Acute Respiratory Distress Syndrome: Adjuncts to Lung-Protective Ventilation

Stunning of pigs with different gas mixtures: Behavioural and physiological reactions

The present study used thirty-one pigs to investigate induction of unconsciousness and behavioural reactions in different gas mixtures: 80% CO₂/air, 90 s; 40% CO₂/30% O₂/air, 180 s; 70% N₂O/30% CO₂, 90 s. All pigs lost consciousness. All presented respiratory difficulties and most pigs involuntary muscle contractions, often before loss of standing posture. Between mixtures, average latencies of certain behaviours and delays between behaviours differed. Following immersion, blood pH was lower than normal. The low pH induced by the CO₂/O₂/air mixture was physiologically associated with hyperoxemia. Relationships between blood gases, different behavioural and heart rate responses are discussed. In conclusion, all mixtures caused discomfort due to respiratory difficulties and the addition of O₂ or N₂O to the CO₂ mixture did not present an advantage.

Induced hypothermia for trauma-related ARDS

We report a case of 27-year-old male with lung contusions related acute respiratory distress syndrome (ARDS) managed by ARDSNet guidelines and additional hypothermia. On 4^th day, post trauma partial pressure of oxygen dropped to 38 mm of mercury (Hg), not improving even on high positive end-expiratory pressure of 18 cm water (H₂O), inverse ratio ventilation and fraction of inspired oxygen of 1. Extracorporeal membrane oxygenation was ruled out due to the risk of hemorrhage from trauma sites. Thereafter, hypothermia along with muscle paralysis was considered to reduce total body oxygen consumption. Patient's condition improved under hypothermia, and he was extubated and taken up for fracture fixation surgeries and discharged later in stable condition.

The role of high-frequency oscillatory ventilation in the treatment of acute respiratory failure in adults

PURPOSE OF REVIEW

High-frequency oscillatory ventilation (HFOV) is increasingly used in adults with the acute respiratory distress syndrome (ARDS), who remain hypoxemic during conventional mechanical ventilation. In this review, we will summarize the trials evaluating HFOV in adults with ARDS and discuss issues relevant to the clinician regarding the use of HFOV.

RECENT FINDINGS

Several observational and randomized trials support the safety of HFOV and improvements in oxygenation in adult patients with severe ARDS, who remain hypoxemic during conventional mechanical ventilation.

SUMMARY

HFOV theoretically meets the goals of lung-protective ventilation. On the basis of the current evidence, HFOV is associated with improvements in oxygenation in severe, adult ARDS. However, whether HFOV influences mortality, length of ICU stay, ventilator-free days, quality-of-life factors and is cost-effective remains to be determined. Large, prospective, randomized controlled trials such as the ongoing OSCAR and OSCILLATE trials will help further define the role of HFOV in adult ARDS.