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Background: Central hemodynamic parameters are typically measured via pulmonary artery catherization-an invasive procedure that involves some risk to the patient and is not routinely available in all settings. Objectives: This study sought to develop a noninvasive method to identify elevated mean pulmonary capillary wedge pressure (mPCWP). Methods: We leveraged data from 248,955 clinical records at the Massachusetts General Hospital to develop a deep learning model that can infer when the mPCWP >15 mmHg using the 12-lead electrocardiogram (ECG). Of these data, 242,216 records were used to pre-train a model that generates useful ECG representations. The remaining 6,739 records contain encounters with direct measurements of the mPCWP. Eighty percent of these data were used for model development and testing (5,390), and the remaining records comprise a holdout set (1,349) that was used to evaluate the model. We developed an associated unreliability score that identifies when model predictions are likely to be untrustworthy. Results: The model achieves an area under the receiver operating characteristic curve (AUC) of 0.80 ± 0.02 (test set) and 0.79 ± 0.01 (holdout set). Model performance varies as a function of the unreliability, where patients with high unreliability scores correspond to a subgroup where model performance is poor: for example, patients in the holdout set with unreliability scores in the highest decile have a reduced AUC of 0.70 ± 0.06. Conclusions: The mPCWP can be inferred from the ECG, and the reliability of this inference can be measured. When invasive monitoring cannot be expeditiously performed, deep learning models may provide information that can inform clinical care.

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PURPOSE: To obtain a point prevalence estimate of alterations in central venous pressure (CVP) produced by active expiration in a consecutive series of intensive care patients. METHODS: We evaluated CVP tracings taken by the nurses at their morning shift change in a consecutive series of 60 cardiac surgery and 59 noncardiac surgery patients. We also assessed change in values due to the change in transducer level. Three physicians and a nurse instructor independently reviewed the tracings and determined whether there was evidence of forced expiration and whether it was type A, defined by decreasing CVP during expiration, or type B, defined by increasing CVP during expiration. RESULTS: Agreement for CVP value was 96% between a physician and a bedside nurse. Twenty-nine percent of participants had active expiration, evenly distributed between A and B types. Active expiration was not related to the type of surgery, use of bronchodilators, and the presence of chronic obstructive lung disease or abdominal distention. Active expiration was more common in nonventilated patients and patients not receiving vasopressor drugs, suggesting they were more awake. CONCLUSION: Active expiration is common in critically ill patients. Failure to recognize it can result in important errors in the estimation of CVP and other hemodynamic measurements.

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To guarantee accurate measurement of central venous pressure (CVP) or pulmonary artery occlusion pressure (PAOP), proper positioning of a reference transducer is a prerequisite. We investigated ideal transducer levels in supine, prone, and sitting position in adults. Chest computed tomography images of 113 patients, taken in supine or prone position were reviewed. For supine position, distances between the back and the uppermost blood level of both atria and their ratios to the largest anteroposterior (AP) diameter of thorax were calculated. For prone position, same distances and ratios were calculated from the anterior chest. For sitting position, distances between the mid-sternoclavicular joint and the most cephalad blood level of both atria and their ratios to the sternal length were calculated. The ratio of the uppermost blood level of right atrium (RA) and left atrium (LA) to the largest AP diameter of thorax was 0.81 ± 0.04 and 0.59 ± 0.03 from the back in supine position. That calculated from the anterior chest in prone position was 0.54 ± 0.03 and 0.46 ± 0.03. The ratio of the most cephalad blood level of RA and LA to the sternal length was 0.70 ± 0.10 and 0.68 ± 0.09 from the mid-sternoclavicular joint in sitting position, which corresponded to the upper border of 4th rib. Optimal CVP transducer levels are at four-fifths of the AP diameter of thorax in supine position, at a half of that in prone position, and at upper border of the 4th sternochondral joint in sitting position. PAOP transducer levels are similar in prone and sitting position, except for supine position which is at three-fifths of the AP diameter of thorax.

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PURPOSE: Pleural pressure measured with esophageal balloon catheters (Peso) can guide ventilator management and help with the interpretation of hemodynamic measurements, but these catheters are not readily available or easy to use. We tested the utility of an inexpensive, fluid-filled esophageal catheter (Peso) by comparing respiratory-induced changes in pulmonary artery occlusion (Ppao), central venous (CVP), and Peso pressures. METHODS: We studied 30 patients undergoing elective cardiac surgery who had pulmonary artery and esophageal catheters in place. Proper placement was confirmed by chest compression with airway occlusion. Measurements were made during pressure-regulated volume control (VC) and pressure support (PS) ventilation. RESULTS: The fluid-filled esophageal catheter provided a high-quality signal. During VC and PS, change in Ppao (∆Ppao) was greater than ∆Peso (bias = -2 mm Hg) indicating an inspiratory increase in cardiac filling. During VC, ∆CVP bias was 0 indicating no change in right heart filling, but during PS, CVP fell less than Peso indicating an inspiratory increase in filling. Peso measurements detected activation of expiratory muscles, development of non-west zone 3 lung conditions during inspiration, and ventilator-triggered inspiratory efforts. CONCLUSIONS: A fluid-filled esophageal catheter provides a high-quality, easily accessible, and inexpensive measure of change in pleural pressure and provided insights into patient-ventilator interactions.

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OBJECTIVE: To investigate reference levels for central venous pressure or pulmonary artery occlusion pressure monitoring in a lateral position. DESIGN: Retrospective observational study. SETTING: A tertiary university hospital. PARTICIPANTS: A total of 204 adults who underwent chest computed tomography scan in the 90° lateral position from November 2006 to February 2015. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Distances from the mid-sternum to the uppermost and lowermost blood levels of both atria were measured. Ratios of the distance from the bottom of the thorax to the uppermost and the lowermost blood levels of both atria to the largest diameter of the thorax were calculated. There were significant differences between the distances from the mid-sternum to the uppermost and the lowermost blood levels of the right atrium and those of the left atrium in the right and left lateral positions, respectively. There were significant differences in the uppermost (3.3±0.1 cm; 95% confidence interval [CI] 3.1-3.5) and the lowermost (4.4±0.1 cm; 95% CI 4.2-4.7) blood levels of the right atrium between the right and left lateral positions. Although the uppermost (1.5±0.1 cm; 95% CI 1.3-1.8) and the lowermost (0.4±0.1 cm; 95% CI 0.2-0.6) blood levels of the left atrium between the right and left lateral positions showed differences, their extent was smaller than the right atrium. The uppermost and the lowermost blood levels of the right atrium lay lower than those of the left atrium in the 90° right lateral position. In contrast, in the 90° left lateral position, the uppermost and the lowermost blood levels of the right atrium lay higher than those of the left atrium. CONCLUSIONS: When monitoring the central venous pressure and pulmonary artery occlusion pressure with patients in the lateral position, changes in the blood level of both atria should be considered when releveling the reference transducer.

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Although invasive hemodynamic monitoring requires considerable skill, studies have shown a striking lack of knowledge of the measurements obtained with the pulmonary artery catheter (PAC). This article reviews monitoring using a PAC. Issues addressed include basic physiology that determines cardiac output and blood pressure; methodology in the measurement of data obtained from a PAC; use of the PAC in making a diagnosis and for patient management, with emphasis on a responsive approach to management; and uses of the PAC that are not indications by themselves for placing the catheter, but can provide useful information when a PAC is in place.

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PURPOSE: In acute respiratory distress syndrome (ARDS) and acute lung injury (ALI), a conservative fluid management strategy improves lung function but could jeopardize extrapulmonary organ perfusion. The objective was to evaluate the diagnostic accuracy of echocardiography to predict tolerance of negative fluid balance (NFB) in patients with ARDS/ALI. MATERIALS AND METHODS: A prospective and observational study in an adult intensive care unit of a university hospital was conducted. All hemodynamically stable patients with ARDS/ALI were included. Echocardiography was performed before NFB and again after 24 hours. Tolerance of NFB was evaluated by the presence of hypotension, acute kidney injury, or need for fluid expansion. The 2 patient groups (tolerating and not tolerating NFB) were compared. RESULTS: Forty-five patients were included. Median age (Q1-Q3) was 58 (52-66) years, and the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen was 205 (163-258) mm Hg. Negative fluid balance was 1950 (1200-2200) mL within 24 hours in the tolerant group. Complications of NFB were observed in 35% cases. After univariate and multivariate logistic regression analyzes, 2 criteria was independently associates with poor tolerance: mitral inflow E wave to early diastolic mitral annulus velocities ratio (E/Ea ratio; odds ratio, 2.02 [1.02-4.02]; P = .04) and weight gain (odds ratio, 1.2 [1.03-1.4]; P = .02). The area under receiver operating characteristic curves was 0.74 for E/Ea and 0.77 for weight gain. CONCLUSIONS: The ratio of E/Ea accurately predicted tolerance of NFB in patients with ARDS/ALI.

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