Gerald W. Staton

A Simple and Accurate Indirect Calorimetry System for Assessment of Resting Energy Expenditure

An indirect calorimetry system was assembled from three readily available major components: a digital pneumotachograph, an oxygen analyzer, and a carbon dioxide analyzer. A one-way valve, face mask, and meteorological balloon completed the system. Accuracy was assessed by comparison to direct calorimetry in hospitalized patients undergoing enteral hyperalimentation. Each subject was on continuous infusion of formula during a 7-day metabolic balance. Direct and indirect calorimetry was performed over the last 4 days of the balance. The overall agreement between the two methods was within 1%. A simple and inexpensive calorimetry system can therefore be assembled to provide an accurate measure of resting energy expenditure.

The influence of positive end-expiratory pressure on intrapericardial pressure and cardiac function after coronary artery bypass surgery

The hemodynamic effects of positive end-expiratory pressure (PEEP) were studied in coronary artery bypass patients by recording intrapericardial and intracardiac pressures, measuring cardiac output by thermodilution, and determining left ventricular volumes by nuclear radiography. An elevation of PEEP to 5, 10, and 15 cm H2O led to a decrease in cardiac output (15% decrease at PEEP 15) as intrapericardial pressure increased and transmural left atrial pressure decreased. Modest volume loading (an increase in left atrial pressure of 3 mm Hg) greatly attenuated the deleterious effects of 15 cm H2O PEEP. There was an excellent correlation between pulmonary capillary wedge pressure and left atrial pressure at PEEP 0 and 5 (r = .85 and r = .83). This correlation was not nearly as reliable at PEEP 15 (r = .54). A predictable increase in intrapericardial pressure was observed as PEEP was applied in these patients. The magnitude of this increase can be estimated by multiplying the change in PEEP (in cm H2O) by 0.4 to estimate the change in intrapericardial pressure (in mm Hg). Using this estimation as a guide, modest volume loading can be used to maintain transmural filling pressures (and cardiac output) when PEEP is used after coronary artery bypass surgery.

Surgical Biopsy of Suspected Interstitial Lung Disease Is Superior to Radiographic Diagnosis

BACKGROUND Different modalities are used to diagnose interstitial lung disease. We compared the effectiveness of minimally invasive surgical biopsy versus high-resolution computed tomography for the diagnosis of interstitial lung disease and report the mortality of the procedure. METHODS We reviewed 194 patients undergoing video-assisted thoracoscopic lung biopsies for the suspicion of interstitial lung disease from January 2003 to February 2012 at Emory University. Demographics and patient characteristics were analyzed in addition to final diagnoses and clinical outcomes. RESULTS Concordance of radiographic diagnosis with final diagnosis was poor, matching pathologic diagnosis in 15% of cases, and specific diagnoses were included in the radiographic differential in only 34% of cases. A specific diagnosis was made after surgical biopsy in 88% of cases. Overall mortality of surgical biopsy was 6.7% (13/194). Major risk factors for death were preoperative supplemental oxygen, ventilator dependence, and age (p < 0.0001, p < 0.0001, and p = 0.03, respectively). Among patients with ventilator dependence preoperatively, the mortality rate was 100% versus 4.8% in patients not ventilator dependent. All biopsy specimens were concordant 91% of the time, and the first two biopsy specimens were concordant 96% of the time. CONCLUSIONS Surgical biopsy should remain the gold standard for diagnosis of interstitial lung disease. The mortality is low with proper patient selection. More than two surgical biopsy specimens may not be needed because the concordance rates among pathologic specimens are very high.

Current concepts in the classification of interstitial lung disease.

The diagnosis and classification of idiopathic interstitial pneumonias continue to be problematic areas for pathologists. The recently proposed American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias defines specific clinical, radiologic, and pathologic criteria for each of the pulmonary disorders that encompass the idiopathic interstitial pneumonias. In this review, the highlights of this classification are presented, along with recommended guidelines for handling lung biopsy specimens and diagnosing interstitial lung diseases.

Mycobacterium paraffinicum causing symptomatic pulmonary infection

ABSTRACT Mycobacterium paraffinicum has been newly recognized as a species. A case of symptomatic pulmonary infection caused by M. paraffinicum is described, and as far as we know, this is the first case of the organism as a human pathogen.