Exhaled breath condensate nitrite and its relation to tidal volume in acute lung injury.
OBJECTIVE
Mechanical ventilation may damage the lung. Low tidal volume (VT) is protective, but VT is scaled to body weight (BW) and may be high in functionally small ARDS lungs. We hypothesized that exhaled breath condensate (EBC) nitrite (NO(2)(-)) concentration may increase with lung distension.


METHODS
Prospective, noncontrolled study.


METHODS
University hospital and medical ICU.


METHODS
Thirty-five ICU patients requiring mechanical ventilation (severe pneumonia, n = 31; exacerbated COPD, n = 4). Patients were scored according to American and European Consensus Conference on ARDS criteria (AECC) [no lung injury, n = 7; acute lung injury, n = 13; ARDS, n = 15], as well as the Murray lung injury severity score (LISS) [score 0, n = 3; score 0.1 to 2.5, n = 19; score > 2.5, n = 13].


METHODS
EBC was collected and analyzed for NO(2)(-), interleukin (IL)-6, and IL-8. Serum was analyzed for IL-6, IL-8, and procalcitonin.


RESULTS
and measurements: EBC NO(2)(-) correlated well with VT (milliliters per kilogram of BW; r = 0.79, p < 0.0001) and expiratory minute volume (r = 0.60, p < 0.0001) but not with other ventilatory parameters or parameters of pulmonary (EBC IL-6, EBC IL-8) or systemic (serum IL-6, IL-8, and procalcitonin) inflammation. The ratio of EBC NO(2)(-) and the size of the VT correlated directly with lung injury (AECC, r = 0.66, p < 0.0001; LISS, r = 0.84, p < 0.0001).


CONCLUSIONS
EBC NO(2)(-) increased linearly with VT. The ratio of EBC NO(2)(-) to VT is assumed to reflect NO(2)(-) release at a given VT. An increase in this ratio indicates an inappropriate increase of NO(2)(-) production most likely due to mechanical stress of the remaining open lung units in injured lungs. We conclude that the EBC NO(2)(-)/VT ratio may help to identify situations of critical mechanical stress.
Gessner
Christian
C
Department of Respiratory and Critical Care Medicine, University of Leipzig, Johannisallee 32, 04103 Leipzig, Germany.
Hammerschmidt
Stefan
S
Kuhn
Hartmut
H
Lange
Tobias
T
Engelmann
Lothar
L
Schauer
Joachim
J
Wirtz
Hubert
H
D000208:Acute Disease; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests; D003422:Critical Care; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis; D009573:Nitrites / Q000032:analysis*; D011014:Pneumonia / Q000628:therapy*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000628:therapy*; D012121:Respiration, Artificial / Q000009:adverse effects*; D012128:Respiratory Distress Syndrome / Q000175:diagnosis*; D012307:Risk Factors; D013990:Tidal Volume / Q000502:physiology
D015415:Biomarkers; D009573:Nitrites; D009569:Nitric Oxide