Differential Diagnosis for the 28-year-old woman
The patient presents with symptoms suggestive of a toxic ingestion, given her history of depression and attempted suicide. The clinical findings of dilated pupils, tachycardia, hypertension, and brisk reflexes can be seen in various toxicities.
Single most likely diagnosis:
- Tricyclic Antidepressant (TCA) overdose: This is likely given her history of depression and the symptoms presented, such as dilated pupils, tachycardia, and brisk reflexes, which are consistent with anticholinergic toxicity often seen in TCA overdose.
Other Likely diagnoses:
- Selective Serotonin Reuptake Inhibitor (SSRI) overdose: While less likely to cause the severe anticholinergic symptoms seen in TCA overdose, SSRIs can still lead to significant toxicity, including serotonin syndrome, which might present with tachycardia, hypertension, and altered mental status.
- Benzodiazepine overdose: Although benzodiazepines are more likely to cause respiratory depression and sedation, in combination with other substances, they could contribute to the patient's altered mental status and potentially some of the other symptoms.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
- Aspirin (Salicylate) overdose: This can present with nonspecific symptoms early on, including tachypnea, tachycardia, and altered mental status. It's crucial to consider salicylate toxicity due to its potential for severe morbidity and mortality if not promptly treated.
- Opioid overdose: Although the patient's symptoms do not strongly suggest opioid overdose (e.g., no mention of pinpoint pupils or significant respiratory depression), it's a diagnosis that cannot be missed due to its high mortality rate if not treated promptly with naloxone.
Rare diagnoses:
- Monoamine Oxidase Inhibitor (MAOI) overdose: MAOIs can cause a variety of symptoms, including hypertensive crisis and serotonin syndrome, but they are less commonly prescribed and thus less likely to be the cause of overdose in this scenario.
Investigations to be performed:
- Electrocardiogram (ECG): To assess for any cardiac arrhythmias or conduction abnormalities, particularly in the context of suspected TCA overdose, which can cause significant cardiac toxicity.
- Venous Blood Gas (VBG) and serum electrolytes: To evaluate the patient's acid-base status and electrolyte balance, which can be affected by various toxic ingestions.
- Toxicology screen: Including specific tests for the suspected substances (e.g., TCAs, SSRIs, salicylates) to confirm the diagnosis and guide treatment.