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Background Oxygen supplementation for exercise-induced hypoxemia is a common clinical practice that improves exercise tolerance. However, we know of no standardized exercise oxygen titration protocol using a single walk test. We report our experience with a protocol developed in our laboratory. Methods Our protocol is based on the 6-min walk test (6MWT). Pulse oximetry readings (oxygen saturation [Spo 2 ]) are monitored, and supplemental oxygen is added in 2 L/min increments to keep Spo 2 > 88%. This continues for at least 6 min of walking with the Spo 2 remaining > 88% for at least 3 min. The records of consecutive patients over 4 months undergoing this procedure were reviewed for test performance, oxygen titration results, and adverse events. Results Two hundred twenty-two patients were tested; only two prematurely terminated the protocol because of intractable dyspnea. One hundred fifty-six patients (38%) required oxygen supplementation, with the first titration most commonly occurring between 1 and 2 min of walking. Nine of the patients had the first titration after 5 min of walking. The average test duration was 7 min (maximum, 15 min). The average number of titrations was 2.2 (maximum six). Sixteen patients could not maintain Spo 2 > 88% for 3 min despite administration of 15 L/min of supplemental oxygen (maximal dose). Conclusions Our protocol was easily performed as a modification of a standard 6MWT with no serious adverse events. Because it is based on a widely accepted measurement of functional capabilities, and because it determined a stable final oxygen dose for ≥ 3 min of walking in most patients, we believe this protocol can be easily adapted for clinical use.

Oxygen supplementation for exercise-induced hypoxemia is a common clinical practice that improves exercise tolerance. However, we know of no standardized exercise oxygen titration protocol using a single walk test. We report our experience with a protocol developed in our laboratory.Our protocol is based on the 6-min walk test (6MWT). Pulse oximetry readings (oxygen saturation [SpoTwo hundred twenty-two patients were tested; only two prematurely terminated the protocol because of intractable dyspnea. One hundred fifty-six patients (38%) required oxygen supplementation, with the first titration most commonly occurring between 1 and 2 min of walking. Nine of the patients had the first titration after 5 min of walking. The average test duration was 7 min (maximum, 15 min). The average number of titrations was 2.2 (maximum six). Sixteen patients could not maintain SpoOur protocol was easily performed as a modification of a standard 6MWT with no serious adverse events. Because it is based on a widely accepted measurement of functional capabilities, and because it determined a stable final oxygen dose for ≥ 3 min of walking in most patients, we believe this protocol can be easily adapted for clinical use.

Background CT scan measures of emphysema and airway disease have been correlated with lung function in cohorts of subjects with a range of COPD severity. The contribution of CT scan-assessed airway disease to objective measures of lung function and respiratory symptoms such as dyspnea in severe emphysema is less clear. Methods Using data from 338 subjects in the National Emphysema Treatment Trial (NETT) Genetics Ancillary Study, densitometric measures of emphysema using a threshold of −950 Hounsfield units (%LAA-950) and airway wall phenotypes of the wall thickness (WT) and the square root of wall area (SRWA) of a 10-mm luminal perimeter airway were calculated for each subject. Linear regression analysis was performed for outcome variables FEV 1 and percent predicted value of FEV 1 with CT scan measures of emphysema and airway disease. Results In univariate analysis, there were significant negative correlations between %LAA-950 and both the WT ( r = −0.28, p = 0.0001) and SRWA ( r = −0.19, p = 0.0008). Airway wall thickness was weakly but significantly correlated with postbronchodilator FEV 1 % predicted (R = −0.12, p = 0.02). Multivariate analysis showed significant associations between either WT or SRWA (β = −5.2, p = 0.009; β = −2.6, p = 0.008, respectively) and %LAA-950 (β = −10.6, p = 0.03) with the postbronchodilator FEV 1 % predicted. Male subjects exhibited significantly thicker airway wall phenotypes (p = 0.007 for WT and p = 0.0006 for SRWA). Conclusions Airway disease and emphysema detected by CT scanning are inversely related in patients with severe COPD. Airway wall phenotypes were influenced by gender and associated with lung function in subjects with severe emphysema.

To compare the ventilation and oxygenation capabilities of jet ventilation at 100 breaths per minute with those of conventional mechanical ventilation (CMV) in adults with respiratory failure, we performed a 2- to 3-h cross-over trial of jet ventilation in 65 stable patients requiring mechanical ventilation. Jet ventilation was delivered with an inspiratory time of 0.2 s through a 1.62-mm injector cannula attached to the proximal endotracheal tube. Drive pressure was adjusted to approximate the arterial PaCO2 on CMV. Measurements of arterial blood gases, peak and mean airway pressures (Paw), blood pressure (BP), and heart rate (HR) were recorded during baseline CMV, after every 30-min period during jet ventilation, and again 30 min after returning the patient to CMV. For analysis, patients were divided into 4 clinical and radiographic patterns: diffuse parenchymal disease (n = 22), focal parenchymal disease (n = 18), obstructive airway disease (n = 6), and nonpulmonary disease (n = 19). Jet ventilation "failures" were characterized by significantly higher minute ventilation requirements, higher levels of PaCO2, higher airway pressures, and smaller PaO2/FIO2 ratios on CMV as compared to the 58 ventilatory "successes." In the ventilatory "successes," peak Paw was significantly lower, but mean Paw, PaCO2, PaO2, FIO2, BP, and HR were not significantly different with jet ventilation as compared to CMV. Moreover, in this ventilatory success group, patients with an increase in the PaO2/FIO2 during jet ventilation were not significantly different from patients with a decrease in PO2/FIO2 in terms of clinical characteristics, ventilation requirements, or gas exchange capabilities on CMV.(ABSTRACT TRUNCATED AT 250 WORDS)

To compare the ventilation and oxygenation capabilities of jet ventilation at 100 breaths per minute with those of conventional mechanical ventilation (CMV) in adults with respiratory failure, we performed a 2- to 3-h cross-over trial of jet ventilation in 65 stable patients requiring mechanical ventilation. Jet ventilation was delivered with an inspiratory time of 0.2 s through a 1.62-mm injector cannula attached to the proximal endotracheal tube. Drive pressure was adjusted to approximate the arterial PaCO2 on CMV. Measurements of arterial blood gases, peak and mean airway pressures (Paw), blood pressure (BP), and heart rate (HR) were recorded during baseline CMV, after every 30-min period during jet ventilation, and again 30 min after returning the patient to CMV. For analysis, patients were divided into 4 clinical and radiographic patterns: diffuse parenchymal disease (n = 22), focal parenchymal disease (n = 18), obstructive airway disease (n = 6), and nonpulmonary disease (n = 19). Jet ventilation "failures" were characterized by significantly higher minute ventilation requirements, higher levels of PaCO2, higher airway pressures, and smaller PaO2/FIO2 ratios on CMV as compared to the 58 ventilatory "successes." In the ventilatory "successes," peak Paw was significantly lower, but mean Paw, PaCO2, PaO2, FIO2, BP, and HR were not significantly different with jet ventilation as compared to CMV. Moreover, in this ventilatory success group, patients with an increase in the PaO2/FIO2 during jet ventilation were not significantly different from patients with a decrease in PO2/FIO2 in terms of clinical characteristics, ventilation requirements, or gas exchange capabilities on CMV.(ABSTRACT TRUNCATED AT 250 WORDS)