Determinants of Transcutaneous Ear Lobe CO2 Tension (PtCO2) at 37°C During On-Pump Cardiac Surgery.

OBJECTIVE: There are no available criteria for determining the optimal flow rate and mean arterial pressure level in patients undergoing cardiopulmonary bypass (CPB). Transcutaneous carbon dioxide tension (PtCO2) has been proposed for microcirculation monitoring and it could be useful for guiding hemodynamic optimization under CPB. The goal of this exploratory study was to determine the factors that influence PtCO2 variations during CPB. DESIGN: Cutaneous ear lobe CO2 tension was monitored along with hemodynamic parameters every 10 minutes during CPB, until aortic unclamping. SETTING: French university teaching hospital. PARTICIPANTS: Patients scheduled for cardiac surgery requiring CPB were prospectively included. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: A total of 41 patients were included (520 observations). There was a statistically significant association between PaCO2 and PtCO2 (beta = 0.493 [0.154-0.832], p = 0.043), mostly when PaCO2 was outside the normal range. When PaCO2 was normal, PtCO2 was inversely correlated with mean arterial pressure (after adjustment for PaCO2 and body temperature: Beta -0.245, SE = 0.037, p<0.001) but not with CPB flow rate (p = 0.11). CONCLUSION: The factors that influence PtCO2 during CPB cardiac surgery are PaCO2, body temperature, and mean arterial pressure. When PaCO2 is normal, a PtCO2 elevation might be explained by insufficient mean arterial pressure. Whether low PtCO2 values during CPB should trigger the administration of vasoconstrictors remains to be evaluated.

Improving ultrasonic measurement of diaphragmatic excursion after cardiac surgery using the anatomical M-mode: a randomized crossover study.

PURPOSE: Motion-mode (MM) echography allows precise measurement of diaphragmatic excursion when the ultrasound beam is parallel to the diaphragmatic displacement. However, proper alignment is difficult to obtain in patients after cardiac surgery; thus, measurements might be inaccurate. A new imaging modality named the anatomical motion-mode (AMM) allows free placement of the cursor through the numerical image reconstruction and perfect alignment with the diaphragmatic motion. Our goal was to compare MM and AMM measurements of diaphragmatic excursion in cardiac surgical patients. METHODS: Cardiac surgical patients were studied after extubation. The excursions of the right and left hemidiaphragms were measured by two operators, an expert and a trainee, using MM and AMM successively, according to a blinded, randomized, crossover sequence. Values were averaged over three consecutive respiratory cycles. The angle between the MM and AMM cursors was quantified for each measurement. RESULTS: Fifty patients were studied. The mean (±SD) angle between the MM and AMM cursors was 37° ± 16°. The diaphragmatic excursion as measured by experts was 1.8 ± 0.7 cm using MM and 1.5 ± 0.5 cm using AMM (p < 0.001). Overall, the diaphragmatic excursion as estimated by MM was larger than the value obtained with AMM in 75 % of the measurements. Bland-Altman analysis showed tighter limits of agreement between experts and trainees with AMM [bias: 0.0 cm; 95 % confidence interval (CI): 0.8 cm] than with MM (bias: 0.0 cm; 95 % CI: 1.4 cm). CONCLUSION: MM overestimates diaphragmatic excursion in comparison to AMM in cardiac surgical patients. Using MM may lead to a lack of recognition of diaphragmatic dysfunction.

Incidence, risk factors and prediction of post-operative acute kidney injury following cardiac surgery for active infective endocarditis: an observational study.

INTRODUCTION: Cardiac surgery is frequently needed in patients with infective endocarditis (IE). Acute kidney injury (AKI) often complicates IE and is associated with poor outcomes. The purpose of the study was to determine the risk factors for post-operative AKI in patients operated on for IE. METHODS: A retrospective, non-interventional study of prospectively collected data (2000-2010) included patients with IE and cardiac surgery with cardio-pulmonary bypass. The primary outcome was post-operative AKI, defined as the development of AKI or progression of AKI based on the acute kidney injury network (AKIN) definition. We used ensemble machine learning ("Super Learning") to develop a predictor of AKI based on potential risk factors, and evaluated its performance using V-fold cross validation. We identified clinically important predictors among a set of risk factors using Targeted Maximum Likelihood Estimation. RESULTS: 202 patients were included, of which 120 (59%) experienced a post-operative AKI. 65 (32.2%) patients presented an AKI before surgery while 91 (45%) presented a progression of AKI in the post-operative period. 20 patients (9.9%) required a renal replacement therapy during the post-operative ICU stay and 30 (14.8%) died during their hospital stay. The following variables were found to be significantly associated with renal function impairment, after adjustment for other risk factors: multiple surgery (OR: 4.16, 95% CI: 2.98-5.80, p<0.001), pre-operative anemia (OR: 1.89, 95% CI: 1.34-2.66, p<0.001), transfusion requirement during surgery (OR: 2.38, 95% CI: 1.55-3.63, p<0.001), and the use of vancomycin (OR: 2.63, 95% CI: 2.07-3.34, p<0.001), aminoglycosides (OR: 1.44, 95% CI: 1.13-1.83, p=0.004) or contrast iodine (OR: 1.70, 95% CI: 1.37-2.12, p<0.001). Post-operative but not pre-operative AKI was associated with hospital mortality. CONCLUSIONS: Post-operative AKI following cardiopulmonary bypass for IE results from additive hits to the kidney. We identified several potentially modifiable risk factors such as treatment with vancomycin or aminoglycosides or pre-operative anemia.

Low social support is associated with an increased risk of postoperative delirium.

STUDY OBJECTIVE: To examine the predictive value of social support in postoperative delirium. DESIGN: Prospective observational study. SETTING: Postoperative recovery room and orthopedic surgery department. PATIENTS: 106 consecutive patients undergoing a planned orthopedic surgery with general anesthesia. MEASUREMENTS: All patients completed questionnaires to assess depressive mood (the Beck Depression Inventory) and social support (Sarason's Social Support Questionnaire) during the preanesthesia visit. Postoperative delirium symptoms were assessed daily using the Memorial Delirium Assessment Scale. Demographic, clinical, and biological data, including anesthesia procedure, were recorded. MAIN RESULTS: Controlling for various potential confounders through multivariate binary logistic regression, postoperative delirium was independently predicted by satisfaction with social support, but neither by depressive mood nor the number of supportive persons. Other significant predictors were the preoperative use of benzodiazepines, age, and type of surgery. CONCLUSION: Patients who report low satisfaction with social support may present with a particular vulnerability to postoperative delirium, even after controlling for physical confounding variables and depressive mood.

Effects of laparoscopic pneumoperitoneum and changes in position on arterial pulse pressure wave-form: comparison between morbidly obese and normal-weight patients.

BACKGROUND: Laparoscopic adjustable gastric banding (LAGB) is commonly indicated in morbidly obese patients. There is controversy regarding the hemodynamic effects of pneumoperitoneum (PNP) in obese patients. PNP and changes in body posture have complex effects on venous return that may be detected by respiratory changes in the arterial pressure waveform. The aim of this study was to compare pneumoperitoneum-induced and reverse Trendelenburg (RT) changes in arterial pulse pressure in obese and normal-weight patients. METHODS: 15 morbidly obese patients undergoing LAGB were compared to 15 normal-weight patients undergoing laparoscopic surgery. Arterial pressure was non-invasively recorded using an arterial tonometer. Respiratory changes in pulse pressure (deltaPp) were recorded in the supine position without and with PNP, and in RT position with pneumoperitoneum. RESULTS: PNP increased deltaPp values in normal weight (P<0.001), but not in obese patients. RT position increased deltaPp values in obese patients, but did not cause additional changes in normal-weight patients. CONCLUSIONS: Unlike normal-weight patients, PNP in the supine position has minimal effect on the arterial pulse-pressure wave-form in obese patients. This observation may reflect physiological differences in total blood volume and loading conditions of the heart between morbidly obese and normal-weight patients, which affect venous return during PNP. Differences in abdominal vascular zone conditions between obese and normal weight-patients may explain these results.

Effects of inhaled nitric oxide administration on early postoperative mortality in patients operated for correction of atrioventricular canal defects.

OBJECTIVE: Postoperative pulmonary hypertension (POPH) substantially increases mortality after repair of congenital heart diseases. Inhaled nitric oxide (NO) has been reported as an effective and specific means of controlling POPH crisis. No randomized, placebo-controlled study has addressed the ability of NO administration to reduce mortality. Such a trial could raise ethical questions. DESIGN: Observational study with historical control subjects based on multivariate confounder scores. SETTING: Surgical pediatric ICU in a university hospital. PATIENTS: Two hundred ninety-four records of patients operated on for atrioventricular (AV) canal between 1984 and 1994 who presented with severe POPH. INTERVENTIONS: All variables found to be predictive for death by univariate tests were entered in a multivariate forward stepwise logistic regression model. Two paired groups regarding risk factors for death and only differing for POPH treatment (NO or conventional treatment) were constructed on the basis of predicted values obtained from this model. Twenty-five patients received NO, and 39 control patients, operated on between 1984 and 1994, received conventional treatment for POPH. MEASUREMENTS AND RESULTS: Postoperative pulmonary pressure, date of operation, and occurrence of an infectious complication were retained in the model. The comparison between the two paired groups showed a significant difference in mortality (24%; 95% confidence interval [CI], 7 to 41%; vs 56%; 95% CI, 37 to 75%, respectively; p = 0.02). CONCLUSIONS: This study suggests that there is a high probability for postoperative mortality reduction associated with administration of inhaled NO when severe POPH occurs in children operated for complete repair of AV canal.

Airway management using the intubating laryngeal mask airway for the morbidly obese patient.

UNLABELLED: We studied the effectiveness of the intubating laryngeal mask airway (ILMA) in morbidly obese patients scheduled for bariatric surgery. We included 118 consecutive morbidly obese patients (body mass index, 45 +/- 5 kg/m(2)). After the induction of general anesthesia, the laryngeal view was classified by the first observer according to the method of Cormack and Lehane. The ILMA was then inserted, and the trachea was intubated through the ILMA by a second observer. The rate of successful tracheal intubation with ILMA was 96.3%. The success rate, the number of attempts, and the total duration of the procedure were not different among patients with low-grade (Cormack 1-2) and patients with high-grade (Cormack 3-4) laryngeal views. The time required for insertion of the ILMA was slightly longer in patients with high-grade laryngeal views. Failures of the technique were not explained by the experience of the practitioner or airway characteristics. No adverse effect related to the technique was reported. Results of this study suggest that using the ILMA provides an additional technique for airway management of morbidly obese patients. IMPLICATIONS: The intubating laryngeal mask airway (ILMA) provides an additional technique for airway management of morbidly obese patients. The best choice of the primary technique (laryngoscopy or ILMA) for tracheal intubation of an adult obese patient remains to be determined.

The clinical relevance of systolic pressure variations in anesthetized nonhypotensive patients.

OBJECTIVE: To assess the accuracy of respiratory-induced systolic pressure variation and its components to detect low left ventricular preload. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Sixty-seven patients undergoing major surgery under general anesthesia. INTERVENTIONS: Transesophageal echocardiographic measurements during apnea and mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: Respiratory-induced systolic pressure variation and its components and left ventricular end-diastolic area obtained by transesophageal echocardiography were noted simultaneously. Arterial pressure indices did not allow a reliable diagnosis of a low left ventricular end-diastolic area using a cut-off value of 7.9 cm(2)/m(2) (inferior boundary of the interquartile range of the areas measured in the authors' group). CONCLUSIONS: These results suggest that systolic pressure variations noticed after induction of general anesthesia do not reflect low left ventricular preload in nonhypotensive patients.

Laparoscopic gastric banding: a minimally invasive surgical treatment for morbid obesity: prospective study of 500 consecutive patients.

OBJECTIVE: To evaluate early and late morbidity of laparoscopic adjustable gastric banding for morbid obesity and to assess the efficacy of this procedure by analyzing its results. SUMMARY BACKGROUND DATA: Laparoscopic adjustable gastric banding is considered the least invasive surgical option for morbid obesity. It is effective, with an average loss of 50% of excessive weight after 2 years of follow-up. It is potentially reversible and safe; major morbidity is low and there is no mortality. METHODS: Between April 1997 and June 2001, 500 patients underwent laparoscopic surgery for morbid obesity with application of an adjustable gastric band. There were 438 women and 62 men (sex ratio = 0.14) with a mean age of 40.4 years. Preoperative mean body weight was 120.7 kg and mean body mass index (BMI) was 44.3 kg. m. RESULTS: Mean operative time was 105 minutes, 84 minutes during the last 300 operations. Mean hospital stay was 4.5 days. There were no deaths. There were 12 conversions (2.4%), 2 during the last 300 operations. Fifty-two patients (10.4%) had complications requiring an abdominal reoperation. Forty-nine underwent a reoperation for minor complications: slippage (n = 43, incisional hernias (n = 3), and reconnection of the catheter (n = 3). Three patients underwent a reoperation for major complications: gastroesophageal perforation (n = 2) and gastric necrosis (n = 1). Seven patients had pulmonary complications and 36 patients experienced minor problems related to the access port. At 1-, 2-, and 3-year follow-up, mean BMI decreased from 44.3 kg. m to 34.2, 32.8, and 31.9, respectively, and mean excess weight loss reached 42.8%, 52%, and 54.8%. CONCLUSIONS: Laparoscopic adjustable gastric banding is a beneficial operation in terms of excessive weight loss, with an acceptably low complication rate. It can noticeably improve the quality of life in obese patients. Half of the excess body weight can be effortlessly lost within 2 years.

Robotic-assisted cardiac surgery: anesthetic and postoperative considerations.

OBJECTIVE: To assess the feasibility of endoscopic telemanipulated cardiac surgery and describe the anesthetic, postoperative, and surgical implications of minimally invasive robotic-assisted cardiac surgery. DESIGN: Prospective study. SETTING: Cardiovascular and transplant center, university hospital. PARTICIPANTS: Twenty patients (13 men, 7 women) scheduled for either coronary artery bypass graft surgery or valve surgery. Mean age was 53 +/- 5 years (range, 31 to 75 years) and mean New York Heart Association class was 2.4. Three patients (6 %) were having redo procedures, and 1 patient had bacterial endocarditis. INTERVENTIONS: Surgery was done with the aid of the daVinci surgical robot (Intuitive Surgical, Mountain View, CA). Induction and maintenance of anesthesia consisted of a target-controlled infusion of remifentanil and propofol. In 11 cases (55%), cardiopulmonary bypass was performed with Port-Access technology (Heartport, Redwood City, CA), and in the remaining 9 cases (45%), conventional femorofemoral bypass was used. MEASUREMENTS AND MAIN RESULTS: Fifteen patients (75 %) were extubated within 6 hours and discharged from the cardiac surgery intensive care unit on postoperative day 1. Two patients (10%) were reexplored in the immediate postoperative period. Two conversions to thoracotomy were reported. One reoperation at 6 months and 1 late death occurred. At 1-year follow-up, excellent functional results were observed in 18 cases. CONCLUSION: Caution should be used when assessing innovative medical-surgical techniques. Despite technical difficulties and lengthy procedures, results were satisfactory. The feasibility of robotic-assisted surgery for coronary artery bypass graft and valve procedures is intuitively appealing.

Prediction of arterial oxygen tension during one-lung ventilation: analysis of preoperative and intraoperative variables.

OBJECTIVE: To determine whether currently available preoperative and intraoperative variables related to arterial oxygen tension (PaO(2)) can be used as predictors for low PaO(2) during one-lung ventilation (OLV). DESIGN: A prospective cohort study. SETTING: Primary university hospital. PARTICIPANTS: Adult patients (n = 92) undergoing thoracic surgery requiring OLV. INTERVENTIONS: Preoperative and intraoperative data, including past medical history, physical examination, and usual preoperative and intraoperative tests, were collected and used as explanatory variables for PaO(2) during OLV by univariate and multivariate analysis. A stepwise logistic regression including the same independent variables was used to identify patients who should be expected to develop arterial hypoxemia (PaO(2) <70 mmHg). Arterial blood gas samples were analyzed 15 minutes after the onset of OLV and after thoracotomy to determine the lowest PaO(2) value during OLV. MEASUREMENTS AND MAIN RESULTS: Preoperative (age, hematocrit, relative perfusion of the nondependent lung) and intraoperative (PaO(2) during 2-lung ventilation and mean arterial pressure at the lowest PaO(2)) variables were identified as independent factors affecting PaO(2) in OLV. PaO(2) during 2-lung ventilation was the only independent variable accounting for arterial hypoxemia when multivariate logistic regression was performed. CONCLUSION: The PaO(2) during OLV can be predicted using routinely available preoperative and intraoperative data. From a clinical point of view, this study failed to identify patients at risk of arterial hypoxemia when OLV is instituted because mainly intraoperative independent variables are involved in the decrease of PaO(2) in this situation.