CI = -3 mg to -0.9 mg; p = .0005), and lower rates of respiratory depression (odds ratio [OR] = 0.89, 95% CI = 0.82-0.97; p = .006), and nausea and vomiting (OR = 0.86, 95% CI = 0.86-0.86; p < .0001). CONCLUSIONS: In patients having cholecystectomy, the addition of IV APAP to perioperative pain management is associated with shorter LOS, lower costs, reduced opioid use, and less frequent nausea/vomiting and respiratory depression compared to oral APAP. These findings should be confirmed in a prospective study comparing IV and oral APAP.

Perioperative THR-184 and AKI after Cardiac Surgery.

AKI after cardiac surgery is associated with mortality, prolonged hospital length of stay, use of dialysis, and subsequent CKD. We evaluated the effects of THR-184, a bone morphogenetic protein-7 agonist, in patients at high risk for AKI after cardiac surgery. We conducted a randomized, double-blind, placebo-controlled, multidose comparison of the safety and efficacy of perioperative THR-184 using a two-stage seamless adaptive design in 452 patients between 18 and 85 years of age who were scheduled for nonemergent cardiac surgery requiring cardiopulmonary bypass and had recognized risk factors for AKI. The primary efficacy end point was the proportion of patients who developed AKI according to Kidney Disease Improving Global Outcomes (KDIGO) criteria. The proportion of patients who developed AKI within 7 days of surgery was similar in THR-184 treatment groups and placebo groups (range, 74%-79%; P=0.43). Prespecified secondary end point analysis did not show significant differences in the severity of AKI stage (P=0.53) or the total duration of AKI (P=0.44). A composite of death, dialysis, or sustained impaired renal function by day 30 after surgery did not differ between groups (range, 11%-20%; P=0.46). Safety-related outcomes were similar across all treatment groups. In conclusion, compared with placebo, administration of perioperative THR-184 through a range of dose exposures failed to reduce the incidence, severity, or duration of AKI after cardiac surgery in high-risk patients.

Postoperative thrombocytopenia: why you should consider antiplatelet therapy?

PURPOSE OF REVIEW: This review addresses the role of platelets in perioperative ischemic complications involving the brain, kidneys, and gastrointestinal tract, and long-term survival in patients undergoing coronary artery bypass grafting surgery. Importantly, findings of several recent clinical studies will be discussed with emphasis on platelet activation and leukocyte inflammatory responses as important mediators of vascular microthrombosis and ischemic injury. RECENT FINDINGS: Our recent findings suggest that in some patients, the hemostatic balance during and after surgery may shift toward a hypercoagulable state and contribute to acute organ failure. SUMMARY: For over 6 decades, major postoperative complications after cardiac surgery have remained unchanged. The potential influence of microthrombosis involving platelets has been underappreciated and use of perioperative antiplatelet therapy remains very limited - primarily because of a culture of fear of bleeding.

Equivalent analgesic effectiveness between perineural and intravenous dexamethasone as adjuvants for peripheral nerve blockade: a systematic review and meta-analysis.

PURPOSE: Dexamethasone is commonly used as an adjuvant to local anesthetics for peripheral nerve blockade; however, uncertainty persists regarding its optimal route of administration and safety. A systematic review and meta-analysis of randomized-controlled trials (RCTs) was conducted to compare the incremental benefits of intravenous (IV) vs perineural (PN) dexamethasone when used as adjuvants for peripheral nerve blockade to improve analgesia. SOURCES: A search strategy was developed to identify eligible articles from the Cochrane and National Library of Medicine databases from inception until June 2017. The National Center for Biotechnology Information Medical Subject Headings browser thesaurus was used to identify search terms and combinations of keywords. Any clinical trial that randomly allocated adult patients (≥ 18 yr old) to receive either IV or PN dexamethasone for peripheral nerve blockade was considered for inclusion. PRINCIPAL FINDINGS: After full-text screening of potentially eligible articles, 14 RCTs were included in this review. Overall, the use of PN dexamethasone did not provide a significant incremental benefit to the duration of analgesia [ratio of means (ROM), 1.23; Hartung-Knapp-Sidik-Jonkman (HKSJ) 95% confidence interval (CI), 0.85 to 1.85; P = 0.23] or to motor block duration (ROM, 1.14; HKSJ 95% CI, 0.98 to 1.31; P = 0.07). Also, at 24-hr follow-up, there was no significant difference between the two groups regarding pain scores (standardized mean difference, 0.36; HKSJ 95% CI, -0.08 to 0.80; I2 = 75%; P = 0.09) and cumulative opioid consumption (mean difference, 5.23 mg; HKSJ 95% CI, -4.60 to 15.06; P = 0.15). Lastly, no long-term nerve-related complications were observed with the use of PN dexamethasone. CONCLUSIONS: The results of our meta-analysis suggest that PN and IV dexamethasone provide equivalent analgesic benefits and have similar safety profiles, when used as adjuvants, for peripheral nerve blockade.

Pre- and postoperative anemia, acute kidney injury, and mortality after coronary artery bypass grafting surgery: a retrospective observational study.

BACKGROUND: Preoperative and postoperative anemia have been identified individually as potential risk factors for postoperative complications after coronary artery bypass grafting (CABG) surgery. Their interrelationship with acute kidney injury (AKI) and long-term mortality, however, has not been clearly defined and was the purpose of this study. METHODS: We retrospectively evaluated 6,130 adult patients undergoing CABG surgery performed at a single large academic medical center. Preoperative and postoperative hemoglobin concentrations were used as continuous predictors of postoperative AKI and mortality. Additionally, sex-specific preoperative (< 13 g·dL-1 in men and < 12 g·dL-1 in women) and postoperative anemia (the median of the lowest in-hospital values) were used as categorical predictors. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guidelines, when serum creatinine rose ≥ 50% during the period between day of surgery and postoperative day ten, or when a 0.3 mg·dL-1 (26.5 µmol·L-1) increase was detected in a rolling 48-hr window from the day of surgery to the tenth postoperative day. The association of preoperative and postoperative hemoglobin levels and anemia patterns with postoperative AKI and mortality were assessed via univariable and multivariable Cox proportional hazard analyses with time-varying effects for postoperative serum hemoglobin concentrations. RESULTS: The median preoperative and median minimum postoperative serum hemoglobin concentrations were 13.1 g·dL-1 and 8.8 g·dL-1, respectively. The incidence of AKI was 58%. Overall, 1,880 (30.7%) patients died an average of 6.8 yr after surgery. After adjusting for differences in baseline and clinical characteristics, on any given day, patients with preoperative anemia (multivariable hazard ratio [HR], 1.23; 95% confidence interval [CI], 1.13 to 1.33; P < 0.001) and those with a combination of preoperative and postoperative anemia (multivariable HR, 1.24; 95% CI, 1.09 to 1.40; P < 0.0008) were at an elevated risk for developing postoperative AKI and mortality (preoperative anemia: multivariable HR, 1.29; 95% CI, 1.15 to 1.44; P < 0.001; preoperative and postoperative anemia: multivariable HR, 1.50; 95% CI, 1.25 to 1.79; P < 0.001). CONCLUSIONS: Our findings suggest that preoperative anemia alone and preoperative anemia combined with postoperative anemia are associated with AKI and mortality after CABG surgery.

Pain and Psychology-A Reciprocal Relationship.

BACKGROUND: Depression typically affects 5% of the general population, but among patients with chronic pain, 30%-45% experience depression. Studies have shown that the relationship between depression and pain is bidirectional: depression is a positive predictor of the development of chronic pain, and chronic pain increases the risk of developing depression. METHODS: This literature review focuses on the relationship between psychology and pain, covering studies that have investigated the association between depression, pain sensitivity, opioid abuse, and gender differences in pain perception. We conducted a PubMed search pairing the word pain with depression, opioid use, and gender differences. RESULTS: The relationship between depression and pain is complex, as suggested by numerous studies that propose depression to be a moderator of the relationship between pain severity, physical functioning, and opioid use. Neuroimaging also suggests an anatomic overlap in the pathway of chronic pain and depression. Positive psychological factors, namely hope, pain acceptance, and optimism, affect the adjustment to persistent pain. CONCLUSION: The intricate relationship between pain and psychology is evidenced by the clinical overlap in their presentations and the overlap between the anatomic regions in the brain associated with the emotional and sensory features of pain and the areas affected by depression. Studies are beginning to improve our understanding of these two systems, but more studies are needed to elucidate the relationship.

Platelet Counts and Postoperative Stroke After Coronary Artery Bypass Grafting Surgery.

BACKGROUND: Declining platelet counts may reveal platelet activation and aggregation in a postoperative prothrombotic state. Therefore, we hypothesized that nadir platelet counts after on-pump coronary artery bypass grafting (CABG) surgery are associated with stroke. METHODS: We evaluated 6130 adult CABG surgery patients. Postoperative platelet counts were evaluated as continuous and categorical (mild versus moderate to severe) predictors of stroke. Extended Cox proportional hazard regression analysis with a time-varying covariate for daily minimum postoperative platelet count assessed the association of day-to-day variations in postoperative platelet count with time to stroke. Competing risks proportional hazard regression models examined associations between day-to-day variations in postoperative platelet counts with timing of stroke (early: 0-1 days; delayed: ≥2 days). RESULTS: Median (interquartile range) postoperative nadir platelet counts were 123.0 (98.0-155.0) × 10/L. The incidences of postoperative stroke were 1.09%, 1.50%, and 3.02% for platelet counts >150 × 10/L, 100 to 150 × 10/L, and <100 × 10/L, respectively. The risk for stroke increased by 12% on a given postoperative day for every 30 × 10/L decrease in platelet counts (adjusted hazard ratio [HR], 1.12; 95% confidence interval [CI], 1.01-1.24; P= .0255). On a given day, patients with moderate to severe thrombocytopenia were almost twice as likely to develop stroke (adjusted HR, 1.89; 95% CI, 1.13-3.16; P= .0155) as patients with nadir platelet counts >150 × 10/L. Importantly, such thrombocytopenia, defined as a time-varying covariate, was significantly associated with delayed (≥2 days after surgery; adjusted HR, 2.83; 95% CI, 1.48-5.41; P= .0017) but not early postoperative stroke. CONCLUSIONS: Our findings suggest an independent association between moderate to severe postoperative thrombocytopenia and postoperative stroke, and timing of stroke after CABG surgery.

Management of Patients on Abuse-Deterrent Opioids in the Ambulatory Surgery Setting.

PURPOSE OF REVIEW: The use of prescription opioids for acute and chronic pain has become more prevalent than ever, and concurrent with the increased prescribing of opioids, there has been a steady increase in opioid abuse. Abuse is commonly associated with physical or chemical manipulation of the original opiate to provide more rapid onset of the active ingredient. RECENT FINDINGS: This growing national public health concern has led to the development of various abuse-deterring opioids with the intent of decreasing the diversion of opioids from their prescribed use. Given the ever-increasing percentage of surgeries performed in the ambulatory surgery setting, anesthesia providers will inevitably encounter more and more patients taking these new opioid formulations with abuse-deterring properties. Consequently, a thorough understanding of these medications is vital for optimal anesthetic management. This article reviews the scope of the problem of prescription opiate abuse, summarizes the currently available abuse-deterring opioids, and discusses the anesthetic management of patients who are taking these new medications in the outpatient setting.

Natural history of nonimmune-mediated thrombocytopenia and acute kidney injury in pediatric open-heart surgery.

OBJECTIVE: Thrombocytopenia and acute kidney injury (AKI) are common following pediatric cardiac surgery with cardiopulmonary bypass (CPB). However, the relationship between postoperative nadir platelet counts and AKI has not been investigated in the pediatric population. Our objective was to investigate this relationship and examine independent predictors of AKI. DESIGN: After IRB approval, we performed a retrospective review of the institution's medical records and database. SETTING: This study was performed at a single institution over a 5-year period. PATIENTS: We included patients <21 years of age undergoing cardiac surgery with CPB. INTERVENTIONS: Demographics, laboratory, and surgical characteristics were captured, and clinical event rates were recorded. MEASUREMENTS: Descriptive statistics were used to evaluate platelet and creatinine distributions. T-tests and chi-squared tests were used to compare characteristics among Acute Kidney Injury Network groups. Multivariable logistic and ordinal logistic regression models were used to determine the association of our predictor of interest, postoperative nadir platelet count and AKI. RESULTS: Eight hundred and fourteen patients (23% infants and 23% neonates) were included in the analysis. Postoperative platelet counts decreased 48% from baseline reaching a mean nadir value of 150 × 109 ·l-1 on postoperative day 3. AKI occurred in 37% of patients including 13%, 17%, and 6% with Acute Kidney Injury Network stages 1, 2, and 3, respectively. The magnitude of nadir platelet counts correlated with the severity of AKI. Independent predictors of severity of AKI include nadir platelet counts, CPB time, Aristotle score, patient weight, intra-operative packed red blood cell transfusion, and having a heart transplant procedure. CONCLUSIONS: In pediatric open-heart surgery, thrombocytopenia and AKI occur commonly following CPB. Our findings show a strong association between nadir platelet counts and the severity of AKI.

Mobile Extracorporeal Membrane Oxygenation Teams: The North American Versus the European Experience.

OBJECTIVE: To evaluate differences in the inclusion of anesthesiologists in mobile extracorporeal membrane oxygenation (ECMO) teams between North American and European centers. DESIGN: A retrospective review of North American versus European mobile ECMO teams. The search terms used to identify relevant articles were the following: "extracorporeal membrane transport," "mobile ECMO," and "interhospital transport." SETTING: MEDLINE review of articles. PARTICIPANTS: None. INTERVENTIONS: None. RESULTS: Between 1986 and 2015, 25 articles were published that reported the personnel makeup of mobile ECMO teams in North America and Europe: 6 from North American centers and 19 from European centers. The included articles reported a total of 1,329 cases: 389 (29%) adult-only cohorts and 940 (71%) mixed-age cohorts. Among North American studies, 0 of 6 (0%) reported the presence of an anesthesiologist on the mobile ECMO team in contrast to European studies, in which 10 of 19 (53%) reported the inclusion of an anesthesiologist (Fisher exact p for difference = 0.05). In terms of number of cases, this discrepancy translated to 543 total cases in North America (all without an anesthesiologist) and 499 cases in Europe (37%) including an anesthesiologist on the team (Fisher exact p for difference<0.001). CONCLUSIONS: This study demonstrated significant geographic discrepancies in the inclusion of anesthesiologists on mobile ECMO teams, with European centers more likely to incorporate an anesthesiologist into the mobile ECMO process compared with North American centers.

Baseline Pulse Pressure, Acute Kidney Injury, and Mortality After Noncardiac Surgery.

BACKGROUND: Increased pulse pressure (PP) is an important independent predictor of cardiovascular outcome and acute kidney injury (AKI) after cardiac surgery. The objective of this study was to determine whether elevated baseline PP is associated with postoperative AKI and 30-day mortality after noncardiac surgery. METHODS: We evaluated 9125 adult patients who underwent noncardiac surgery at Duke University Medical Center between January 2006 and December 2009. Baseline arterial blood pressure was defined as the mean of the first 5 measurements recorded by the automated record keeping system before inducing anesthesia. Multivariable logistic regression analysis was performed to determine whether baseline PP adjusted for other perioperative risk factors was independently associated with postoperative AKI and 30-day mortality. RESULTS: Of the 9125 patients, the baseline PP was <40 mm Hg in 1426 (15.6%), 40-80 mm Hg in 6926 (75.9%), and >80 mm Hg in 773 (8.5%) patients. The incidence of AKI was 19.8%, which included 8.4% (151 patients) and 4.2% (76 patients) who experienced stage II and III AKI, respectively. In the risk-adjusted model for postoperative AKI, elevated baseline PP was associated with higher odds for postoperative AKI (adjusted odds ratio [OR] for every 20 mm Hg increase in PP, 1.17; 95% confidence interval [CI], 1.10-1.25; P < .0001). Also elevated baseline preoperative PP was significantly associated with mild (stage I; OR, 1.19; 95% CI, 1.11-1.27; P < .0001), but not with more advanced stages of postoperative AKI or with an incremental risk for 30-day mortality. CONCLUSIONS: We found a significant association between elevated baseline PP and postoperative AKI in patients who underwent noncardiac surgery. However, elevated PP was not significantly associated with more advanced stages of postoperative AKI or 30-day mortality in these patients.

Platelet Counts, Acute Kidney Injury, and Mortality after Coronary Artery Bypass Grafting Surgery.

BACKGROUND: Cardiac surgery requiring cardiopulmonary bypass is associated with platelet activation. Because platelets are increasingly recognized as important effectors of ischemia and end-organ inflammatory injury, the authors explored whether postoperative nadir platelet counts are associated with acute kidney injury (AKI) and mortality after coronary artery bypass grafting (CABG) surgery. METHODS: The authors evaluated 4,217 adult patients who underwent CABG surgery. Postoperative nadir platelet counts were defined as the lowest in-hospital values and were used as a continuous predictor of postoperative AKI and mortality. Nadir values in the lowest 10th percentile were also used as a categorical predictor. Multivariable logistic regression and Cox proportional hazard models examined the association between postoperative platelet counts, postoperative AKI, and mortality. RESULTS: The median postoperative nadir platelet count was 121 × 10/l. The incidence of postoperative AKI was 54%, including 9.5% (215 patients) and 3.4% (76 patients) who experienced stages II and III AKI, respectively. For every 30 × 10/l decrease in platelet counts, the risk for postoperative AKI increased by 14% (adjusted odds ratio, 1.14; 95% CI, 1.09 to 1.20; P < 0.0001). Patients with platelet counts in the lowest 10th percentile were three times more likely to progress to a higher severity of postoperative AKI (adjusted proportional odds ratio, 3.04; 95% CI, 2.26 to 4.07; P < 0.0001) and had associated increased risk for mortality immediately after surgery (adjusted hazard ratio, 5.46; 95% CI, 3.79 to 7.89; P < 0.0001). CONCLUSION: The authors found a significant association between postoperative nadir platelet counts and AKI and short-term mortality after CABG surgery.