Head of Emergency at Sydney’s Royal Prince Alfred, Dr Tim Green, reports on the common and not-so-common cases that occur on his beat.
1. Fishy business
Beryl was bright red when I first saw her on an ambulance stretcher in my Emergency Department at Royal Prince Alfred Hospital in Sydney on a typically busy Monday afternoon. From the other side of the staff base, I could see that she needed to be sorted out now. I grabbed my intern, Charles, who was in his first week as a new doctor – I was planning an introduction to the management of life-threatening allergies, or so I thought.
We moved Beryl into our resuscitation room. She had a racing heart, a pulse rate of 120, excessive for a normally well 52-year-old office manager. Fortunately, her blood pressure was normal; she had no breathing difficulties and appeared alert and responsive. We had time to take a good history.
Beryl had gone to her favourite hot bread shop for her usual lunch: tuna salad on a crusty roll. Today she noticed a slightly peppery taste, which was unusual, but not unpleasant. But as she finished the roll, her head started to throb. Soon her heart was pounding and she began to feel anxious. She also felt nauseous, her headache worsened and her friends noticed her face and arms growing redder and redder. Her symptoms had all the hallmarks of a severe allergic reaction.
But in this case, something didn’t add up. Charles pointed out that while Beryl’s skin was bright red, there were no hives or swelling. Beryl had no wheeze or difficulty breathing and her blood pressure was normal. Her symptoms did seem closely related in time to her lunch, but she had been eating at the same place most workdays for years.
And then the penny dropped… the clue was the tuna. While seafood is a common cause of allergy, prawns, lobster or shellfish are usually the culprits. Tuna rarely causes a problem. But these muscular fish contain a high concentration of an amino acid called histidine and if the fish is not chilled sufficiently after being caught, the histidine can be converted to histamine. High doses of histamine cause exactly the symptoms that Beryl experienced. We cancelled the adrenaline injection and gave her simple anti-histamine tablets. Remarkably, her red skin returned to normal and her headache, palpitations and anxiety resolved. Instead of referring Beryl to the allergy clinic, we notified the public health unit whose investigations revealed that a bad batch of canned tuna was responsible.
Beryl had suffered Scombroid food poisoning. This is common in tropical climates where the warm seawater, warm climate and delays to refrigeration contribute to the risk of histamine production in fish. The histamine may give the fish a mild peppery or metallic taste, but there is usually no other clue that the fish has ‘gone off’. Once the histamine enters our system, it causes a red rash, headache and other symptoms. Fortunately our cooler waters and Australia’s high public health standards in make Scombroid food poisoning a rare occurrence.
And unlike anaphylaxis (a severe allergic reaction), it is not life threatening.
2. Going Nutty
Later in our shift that same day intern Charles looked after Morgan, a three-year-old girl who’d gone out with her parents to a Thai restaurant and had been picking at mum’s stir-fry. Morgan had suffered from a cow’s milk allergy as a baby and had been changed to a soy milk formula. Apart from this little hiccough, she was a healthy and adventurous girl. But while the adults were contemplating a sticky rice dessert, Morgan started to itch and scratch and her mum noticed her lips swelling and her breathing become laboured. Within minutes, Morgan’s skin was red and swollen with hives.
It seemed an eternity, but within 10 minutes the ambulance arrived. Rick, an experienced paramedic, recognised true anaphylaxis and injected a dose of adrenaline into Morgan’s puffy red thigh. By the time she arrived in our ED, she was beginning to again display her three-year-old attitude. There was little for Charles to do but observe her recovery and take a detailed history of what had preceded this episode. As it happened the stir-fry contained prawns, cashews, satay sauce, fish sauce, soy sauce as well as a whole range of vegetables and spices. It was impossible to guess what exactly had been the cause of this allergic reaction.
Charles referred Morgan to our Allergy Clinic where extensive skin testing found that she was allergic to cashew nuts as well as peanuts. Morgan’s parents were taught how to recognise the warning signs and how to treat a serious allergy with an adrenaline “Epipen” which they now carry wherever Morgan goes.
