The Effect of Intermittent. Negative Pressure Ventilation and Long-term Oxygen Therapy for Patients With COPD – Materials
In all patients, the following determinations were performed at the time of admission: arterial blood gas analysis and pH (BMS3 and ABL2 apparatus, Radiometer, Copenhagen), and electrocardiographic (ECG) recordings. The values of Pa02, PaC02, pH, and the ECG data were also obtained at the end of the ventilatory treatment, when a stable clinical phase was reached, and at discharge. These parameters were checked monthly at the periodic visits that the patients received at our outpatient division. Cor pulmonale on ECG was diagnosed when one or both of the following criteria were present: P pulmonale and right ventricular hypertrophy (alone or associated with right axis deviation or right ventricular overload or complete or incomplete bundle right branch block). The FEVr RV, and FEV/VC were determined at discharge when a clinically stable phase of the disease was reached. At the time of admission, all patients underwent ventilatory treatment by means of a body ventilator (Iron Lung, Pulmolife, Biella, Italy) together with oxygen therapy and administration of standard drugs (theophylline, 6-agonists, cardiokinetic agents, diuretics, mucolytic agents, and antibiotic agents). No sedative drugs were given routinely to the patients before institution of the ventilatory treatment. buy claritin online
The ventilatory treatment was instituted immediately when a comatose state was present or when a hypercapnic acidosis (PaC02 > 75 mm Hg; pH > 7.25) associated with neurologic signs of deteriorating sensorium persisted for at least 24 h despite intensive pharmacologic treatment. Ventilatory treatment was carried out continuously until the consciousness recovered and/or PaCOz fell below 65 mm Hg and pH rose above 7.30. Afterwards, the ventilatory treatment was provided intermittendy (from a maximum of 2 h four times daily to a minimum of 1 h four times daily) until stable levels of PaCOz (50 to 55 mm Hg) and pH (7.37 to 7.40) were reached. The ventilator was set to deliver pressures ranging from – 40 to – 60 cm H20 (negative pressure) and from + 10 to + 20 cm H20 (positive pressure) at a rate of 15 breaths/min. The negative pressures were chosen to elicit a tidal volume of more than 500 ml (recorded at the mouth by means of Wright’s ventilograph). The modalities of institution and administration of the ventilatory treatment have been reported previously.
At discharge, 38 patients were subjected to a 3-month monitoring of Pa02 (with measurements of Pa02 every 2 weeks) and were then started on a regimen of LTOT by means of a liquid oxygen system. Oxygen therapy (at least 15 h/d, range 15 to 18) was prescribed in all cases where the Pa02 value (in air and at rest for at least 1 h) was equal to or less than 55 mm Hg. Three subjects were not compliant with their oxygen prescription and were therefore excluded from the study.