Safe PTT Values for Surgery

For safe surgery, the activated partial thromboplastin time (aPTT) should be maintained at less than 1.5 times the normal control value. 1, 2

General Guidelines for Surgical Procedures

The World Journal of Emergency Surgery consensus guidelines recommend maintaining a prothrombin time (PT)/activated partial thromboplastin time (aPTT) value of < 1.5 times normal control during interventions for life-threatening hemorrhage or emergency neurosurgery (including ICP probe insertion) 1
This recommendation has a strong agreement level of 92.5% among experts 1
Point-of-care tests such as thromboelastography (TEG) and rotational thromboelastometry (ROTEM) should be utilized when available to better assess and optimize coagulation function during surgical interventions 1, 3

For emergency neurosurgery, particularly strict adherence to aPTT < 1.5 times normal control is essential 1
In addition to aPTT control, platelet count should be maintained at > 50,000/mm³ for life-threatening systemic hemorrhage, with higher values advisable for neurosurgical procedures 1
For patients with traumatic brain injury requiring surgery, maintaining proper coagulation parameters is critical to prevent secondary brain injury from hemorrhagic complications 1

For patients on dabigatran requiring urgent invasive procedures with very high hemorrhage risk (e.g., neurosurgery):
- If dabigatran concentration is ≥ 30 ng/ml or unknown, reversal with idarucizumab is recommended 1
- If dabigatran concentration is < 30 ng/ml, the procedure can proceed 1
For patients on warfarin, PT/INR determination is recommended just prior to any dental or surgical procedure 2

Abnormally fast PTTs (< 23 seconds) have been associated with increased risk of adverse events including death, thrombosis, and bleeding 4
Studies suggest that the value of preoperative PT testing is limited in patients with a normal bleeding history, with only 0.2% of patients without clinical indications potentially benefiting from the test 5
Different commercial PT and aPTT tests show variable sensitivity in detecting dilutional coagulopathy, which can affect diagnostic and treatment decisions 6

For patients requiring massive transfusion protocol initiation, transfusion of RBCs/Plasma/PLTs at a ratio of 1/1/1 is recommended initially, with subsequent adjustments based on laboratory values 1
When transitioning from heparin to warfarin therapy, it's important to note that warfarin may increase aPTT test results even after heparin is discontinued 2
A severe elevation in aPTT (>50 seconds) with PT/INR in the desired range has been identified as an indication of increased risk of postoperative hemorrhage 2

Normal aPTT and PT values do not exclude clinically relevant levels of direct oral anticoagulants (DOACs) 1
For patients on dabigatran, a normal thrombin time (TT) excludes clinically relevant levels, while a normal aPTT usually excludes clinically relevant levels if a sensitive reagent is used 1
The relationship between increased bleeding and elevated PT/aPTT may be more complex than suggested by current practice guidelines, as test sensitivity varies significantly between laboratories 6
Age can affect normal PTT values - infants under 0.5 years typically have longer PTT times (mean 37.65 sec) compared to older children (mean 32.72 sec) 7