Autobox 6200

According to American Thoracic Society/European Respiratory Society guidelines, all patients underwent post-bronchodilator pulmonary function testing (V_max 229 and Autobox 6200; Sensormedics, Yorba Linda, CA, USA) including spirometry measurements.12 COPD patients inhaled 400 μg of salbutamol 20 minutes before testing. We measured dynamic spirometry values, FEV₁, forced vital capacity (FVC), airway obstruction (FEV₁/FVC), and resting slow vital capacity (VC), which represent a reference point of chest hyperinflation.

Patients performed a series of pulmonary function tests (PFT) (V_max 229 and Autobox 6200, Sensormedics, Yorba Linda, California) including spirometry, body plethysmography and diffusion capacity measurement [20 (link), 21 (link)]. Normal values were those of NHANES III standards [21 (link)]. Patients inhaled 400μg of salbutamol via a spacer 20 minutes before testing.
Immediately following the completion of PFTs, an incremental exercise test was performed on an electronically braked cycle ergometer (Ergoline-900, Marquette). After a 3-minute rest and a 3-minute constant pedalling at 20W, the work rate was increased 5 or 10 W/min in ramp profile. The ramp slope was: FEV₁ <1.0Litre – 5W/min, FEV₁ >1.0Litre – 10W/min. Pedalling rate was kept constant at approximately 60rpm. Pulmonary ventilation (‘V_E), oxygen uptake (‘VO₂) and carbon-dioxide output (‘VCO₂) were measured breath-by-breath by a mass flow-sensor and exercise metabolic measurement system (V_max29c, SensorMedics). Lactic acidosis threshold (LAT) was identified by the modified V-slope method [22 (link)]. Heart rate, 12-lead ECG (Cardiosoft, SensorMedics) and oxygen saturation by a pulsoximeter (SatTrak, SensorMedics) was monitored. Maximal voluntary ventilation was estimated as 40xFEV₁ [23 (link)]. Breathlessness and leg fatigue were evaluated at peak exercise by modified Borg scale [24 (link)].

All pulmonary volume measurements were obtained with the same methodology and device. Functional residual capacity (FRC) was evaluated from the volume of thoracic gas, measured in a body plethysmograph (Sensormedics Autobox 6200). Inspiratory and expiratory volumes were thereafter evaluated from the volume flow in a mass flow sensor (Sensormedics 2200). At least three sufficient measurements were required. Peak to peak variation of the oral pressure was not allowed to exceed 2 kPa. Open pressure‐volume‐loops were disregarded. The mean value of three FRC measurements was calculated and this value should not deviate from the single measurements with more than 5%. TLC was calculated as FRC + the highest value of inspiratory capacity (IC). One trained laboratory technician, with more than 20 years of experience in lung function testing, performed all measurements. Pre‐bronchodilator values were used in this study, and the GLI 2021 reference values were applied (Hall et al., 2021 (link)).