Nematocysts
(Redirected from Nematocyst)
Background
- Jellyfish; box jellyfish is most deadly
- Most toxic: Australia and other Indo-Pacific waters
Portuguese Man-O-War {Physalia physalis)
A selection of various sea anemones
Nematocyst Mechanism
- Physical contact or osmotic gradient causes discharge of nematocysts
- A spring loaded venom delivery system
- Once opened, a nematocyst releases all of its contained venom
Clinical Features
- Isolated stinging, pain
- Severe
Irukandji syndrome[1]
- Usually develops within 2 hours of envenomation & can last up to 2 days
- Rare but potentially fatal complication. It often involves intense pain, diffuse muscle cramps, vasconstriction and marked hypertension due to a catacholamine surge.
- Beware of hypertensive emergency: Look for signs of end organ damage (ie ACS, CHF, intracranial hemorrhage, renal injury)
Differential Diagnosis
Marine toxins, envenomations, and bites
- Toxins
- Ciguatera
- Scombroid
- Tetrodotoxin (e.g. pufferfish)
- Shellfish poisoning
- Amnesic shellfish poisoning
- Diarrheal shellfish poisoning
- Neurotoxic shellfish poisoning
- Paralytic shellfish poisoning
- Stingers
- Venomous fish
- Cone shell
- Lionfish
- Sea urchins
- Crown-of-Thorns Starfish
- Stonefish
- Other: Catfish, zebrafish, scorpion fish
- Nematocysts
- Coral reef
- Fire coral
- Jellyfish (Cnidaria)
- Portuguese man-of-war
- Sea anemones
- Seabather's eruption
- Phylum porifera (sponges)
- Bites
- Infections
Evaluation
- Generally a clinical diagnosis
Management
- Remove tentacles and nematocysts
- Hot salt water immersion (inactivates heat labile toxins), submerging the area in 45 ℃ water for 20 minutes has been shown to provide significant pain relief[2]
- Stingose is a topical solution composed of 20% aluminum sulfate and 1.1% surfactant.
- Used for pain control, venom removal via osmosis, & venom neutralization via denaturation of proteins and polysaccharides through interactions with the aluminum ion.[3]
- Consider topical lidocaine
- Consider oral or parenteral analgesia for severe pain
- In general, avoid acetic acid (vinegar) since it mostly increases the firing of nematocysts and therefore increases pain.[4]
- Symptomatic treatment for Irukandji syndrome
- Consider fentanyl for pain and antihypertensives such as magnesium sulfate and nitroglycerin
- Antivenom is only readily available in Australia for severe box jellyfish sting
Avoid
- Urine, ethanol, ammonia,
- Acetic acid/vinegar (unless box jellyfish) [7]
- Fresh or tap water (causes nematocyst discharge via the osmotic gradient)
Disposition
See Also
References
- Ward NT, Darracq MA, Tomaszewski C, et al. Evidence based treatment of jellyfish stings in North America and Hawaii. Ann Emerg Med. 2012;60(4):339-414.
- Cegolon L, Heymann WC, Lange JH, et al. Jellyfish stings and their management: a review. Mar Drugs. 2013;11(2): 523-50
- ↑ Hauglid, C., Kiel, J., & Schmidt, A. (2021, April 23). Emergen-Sea Medicine: Overview of Marine Envenomations - Page 4 of 5. ACEP Now. https://www.acepnow.com/article/emergen-sea-medicine-overview-of-marine-envenomations/4/.
- ↑ #Isbister GK, Currie BJ. Hot water immersion v icepacks for treating pain of Chironex fleckeri stings: a randomised controlled trial. Med J Aust. 2017 Oct 16;207(8):362. PubMed PMID: 29020913.
- ↑ Hauglid, C., Kiel, J., & Schmidt, A. (2021, April 23). Emergen-Sea Medicine: Overview of Marine Envenomations - Page 4 of 5. ACEP Now. https://www.acepnow.com/article/emergen-sea-medicine-overview-of-marine-envenomations/4/.
- ↑ Hauglid, C., Kiel, J., & Schmidt, A. (2021, April 23). Emergen-Sea Medicine: Overview of Marine Envenomations - Page 4 of 5. ACEP Now. https://www.acepnow.com/article/emergen-sea-medicine-overview-of-marine-envenomations/4/.
- ↑ Yanagihara AA, Wilcox CL. Cubozoan Sting-Site Seawater Rinse, Scraping, and Ice Can Increase Venom Load: Upending Current First Aid Recommendations. Toxins (Basel). 2017;9(3):105. Published 2017 Mar 15. doi:10.3390/toxins9030105
- ↑ Hauglid, C., Kiel, J., & Schmidt, A. (2021, April 23). Emergen-Sea Medicine: Overview of Marine Envenomations - Page 4 of 5. ACEP Now. https://www.acepnow.com/article/emergen-sea-medicine-overview-of-marine-envenomations/4/.
- ↑ Hauglid, C., Kiel, J., & Schmidt, A. (2021, April 23). Emergen-Sea Medicine: Overview of Marine Envenomations - Page 4 of 5. ACEP Now. https://www.acepnow.com/article/emergen-sea-medicine-overview-of-marine-envenomations/4/.