Lethal nitrous oxide (N2O) intoxication during surgery: the contribution of immunohistochemistry in identifying the cause of death: a case report

BACKGROUND

Nitrous oxide (N2O) is a gas used in medicine for its analgesic, anxiolytic and amnesic properties. It is a drug considered safe if adequately administered. In the literature, accidental N2O-related deaths are rare. They are mostly related to inhalation of this substance for recreational and autoerotic purposes; rarely are reported deaths due to incorrect administration of medical gas in anesthesia. The diagnosis of death from acute N2O intoxication is complex and is generally an exclusion diagnosis: the macroscopic and microscopic post-mortem signs are entirely nonspecific. Furthermore, the circumstantial data are not always supportive and can even be confusing, mainly if the death occurred inside a hospital.

CASE PRESENTATION

We describe a particular case of death from acute nitrous oxide poisoning in a hospital environment, of a Caucasian male of 72-years-old. The intoxication occurred during a minimally invasive vascular surgery due to an incorrect assembly of the supply lines of medical gases (O2 and N2O). The identification of the cause of death resulted from the analysis of circumstantial data, macroscopic and microscopic autoptic findings, and immunohistochemical investigations based on the search for antibodies anti E-selectin, P-selectin, and HIF 1-α.

CONCLUSION

Although not pathognomonic of asphyxiation by N2O, the latter molecules are a valid and early marker of hypoxic insult. Therefore, in concert with all other findings, it may constitute valid support for the forensic pathologist to ascertain the cause of death in case of suspected intoxication by N2O.

Hypoxia-inducible factor-1α in acute ischemic stroke: neuroprotection for better clinical outcome

Background

Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor which maintains cellular homeostasis in response to hypoxia. It can trigger apoptosis while stimulating angiogenesis process and decrease neurological deficit after an ischemic stroke. Up until now, this protein complex has not been widely investigated especially in stroke patient.

Objective

Here, we examined the potential of HIF-1α as a marker for neuroplasticity process after ischemic stroke.

Methods

Serum HIF-1α were measured in acute ischemic stroke patients. National Institute of Health Stroke Scale (NIHSS) were assessed on the admission and discharge day (between days 7 and 14). Ischemic stroke divided into 2 groups: large vessel disease (LVD, n = 31) and small vessel disease (SVD, n = 27). Statistical significances were calculated with Spearman rank test.

Results

A total of 58 patients, 31 with large artery atherosclerosis LVD and 27 with small vessel disease (SVD) were included in this study. HIF-1α level in LVD group was 0.5225 ± 0.2459 ng/mL and in SVD group was 0.3815 ± 0.121 ng/mL. HIF-1α was higher (p = 0.004) in LVD group than in SVD group. The initial NIHSS score in LVD group was 15.46 ± 2.61 and discharge NIHSS score was 13.31 ± 3.449. Initial NIHSS score in SVD group was 6.07 ± 1.82 and the discharge NIHSS was 5.703 ± 1.7055. In both SVD and LVD group, HIF-1α were significantly correlated with initial NIHSS (both p < 0.001) and discharge NIHSS (p < 0.0383 r = 0.94, p < 0.001, r = 0.93, respectively).

Conclusions

HIF-1α has a strong correlation with NIHSS and it may be used as predictor in acute ischemic stroke outcome.