Life-threatening cardiac failure in a healthy young female with Irukandji syndrome.

We present a case of a previously well 24-year-old female patient who developed severe and life-threatening Irukandji syndrome that required ventilation and inotropic support. This case provides further evidence that there are jellyfish other than the Irukandji jellyfish that can cause cardiac decompensation, and there is a suggestion that application of a pressure immobilization bandage may worsen the envenomation. We include our recommended treatment for the Irukandji syndrome.

Pressure immobilisation bandages in first-aid treatment of jellyfish envenomation: current recommendations reconsidered.

OBJECTIVE: To evaluate whether applying pressure equivalent to that of pressure immobilisation bandages (PIB) causes release of additional venom from discharged jellyfish nematocysts. DESIGN: In-vitro experiment--the venom beads released from electrically activated Chiropsalmus sp. nematocysts were viewed under direct microscopy before and after applying 40 mmHg pressure (replicating the pressure of PIB); and saline washings of discharged nematocysts before and after applying pressure were tested for toxicity (time to ventricular standstill after injecting into live prawns). RESULTS: Applying 40 mmHg pressure caused the venom beads to visibly increase in size, consistent with pressure expressing further venom from the discharged nematocysts. First washings of the nematocyst shafts before compression produced ventricular standstill in prawns within 60 seconds (n=3); second washings did not produce standstill during 540 seconds of observation (n=3); and washings after applying 40 mmHg pressure showed a return of toxicity, with ventricular standstill in all prawns within 180 seconds (n=3). CONCLUSION: Discharged nematocysts are by no means empty and harmless. Applying pressure results in further release of nematocyst venom. The currently recommended practice of applying PIB in the initial treatment of patients stung by a jellyfish may exacerbate the envenomation, and thus should not be recommended.

A year's experience of Irukandji envenomation in far north Queensland.

Envenomation by the Irukandji jellyfish (Carukia barnesi) can result in an array of systemic symptoms known as Irukandji syndrome. In 1996, 62 people presented to Cairns emergency departments with Irukandji envenomation: 57 developed systemic symptoms, and 38 required parenteral narcotics. All patients were discharged home within 24.5 hours, except for two who required high-dependence care for pulmonary oedema. Patients were more likely to be stung on hotter days, with lower-than-average rainfall in the past seven days, and with winds from the north, but less-than-average wind speed. We offer a protocol for treating patients with Irukandji envenomation.

Heart-rate changes during covert rehearsal and response execution.

The phasic ardiac responses and reaction times (RT) of 27 normal adult males were examined during a fixed-foreperiod RT task involving three levels of difficulty of rehearsal, with subject instructed to respond to the reaction signal following one of three delay periods. The results indicated accelerative heart-rate changes corresponding to the requirements of the rehearsal task, regardless of the timing of the motor response. The magnitude of the decelerative component appeared to be primarily dependent on the stimulus detection and requirements of the response decision signalled by the stimuli. Preparation to make a motor response per se did not influence heart-rate deceleration significantly. Potential applications of the heart-rate measure as an independent physiological index of activities related to the processes of memory and attention were suggested.

Changes in GSR and heart rate during listening to tones, words, and nonsense syllables.

In order to compare the habituation of orienting responses to tones, words, and nonsense syllables, GSR and heart rate were recorded following mass (habituation) and discrete presentations of the stimuli. Each of 36 10-yr.-old boys and 36 male undergraduates listened to two presentations of a tone (word and nonsense syllable in a random order) under discrete condition in contrast to 40 presentations under mass condition. Immediately following 2 or 40 presentations, habituation of orienting response was measured while five instances of the stimulus were slowly presented. Results indicated (i) habituation of GSR but not of heart rate, (ii) nonsense syllables evoked the strongest GSRs and heart-rate changes among the three stimuli, and (iii) children showed stronger reactions than the adults in some measure of GSR and heart rate. These results were discussed in terms of the theory of Sokolov.