Death caused by addictive inhalation of nitrous oxide

Abstract

Intoxications with nitrous oxide have been, and still are, a rarity in forensic medicine. Apart from accidental overdose during hospital procedures, intoxication with this gas is the result of voluntary inhalation. We report the fatal case of a 32-year-old male who died during inhalation of nitrous oxide from whipped dairy cream cans and hint on the role of the internet in creating new behaviors among drug addicts. We rely on the autopsy report from the Department of Forensic Medicine, Pomeranian Medical University in Szczecin, on laboratory tests, and court files. Neither the autopsy nor the toxicologic and histopathologic tests disclosed the exact cause of death. However, circumstances in which the body was discovered were indicative that death resulted from cardiorespiratory failure. The present case is interesting with regard to its rarity, diagnostic difficulties and potential harm from nitrous oxide used by the food industry.

Introduction

Studies on the abuse of psychoactive drugs have a long history. Over the years, there has been a noticeable change in the methods of intoxication and the choice of psychostimulants has continued to expand. The intravenous route is becoming less popular, being replaced by the oral one. Inhalation is also common, particularly in the case of cannabis preparations and organic solvents. With increasing access to the internet, there is quick exchange of information on new recreational drugs and on personal experiences not only with the most popular psychoactive agents but also with those rarely used, like nitrous oxide. Nitrous oxide is known as the “laughing gas” because it causes euphoric, anxiolytic and narcotic effects. Tolerance and psychological dependence on this gas have been reported in chronic users. ¹

Nitrous oxide is rapidly taken up from the lungs to other tissues. Its solubility in blood is low; it is metabolized to a minimal extent and is removed quickly from the body through the lungs. The action of nitrous oxide shifts from analgesia to anesthesia in a dose-dependent manner, making this gas a useful modality for induction of anesthesia and for general-purpose analgesia (treatment of wounds, diagnostic procedures, etc.). Nitrous oxide is usually administered together with oxygen to maintain anesthesia or to produce short-term analgesia.^2,3 The effective and safe proportion of nitrous oxide to oxygen for analgesia is 70:30; more nitrous oxide in this mixture induces respiratory distress. ⁴ At higher concentrations, nitrous oxide diffuses out of the blood into alveoli causing hypoxemia, coma and death. ⁵ Acute exposure to nitrous oxide may be connected with cardiovascular variability. ⁶ Chronic exposure to nitrous oxide is associated with decrements of lung function, hematological problems, marrow suppression and neurologic symptoms.^7,8

Nitrous oxide has been certified for use as a food additive to generate foam. This property is particularly exploited by producers of whipped cream. A typical can of whipped cream may release up to 1.5 L of nitrous oxide. ⁴ Nitrous oxide is on the E-list of food additives (code E-942) certified for use in the European Union and deemed safe for humans. ⁹

It appeared quite improbable to us that nitrous oxide, normally unavailable in pure form, will be used for intoxication. It also seemed impossible that this compound can be generated at home in adequate quantities and with an acceptable purity. Bearing this in mind, our case is interesting from the theoretical and practical point of view and merits presentation.

Case report

In the afternoon of 23 March, 2008, the body of a 32-year-old male was discovered. The man, a computer scientist, was living alone and was on pension due to paresis of the right upper extremity as a consequence of an accident 10 years ago (Figure 1). Next to his body lay a backpack filled with whipped cream cans. According to the label, the can contained E-942 as propellant (Figure 2). A large number of cans emptied of the gas were found at the site. The body was lying on a bed and was connected to a professional anesthesia system through rubber pipes and a thin rubber tube leading to a face mask immobilized to the face with a bicycle tube. One of the pipes was connected to an arm blood pressure monitor and the pump of the monitor was replaced by a whipped cream can. The man was last seen alive 2 days before.

Figure 1.

The corpse at the site.

Figure 2.

A whipped cream can connected to a blood pressure monitor.

Results

The autopsy was performed on 4 April, 2008, at the Department of Forensic Medicine, Pomeranian Medical University. Advanced putrefaction of the skin and lung edema were noted (Figure 3). Staining with hematoxylin and eosin of histologic sections of internal organs demonstrated putrefaction, autolysis, cerebral edema (Figure 4) and acute anoxemic lesions of the myocardium (Figures 5). Specimens collected for toxicology tests using gas chromatography, high-performance liquid chromatography and gas chromatography–mass spectrometry were negative for exogenous organic compounds with pharmacologic, psychotropic or narcotic properties.

Figure 3.

Histological examination of lung tissue showing significant autolysis and putrefaction (HE staining).

Figure 4.

Autolysis and edema of the brain (HE staining).

Figure 5.

Autolysis and acute anoxemic lesions of the myocardium (HE staining).

On the basis of the circumstances, autopsy findings and laboratory tests, it was concluded that the death of this 32-year-old male was due to acute cardiorespiratory failure following generalized hypoxia during inhalation of nitrous oxide from whipped cream cans. Apparently, the supply of oxygen from the anesthesia system was inadequate and the tightly fitting face mask prevented inflow of air. Moreover, the reaction to hypoxia was suppressed by disorders of consciousness.

Discussion

The intravital and postmortem confirmation of exposure to nitrous oxide is difficult due to the physicochemical properties of this gas and indirect mechanism of its toxicity. Deep hypoxia may ensue during inhalation of nitrous oxide through a face mask. It is a well-known fact that significant elevation in the concentration of nitrous oxide leads to hypoxia and death. ¹⁰

Using our case as an example, one may notice the role of the internet in disseminating information on drugs. The internet provides detailed instructions on how to obtain and use various psychostimulants. Among them are simple methods to procure nitrous oxide “at home” and to administer the gas effectively.

Fatal cases resulting from nitrous oxide intoxication are of accidental origin and of abuse.^5,10,11 Wide availability of products containing nitrous oxide and the growing use of this gas as a recreational drug will result in more cases of toxicity seen in daily practice. In the absence of reliable data on the cause of unconsciousness and death, the right diagnosis of intoxication by nitrous oxide can hardly be made.