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Henry E Fessler

Publications and source records attributed to Henry E Fessler.

11 recordsLinked to original sources
PubMed2006

Variability of spirometry in chronic obstructive pulmonary disease: results from two clinical trials.

OBJECTIVE: Our goal is to determine short-term intraindividual biologic and measurement variability in spirometry of patients with a wide range of stable chronic obstructive pulmonary disease severity, using datasets from the National Emphysema Treatment Trial (NETT) and the Lung Health Study (LHS). This may be applied to determine criteria that can be used to assess a clinically meaningful change in spirometry. METHODS: A total of 5,886 participants from the LHS and 1,215 participants from the NETT performed prebronchodilator spirometry during two baseline sessions. We analyzed varying criteria for absolute and percent change of FEV(1) and FVC to determine which criterion was met by 90% of the participants. RESULTS: The mean +/- SD FEV(1) for the initial session was 2.64 +/- 0.60 L (75.1 +/- 8.8% predicted) for the LHS and 0.68 +/- 0.22 L (23.7 +/- 6.5% predicted) for the NETT. The mean +/- SD number of days between test sessions was 24.9 +/- 17.1 for the LHS and 85.7 +/- 21.7 for the NETT. As the degree of obstruction increased, the intersession percent difference of FEV(1) increased. However, the absolute difference between tests remained relatively constant despite the severity of obstruction (0.106 +/- 0.10 L). Over 90% of participants had an intersession FEV(1) difference of less than 225 ml irrespective of the severity of obstruction. CONCLUSIONS: Absolute changes in FEV(1) rather than percent change should be used to determine whether patients with chronic obstructive pulmonary disease have improved or worsened between test sessions.

Aged↗
PubMed2006

Four methods of measuring tidal volume during high-frequency oscillatory ventilation.

OBJECTIVE: Assess the accuracy of four different methods of measuring tidal volume during simulated high-frequency oscillatory ventilation. DESIGN: In vitro study. SETTING: Research laboratory. SUBJECTS: Three differential pressure pneumotachometers, a modified Pitot tube, an ultrasound flowmeter, and an adult hot wire anemometer. INTERVENTIONS: Each device was placed in series with a Sensormedics 3100B high-frequency ventilator and an 8.0-mm endotracheal tube attached to a 48.9-L plethysmograph. Inspiratory/expiratory ratio was fixed at 1:1 and mean airway pressure at 10 cm H2O. Tidal volumes were calculated at each combination of frequency (f: 3, 4, 6, 8, 10, 12 Hz) and pressure amplitude (DeltaP: 30, 60, 90 cm H2O) by digital integration of the sampled flow signals from each device and compared with those calculated from pressure changes within the plethysmograph. The protocol was repeated after incorporation of frequency-specific calibrations to the flow-measuring algorithm of each device. The hot wire anemometer was further evaluated at Fio2 of 1.0, 37 degrees C, 80% humidity, mean airway pressure of 20 cm H2O, and an inspiratory/expiratory ratio of 1:2. MEASUREMENTS AND MAIN RESULTS: Tidal volumes were 36-305 mL. Bland-Altman analysis demonstrated that each device exhibited systematic bias before frequency-specific adjustment. After frequency-specific adjustment of the flow-measuring algorithm, the two most accurate and precise devices were the Hans Rudolph pneumotachometer, which exhibited a mean error of 0.2% (95% confidence interval, -3.0% to 3.4%), and the hot wire anemometer, which had a mean error of -1.1% (95% confidence interval, -5.5% to 3.3%). The hot wire anemometer remained accurate at Fio2 1.0, 37 degrees C, 80% humidity, mean airway pressure of 20 cm H2O, and an inspiratory/expiratory ratio of 1:2. CONCLUSIONS: Tidal volume can be measured during high-frequency oscillatory ventilation using a variety of techniques. Frequency-specific calibration improves the accuracy and precision of tidal volume measurements. Hot wire anemometry exhibits stable performance characteristics across the range of temperature, humidity, Fio2, and inspiratory/expiratory ratios encountered clinically, has a small deadspace, is unaffected by mean airway pressure, and is therefore suitable for clinical applications.

Adult↗
PubMed2005

Lung volume reduction surgery.

Lung volume reduction surgery (LVRS) has been widely studied and has been available for the treatment of advanced emphysema for 10 years. This paper reviews some of the historical attempts at surgical treatment of emphysema, the physiology of LVRS, and the modern data on patient selection, risks, and benefits. Data from the National Emphysema Treatment Trial are presented in the context of the large body of case series and smaller randomized trials that have preceded that study. Future technologies of bronchoscopic lung volume reduction are also discussed.

Bronchoscopy↗
PubMed2005

Protocols for lung protective ventilation.

Protocols have a well-established role in clinical research and are increasingly being used to direct routine clinical care. In this article, we review the differing goals of research and clinical protocols and outline the similar process for their development. We use the mechanical ventilation protocol of the ARDS Network trial comparing small with traditional tidal volumes as an example. As a starting point for debate, we also suggest guiding principles and specific components of a protocol for high-frequency oscillatory ventilation.

High-Frequency Ventilation↗
PubMed2004

A prospective, controlled trial of a protocol-based strategy to discontinue mechanical ventilation.

Weaning protocols can improve outcomes, but their efficacy may vary with patient and staff characteristics. In this prospective, controlled trial, we compared protocol-based weaning to usual, physician-directed weaning in a closed medical intensive care unit (ICU) with high physician staffing levels and structured, system-based rounds. Adult patients requiring mechanical ventilation for more than 24 hours were assigned to usual care (UC) or protocol weaning based on their hospital identification number. Patients assigned to UC (n=145) were managed at their physicians' discretion. Patients assigned to protocol (n=154) underwent daily screening and a spontaneous breathing trial by respiratory and nursing staff without physician intervention. There were no significant baseline differences in patient characteristics between groups. The proportion of patients (protocol vs. UC) who successfully discontinued mechanical ventilation (74.7% vs. 75.2%, p=0.92), duration of mechanical ventilation (median [interquartile range]: 60.4 hours [28.6-167.0 hours] vs. 68.0 hours [27.1-169.3 hours], p=0.61), ICU (25.3% vs. 28.3%) and hospital mortality (36.4% vs. 33.1%), ICU length of stay (115 vs. 146 hours), and rates of reinstituting mechanical ventilation (10.3% vs. 9.0%) was similar. We conclude that protocol-directed weaning may be unnecessary in a closed ICU with generous physician staffing and structured rounds.

Adult↗
PubMed2002

Hemodynamic characterization of patients with severe emphysema.

In 120 patients with severe emphysema evaluated for participation in the National Emphysema Treatment Trial, pulmonary hemodynamics and ventricular function were assessed. Pulmonary function tests were (%predicted): FEV(1) = 27%; residual volume = 224.6%; diffusion capacity = 26.7%. In 90.8% of patients, end-expiratory pulmonary artery mean pressure was > 20 mm Hg; in 61.4%, end-expiratory wedge pressure was > 12 mm Hg. Cardiac index was normal. Mean pulmonary artery pressure correlated inversely with arterial PO(2), and severity of emphysema, and directly with wedge pressure. Multiple stepwise regression revealed that arterial PO(2) was not an independent predictor of mean pulmonary artery pressure. No correlation was found between indices of emphysema severity and PA pressures. Diastolic ventricular pressures were increased without evidence of systolic dysfunction. We conclude that (1) elevations of pulmonary vascular pressures are common, (2) pulmonary hypertension may be related to factors other than hypoxia, (3) pulmonary hypertension does not impair resting systemic O(2) delivery, and (4) elevated cardiac diastolic pressures do not represent systolic dysfunction.

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PubMed2002

Improvement in spirometry following lung volume reduction surgery: application of a physiologic model.

According to a previously published theoretical model of emphysema, the ratio of RV to TLC (RV/TLC) reflects the size mismatch between the hyperinflated lungs in the disease and the surrounding chest. The model suggests that RV/TLC is an important predictor of improvement in FVC and that increased FVC is an important determinant of increased FEV(1) after lung volume reduction surgery (LVRS). We tested these predictions in 13 patients undergoing LVRS, in whom we made detailed measurements of lung mechanics. Using stepwise regression, we found that RV/TLC was the only preoperative independent predictor of the increase in FVC. Seventy percent of the increase in FEV(1) was attributable to increased FVC, with the remainder due to increased FEV(1)/FVC. In a separate group of 78 LVRS patients evaluated with standard preoperative pulmonary function tests, RV/TLC again was found to correlate with the increase in FVC, and changes in FEV(1) were also due largely to changes in FVC. However, RV/TLC was not predictive of the increase in FEV(1) among the group of 78 patients, because FEV(1)/FVC in patients with a low preoperative RV/TLC often increased despite little change in FVC. These findings support the proposed mechanism for increased FVC following LVRS. They also illustrate the limitations of the model, and suggest further hypotheses for selecting patients who may benefit from surgery.

Aged↗