This is a study to determine the testosterone serum levels in male patient with acute respiratory failure requiring mechanical ventilation. The objective is to determine if low levels exist in this population and if it correlates with length of mechanical ventilation.

Hypothesis: Serum testosterone levels in mechanically ventilated male patients are significantly decreased from normal levels and correlate with disease severity and outcomes.

Study Objectives

1. To confirm and quantify the presence of hypotestosteronemia in critically ill male patients with acute respiratory failure requiring mechanical ventilation via endotracheal intubation.
2. To correlate serum testosterone levels with disease severity, short-term outcomes, and survival in mechanically ventilated male patients.
3. To determine if demographic patient characteristics, such as age, admitting diagnosis, or the presence of co-morbidities, affect serum testosterone levels during mechanical ventilation.

Inclusion Criteria:

1. Male
2. Age > 18
3. Admission diagnosis of acute respiratory failure requiring endotracheal intubation and mechanical ventilation for > 24 hours
4. APACHE II score > 15 (APACHE: Acute Physiology and Chronic Health Evaluation - general indicator of disease severity and outcomes predictor)

Exclusion Criteria:

1. Chronic mechanical ventilation (i.e. patients on mechanical ventilatory support for > 21 days for at least 6 hours per day)
2. Patients on mechanical ventilation for > 48 hours prior to MICU admission
3. Non-invasive mechanical ventilation
4. Patients intubated and mechanically ventilated for drug overdose and anticipated to be intubated for < 24 hours
5. Known diagnosis of hypogonadism (requiring testosterone hormonal supplementation) or currently receiving testosterone therapy or received testosterone therapy within 30 days of MICU admission
6. History of testicular, prostate or pituitary tumor
7. Chronic use of systemic steroids prior to admission
8. Terminally ill patients who are not expected to live longer that 3 months

All adult male patients with acute respiratory failure on mechanical ventilation