Material and methods
A retrospective observational study was conducted in the Medical
Intensive Care Unit (MICU) of University-affiliated hospital during the
pandemic period. Twenty-nine adult patients fulfilling the Berlin
criteria of definition of ARDS [15] admitted to MICU were included
in the study. The patients’ clinical histories were taken and routine
blood and urine investigations including complete hemogram, renal
function tests, serum electrolytes, liver function tests, urine routine,
chest X‐ray, arterial blood gas analysis, and electrocardiogram were
performed in every patient and were later repeated depending on clinical
profile. SAPS II and APACHE II scoring were calculated on day 1. The
study included all mechanically ventilated patients with a diagnosis of
Influenza A (H1N1) pneumonia complicated by ARDS. During the Influenza A
(H1N1) pandemic period, most patients admitted with ARDS were Influenza
A (H1N1) positive (> 90%). The diagnosis of Influenza A
(H1N1) infection in all patients was confirmed by real-time reverse
transcriptase polymerase chain reaction (RT-PCR) of nasopharyngeal swab
specimens and respiratory secretions at the time of hospital admission.
Based on death end-point within 28 days after diagnosis or admission,
the patients were divided into survivor or non-survivor groups. All
patients with ARDS caused by Influenza A (H1N1) pneumonia were treated
using the same principle of mechanical ventilation - volume control
ventilation with appropriate positive end-expiratory pressure (PEEP)
according to the fraction of inspired oxygen (FiO2) (lung protective
ventilation strategies). This study was approved by the Institutional
Ethical Committee.