Please answer question 8! There are many examples of both vertebrates and invert
ID: 3478337 • Letter: P
Question
Please answer question 8!
There are many examples of both vertebrates and invertebrates that use toxins to subdue and predigest their prey. Many of these toxins are neurotoxins that influence both the central nervous system and affect the function of the neuromuscular junction to cause paralysis. Many venoms are hemo- or cytotoxic causing bleeding, clotting or necrosis of tissues. The following medical case is a real story of a Canadian woman returning from a trip to Peru.
A 22-year-old woman who was previously healthy presented with a 4-day history of expanding ecchymoses. She had no other bleeding manifestations and denied any other symptoms such as muscle or joint pain, rashes, and had undergone no physical trauma. Her medical history
was unremarkable. She was not taking any medication, and she had no family history of bleeding problems or hematologic disorders. Her last normal menstrual period was 2 weeks before admission. The patient had no fever or inflammation of the lymph nodes, normal vital signs, and results of her cardiovascular, respiratory and abdominal examinations were normal.
Seven days before admission the patient had returned from northeastern Peru, where she had stepped barefoot on 5 caterpillars. Immediately after contact with the caterpillars, she experienced burning pain in her foot, radiating proximally to her thigh. The pain worsened when she walked. A headache also developed. Both the foot pain and headache resolved over the subsequent 12 hours and she did not seek medical care at that time. Initial laboratory tests are summarized in Table 1 below.
We diagnosed an atypical presentation of disseminated intravascular coagulation or primary fibrinolysis triggered by an unknown process. We started treatment with fresh frozen plasma, cryoprecipitate and fibrinogen concentrate. In view of her presenting signs and symptoms and travel history, we searched MEDLINE and Google Scholar, which revealed the possibility of caterpillar envenomation that could account for all her clinical symptoms and laboratory results.
Although our local poison control center had no knowledge of caterpillar envenomation, they facilitated contact with clinicians from Brazil, who recommended immediate administration of a locally produced antivenin. We made arrangements to obtain the antivenin from Brazil, which took 48 hours to arrive.
Our patient's condition remained stable for the initial 48 hours. On her third day in hospital (10th day after envenomation), alveolar hemorrhage, anuric acute kidney injury and hemodynamic instability developed. She received mechanical ventilation, vasoactive agents and continuous renal replacement therapy. There was evidence of progressive microangiopathic hemolytic anemia (loss of red blood cells), consumptive thrombocytopenia (loss of platelets) and disseminated intravascular coagulation. We received the antivenin from Brazil and administered it on the 10th day after envenomation (third day in hospital); however, our patient's organ dysfunction progressed, and she died of multiorgan failure later that day.
8. Anucric kidney injury is caused by blood clots in the renal artery. Explain why this patient suffered damage from blood clots, but is also suffering from uncontrolled bleeding (hemorrhage)
Table 1: Results of initial laboratory tests performed for a 22-year-old woman who presented with a 4-day history of expanding ecchymoses Test Hemoglobin, g/L Platelet count, x 10 /L Leukocyte count, x 10'/L Haptoglobin, mg/L Total bilirubin, mol/L Lactate dehydrogenase, U/L Creatinine, mol/L International normalized ratio Partial thromboplastin time, s Fibrinogen, g/L D-dimer, ng/mL FEU 1:1 mixing of patient's plasma with normal pooled plasma Coagulation factor II, U/mL Coagulation factor V, U/mL Coagulation factor XIII, U/mL Peripheral blood smear Human chorionic gonadotropin, U/L Pelvic ultrasound Result (reference range) 125 (120-160) 216 (140-450) 7.9 (4.0-11.0) 610 (650-1900) 16 (Explanation / Answer
Looking at the patients history and laboratory tests the patient is likely to be suffering from a condition called as "Disseminated Intravascular Coagulation" also called as DIC. This condition is characteized by widespread activation of coagulation pathway, increased generation of thrombi, impaired fibrinolytic and anti coagulant mechanism ultimately resulting in increased tendency to form blood clots or thrombi. This pathophysiology has resulted in anuric renal failure in the present case because of obstruction of small and medium sized capillaries of renal artery.
If the patient has a tendency for increased thrombi formation, how she is also suffering from uncontrolled bleeding??????
Answer to this is explained below:
Since the coagulation system is activated, over time it will lead to more and more consumption of almost all clotting factors, leading to a state which now is deficient in clotting factors since the synthesis of clotting factors cannot match up with the pace at which they are consumed in DIC. Hence the patient has uncontrolled bleeding.