Case Study: Unusual Poisoning with Telmisartan & Hydrochlorothiazide

Introduction

Poisoning cases, especially those involving medications, are critical medical emergencies that demand swift and precise interventions. While there are standard protocols for managing common poisonings, rare cases can challenge even experienced clinicians. This case study explores an unusual instance of antihypertensive medication poisoning involving Telmisartan (an angiotensin II receptor blocker) and Hydrochlorothiazide (a thiazide diuretic), highlighting the complexities of treatment, and how innovative strategies helped to save a life. 

Case Summary

A 48-year-old male resident of Lunawada, with a known history of hypertension, presented with an ingestion of 60 tablets of Telmisartan (40 mg) and Hydrochlorothiazide (12.5 mg) after a domestic altercation with his wife. The overdose occurred in the morning of January 7, 2024. The patient experienced vomiting and giddiness, prompting him to seek care at a local hospital by the evening. There, he was found to be in a hypotensive state with a blood pressure of 60 mmHg systolic. Vasopressor support (noradrenaline) was initiated, and he was referred to Sterling Hospital, Vadodara, where he arrived at 11:00 p.m. Interestingly, the patient had a similar episode of ingestion a year prior, which resulted in admission to a hospital in Godhra for 2-3 days, from which he recovered without major complications. 

On Admission to Sterling Hospital

Upon admission, the patient was conscious and oriented, with a Glasgow Coma Scale (GCS) score of 15/15. However, he remained hypotensive despite vasopressor support with both noradrenaline and Vasopressin. His initial blood pressure was 70/40 mmHg. Routine investigations were performed, and a central venous catheter was inserted to administer maximum doses of vasopressors. Despite these efforts, the patient's blood pressure remained low (80/40 mmHg).

An intra-arterial line was placed to monitor blood pressure more accurately. Other important steps included the insertion of a Foley catheter, which showed minimal urine output (5-10 ml), and a Ryle's tube for gastric lavage, although activated charcoal and lavage were deemed ineffective due to the nature of the drugs ingested. 

Investigations and Initial Management

Initial bloodwork showed acute kidney injury (AKI) and metabolic acidosis:

Creatinine : 3.0 mg/dL

Sodium  : 135 mEq/L

Potassium : 3.8 mEq/L

Chloride  : 100 mEq/L

Bicarbonate : 18 mEq/L

Arterial Lactate : 9.7 mmol/L 

The patient's arterial blood gases (ABG) demonstrated a mixed metabolic and respiratory acidosis, with a pH of 7.37. Repeat ABG testing showed worsening acidosis, prompting the initiation of bicarbonate infusion and continued IV fluids at a rate of 100 ml/hour. The patient's echocardiogram (2D Echo) indicated mild mitral and tricuspid regurgitation, but overall, cardiac function remained preserved with an ejection fraction (EF) of 56%. 

Challenges in Management

The combined overdose of Telmisartan and Hydrochlorothiazide posed unique challenges:

Hemodialysis: Literature indicated that these medications are not effectively removed via hemodialysis, making drug removal impossible.

Shock: The patient experienced severe shock, requiring high doses of vasopressors to maintain blood pressure. His renal function was rapidly deteriorating, with severe lactic acidosis.

Considering these complications, Continuous Renal Replacement Therapy (CRRT) was initiated. Given the preserved left ventricular (LV) function, Veno-Arterial Extracorporeal Membrane Oxygenation (V-A ECMO) was considered but deferred in favor of CRRT with an oXiris filter to address metabolic acidosis and lactic acid clearance.

Experimental Therapies

Given the critical state of the patient, experimental therapies were implemented to support the management of shock and acidosis:

Methylene Blue: A 200 mg dose was infused over two hours to counteract vasoplegic shock.

Vitamin C: High-dose Vitamin C (1 gm IV every six hours) was administered as part of metabolic support.

Insulin and Dextrose: Used to optimize glucose metabolism.

Hydrocortisone: 50 mg IV every six hours to address potential adrenal insufficiency.

Course of Treatment: Days 1-6

Despite these interventions, the patient's condition remained critical. On Day 2, CRRT-CVVHDF was initiated using the Baxter CRRT machine with the oXiris filter. This was combined with heparin to prevent clotting of the circuit. Hemodynamic instability remained a major concern, requiring continuous monitoring of arterial lactate and blood gas analysis.

Although intubation and mechanical ventilation were discussed with the family, the patient's mental alertness and preserved cardiac function led to a mutual decision to withhold intubation unless absolutely necessary.

By Day 6, significant improvements were noted:

· Arterial lactate had reduced to 0.9 mmol/L.

· Vasopressors (Adrenaline and Vasopressin) were gradually tapered, reflecting the patient's improving shock state.

· The patient's urine output had started to increase, signaling some recovery of renal function.

Days 7-10: Stabilization

By Day 7, after six days of CRRT, the patient's lactic acidosis had resolved, and urine output increased to 25 ml/hour. However, serum creatinine continued to rise, reaching 8.9 mg/dL. Despite this, vasopressors were discontinued, and the patient's oxygen requirements decreased to 3 liters per minute.

On Day 10, the patient developed a high-grade fever, which prompted the removal and replacement of central venous catheters, and a course of antibiotics was initiated after obtaining blood cultures. By this time, the patient's condition had stabilized, and ICU psychosis, a common complication of prolonged critical illness, was managed supportively. 

Days 11-17: Discharge and Follow-Up

Over the next few days, the patient's condition remained stable, and he was gradually mobilized. Urine output improved to 2 liters per day, though serum creatinine remained elevated at 12.5 mg/dL. The option of elective hemodialysis was discussed, but the patient declined further dialysis.

By Day 15, the patient was discharged with detailed instructions and risk-explained consent. Follow-up reports showed a steady decrease in creatinine levels, reaching 3.09 mg/dL by Day 45, and the patient was symptomatically much better.

Conclusion

This case illustrates the complexities of managing an unusual poisoning with no specific antidote or established treatment guidelines. Delayed therapy, severe shock, and acute kidney injury posed significant hurdles. However, through innovative and experimental approaches such as CRRT with an oXiris filter, the crisis was managed effectively, saving a young life. The decision to avoid elective intubation and mechanical ventilation helped reduce hospitalization time and associated costs, making this a remarkable example of life-saving medical care in a resource-efficient manner.