Evaluation of exhaled nitric oxide in acute paraquat poisoning: a pilot study

Abstract

Background: Fractional exhaled nitric oxide (FENO) is nitric oxide (NO) in the lower airway measured by oral exhalation. FENO can be a useful non-invasive marker for asthma. Paraquat-mediated lung injury can be reflective of an ROS-induced lung injury. We aimed to verify if FENO is a clinical parameter of ROS formation and responsiveness to medical therapies in acute paraquat intoxication.

Material and methods: We recruited 12 patients admitted with acute paraquat poisoning. A portable and noninvasive device called NIOX MINO™ (Aerocrine AB, Solna, Sweden) was used to measure FENO. Measurements were made at the time of hospital admission and at 24, 48, 72, 96, and 120 h after paraquat ingestion.

Results: Six out of the total 12 recruited patients had general conditions (e.g. oral pain) that made it difficult for them to exhale with adequate force. Mean plasma paraquat level was 1.4 ± 2.5 g/mL. We found no direct correlation between the paraquat levels (both ingestion amount and plasma concentration) and FENO (initial, maximal, and minimal values). All the measured FENO values were no greater than 20 ppb for the 2 patients who died. FENO did not vary more than 20% from the baseline. Compared to the above findings, FENO measurements were found to be greater than 20 ppb for the patients who survived. FENO tends to reach its peak value at between 50 h and 80 h.

Conclusions: FENO did not predict mortality, and there was no increase of FENO in patients with severe paraquat intoxication.

Figure 1

Sequential variation of exhaled Nitric oxide in six patients. The horizontal dash line is indication of inflammation suggested by the American Thoracic Society. Two dead patients (case 1: ●, case 3: ◆) showed lower than 20 ppb of FENO. Case 1: ● (death), Case 2: ○ (survival), case 3: ◆ (death), case 4: × (survival) case 5: ◇ (survival), case 6: ■ (survival).