Case reports 339

but took his own discharge 12 hours after ulceration and transmural acute inflammation, J Accid Emerg Med: first published as 10.1136/emj.14.5.339 on 1 September 1997. Downloaded from admission. At that time an abdominal ultra- with submucosal oedema and vascular conges- sound was negative and full blood count was tion. Parts of the wall were completely gangre- normal. nous and the appearance was in keeping with On the present admission routine blood ischaemic injury. examination revealed a leucocytosis of 23.1x109/l, haemoglobin of 15.0 g/l, and normal serum amylase and liver function tests. Discussion Plain abdominal radiographs showed localised The use of seat belts has reduced the incidence dilated loops of bowl in the upper quadrant to and severity of road traffic accidents injuries.' the left with a few fluid levels. There was no Nevertheless, seat belt themselves can cause free intraperitoneal gas and chest x ray showed serious injuries. In abdominal trauma the no rib fractures. underlying viscera may be crushed between the After three hours of resuscitation, seat belt, the abdominal wall, and the lumbar laparotomy was undertaken through a midline vertebrae if the anterior abdominal muscles are incision. There was a three inch long ischaemic relaxed at the moment of impact, or if the vis- segment in the upper sigmoid colon, which was cera are distended or pathologically enlarged. severely bruised with areas of gangrene and Late presentation occurs if the bowel is not necrosis. Its surface was thin in places and ruptured immediately. In such cases sepsis may about to perforate. Nine inches of colon were develop, with increased mortality. A high index resected. Five inches proximal to this, the lower of suspicion is necessary to avoid diagnostic descending colon showed a five inch long seg- delays. Serious injuries to other passengers are ment which was contused, indurated, and evidence of the violence of the accident, as is thickened but viable. Both areas of damage abdominal wall bruising. corresponded with the position of seat belt Patients at risk should be admitted to hospital straps. A Hartmann's procedure was carried and regular observations and serial examinations out without difficulty. The rest of the performed. A variety of further investigations laparotomy was normal. Postoperative recov- including minilaparoscopy may be helpful. ery was uneventful. 1 Howdieshell TR, Delaurier G. An unusual injury of the sig- Histopathology of the resected segment moid colon produced by seat belt trauma. Am Surg showed extensive mucosal necrosis with focal 1 993;59:355-8.

Saturday night blue a case of near fatal poisoning from the abuse of amyl nitrite http://emj.bmj.com/ Tom Stambach, Kevin Haire, Neil Soni, Jeremy Booth

Abstract highlighted the important features of this

A case of severe methaemoglobinaemia uncommon toxicological problem. on October 1, 2021 by guest. Protected copyright. caused by the abuse of volatile nitrites is Chelsea and reported. The agents are commonly Case report Westminster Hospital, abused, but this complication is rare. The An unknown white woman in her early London SW1O: clinical presentation can make diagnosis twenties was found collapsed outside a police Department of difficult; however, the subsequent treat- station. She was initially thought to be dead, as Anaesthetics ment needs to be rapid to avoid serious T Stambach she was blue, there was no obvious breathing, K Haire morbidity or mortality. This report and no pulse was palpable. An ambulance was presents the clinical picture and the back- called and on their arrival the crew detected a Intensive Care Unit ground information leading to the detec- pulse, some respiration was evident, and she N Soni tion and treatment of this unusual was treated with 100% oxygen and a total of 1.6 mg naloxone. She Accident and problem. remained blue, her Emergency (7Accid Emerg Med 1997;14:339-340) respiration was unchanged, and a pulse oxime- Department ter read 83%. S J Booth Keywords: methaemoglobinaemia; volatile nitrites; di- On arrival in accident and emergency (A&E) agnosis; treatment. she was profoundly cyanosed with rapid Correspondence to: irregular respiration, pulse 1 30/min, blood Mr S Jeremy Booth, Accident and Emergency Department, pressure 80/30 mm Hg, and marked peripheral Chelsea and Westminster The use of volatile nitrites as drugs of abuse is vasoconstriction. Her pupils were dilated but Hospital, Fulham Road, commonplace. We present here an uncommon weakly reactive, Glasgow coma score 5. She London SW10 9NH. but potentially fatal complication of their use. was actively resuscitated with a rapid infusion Accepted for publication Rapid diagnosis and treatment in this case of colloid and was intubated and ventilated 11 March 1997 resulted in a full recovery and we have with 100% oxygen. Arterial blood gases 340 Case reports

showed pH 7.1, Po, 56 kPa, Sao, 100%, base methaemoglobin. Contraindications to the use J Accid Emerg Med: first published as 10.1136/emj.14.5.339 on 1 September 1997. Downloaded from excess -16. Pulse oximetry read 85%. The of methylene blue include cyanide poisoning, methaemoglobin level was 83% on co- where sodium nitrite is given, producing meth- oximetry. Gastric lavage produced a pungent aemoglobin which binds to the cyanide ion to smelling fluid, and a diagnosis of methaemo- form inert cyanmethaemoglobin. In this situa- globinaemia due to volatile nitrite ingestion tion methylene blue frees the bound cyanide. was made. Glucose-6-phosphate deficiency is a relative She was given 2 mg/kg methylene blue intra- contraindication, as methylene blue may in- venously and admitted to intensive care. After duce haemolytic anaemia.4 one hour her methaemoglobin had fallen to It is important to appreciate that pulse 26% and she was given a further 1 mg/kg oximetry can be misleading. It measures the methylene blue. An hour later the methaemo- ratio of absorption oflight at 660 nm (the point globin was 7%. She continued to improve and of maximum difference between oxyhaemo- was extubated seven hours later. She made a globin and deoxyhaemoglobin) and at 940 nm full recovery. (where absorbances are virtually identical). It transpired that she had purchased a bottle Methaemoglobin shifts this ratio towards 1.0, of "poppers", and had drunk the contents (15 corresponding to a saturation of 85%, so at ml) rather than sniffing it. Feeling unwell, she high concentrations the reading becomes had been put by her boyfriend in a taxi and meaningless. Methylene blue mimics reduced when she became unconscious he fled, leaving haemoglobin, so a falsely low reading is the driver to take her to the police station. obtained.5 6 Arterial blood gas analysis measures dis- Discussion solved oxygen concentrations and hence partial "Poppers" is the street name for volatile nitrites pressures, so it is unaffected by dyshaemoglob- taken by inhalation. The exact composition ins. The saturation value is derived, assuming varies, and amyl, butyl, and isobutyl nitrite are all used. "Liquid Gold" is isobutyl nitrite, sold normal haemoglobin, and can give a false sense as a "room odoriser".' Clinical effects lasting a of security. minute or two include vasodilatation causing Co-oximetry uses spectral absorption to tachycardia and hypotension.' Smooth muscle measure oxy-, deoxy-, carboxy-, and methae- relaxation and euphoria are said to prolong moglobin directly. This is more useful since orgasm, hence its popularity. Perioral dermati- tissue oxygen delivery depends on blood tis may occur after repeated use' and tracheo- oxygen content, that is, oxyhaemoglobin levels. bronchitis and haemolytic anaemia have been Methylene blue does affect co-oximetry. It reported. alters values, but the level of effect is a 4.3% Methaemoglobin is formed by oxidation of negative error in methaemoglobin readings at a ferrous (Fe"+) haem to ferric (Fe3+), which is concentration of 25 mg/dm' and this incapable of binding oxygen for transport. measurement change is probably below clinical Normal blood levels are 0-2%, and below 15% significance in this scenario. clinical effects are unlikely. The characteristic Cases of poisoning by volatile nitrites are slate grey cyanosis appears at up to 30%, with regularly reported, both ingestion and inhala- http://emj.bmj.com/ headache fatigue and dizziness. At up to 50%, tion having fatal consequences.` In this case tachycardia, dyspnoea, and severe weakness are the level of 83% is extremely high and was seen. At levels of more than 50% the effects of likely to be fatal. Astute clinical diagnosis, the cellular hypoxia appear, with acidosis, cardiac availability of co-oximetry, and rapid treatment dysrhythmias, respiratory depression, and with methylene blue prevented an almost fatal coma. overdose of what may be becoming an increas- There are two rare congenital forms: haemo- ingly popular drug. on October 1, 2021 by guest. Protected copyright. globin M disease, and a deficiency of the enzyme methaemoglobin reductase. 1 Dixon DS, Reisch RF, Santinga BS. Methaemoglobinaemia resulting from ingestion of isobutyl nitrite, a "room Poisoning is far more common. Agents caus- odorizer" widely used for recreational purposes. J Forensic ing methaemoglobinaemia include nitrates and Sci 1987;22:587-93. 2 Haley TJ. Review of the physiological effects of amyl, butyl, nitrites, aniline dyes, chlorate salts, nitroben- and isobutyl nitrites. Clin Toxicol 1980;1 6:317-29. zene, and the drugs benzocaine, chloroquine, 3 Fisher AA, Brancaccio RR, Jelinek JE. Facial dermatitis in men due to inhalation of butyl nitrite. Cutis 1981;15:146- dapsone, lignocaine, phenacetin, prilocaine, 53. and sulphonamides. Susceptibility is variable 4 Hall AH, Kulig KW, Rumack BH. Drug- and chemical- induced methaemoglobinaemia. Clinical features and but pre-existing cardiopulmonary disease in- management. Med Toxicol 1986;1 :253-60. creases the severity of clinical effects. 5 Rieder HU, Frei FJ, Zbinden AM, Thomson DA. Pulse oxi- Definitive treatment is based on reducing metry in methaemoglobinaemia. Failure to detect low oxy- gen saturation. Anaesthesia 1989;44:326-7. the Fe3+ with methylene blue and preventing 6 Tremper KK, Barker SJ. Pulse oximetry. Anesthesiology further absorption of the oxidising agent. In 1989;70:98-108. 7 O'Toole JB, Gordon BR, Dixon DS. Ingestion of isobutyl extreme cases exchange transfusion has been nitrite. A recreational chemical of abuse causing fatal used and has been effective in improving methaemoglobinaemia. J Forensic Sci 1987;32: 1811-2. 8 Machabert R, Testud F, Descotes J. Methaemoglobinaemia oxygen carriage. Methylene blue acts as a sub- due to amyl nitrite inhalation: a case report. Hum Exp strate for NADPH dependent methaemo- Toxicol 1994;13:313-4. 9 Bradberry S, Whittington R, Parry D, Vale J. Fatal methae- globin reductase, producing leucomethylene moglobinaemia due to inhalation of isobutyl nitrite. Chin blue, which increases the rate of conversion of Toxicol 1994;32: 179-84.