Comparison of forehead and finger oximetry sensors during the six minute walk test.

BACKGROUND: Measurement of oxygen saturation (SpO2) during the 6 minute walk test (6MWT) could be impacted by the measurement site. AIMS: To compare SpO2 and heart rate (HR) between forehead and finger sensors during the 6MWT. Sensor readings were also to be compared for signal quality and with capillary blood gas (CBG) pre and post 6MWT. METHOD: 80 subjects with pulmonary vascular disease (PVD) and/or interstitial lung disease (ILD) performed the 6MWT. Pulse oximetry was recorded at 30 s intervals. CBG was taken pre and post 6MWT to determine capillary oxygen saturation (SCO2). RESULTS: The forehead sensor recorded higher values for SpO2 (p < 0.001) and HR (p < 0.01) compared with the finger sensor during the 6MWT. For both sensors, the demonstrated bias compared to CBG post 6MWT was higher and more variable in subjects who desaturated. During the 6MWT there was a higher occurrence (p < 0.001) of poor signal quality in the finger sensor compared with the forehead sensor. CONCLUSION: This study suggests that the sensor site can impact pulse oximetry readings. The variance in bias suggests pulse oximetry may not accurately reflect SCO2 measurements particularly in subjects who desaturate during 6MWT.

The association of six-minute walk work and other clinical measures to cardiopulmonary exercise test parameters in pulmonary vascular disease.

INTRODUCTION: In pulmonary vascular disease exercise, abnormalities can include reduced exercise capacity, reduced oxygen pulse and elevated VE/VCO2. The association of clinical measures such as six-minute walk work, haemodynamics, lung function and echocardiogram to peak VO2, O2 pulse and VE/VCO2 has not been fully investigated in pulmonary vascular disease. AIMS: To determine the relationship of six-minute walk work and other clinical measures to peak VO2, peak O2 pulse and VE/VCO2. Additionally, to investigate the ability to predict peak VO2 from six-minute walk work and other clinical parameters. METHODS: Clinical data was retrospectively analysed from 63 chronic thromboembolic pulmonary hypertension (CTEPH) and 54 chronic thromboembolic disease (CTED) patients. Six-minute walk test measures, haemodynamics, lung function and echocardiographic measures were correlated with peak VO2, peak O2 pulse and VE/VCO2. Predictive equations were developed to predict peak V̇O2 in both CTEPH and CTED cohorts and subsequently validated. RESULTS: A number of clinical parameters correlated to peak VO2, peak O2 pulse and VE/VCO2. Six-minute walk work and transfer factor for carbon monoxide demonstrated the strongest correlation to peak VO2 and peak O2 pulse. The validation of the predictive equations showed a variable level of agreement between measured peak VO2 and calculated peak VO2 from the predictive equations. CONCLUSION: Six-minute walk work and additionally a number of clinical test parameters were associated to peak VO2, peak O2 pulse and VE/VCO2. Six-minute walk work and transfer factor for carbon monoxide were particularly highly correlated to peak VO2 and similarly to peak oxygen pulse. The validation of the predictive equations showed a variable level of agreement and therefore may have limited clinical applicability.

The risks of applying normative values in paediatric cardiopulmonary exercise testing: a case report.

A clinical case in a paediatric subject highlights the urgent requirement for cardiopulmonary exercise testing age-related reference values to be harmonised, to ensure appropriate clinical interpretation and patient management https://bit.ly/36WgOSO.

Electrical circuit models of the human respiratory system reflect small airway impairment measured by impulse oscillation (IOS).

The use of the forced oscillatory input impedance parameter, frequency-dependence of Resistance (fdR), to assess small airway impairment (SAI) has not been widely accepted due to concern about the effects of "upper airway shunt" on oscillometric resistance and low frequency reactance. On the other hand, recent medical studies suggest that low frequency reactance is a very sensitive index of treatment intervention directed at small airways. The present study was undertaken to analyze and compare Impulse Oscillometry (IOS) resistance and reactance data with model-derived indices of small airway function from two models of the respiratory impedance, one with, and the other without an element for upper airway shunt capacitance. Fifty six patients with stable chronic obstructive lung disease of varying severity due to Cystic Fibrosis (CF) and 21 patients with asthma were evaluated by IOS testing. IOS data were input into the augmented RIC (aRIC) model with an upper airway shunt capacitance, and the extended RIC (eRIC) model, without a shunt capacitance element. Model-derived indices were compared between the two models for CF patients separately from asthma patients. We conclude that IOS indices of SAI are modeled equally well with or without upper airway shunt capacitance, and do not seem to be dependent on upper airway shunt capacitance.