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Prognosis of Patients With Advanced Idiopathic Pulmonary Fibrosis Requiring Mechanical Ventilation for Acute Respiratory Failure: Results

At the time of intubation (day 0), volume-control ventilation was used with tidal volume ranging from 8 to 13 mL/kg and respiratory rate from 16 to 20 breaths/min. The corresponding mean peak airway pressure that resulted at day 0 was 50 ± 7 cm H2O (range, 25 to 85 cm H2O).
A precipitating cause of ARF was identified in nine patients (39%). Investigations performed after intubation in order to assess the cause of ARF were as follows: transthoracic echocardiography (n = 8), right heart catheterization (n = 7), bronchial microbiological sampling (n = 17 including 10 perfibro-scopic sampling), and pathologic analysis (n = 9). Seven patients who died very early after intubation were not investigated. Bacterial pneumonia was documented in five patients; in four of them, pneumonia was hospital acquired. The causative agents were Staphylococcus aureus in four patients (the strain was resistant to methicillin in two cases), and Pseudo-monas aeruginosa in one patient. Pneumonia was diagnosed 24 h after an open lung biopsy in one patient, and 24 h after a BAL in one patient, whereas no precipitating factor of pneumonia was identified in the remaining patients. The other causes of ARF were left ventricular failure (n = 2), pneumothorax (n = 1), and BAL (n = 1). In the remaining 14 patients, no evident cause was identified. Among these 14 patients, 4 patients presented at ICU admission with an influenza-like syndrome associated with blood leukocytosis > 15,000/μL and new pulmonary infiltrate on the chest radiograph. No documented infection was found in these four patients, but they were all already receiving antibiotic therapy at the time of ARF. mycanadianpharmacy

With the exception of one patient who successfully received a single-lung transplant 6 h after initiation of MV, the remaining 22 patients died while receiving MV. The survival curve of these 22 patients is shown in Figure 1. The duration of MV varied greatly among these 22 patients (median 3 days; range, 1 h to 60 days). Two patients died within the first 2 h after initiation of MV, and 10 patients (45%) died by the end of day 2. The duration of MV correlated positively with baseline VC (percent predicted) (R = 0.54; p = 0.01; Fig 2) and baseline TLC (percent predicted) (R = 0.71; p < 0.001; Fig 3). The duration of MV correlated negatively with baseline PaC02 (R = —0.47; p = 0.03) and the duration of evolution of IPF (R = —0.50; p = 0.01), and did not correlate with the duration of immunosuppressive therapy (R = — 0.24; p = 0.27) or duration of oxygen therapy prior to ICU admission (R = — 0.32; p = 0.14).
Results of arterial blood gas analysis performed just before initiation of MV were available for all 23 patients. Patients had severe hypoxemia (mean Pa02, 59 ± 5 mm Hg) despite high oxygen flow rate (mean oxygen flow rate, 16 ± 9 L/min). Because some patients died (or received LTx in one case) at various time points after initiation of MV, blood gas analysis was not available for every patient at each time point. Blood gas analysis performed within 6 h after the initiation of MV (Fig 4) showed profound hypoxemia (Pa02/Fl02 ratio at 82 ± 38 mm Hg). Only four patients had a Pa02/Fl02 ratio > 100 mm Hg. PaC02 value recorded just before intubation (47.7 ± 14 mm Hg) was higher (p = 0.03) than baseline PaC02 value, ie, the value obtained when patients were in a stable condition (41 ± 4 mm Hg; Fig 5). In addition, the use of MV failed to rapidly correct PaC02 since the PaC02 value measured at day 0 (73 ± 31 mm Hg) was significantly higher (p < 0.001) than that measured before intubation (Fig 5). Similarly, PaC02 values at day 1 and day 2 were still higher than the PaC02 value measured before MV (p < 0.001 and p = 0.015, respectively). After day 2, the PaC02 value did not differ significantly from the PaC02 value obtained before MV.
Fig1
Figure 1. Survival curve of patients with IPF who received MV. The patient who received a successful single-lung transplant 6 h after intubation is not represented on this curve.
Fig2
Figure 2. Correlation between baseline VC (percent predicted) and duration of MV (R = 0.50 and p = 0.01).
Fig3
Figure 3. Correlation between baseline TLC (percent predicted) and duration of MV (R = 0.71 and p < 0.001).
Fig4
Figure 4. Evolution of Pao2/Fio2 ratio under MV. Vertical bar charts represents means and SDs. Day 0 corresponds to calculation of Pao2/Flo2 ratio within 6 h after intubation.
Fig5
Figure 5. Evolution of Paco2. Vertical bar charts represent means and SDs. Baseline Paco2 was measured before the current hospitalization with the patient in stable condition; beMV Pac02 represents the value of Paco2 measured just before intubation; day 0 corresponds to measurement of Paco2 within 6 h after intubation. * = p < 0.001 in comparison with baseline Paco2; f = p < 0.001 in comparison with Paco2 before MV; Ц = p = 0.015 in comparison with Paco2 before MV.