How long should dalteparin (Fragmin) be held prior to thoracentesis?

Dalteparin Discontinuation Before Thoracentesis

Dalteparin (Fragmin) should be discontinued at least 12 hours before thoracentesis to minimize bleeding risk. 1

Evidence-Based Recommendations

The American College of Cardiology/American Heart Association guidelines specifically address the timing of dalteparin discontinuation before invasive procedures:

• For patients undergoing CABG (which is considered a high bleeding risk procedure similar to thoracentesis), dalteparin should be discontinued 12-24 hours before the procedure 1
• This recommendation is based on evidence showing that patients receiving dalteparin within 12 hours of operation had significantly greater blood loss than those who stopped it earlier 1

Risk Stratification

The timing of discontinuation should consider:

1. Bleeding risk of thoracentesis:

   • Thoracentesis is considered a moderate-to-high bleeding risk procedure
   • Involves puncturing the pleural space with potential for bleeding complications

2. Patient's thrombotic risk:

   • For high thrombotic risk patients, the minimum discontinuation period (12 hours) may be appropriate
   • For lower thrombotic risk patients, a longer discontinuation period (24 hours) provides additional safety margin

Practical Algorithm

1. Standard recommendation: Stop dalteparin 12-24 hours before thoracentesis

   • For once-daily dosing regimens: Skip the dose on the day before procedure
   • For twice-daily dosing regimens: Skip the evening dose before and morning dose of procedure day

2. Special populations:

   • Renal impairment: Consider longer discontinuation period (24 hours) for patients with severe renal impairment (CrCl <30 mL/min) due to prolonged half-life 1
   • Elderly patients: Use caution and consider the longer discontinuation period 1

3. Post-procedure resumption:

   • Dalteparin can typically be resumed 24 hours after thoracentesis if hemostasis is adequate
   • For patients at high risk of thrombosis, consider prophylactic dosing (rather than therapeutic) for the first 24 hours post-procedure 1

Common Pitfalls

• Inadequate discontinuation time: Failing to stop dalteparin at least 12 hours before thoracentesis increases bleeding risk
• Not accounting for renal function: Dalteparin clearance may be reduced in patients with renal impairment, potentially requiring longer discontinuation periods
• Forgetting to adjust timing based on dosing schedule: The timing should account for whether the patient is on once-daily or twice-daily dosing regimen

Conclusion

The evidence clearly supports discontinuing dalteparin at least 12 hours before thoracentesis, with consideration for extending this to 24 hours in patients with higher bleeding risk or renal impairment. This approach balances the need to minimize bleeding complications while not excessively increasing thrombotic risk.