Alain Deschamps

A Proposed Algorithm for the Intraoperative Use of Cerebral Near-Infrared Spectroscopy

Near-infrared spectroscopy (NIRS) is a technique that can be used as a noninvasive and continuous monitor of the balance between cerebral oxygen delivery and consumption. The authors develop and propose an algorithm for the use of NIRS based on optimizing factors that can affect cerebral oxygen supply/demand. These factors are the position of the vascular cannula, perfusion pressure, arterial oxygen content, partial pressure of carbon dioxide, haemoglobin, cardiac output, and the cerebral metabolic rate of oxygen. Dissemination of a useful treatment algorithm is the primary purpose of this article. Further multicenter studies are necessary to confirm the benefits and cost-effectiveness of this promising monitoring modality.

The Relationship Between Cerebral Oxygen Saturation Changes and Postoperative Cognitive Dysfunction in Elderly Patients After Coronary Artery Bypass Graft Surgery

OBJECTIVE The aim of this study was to evaluate the predictive value of cerebral regional oxygen saturation (rSO(2)) in the occurrence of postoperative cognitive dysfunction (POCD) in elderly patients undergoing coronary artery bypass graft (CABG) surgery. DESIGN A prospective study. SETTING University hospital. PARTICIPANTS A total of 61 patients (84% male) with a mean age of 70.39 ± 4.69 on a waiting list for CABG surgery were enrolled in the study. INTERVENTION A complete neurocognitive evaluation was performed 1 day before surgery as well as 4 to 7 days and 1 month after surgery. During surgery, rSO(2) was monitored continuously. MEASUREMENTS AND MAIN RESULTS POCD was defined as a reduction of 1 standard deviation on 2 or more neuropsychologic indices. Forty-six patients (80.7%) developed early POCD, and 23 (38.3%) showed late POCD. Patients whose rSO(2) decreased to less than 50% during the surgery experienced more POCD 4 to 7 days after surgery (p = 0.04). In addition, a decrease of more than 30% from the patients baseline rSO(2) was associated with POCD 1 month after surgery (p = 0.03). CONCLUSION Intraoperative cerebral oxygen desaturation is associated with early and late POCD in elderly patients. Cerebral oximetry is a promising tool in the prediction of subtle neuropsychologic deficits and further studies are needed.

Pulmonary hypertension in cardiac surgery.

Pulmonary hypertension is an important prognostic factor in cardiac surgery associated with increased morbidity and mortality. With the aging population and the associated increase severity of illness, the prevalence of pulmonary hypertension in cardiac surgical patients will increase. In this review, the definition of pulmonary hypertension, the mechanisms and its relationship to right ventricular dysfunction will be presented. Finally, pharmacological and non-pharmacological therapeutic and preventive approaches will be presented.

Perioperative right ventricular dysfunction.

Purpose of review To evaluate new information on the importance of right ventricular function, diagnosis and management in cardiac surgical patients. Recent findings There is growing evidence that right ventricular function is a key determinant in survival in cardiac surgery, particularly in patients with pulmonary hypertension. The diagnosis of this condition is helped by the use of specific hemodynamic parameters and echocardiography. In that regard, international consensus guidelines on the echocardiographic assessment of right ventricular function have been recently published. New monitoring modalities in cardiac surgery such as regional near-infrared spectroscopy can also assist management. Management of right ventricular failure will be influenced by the presence or absence of myocardial ischemia and left ventricular dysfunction. The differential diagnosis and management will be facilitated using a systematic approach. Summary The use of right ventricular pressure monitoring and the publications of guidelines for the echocardiographic assessment of right ventricular anatomy and function allow the early identification of right ventricular failure. The treatment success will be associated by optimization of the hemodynamic, echocardiographic and near-infrared spectroscopy parameters.

Baseline Regional Cerebral Oxygen Saturation Correlates With Left Ventricular Systolic and Diastolic Function

OBJECTIVE To evaluate the correlation between baseline cerebral oxygen saturation (ScO(2)) and cardiac function as assessed by pulmonary artery catheterization and transesophageal echocardiography (TEE). DESIGN A retrospective study. SETTING A tertiary care university hospital. PARTICIPANTS Cardiac surgery patients. MEASUREMENTS AND RESULTS Patients undergoing cardiac surgery with bilateral recording of their baseline ScO(2) using the INVOS 4100 (Somanetics, Troy, MI) were selected. A pulmonary artery catheter was used to obtain their hemodynamic profile. Left ventricular (LV) systolic and diastolic function was evaluated by TEE, after the induction of anesthesia, using standard criteria. A model was developed to predict ScO(2). A total of 99 patients met the inclusion criteria. There were significant correlations between mean ScO(2) values and central venous pressure (CVP) (r = -0.31, p = 0.0022), pulmonary capillary wedge pressure (r = -0.25, p = 0.0129), mean pulmonary artery pressure (MPAP) (r = -0.24, p = 0.0186), mean arterial pressure/MPAP ratio (r = 0.33, p = 0.0011), LV fractional area change (<35, 35-50, and >or=50, p = 0.0002), regional wall motion score index (r = -0.27, p = 0.0062), and diastolic function (p = 0.0060). The mean ScO(2) had the highest area under the receiver operating characteristic curve (0.74; confidence interval, 0.64-0.84) to identify LV systolic dysfunction. A model predicting baseline ScO(2) was created based on LV systolic echocardiographic variables, CVP, sex, mitral valve surgery, and the use of beta-blocker (r(2) = 0.42, p < 0.001). CONCLUSION Baseline ScO(2) values are related to cardiac function and are superior to hemodynamic parameters at predicting LV dysfunction.

The concept of ventricular reserve in heart failure and pulmonary hypertension: an old metric that brings us one step closer in our quest for prediction.

Purpose of review Ventricular reserve is emerging a strong predictor of outcome in heart failure and cardiovascular disease. Ventricular reserve is the term used to describe the extent of increase or change in ventricular function that occurs during exercise or pharmacological stress (typically with dobutamine). Recent findings The interest in ventricular reserve lies in its ability to assess viability in coronary artery disease, to predict clinical outcome and response to therapy in patients with heart failure and to screen patients for early cardiovascular disease. Summary In this paper, we will review the emerging role of ventricular reserve in heart failure and pulmonary hypertension. We will also explore the mechanisms involved in the pathophysiology of impaired ventricular reserve and discuss future directions of research in the field.

Innovative Approaches in the Perioperative Care of the Cardiac Surgical Patient in the Operating Room and Intensive Care Unit

Perioperative care for cardiac surgery is undergoing rapid evolution. Many of the changes involve the application of novel technologies to tackle common challenges in optimizing perioperative management. Herein, we illustrate recent advances in perioperative management by focusing on a number of novel components that we judge to be particularly important. These include: the introduction of brain and somatic oximetry; transesophageal echocardiographic hemodynamic monitoring and bedside focused ultrasound; ultrasound-guided vascular access; point-of-care coagulation surveillance; right ventricular pressure monitoring; novel inhaled treatment for right ventricular failure; new approaches for postoperative pain management; novel approaches in specialized care procedures to ensure quality control; and specific approaches to optimize the management for postoperative cardiac arrest. Herein, we discuss the reasons that each of these components are particularly important in improving perioperative care, describe how they can be addressed, and their impact in the care of patients who undergo cardiac surgery.

Reversal of decreases in cerebral saturation in high-risk cardiac surgery.

OBJECTIVES To measure the incidence of cerebral desaturation during high-risk cardiac surgery and to evaluate strategies to reverse cerebral desaturation. DESIGN Prospective observational study followed by a randomized controlled study with 1 intervention group and 1 control group. SETTING Tertiary care center specialized in cardiac surgery. PARTICIPANTS All patients were scheduled for high-risk cardiac surgery, 279 consecutive patients in the prospective study and 48 patients in the randomized study. INTERVENTIONS An algorithmic approach of strategies to reverse cerebral desaturation. In the control group, no attempts were made to reverse cerebral desaturation. MEASUREMENTS AND MAIN RESULTS Cerebral saturation was measured using near-infrared reflectance spectroscopy. A decrease of 20% from baseline for 15 seconds defined cerebral desaturation. The success or failure of the interventions was noted. Demographic data were collected. Models for predicting the probability and the reversal of cerebral desaturation were based on multiple logistic regressions. In the randomized study, 12 hours of measurements were continued in the intensive care unit without interventions. Differences in desaturation load (% desaturation × time) were compared between groups. Half of the high-risk patients had cerebral desaturation that could be reversed 88% of the time. Interventions resulted in smaller desaturation loads in the operating room and in the intensive care unit. CONCLUSIONS Cerebral desaturation in high-risk cardiac surgery is frequent but can be reversed most of the time resulting in a smaller desaturation load. A large randomized study will be needed to measure the impact of reversing cerebral desaturation on patients outcome.

Toward a new approach for the detection of pain in adult patients undergoing cardiac surgery: Near-infrared spectroscopy—A pilot study

OBJECTIVE This pilot study examined the discriminant validity and criterion validity of regional cerebral oxygenation measurement (rSO₂), using the near-infrared spectroscopy (NIRS) technique (INVOS-4100 system, Somanetics, Troy, MI) for measuring pain during nociceptive procedures in adults undergoing cardiac surgery. METHODS A repeated-measures, within-subjects design was used, and 40 adult patients participated. Data collection was completed during 2 test periods: (1) while patients were awake, before the induction of anesthesia (first test period); and (2) after the induction of anesthesia, while patients remained under the effects of anesthesia (second test period). Each test period included a baseline, a tactile stimulus (skin disinfection), nociceptive stimuli (e.g., intravenous and arterial line insertions, sternal bone incision and thorax opening), and a postprocedure evaluation. RESULTS Increased rSO₂ values (P < .001) were acquired during nociceptive procedures in both test periods. No significant associations were evident between rSO₂, pain behaviors, and the patients self-report of pain intensity, but this may be attributable to a low range of variability. CONCLUSIONS Although further research is needed in critically ill adult patients undergoing more painful procedures, the NIRS may become a promising technique for assessing pain.

Right Ventricular Depression After Cardiopulmonary Bypass for Valvular Surgery

OBJECTIVE To assess if right ventricular (RV) dysfunction is associated with increased mortality after cardiac surgery. DESIGN Post-hoc analysis of a single-center double-blind randomized controlled trial. SETTING University hospital. PARTICIPANTS A total of 120 patients undergoing simple or complex valvular surgery. INTERVENTIONS Patients were randomized to receive intravenous amiodarone or placebo intraoperatively. As secondary analysis, patients were divided into those requiring or not requiring postoperative inotropic agents. MEASUREMENTS AND MAIN RESULTS After cardiopulmonary bypass (CPB), there were significant increases in heart rate, cardiac index, systolic and mean arterial pressures, central venous pressure and pulmonary capillary wedge pressure with reduction in systemic vascular resistance (p<0.05). Right ventricular end-systolic area became larger in those without inotropes and tricuspid annular plane systolic excursion was reduced in all patients; mitral annular systolic velocities were higher in patients receiving inotropes. Both right- and left-sided Doppler signals were altered significantly after CPB, which may be attributed to increased filling pressure. Inotropic agents were required in 56 patients after CPB (47%). The use of inotropic agents was associated with increased left and right atrial velocities (p<0.05). There were no differences in postoperative complications between groups; however, the number of deaths at 6 years was increased in patients who received inotropes after CPB (p = 0.0247). CONCLUSIONS The increases in right-sided dimensions after CPB are associated with reduction in RV function and increased biventricular filling pressure, suggesting worsening biventricular function and interventricular dependence. Inotropic medications were associated with unaltered RV dimensions and increased biatrial activity.