Individualized ventilation in influenza A (H1N1) infection: The experience of a single intensive care unit
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Pneumonologist, Intensive Care Physician, Intensive Care Unit, Heraklion University General Hospital
Pneumonologist, Intensive Care Physician, ICU Registrar A, ICU, Heraklion University General Hospital
Pneumonologist, Intensive Care Physician, ICU Registrar A, ICU, Heraklion University General Hospital
Pneumonologist, Intensive Care Physician, Assistant Professor of Intensive Care Medicine, ICU, Heraklion University General Hospital, Medical School, University of Crete, Heraklion
Physician-Intensive Care Physician, ICU Registrar Β, ICU, Heraklion University General Hospital
ICU Director, Professor of Intensive Care Medicine, ICU, Heraklion University General Hospital, Medical School, University of Crete, Heraklion, Crete
Dimitris Georgopoulos   

ICU, University General Hospital of Heraklion, University of Crete P.O. Box 1352, 71110 Heraklion Greece
Pneumon 2012;25(2):228–236
• Although ALI/ARDS associated with H1N1 infection usually affects young, previously healthy individuals, it is often severe leading to prolonged ICU stay • Reported mortality rates in ICU patients differ substantially between centres • Efforts to avoid the development of VILI appear to play an important role in the course of the disease • Even in the most severe forms of ARDS, the application of non conventional strategies (oesophageal pressure measurement, HFOV, ECCO2-R) to individualize treatment might lead to a favourable outcome
Severe influenza A infection (H1N1) is associated with acute respiratory failure the management of which challenges intensive care unit (ICU) physicians. The clinical features and outcome of all patients with laboratory-confirmed H1N1 admitted to the Heraklion University Hospital adult ICU during the last two years are reported.

A retrospective observational single centre study was conducted at a tertiary ICU. The medical records of all patients admitted to the ICU with H1N1 infection 10th July 2009 - 1st May 2011 were reviewed. The data collected included demographic characteristics of the patients, the clinical manifestations and illness severity assessed by the Acute Physiology and Chronic Health Evaluation (APACHE) II, and interventions and complications during the ICU stay. The duration of mechanical ventilation, the length of ICU stay and the 60 day mortality were used as outcome indices.

During the study period 23 patients with H1N1 were admitted to the ICU. They were relatively young (median age 39 yrs) with a median APACHE II on admission of 12 (range 5-22). In 7 patients (30.4%) there were no comorbidities on admission. In all cases the reason for admission was acute respiratory failure, with a median PaO2/FiO2 128 mmHg (range 83-376). Acute lung injury/ acute respiratory distress syndrome (ALI/ARDS) was the cause of respiratory failure in 21 patients (91.3%), while 2 presented with acute exacerbation of chronic obstructive pulmonary disease (COPD). Twenty patients (87%) required mechanical ventilation; 10 invasive, 5 non invasive and 5 both. Non conventional ventilator management, including oesophageal balloon insertion, high frequency oscillatory ventilation (HFOV), extracorporeal CO2 removal (ECCO2-R) and prone positioning were applied in 8 patients (34.8%). The median duration of mechanical ventilation and median length of ICU stay were 11.6 and 18.6 days, respectively. One patient died (4.3 % mortality).

The necessity for non conventional ventilator strategies and the prolonged need for life support characterize the severity of ARDS associated with H1N1 infection. An individualized ventilator approach, based on the principles of lung protective ventilation may have a significant influence on the course of the disease.

APACHE, acute physiology and chronic health evaluation; ALI, acute lung injury; ARDS, acute respiratory distress syndrome; COPD, chronic obstructive pulmonary disease; HFOV, high frequency oscillatory ventilation; ECCO2-R, extracorporeal CO2 removal; rRT-PCR, real-time reverse transcriptase polymerase chain reaction; AKI, acute kidney injury; CDC, Centers for Disease Control and Prevention; BMI, body mass index; NIMV, non invasive mechanical ventilation; Pplat, static end-inspiratory plateau pressure; PEEP, positive end expiratory pressure; FiO2, inspired fraction of oxygen; Plend, transpulmonary pressures at end-expiration; Plins, transpulmonary pressure at end-inspiration; RRT, renal replacement therapy; PL, transpulmonary pressure; VT, volume tidal; ΔP, delta pressure; BAL, bronchoalveolar lavage; ALL, acute lymphocyte leukemia; AF, atrial fibrillation; HC, hypertrophic cardiomyopathy; CAD, coronary artery disease; MM, multiple myeloma; AECOPD, acute exacerbation of chronic obstructive pulmonary disease; VILI, ventilator induced lung injury; MV, mechanical ventilation.
The authors would like to thank all members of the adult Intensive Care Unit staff at the University Hospital of Heraklion who, through their tireless and skillful efforts substantially contributed to the favourable outcome of this complex disease in these patients.
The authors have no competing interest to disclose.
EA developed the study design and carried out the data collection, data analysis, manuscript draft and revision. NX contributed with critical manuscript revisions. GP contributed with critical manuscript revisions. EK carried out data collection and manuscript revision. EA contributed with manuscript revision. DG brought up the study idea and carried out critical manuscript revision. All authors have read and approved the manuscript for publication.
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