Feasibility of continuous non-invasive delivery of oxygen monitoring in cardiac surgical patients: a proof-of-concept preliminary study.

PURPOSE: Oxygen delivery (DO2) and its monitoring are highlighted to aid postoperative goal directed therapy (GDT) to improve perioperative outcomes such as acute kidney injury (AKI) after high-risk cardiac surgeries associated with multiple morbidities and mortality. However, DO2 monitoring is neither routine nor done postoperatively, and current methods are invasive and only produce intermittent DO2 trends. Hence, we proposed a novel algorithm that simultaneously integrates cardiac output (CO), hemoglobin (Hb) and oxygen saturation (SpO2) from the Edwards Life Sciences ClearSight System® and Masimo SET Pulse CO-Oximetry® to produce a continuous, real-time DO2 trend. METHODS: Our algorithm was built systematically with 4 components - machine interface to draw data with PuTTY, data extraction with parsing, data synchronization, and real-time DO2 presentation using a graphic-user interface. Hb readings were validated. RESULTS: Our algorithm was implemented successfully in 93% (n = 57 out of 61) of our recruited cardiac surgical patients. DO2 trends and AKI were studied. CONCLUSION: We demonstrated a novel proof-of-concept and feasibility of continuous, real-time, non-invasive DO2 monitoring, with each patient serving as their own control. Our study also lays the foundation for future investigations aimed at identifying personalized critical DO2 thresholds and optimizing DO2 as an integral part of GDT to enhance outcomes in perioperative cardiac surgery.

Perioperative temperature management: a survey of 6 Asia-Pacific countries.

BACKGROUND: Anesthesia leads to impairments in central and peripheral thermoregulatory responses. Inadvertent perioperative hypothermia is hence a common perioperative complication, and is associated with coagulopathy, increased surgical site infection, delayed drug metabolism, prolonged recovery, and shivering. However, surveys across the world have shown poor compliance to perioperative temperature management guidelines. Therefore, we evaluated the prevalent practices and attitudes to perioperative temperature management in the Asia-Pacific region, and determined the individual and institutional factors that lead to noncompliance. METHODS: A 40-question anonymous online questionnaire was distributed to anesthesiologists and anesthesia trainees in six countries in the Asia-Pacific (Singapore, Malaysia, Philippines, Thailand, India and South Korea). Participants were polled about their current practices in patient warming and temperature measurement across the preoperative, intraoperative and postoperative periods. Questions were also asked regarding various individual and environmental barriers to compliance. RESULTS: In total, 1154 valid survey responses were obtained and analyzed. 279 (24.2%) of respondents prewarm, 508 (44.0%) perform intraoperative active warming, and 486 (42.1%) perform postoperative active warming in the majority of patients. Additionally, 531 (46.0%) measure temperature preoperatively, 767 (67.5%) measure temperature intraoperatively during general anesthesia, and 953 (82.6%) measure temperature postoperatively in the majority of patients. The availability of active warming devices in the operating room (p < 0.001, OR 10.040), absence of financial restriction (p < 0.001, OR 2.817), presence of hospital training courses (p = 0.011, OR 1.428), and presence of a hospital SOP (p < 0.001, OR 1.926) were significantly associated with compliance to intraoperative active warming. CONCLUSIONS: Compliance to international perioperative temperature management guidelines in Asia-Pacific remains poor, especially in small hospitals. Barriers to compliance were limited temperature management equipment, lack of locally-relevant standard operating procedures and training. This may inform international guideline committees on the needs of developing countries, or spur local anesthesiology societies to publish their own national guidelines.

New-Onset Atrial Fibrillation After Cardiac Surgery is a Significant Risk Factor for Long-Term Stroke: An Eight-Year Prospective Cohort Study.

OBJECTIVES: This study sought to determine the incidence and significance of new-onset atrial fibrillation as a risk factor for long-term stroke and mortality after cardiac surgery. DESIGN: A prospective cohort study. SETTING: Two large tertiary public hospitals. PARTICIPANTS: The study comprised 3008 patients who underwent coronary artery bypass grafting and/or valve surgery from 2008 to 2012. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: New-onset atrial fibrillation was analyzed as a risk factor for postoperative stroke using a multivariate logistic regression model after adjustment for potential confounders. A Cox regression model with time-dependent variables was used to analyze relationships between new-onset atrial fibrillation and postoperative survival. New-onset atrial fibrillation was detected in 573 (19.0%) patients. Stroke occurred in 234 (7.8%) patients during the mean postoperative follow-up period of six ± two years. The incidence of postoperative stroke in patients with new-onset atrial fibrillation (9.9%) and patients with both preoperative and postoperative atrial fibrillation (13.8%) was higher than in patients with no atrial fibrillation (6.8%) (p = 0.002). New-onset atrial fibrillation (odds ratio, 1.53; 95% confidence interval [CI], 1.08-2.18; p = 0.017) was identified as an independent risk factor for postoperative stroke. A total of 518 (17.2%) mortalities occurred within the mean postoperative follow-up period of eight ± two years. New-onset atrial fibrillation was associated with shorter survival (hazard ratio, 1.49; 95% CI, 1.22-1.81; p < 0.001) compared with patients with no atrial fibrillation. CONCLUSIONS: New-onset atrial fibrillation is a significant risk factor for long-term stroke and mortality after cardiac surgery. Close monitoring and treatment of this condition may be necessary to reduce the risk of postoperative stroke and mortality.

Wider perioperative glycemic fluctuations increase risk of postoperative atrial fibrillation and ICU length of stay.

INTRODUCTION: Postoperative atrial fibrillation (POAF) is a common complication following cardiac surgery associated with increased morbidity and mortality. Although sustained hyperglycemia is a known risk factor of AF and poor ICU outcomes, emerging in-vitro studies reveal acute glycemic fluctuations to be an additional independent predictor of AF. The effect of acute glycemic fluctuations on the incidence of POAF in the clinical setting remains unclear. We aim to investigate the effect of the magnitude of acute perioperative glycemic fluctuations on the incidence of POAF in a multi-ethnic Southeast-Asian population. METHODS: We obtained data from1743 patients who underwent elective CABG in a tertiary heart centre from 2009-2011. Patients were kept to a tight baseline glycemic control in accordance with hospital protocol. The magnitude of the difference between the highest and lowest perioperative glucose levels up till the first 48 postoperative hours was employed as a measure of glycemic fluctuation. Patients were divided into 4 groups for analysis based on the magnitude of glycemic fluctuation:A)0-2mmol/L(N = 147); B)>2-4mmol/L(N = 426); C)>4-6mmol/L(N = 513); D)>6mmol/L(N = 657).Our primary outcome was the incidence of POAF. Secondary outcomes included ICU and 30-day mortality and length of stay. RESULTS: The overall incidence of POAF was 14.7%. This increased as the magnitude of glycemic fluctuation increased, and was statistically highest in Group D(16.4%) as compared with the other 3 sub-groups. Multivariate logistic regression revealed the magnitude of perioperative glycemic fluctuation to be an independent risk factor of POAF(O.R.1.06, 95% C.I.1.01-1.11, p = 0.014).ICU length of stay was statistically highest in Group D(63.1 hours, p = < .001). However, ICU and 30 day mortality rates were similar among the 4 groups. CONCLUSION: Increased magnitudes of acute perioperative glycemic fluctuations are associated with a significantly increased risk of POAF and length of ICU stay; and should therefore be minimised but balanced against the risks of hypoglycemia so as to avoid POAF and optimise patient outcomes.

A Clinical Prediction Model for Postcardiac Surgery Atrial Fibrillation in an Asian Population.

BACKGROUND: Postoperative atrial fibrillation (AF) is associated with increased morbidity, mortality, and resource utilization. Current prediction models for postoperative AF are based primarily on Western populations. In this study, we sought to develop a clinical prediction rule for postcardiac surgery AF for a multiethnic Asian population. METHODS: Two thousand one hundred sixty-eight patients undergoing coronary artery bypass graft or valve surgery with cardiopulmonary bypass were prospectively enrolled in this observational study between August 2008 and July 2012 at Singapore's 2 national heart centers. Postoperative AF was defined as an irregularly irregular electrocardiogram rhythm without identifiable P wave after surgery and before hospital discharge that lasted more than an hour, or affected hemodynamics (ie, systolic blood pressure <90 mm Hg or mean arterial blood pressure <60 mm Hg), or required medical treatment. Patients had continuous telemetry monitoring for at least 72 hours while in the intensive care or high-dependency units postoperatively. Subsequently, patients had a 12-lead electrocardiogram daily and when symptomatic. Multivariable logistic regression was used to determine significant predictors of postcardiac surgery AF, and a scoring system was developed. The model was internally validated in an additional 500 patients. RESULTS: Postoperative AF occurred in 17.3% of patients, with a peak occurrence in the first 72 hours after surgery. Multivariate logistic regression analysis identified age ≥65 years (odds ratio [OR], 1.44; 95% confidence interval [CI], 1.11-1.85, P = 0.005), history of AF (OR, 3.65; 95% CI, 2.52-5.30, P < 0.001), inotrope use (OR, 1.74; 95% CI, 1.31-2.32, P < 0.001), cardiopulmonary bypass duration >120 minutes (OR, 1.92; 95% CI, 1.47-2.52, P < 0.001), and Chinese ethnicity (Chinese versus Indian OR, 2.09; 95% CI, 1.28-3.41, P = 0.003) or Malay (Malay versus Indian OR, 2.43; 95% CI, 1.36-4.05, P = 0.002) to be independently associated with postoperative AF. The area under the receiver-operator characteristic curve of the model was 0.704 (95% CI, 0.674-0.734). Internal validation produced an area under the receiver-operator characteristic curve of 0.756 (95% CI, 0.690-0.821). CONCLUSIONS: Clinical risk factors for AF after cardiac surgery in an Asian population are similar to that reported from primarily Western populations, but specific ethnicity influences susceptibility.

Wider Perioperative Glycemic Fluctuations Increase Risk of Postoperative Acute Kidney Injury: A Prospective Cohort Study.

Acute kidney injury (AKI) is a common complication after cardiac surgery. Recent studies have revealed emerging associations between the magnitude of acute glycemic fluctuations and intensive care unit (ICU) mortality rates. However, the effect of acute glycemic fluctuations on the development of postoperative AKI remains unclear. Thus, we aim to investigate the effect of the magnitude of acute perioperative glycemic fluctuations on the incidence of postoperative AKI.We conducted a prospective cohort study by prospectively obtaining data from all patients who underwent elective coronary artery bypass grafting in a tertiary heart institution from 2009 to 2011. The magnitude of the difference between the highest and lowest perioperative glucose levels within 48 hr was calculated as a measure of perioperative glycemic fluctuation. Patients were divided into 4 groups for analysis based on the magnitude of perioperative glycemic fluctuation-A: 0 to 2 mmol/L; B: >2 to 4 mmol/L; C: >4 to 6 mmol/L; and D: >6 mmol/L. We analyzed the incidence of postoperative AKI, ICU mortality and ICU length of stay as primary and secondary outcomes, respectively. Both univariate and multivariate analyses were used.We analyzed data from 1386 patients. The overall incidence of AKI was 29.9% and increased with wider glycemic fluctuation. The incidence of AKI was statistically highest in Group D (38.3%), followed by Groups C (28.6%), B (21.7%), and A (17.4%), respectively (P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.001). A similar trend was observed among both diabetics and nondiabetics (P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.001 and P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.002, respectively). Multivariate logistic regression showed the magnitude of perioperative glycemic fluctuations to be an independent risk factor in the development of AKI (P < 0.001, odds ratio 1.180, 95% confidence interval 1.116-1.247). ICU length of stay was statistically highest in Group D (58.3[REPLACEMENT CHARACTER]hr) compared with Groups C (44.5[REPLACEMENT CHARACTER]hr), B (37.3[REPLACEMENT CHARACTER]hr), and A (32.8[REPLACEMENT CHARACTER]hr, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.003). ICU mortality rate was comparable among all 4 groups (P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.172).Wide acute perioperative glycemic fluctuations should be avoided as they are associated with a significantly increased risk of AKI and ICU length of stay in both the diabetics and the nondiabetics.

Mitral valve surgery and acute renal injury: port access versus median sternotomy.

BACKGROUND: Many outcomes and complications of minimally invasive and conventional cardiac surgery await comparison. Patients undergoing mitral valve surgery commonly sustain renal injury. Using peak postoperative fractional change of serum creatinine as a marker of renal injury, we tested the hypothesis that mitral valve surgery with port access minithoracotomy (Port) and conventional surgery with a median sternotomy (MS) incision are associated with different degrees of acute renal injury. METHODS: We evaluated data from all isolated mitral valve operations by a single surgeon between 1990 and 2000 (MS = 90, Port = 227). We also performed a secondary analysis of mitral valve surgeries performed by both MS and Port approaches in a concurrent period from 1996 to 2002 (MS = 93, Port = 240). Univariable and multivariable tests were used to determine the association of surgical technique with peak postoperative creatinine (CrmaxPost) and peak postoperative fractional change in creatinine (%deltaCr); p less than 0.05 was considered significant. RESULTS: In our analysis that accounted for the date of surgery, we observed a highly significant independent association between surgical approach and %deltaCr, indicating a greater risk of acute renal injury in the MS group (F value 13.33; p = 0.0003). Similar findings were noted in the secondary (time-concurrent) analysis of %deltaCr (F value 12.65; p = 0.0176). CONCLUSIONS: We present retrospective evidence of reduced acute renal injury associated with the port access technique in mitral valve surgery patients. Our findings suggest that a port access minithoracotomy approach to mitral valve surgery may be preferable to conventional methods for patients with high renal risk.