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  • Meeting abstract
  • Open Access

A comparison of pulmonary artery occlusion pressure (PaOP) measurements using pressure controlled ventilation (PCV) versus airway pressure release ventilation (APRV)

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Critical Care20004 (Suppl 1) :P7

  • Published:


  • Cardiac Index
  • Acute Lung Injury
  • Optimal Time
  • Full Text
  • Positive Pressure

Full text


To determine the optimal time within the APRV phase cycle to accurately measure PaOP.


Ten consecutive patients with acute lung injury (ALI) managed with PCV and a pulmonary artery catheter (PAC) were studied. Demographic data was recorded. Patients served as their own controls and were ventilated by a Drager Evita 4 Pulmonary Workstation. No patients received paralytics. PCV settings (AC mode) achieved a pCO2 of 35–45 (torr) and a pO2 > 60 (torr) on 60% O2; PEEP was not controlled. Hemodynamic profiles were recorded 30 min after achieving the above pCO2 and pO2values. Patients were then changed to APRV to achieve the same pCO2 and pO2 values and hemodynamic measurements were repeated at 30 min. All medications were held constant. PaOP tracings (mmHg) were recorded and compared to the downloaded flow-time trace from the ventilator (Evitaview software). The PCV PaOP was recorded at the end of exhalation and served as the standard for comparisons. PaOP was recorded during the APRV phase cycle (positive pressure and release) and compared to the PCV value. Data are shown as means ± standard deviation and were compared using a two-tailed paired t-test; significance assumed for P < 0.05.


Principal diagnoses were trauma (66%), abdominal sepsis (32%), and other (2%). Mean age was 54 ± 6.2years. PCV blood gas values were pH 7.34 ± 0.04, pCO239.3 ± 3.8, pO2 77.4 ± 9.5. APRV blood gas values were pH 7.37 ± 0.03, pCO2 35.5 ± 2.8, pO2 98 ± 11, (P< 0.05 vs PCV). The PCV PaOP was 16.3 ± 3 on a PEEP of 13.6 ± 2.2 cmH2O with a CI of 3.2 ± 0.5 L/min/m2 and an SvO2 of 76.8 ± 4.5% at a hemoglobin of 9.6 ± 1.04 gm%.The APRV PaOP during the positive pressure phase was 21.2 ± 3.3 (initial), 19 ± 2.5 (mid), and 20.5 ± 2.8 (end); P<0.01 for all versus PCV. The APRV PaOP during the release phase was 19 ± 2.7 (initial, P < 0.05), 17.7 ± 2.3 (mid, P = 0.09), and 16.4 ± 2.6 (end, P = 0.9). CI was significantly increased at 3.6 ± 0.4 (P<0.01 vs PCV) while SvO2 was unchanged at 79.1 ± 4.1 (P> 0.05 vs PCV).


APRV increases the measured PaOP during the positive pressure phase. PaOP may be reliably measured at the midpoint or end of the release phase of APRV. APRV increases oxygenation and cardiac index compared to PCV in patients with acute lung injury.

Authors’ Affiliations

Departments of Surgery and Emergency Medicine, Division of Trauma and Critical Care, Medical College of PA Hospital, 3300 Henry Avenue, Philadelphia, PA 19129, USA


© Current Science Ltd 2000