Propylene Glycol–Associated Renal Toxicity from Lorazepam Infusion

Propylene Glycol Toxicity: A Severe Iatrogenic Illness in ICU Patients Receiving IV Benzodiazepines

STUDY OBJECTIVES

Benzodiazepines are commonly administered to medical ICU (MICU) patients. Propylene glycol (1,2-propanediol) is the solvent used to deliver lorazepam and diazepam IV. Although propylene glycol toxicity is increasingly recognized and reported, its incidence is unknown. Herein, we describe five MICU patients who acquired severe propylene glycol toxicity due to IV lorazepam or diazepam administration. Additionally, we evaluate the incidence of propylene glycol toxicity in MICU patients receiving IV lorazepam or diazepam.

DESIGN

Case series and prospective, observational study.

SETTING

Eighteen-bed MICU in a 550-bed urban academic hospital.

PATIENTS AND METHODS

MICU patients administered IV benzodiazepines during a 3-month period were enrolled. Patients were categorized according to the IV benzodiazepine that they received. Laboratory data and highlights of their clinical course were recorded daily. The incidence of propylene glycol toxicity was determined and the groups compared.

RESULTS

Forty-four patients were enrolled. Twenty-one patients received a benzodiazepine delivered in propylene glycol (lorazepam or diazepam), and 23 patients received a benzodiazepine delivered in an alternative solvent (midazolam). We found that four patients (19%) who received IV lorazepam or diazepam had metabolic evidence of propylene glycol toxicity. None of the patients had clinical deterioration. Neither metabolic abnormality nor clinical deterioration suggestive of propylene glycol toxicity were identified in subjects receiving IV midazolam.

CONCLUSION

Propylene glycol toxicity is a potentially life-threatening iatrogenic complication that is common and preventable. It should be considered whenever a patient has an unexplained anion gap, unexplained metabolic acidosis, hyperosmolality, and/or clinical deterioration. Close monitoring of all patients receiving IV lorazepam or diazepam for early evidence of propylene glycol toxicity is warranted.

Adverse Events Associated with Sedatives, Analgesics, and Other Drugs That Provide Patient Comfort in the Intensive Care Unit

Since the 2002 publication of multidisciplinary clinical practice guidelines for intensive care unit (ICU) sedation and analgesia, additional information regarding adverse drug events has been reported. Our understanding of the risks associated with these sedative and analgesic agents promises to improve outcomes by helping clinicians identify and respond to therapeutic misadventures sooner. This review focuses on many issues, including the potentially fatal consequences associated with the propofol infusion syndrome, the evolving understanding of propylene glycol intoxication associated with parenteral lorazepam, new data involving high-dose and long-term dexmedetomidine therapy, haloperidol- and methadone-related prolongation of QTc intervals on the electrocardiogram, adverse events associated with atypical antipsychotics, and the potential for nonsteroidal antiinflammatory drugs to interfere with bone healing.

Sedation, analgesia, and neuromuscular blockade for high-frequency oscillatory ventilation

OBJECTIVE

To provide a comprehensive review of the issue related to the administration of sedative, analgesic, and neuromuscular blocking agents (NMBA) to patients who are receiving ventilatory support for acute respiratory distress syndrome (ARDS) with high-frequency oscillatory ventilation.

RESULTS

Sedative, analgesic, and NMBA are used with great frequency in patients with severe ARDS who are undergoing high-frequency oscillatory ventilation. In particular, the use of NMBA has been higher than for other ARDS populations. Important considerations for effective treatment include careful patient evaluation, patient-based medication selection, identification of treatment goals with periodic re-assessment, titration of medications to objective parameters such as sedation scales and peripheral nerve stimulation, use of intermittent therapy when feasible, implementation of drug interruption strategies, and discontinuation of medications at the earliest possible time. It is important to recognize that patients evolve from severe ARDS through phases of recovery to the resolution of respiratory failure and that ventilatory management, as well as sedative and related medication requirements, will vary markedly over the course of this process.

CONCLUSIONS

A multidisciplinary, structured approach that is based on the considerations described should help achieve optimal results in this challenging patient population.

Relationship of continuous infusion lorazepam to serum propylene glycol concentration in critically ill adults*

OBJECTIVES

The primary objective was to evaluate the relationship between high-dose lorazepam and serum propylene glycol concentrations. Secondary objectives were a) to document the occurrence of propylene glycol accumulation associated with continuous high-dose lorazepam infusion; b) to assess the relationship between lorazepam dose, serum propylene glycol concentrations, and propylene glycol accumulation; and c) to assess the relationship between the osmol gap and serum propylene glycol concentrations.

DESIGN

Prospective, observational study.

SETTING

Tertiary care, medical intensive care unit.

PATIENTS

Nine critically ill adults receiving high-dose lorazepam (> or =10 mg/hr) infusion.

INTERVENTIONS

Cumulative lorazepam dose (mg/kg) and the rate of infusion (mg.kg(-1).hr(-1)) were monitored from initiation of lorazepam infusion until 24 hrs after discontinuation of the high-dose lorazepam infusion. Serum osmolarity was collected at 48 hrs into the high-dose lorazepam infusion and daily thereafter. Serum propylene glycol concentrations were drawn at 48 hrs into the high-dose lorazepam infusion, and the presence of propylene glycol accumulation, as evidenced by a high anion gap (> or =15 mmol/L) metabolic acidosis with elevated osmol gap (> or =10 mOsm/L), was assessed at that time.

MEASUREMENTS AND MAIN RESULTS

The mean cumulative high-dose lorazepam received and mean high-dose lorazepam infusion rate were 8.1 mg/kg (range, 5.1-11.7) and 0.16 mg.kg(-1).hr (-1)(range, 0.11-0.22), respectively. A significant correlation between high-dose lorazepam infusion rate and serum propylene glycol concentrations was observed (r =.557, p =.021). Osmol gap was the strongest predictor of serum propylene glycol concentrations (r =.804, p =.001). Propylene glycol accumulation was observed in six of nine patients at 48 hrs. No significant correlation between duration of lorazepam infusion and serum propylene glycol concentrations was observed (p =.637).

CONCLUSION

Propylene glycol accumulation, as reflected by a hyperosmolar anion gap metabolic acidosis, was observed in critically ill adults receiving continuous high-dose lorazepam infusion for > or =48 hrs. Study findings suggest that in critically ill adults with normal renal function, serum propylene glycol concentrations may be predicted by the high-dose lorazepam infusion rate and osmol gap.