Comparison of arterial and venous whole blood clot initiation, formation, and strength by thromboelastography in anesthetized swine

Prediction of persistent ventricular dilation by initial ventriculomegaly and clot volume in a porcine model

OBJECTIVE

While intraventricular hemorrhage (IVH) is associated with posthemorrhagic ventricular dilation (PHVD), not all infants affected by high-grade IVH develop PHVD. The authors aimed to determine clot-associated predictors of PHVD in a porcine model by varying the amount and rate of direct intraventricular injection of whole autologous blood.

METHODS

Seven 1-week-old piglets underwent craniectomy and injection of autologous blood into the right lateral ventricle. They survived for a maximum of 28 days. MRI was performed prior to injection, immediately postoperatively, and every 7 days thereafter. T1-weighted, T2-weighted, and susceptibility-weighted imaging (SWI) sequences were used to segment ventricular and clot volumes. Spearman correlations were used to determine the relationship between blood and clot volumes and ventricular volumes over time.

RESULTS

The maximum ventricular volume was up to 12 times that of baseline. One animal developed acute hydrocephalus on day 4. All other animals survived until planned endpoints. The interaction between volume of blood injected and duration of injection was significantly associated with clot volume on the postoperative scan (p = 0.003) but not the amount of blood injected alone (p = 0.38). Initial postoperative and day 7 clot volumes, but not volume of blood injected, were correlated with maximum (p = 0.007 and 0.014) and terminal (p = 0.014 and 0.036) ventricular volumes. Initial postoperative ventricular volume was correlated with maximum and terminal ventricular volume (p = 0.007 and p = 0.014).

CONCLUSIONS

Initial postoperative, maximum, and terminal ventricular dilations were associated with the amount of clot formed, rather than the amount of blood injected. This supports the hypothesis that PHVD is determined by clot burden rather than the presence of blood products and allows further testing of early clot lysis to minimize PHVD risk.

Comparison of Coagulation Parameters in Arterial and Venous Blood in Cardiac Surgery Measured Using the Quantra System

Objective:

Perioperative coagulation testing often is performed with arterial samples even though device reference ranges typically are established in venous samples. Although limited studies exist comparing coagulation parameters across sampling sites, viscoelastic testing devices have demonstrated some differences. The objective of this study was to compare coagulation parameters determined using the Quantra System for venous and arterial samples.

Design:

Prospective, observational study.

Setting:

Tertiary care university hospital.

Participants:

The study comprised 30 adult patients undergoing cardiac surgery.

Interventions:

Paired arterial and venous samples were obtained at 2 of the following time points: baseline, during bypass, or after protamine reversal of heparin. Quantra measurements included Clot Time (CT), Heparinase Clot Time (CTH), Clot Time Ratio (CTR), Clot Stiffness (CS), and Fibrinogen (FCS) and Platelet (PCS) Contributions to clot stiffness.

Measurements and Main Results:

The relationship and agreement between matched data pairs were established and statistical analysis was performed via paired t tests. CTR, CS, FCS, and PCS were unaffected by the sampling site, whereas CT and CTH demonstrated statistically significant differences between arterial and venous samples (p < 0.001). Arterial clot times were prolonged relative to the venous ones with a mean percent error of 14.2 % and 11.9 %, respectively. These results are in general agreement with those reported for other viscoelastic testing devices.

Conclusions:

This study demonstrates that Quantra clot stiffness-based parameters (CS, FCS, PCS) are unaffected by sampling site, whereas the clot time parameters (CT and CTH) show good correlation in the presence of a bias. CTR, a ratio of CT and CTH, also is unaffected.