Inspiratory effort and measurement of dynamic intrinsic PEEP in COPD patients : effects of ventilator triggering systems

• Published in: Intensive care medicine 1995-11, Vol.21 (11), p.896-903
• Main Authors: RANIERI, V. M, MASCIA, L, PETRUZZELLI, V, BRUNO, F, BRIENZA, A, GIULIANI, R
• Format: Article
• Language: English
• Subjects: Acute Disease; Aged; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Bias; Biological and medical sciences; Emergency and intensive respiratory care; Female; Humans; Intensive care medicine; Lung Diseases, Obstructive - complications; Male; Medical sciences; Middle Aged; Monitoring, Physiologic - methods; Positive-Pressure Respiration - adverse effects; Positive-Pressure Respiration - methods; Positive-Pressure Respiration, Intrinsic - diagnosis; Positive-Pressure Respiration, Intrinsic - etiology; Prospective Studies; Respiratory Insufficiency - etiology; Respiratory Insufficiency - physiopathology; Respiratory Insufficiency - therapy; Ventilator Weaning; Work of Breathing
• ISSN: 0342-4642; 1432-1238
• DOI: 10.1007/BF01712330

To investigate effects of ventilator triggering systems (pressure and flow triggering: PT and FT) on measurement of dynamic intrinsic PEEP (PEEPidyn) and patient-ventilator interaction in patients with chronic obstructive pulmonary disease during weaning from mechanical ventilation. Prospective study. Medical/surgical intensive care unit of an academic hospital. 6 COPD patients with acute respiratory failure ready to wean. We measured flow, airway opening, esophageal and gastric pressures. Minute ventilation, breathing pattern and pressure time product (PTP) of the respiratory muscles and of the diaphragm were obtained during spontaneous ventilation through a mechanical ventilator (Puritan-Bennett 7200ae). Two triggering systems, namely PT and FT, were evaluated. The inspiratory muscles effort necessary to overcome the triggering system overestimated PEEPidyn measurement of an amount equal to 49 +/- 2 and 58 +/- 3% during respectively pressure and flow triggering. FT increased tidal volume and minute ventilation and decrease PTP/b and PTP/min of the respiratory muscles and diaphragm. To correctly measure PEEPidyn, the inspiratory effort produced to overcome PEEPi and to trigger the ventilator must be discriminated. Application of flow triggering requires less effort to initiate inspiration and provide a positive end-expiratory pressure level that is able to unload the respiratory muscles by reducing PEEPi. With flow triggering higher minute ventilation are obtained in COPD patients during the weaning phase.