Acute arsenic poisoning primarily affects which organ system, leading to severe gastrointestinal and cardiovascular collapse?

Explanation

## Acute Arsenic Poisoning: Organ System Involvement **Key Point:** Acute arsenic poisoning primarily affects the **gastrointestinal tract and cardiovascular system**, causing severe hemorrhagic gastroenteritis, dehydration, and circulatory collapse. ### Pathophysiology of Acute Arsenic Toxicity 1. **Gastrointestinal Effects** (onset within 30 minutes to 2 hours) - Arsenic acts as a corrosive irritant to the GI mucosa - Causes hemorrhagic gastroenteritis with severe vomiting and diarrhea ("rice-water stools") - Leads to massive fluid and electrolyte loss - Abdominal pain, tenesmus, and bloody diarrhea are hallmark features 2. **Cardiovascular Effects** (secondary to GI losses and direct toxicity) - Severe dehydration → hypovolemic shock - Direct myocardial depression from arsenic - Arrhythmias (prolonged QT interval, torsades de pointes) - Hypotension and circulatory collapse - Death often occurs from cardiovascular shock within 24–48 hours in severe cases ### Timeline of Acute Arsenic Poisoning ```mermaid flowchart TD A[Arsenic ingestion]:::outcome --> B[0.5-2 hours: GI symptoms]:::outcome B --> C[Severe vomiting & diarrhea]:::action C --> D[Fluid & electrolyte loss]:::urgent D --> E[Hypovolemic shock]:::urgent E --> F[Cardiovascular collapse]:::urgent A --> G[Direct myocardial toxicity]:::outcome G --> H[Arrhythmias, QT prolongation]:::outcome H --> F F --> I{Treatment initiated?}:::decision I -->|Yes: IV fluids, BAL| J[Potential recovery]:::action I -->|No| K[Death in 24-48 hours]:::urgent ``` **High-Yield:** The **"rice-water stools"** of acute arsenic poisoning resemble those of cholera—this is a classic forensic medicine teaching point and frequently tested in NEET PG. ### Clinical Features of Acute Arsenic Poisoning | System | Feature | Mechanism | |--------|---------|----------| | **GI** | Hemorrhagic gastroenteritis | Corrosive irritation of mucosa | | **GI** | Severe vomiting & diarrhea | Fluid secretion, mucosal damage | | **GI** | Abdominal pain, tenesmus | Irritation of GI tract | | **CV** | Hypotension, shock | Hypovolemia + direct myocardial depression | | **CV** | Arrhythmias (QT prolongation) | Direct cardiotoxicity | | **Metabolic** | Hyperkalemia, acidosis | Tissue damage, fluid loss | | **Renal** | Acute kidney injury | Hypovolemia, direct tubular toxicity | **Clinical Pearl:** The severity of acute arsenic poisoning depends on the **dose, route, and formulation**. Soluble salts (arsenic trioxide, sodium arsenite) are more rapidly absorbed and toxic than insoluble forms. Lethal dose is approximately 100–300 mg of arsenic trioxide. **Warning:** Do NOT confuse acute arsenic poisoning with chronic arsenic poisoning—acute poisoning is dominated by GI and CV symptoms and rapid deterioration, while chronic poisoning presents with peripheral neuropathy, skin changes (Mees' lines, hyperkeratosis), and malignancy risk. ### Management Priorities 1. **Immediate:** IV fluid resuscitation (aggressive), electrolyte correction 2. **Specific antidote:** Dimercaprol (BAL) or DMSA (succimer) for arsenic chelation 3. **Supportive:** Cardiac monitoring, management of arrhythmias, treatment of shock 4. **Decontamination:** Activated charcoal (limited efficacy for metals), gastric lavage if early