[Eighteen cases of 2009 influenza A H1N1 associated with respiratory failure in adults].

OBJECTIVE: To investigate the clinical feature, treatment and outcome of respiratory failure in patients with 2009 influenza A H1N1 infection in critically ill adults. METHODS: A prospective observational study of 18 patients with respiratory failure suffering from 2009 influenza A H1N1 infection admitted between November 22, 2009 and January 16, 2010. Their clinical data were analyzed. RESULTS: Respiratory failure occurred in 18 patients with confirmed (n=9) or probable (n=9) 2009 influenza A H1N1. Among the 18 patients 8 patients were male, 10 patients were female (7 were pregnant or postpartum). Eight patients had pre-existing medical conditions. Twelve patients were between 20 and 40 years of age, the mean age was 37.1 years. Three were obese with body mass index over 30 kg/m (2). The 28-day mortality was 33.3% (6/18) with 1 additional late death. The median duration from the onset of the illness to hospital admission was 4.1 days (1-5 days) and from the onset to first dose of oseltamivir was 5.5 days (2-12 days), from onset to mechanical ventilation initiation was 6.8 days (4-12 days). Seventeen patients had primary viral pneumonia and 1 patient had an asthma exacerbation and 3 patients experienced multiple organ dysfunction syndrome (MODS). Twelve patients received corticosteroids, 10 patients required vasopressors. All patients were mechanically ventilated, 1 patient underwent extracorporeal membrane oxygenation (ECMO). Patients who died had higher acute physiology and chronic health evaluation II score compared to survivors (29.2 + or - 7.3 vs. 18.6 + or - 6.4, P=0.02). All deceased patients received high-level ventilation settings [peak inspiratory pressure > or = 35 cm H(2)O (1 cm H(2)O=0.098 kPa) and positive end-expiratory pressure > or = 18 cm H(2)O] within the first 7 days of ventilation, and the hypoxemia [oxygenation index < or = 60 mm Hg (1 mm Hg=0.133 kPa)] lasted 24 hours. In contrast only 1 among survivors did (9.1% vs. 100.0%, P<0.01). Compared with survivors, acute kidney injury and barotrauma occurred more frequently in non-survivors (42.9% vs. 27.3%, 28.6% vs. 9.1%, both P<0.05). Whereas all deceased patients received vasopressors, only 4 survivors required vasopressor support (100.0% vs. 36.4%, P<0.05). CONCLUSION: Severe acute respiratory distress syndrome is the most common manifestation in critically ill patients with 2009 influenza A H1N1 infection in adult. Failure to obtain satisfactory oxygenation with high-level ventilation settings within the first 7-days, onset of acute kidney injury and barotrauma, and continuous need for vasopressors portend a poor prognosis.

[Clinical effects of low-stretch ventilation on acute respiratory distress syndrome].

OBJECTIVE: To investigate the effectiveness of low-stretch as compared with low-tidal-volume strategy in the treatment of acute respiratory distress syndrome (ARDS). METHODS: Eighty-five cases of ARDS patients were randomly divided into low-stretch group (42 cases) and low-tidal-volume group (43 cases). The former group of patient received pressure assist control mode with not higher than 35 cm H(2)O (1 cm H(2)O=0.098 kPa) of peak pressure or pressure support mode ventilation with not higher than 30 cm H(2)O of Pplateau, while in low-tidal-volume group tidal volume of no more than 6 ml/kg of predicted body weight was given. The mortality rate within 28 days, the incidence of hypercapnia, the duration of using sedatives and neuromuscular blockade agents, the time of ventilation and the length of intensive care unit (ICU) stay were compared between two groups. According to the monitored expiratory tidal volume (V(T)e), the low-stretch group was divided into low-tidal-volume subgroup (V(T)e < or =6 ml/kg, 11 cases) and non-low-tidal-volume subgroup (V(T)e >6 ml/kg, 31 cases). The mortality within 28 days and the incidence of hypercapnia were compared between two subgroups. RESULTS: There was no significant difference in the 28-day mortality rate between two groups (34.0% vs. 37.0%, P>0.05), but patients of low-stretch group had lower incidence of hypercapnia than low-tidal-volume group (10.6% vs. 40.7%, P<0.05), and also the duration of using sedatives [(4.5+/-1.2) days vs. (8.7+/-2.3) days] and neuromuscular blockade agents [(8.4+/-2.1) days vs. (10.7+/-1.2) days], and the length of ventilation and ICU stay [(10.2+/-2.2) days vs. (13.7+/-3.1) days, all P<0.05] were less. Low tidal volume occurred in 26.2% of low-stretch group, and the low-tidal-volume subgroup had higher 28-day mortality rate (40.8%) and incidence of hypercapnia (65.7%) than non-low-tidal-volume subgroup (13.2% and 8.6%, both P<0.05). CONCLUSION: Compared with low-tidal-volume strategy, low-stretch strategy can reduce the incidence of hypercapnia, the length of ventilation and ICU stay for ARDS patients, but have similar mortality rate. When low-stretch strategy is exercised, an inappropriate low tidal volume may be associated with poor outcome of ARDS.