PURPOSE: Mechanical ventilation is an important tool in the management of respiratory failure in the critically ill patient. Although mechanical ventilation can be a lifesaving intervention, it is also known to carry several side-effects and risks. Maximizing oxygenation is one of the primary goals of mechanical ventilation. However, while on mechanical ventilation, patients frequently experience hypoxic events resulting from various causes which need to be properly evaluated and treated.
METHODS: Data was obtained by prospectively reviewing all intensive care admissions during the period from March 2009 to March 2010 at a 651 bed urban medical center. Patients who developed hypoxemia (oxygen saturation ≤88% and a PaO2 ≤60 torrs) while on mechanical ventilation were investigated for the cause of hypoxic event.
RESULTS: During the study period 955 patients required mechanical ventilation. There were a total of 79 patients who developed acute hypoxia. There were 39 males and 40 females ranging between 22 to 91 years. The causes of acute hypoxia in decreasing order of occurrences were pulmonary edema (29%), atelectasis (28%), pneumothorax (13%), pneumonia (10%), ARDS (9%), endotracheal tube malfunction (6%), airway bleeding (3%) and pulmonary embolism (3%).
CONCLUSIONS: Appropriate evaluation of all hypoxic events must begin at the bedside. A step-by-step approach must include a thorough physical examination. Evaluation of the endotracheal tube can immediately reveal dislodgement, bleeding and secretions. Correlation of physical examination findings with those on chest radiograph is essential. Each hypoxic event may require a different intervention depending on its etiology. When presented with a hypoxic event, the physician must consider all the above causes. Instead of simply increasing the fraction of oxygen in the inspired air to overcome hypoxia a concerted effort in appropriate problem solving can reduce the likelihood of an incorrect diagnosis and inappropriate management response.
CLINICAL IMPLICATIONS: When presented with a hypoxic event, the physician must consider a potentially wide ranging differential diagnosis. Being aware of which hypoxic events occur most frequently can help the clinician in appropriate problem solving.
DISCLOSURE: The following authors have nothing to disclose: Nader Mahmood, Fawad Chaudry, Hamad Azam, Muhammad Ali, Maria Alfakir, M. Khan
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