Age and sex predict PaO2/FiO2 ratio in brain-dead donor lungs

To define the prevalence of various ranges of the ratio of partial arterial oxygen tension to fraction of inspired oxygen (Pao(2)/Fio(2)) and to determine correlative and predictive variables of donor lung Pao(2)/Fio(2).

From the brain death database of Masih Daneshvari Hospital Organ Procurement Center, we extracted demographic data, cause of injury, patient clinical condition, and laboratory findings as independent data. Donor lung suitability was determined with an oxygen challenge test, with results of 400 mm Hg considered ideal; 300 to 399 mm Hg, good; 200 to 299 mm Hg, borderline; and less than 200 mm Hg, not acceptable.

Using the Pao(2)/Fio(2) cutoff points, 6.7% of donor lungs were considered ideal; 26.7%, good; 40%, borderline; and 26.7%, unacceptable. Mean (SD; range) Pao(2)/Fio(2) was 266.6 (85.6; 110-460). The Pao(2)/Fio(2) was significantly correlated with age (r = -0.35; P = .02). After entering the study variables into a linear regression model, age (-2.3; P = .008) and sex (51.5; P = .04) were significant predictors of donor lung suitability (R(2) = 0.95; P < .001).

Results of oxygen challenge tests demonstrated better suitability of lungs from male and younger brain-dead donors. This finding is independent of other variables including cause of brain death and clinical and paraclinical data.