Preoperative Echocardiographic Indices of Diastolic Dysfunction and Brain Natriuretic Peptide in Predicting Postoperative Atrial Fibrillation After Noncardiac Surgery.

BACKGROUND: We have shown previously that either echocardiographic indices of diastolic dysfunction or increased preoperative brain natriuretic peptide (BNP) predict postoperative atrial fibrillation (POAF). Because these 2 predictors of POAF have not been evaluated together, our goal was to further elucidate their concurrent role in patients undergoing noncardiac thoracic surgery. METHODS: We retrospectively identified 191 patients who had a preoperative transthoracic echocardiogram and serum BNP level collected as part of routine care before major lung or esophageal resection. Clinical and echocardiographic data were compared between patients who did or did not develop POAF (>5 minutes), and prognostic factors for POAF were identified. RESULTS: Univariate associations with POAF (41 of 191; 22% patients) included older age (P = .04), male sex (P = .01), hypertension (P = .03), increased body mass index (P = .01), and prolonged transmitral flow deceleration time (P < .0001), whereas BNP was not statistically significant (P = .07). Stepwise logistic regression analysis showed that both increasing transmitral flow deceleration time (continuous data log base 2 transformed; odds ratio, 16.05; 95% confidence interval, 3.74-68.96; P = .0002) and left atrial diastolic volume index (continuous data log base 2 transformed; odds ratio, 3.29; 95% confidence interval, 1.22-8.91; P = .02) were independent risk factors of POAF (area under the receiver operating characteristic curve = 0.73). There was no significant interaction between BNP and the 2 independent variables (P = .60, and P = .90), respectively. CONCLUSIONS: In a cohort of patients who had echocardiography and BNP measurements before undergoing major thoracic surgery, this study showed that when evaluated together greater preoperative left atrial diastolic volume index and transmitral flow deceleration time but not BNP levels were independent predictors for POAF.

Anesthesia and the patient with pericardial disease.

PURPOSE: Pericardial diseases present unique perioperative considerations for the anesthesiologist. The purpose of this review is to provide a summary of the pertinent issues related to the etiology, diagnosis, pathophysiology, and perioperative management of patients presenting for operative treatment of pericardial disease. SOURCE: A selective search of the anesthesia, cardiology, and cardiothoracic surgical literature was carried out with particular emphasis on acute pericarditis, effusion, tamponade, and constrictive pericarditis. PRINCIPAL FINDINGS: The anesthesiologist needs to be well versed in the etiology (i.e., differential diagnosis), pathophysiology, and diagnostic modalities in order to best prepare the patient for surgery. Diagnosis and guidance of management requires a working knowledge of the specific associated hemodynamic consequences, particularly of the impaired diastolic function that can occur. Echocardiography is essential in the diagnosis and management of these patients. CONCLUSIONS: Patients with acute and chronic pericardial diseases often require the need for surgical intervention. Several unique features of acute tamponade and constrictive pericarditis require careful perioperative consideration. With proper preparation and pre-anesthetic optimization, patients with a variety of pericardial diseases can be safely managed before, during, and after their surgical intervention.

Resolution of pulmonary edema with variable mechanical ventilation in a porcine model of acute lung injury.

OBJECTIVE: Resolution of the acute respiratory distress syndrome (ARDS) requires clearance of pulmonary edema. Biologically variable ventilation (BVV) strategies that improve gas exchange, lung mechanics, and inflammatory mediators in ARDS may be beneficial in this regard. We used quantitative computed tomography (CT), a single indicator thermodilution system (PiCCO®) to determine extravascular lung water (EVLW), and the change in edema protein concentration over time to compare edema clearance with BVV vs conventional mechanical ventilation (CMV) in a porcine ARDS model. METHODS: Sixteen pigs with oleic acid lung injury were randomized to four hours of ventilation with either CMV (n = 8) or BVV (n = 8) at identical low tidal volume and minute ventilation over time. Hemodynamic variables, gas exchange, lung mechanics, and PiCCO derived EVLW were determined hourly. Computed tomography images and edema fluid samples were obtained at baseline lung injury and after four hours of ventilation. Wet and dry lung weights were determined postmortem. RESULTS: At four hours with BVV, peak airway pressure was decreased significantly and lung compliance improved compared with CMV (P = 0.003; P < 0.001, respectively). Hemodynamic variables and gas exchange were not different between groups. Also at four hours, computed tomography revealed an increase in total gas volume (P = 0.001) and a decrease in total lung weight and global lung density (P = 0.005; P = 0.04 respectively) with BVV. These findings were associated with a significant increase in the gas volume of normally aerated lung regions (P < 0.001) and a decrease in the poorly and non-aerated lung regions (P = 0.001). No change in any CT parameter occurred with CMV. The lung weights derived from computed tomography correlated well with postmortem wet weights (R(2) = 0.79; P < 0.01). The decrease in PiCCO derived EVLW from injury to four hours did not differ significantly between BVV and CMV. Extravascular lung water showed no correlation with postmortem wet weights and significantly underestimated lung water. Average alveolar fluid clearance rates were positive (1.4%·hr(-1) (3%)) with BVV and negative with CMV (-2.0%·hr(-1) (4%)). CONCLUSIONS: In a comparison between BVV and CMV, computed tomography evidence suggests that BVV facilitates enhanced clearance and/or redistribution of edema fluid with improved recruitment of atelectatic and poorly aerated lung regions; no such evidence was seen with either single thermodilution measurement of EVLW or edema clearance rates. The results of computed tomography provide further evidence of the benefit of BVV over conventional ventilation in ARDS.

Lactate flux during carotid endarterectomy under general anesthesia: correlation with various point-of-care monitors.

PURPOSE: The ability to assess the brain-at-risk during carotid endarterectomy (CEA) under general anesthesia remains a major clinical problem. Point-of-care monitoring can potentially dictate changes to management intraoperatively. In this observational study, we examined the correlation between a series of point-of-care monitors and lactate flux during CEA. METHODS: Both neurosurgeons and vascular surgeons participated in the study. The patients underwent arterial-jugular venous blood sampling for oxygen, carbon dioxide, glucose, and lactate, n = 26; bispectral index (BIS) monitoring ipsilateral to side of surgery, n = 26; raw and processed electroencephalogram (EEG), n = 22; and bi-frontal cerebral oximetry using the Fore-Sight monitor, n = 20. RESULTS: One patient experienced a new neurological deficit when assessed at 24 hr following surgery. Lactate flux into the brain was correlated with the greatest decrease in cerebral oximetry with carotid cross-clamping; lactate efflux was correlated with the least. The most noticeable changes in processed EEG (density spectral analysis) were also seen with lactate influx, but at a slower time resolution than cerebral oximetry. Loss of autoregulatory behaviour was demonstrated with lactate influx; however, no correlation was seen between lactate flux and BIS monitoring. CONCLUSION: There was a correlation between cerebral oximetry and lactate flux during carotid cross-clamping. The Fore-Sight monitor may be of value as a point-of-care monitor during CEA under general anesthesia. A novel finding of this study is lactate flux into the brain in the presence of a large difference in cerebral oxygenation during cross-clamping of the carotid artery. Registered at clinicaltrials.gov: NCT000737334.

Identifying drugs that cause dizziness.

OBJECTIVE: To present an alternative technique for identification side effects of drugs. BACKGROUND: Drugs are commonly thought to cause dizziness but traditional methods of associating drugs with the symptom may be insensitive. A "reverse" method of identifying associations between dizziness and drugs is illustrated. The technique could be generally applied to other side effects. METHODS: Medication use was recorded for one hundred two patients who presented with dizziness. After dividing the medications into pharmaceutical categories the percent of dizzy patients taking the drugs was contrasted with the percent of the population as a whole taking the same categories based on a large national drug database. FINDINGS: Angiotensin converting enzyme (ACE) inhibitors were more likely to be associated with dizziness than other medications. CONCLUSION: The reverse association method outlined may be helpful in identifying medications and side effects.