Cole Jon B, Stellpflug Samuel J, Gross Eric A, Smith Stephen W
Hennepin Regional Poison Center, Hennepin County Medical Center, Minneapolis, MN 55415, USA.
Pediatr Emerg Care. 2011 Dec;27(12):1175-7. doi: 10.1097/PEC.0b013e31823b0e47.
Diphenhydramine is an antihistamine commonly implicated in overdose. It has many pharmacologic effects, including sodium channel blockade. Overdoses in toddlers causing QRS prolongation are only rarely reported and never with effective use of sodium bicarbonate. We report a diphenhydramine overdose in a toddler with multiple markers of sodium channel blockade effectively treated with sodium bicarbonate.
A 13-month-old infant girl was brought in by the emergency medical service for a witnessed tonic-clonic seizure. Two hours previously, the child had been found with an open bottle of 25-mg diphenhydramine tablets, 24 of which were missing. Midazolam was administered with seizure resolution. Examination revealed 4-mm reactive pupils; nystagmus; warm, dry, flushed skin; and altered mental status. Initial electrocardiograms revealed sinus tachycardia at a rate of 180 beats per minute, a prolonged QRS of 130 milliseconds (from a baseline of 65 milliseconds), and a positive terminal R wave in aVR, which later resolved after sodium bicarbonate treatment. The patient was discharged home the following day with no sequelae.
Diphenhydramine toxicity is a common poisoning in children. Toxicity typically presents with signs and symptoms of the anticholinergic toxidrome. Diphenhydramine also has sodium channel-blocking properties, and this can be shown in the form of prolonged QRS and a terminal R wave in aVR. QRS prolongation and aVR abnormalities from diphenhydramine ingestion in a toddler have been reported, but effective use of sodium bicarbonate has not.
Electrocardiographic finding consistent with sodium channel blockade should be recognized as a complication of pediatric diphenhydramine overdose, and they seem responsive to hypertonic sodium bicarbonate.
苯海拉明是一种常用于治疗过敏的药物，也常与药物过量有关。它具有多种药理作用，包括钠通道阻滞。幼儿因苯海拉明过量导致QRS波延长的情况鲜有报道，且从未有过使用碳酸氢钠有效治疗成功案例。我们报告了一名幼儿因苯海拉明过量出现多种钠通道阻滞标志物，经碳酸氢钠有效治疗的病例。
一名13个月大的女婴被紧急医疗服务人员送来，她被目击到发生了强直阵挛性癫痫发作。两小时前，发现孩子身边有一瓶打开的25毫克苯海拉明片剂，少了24片。给予咪达唑仑后癫痫发作得到缓解。检查发现瞳孔对光反射4毫米；眼球震颤；皮肤温暖、干燥、发红；精神状态改变。初始心电图显示窦性心动过速，心率为每分钟180次，QRS波延长至130毫秒（基线为65毫秒），aVR导联终末R波阳性，经碳酸氢钠治疗后这些症状后来消失。患者第二天出院，无后遗症。
苯海拉明中毒是儿童常见的中毒情况。中毒通常表现为抗胆碱能中毒综合征的体征和症状。苯海拉明还具有钠通道阻滞特性，这可表现为QRS波延长和aVR导联终末R波。有报道称幼儿因摄入苯海拉明出现QRS波延长和aVR导联异常，但未有效使用碳酸氢钠治疗成功案例。
与钠通道阻滞一致的心电图表现应被视为小儿苯海拉明过量的并发症，且它们似乎对高渗碳酸氢钠有反应。
