A Study Comparing Factor Level and Inhibitor Titer Testing

Results Drawn from Central Venous lines and Venipuncture

Judy Kauffman, RN, CPNP

Andrew Wilson, RN, CPHON

Kansas City Regional Hemophilia Center

The Problem

• Many opinions about whether accurate factor levels/ inhibitor titers can be obtained from CVLs

• Children with poor venous access hospitalized after venipuncture?

• The big issue: parents not willing to participate in research due to requirement for peripheral lab draws

Literature Review

• Multiple studies comparing CVL vs. venipuncture for drug levels (MTX, abx)– Most show that technique used to draw the

CVL specimen determines accuracy

Comparison of Coagulation Testing

• McLaren, et al (2000) & Humphries and Baldwin (2009) showed that PT, aPTT, fibrinogen can be accurately drawn from CVL

• Hinds, et al (2002) concluded that PT, aPTT drawn from CVL were not accurate

• Lindley, et al (1994) compared FVII levels drawn from CVL with venipuncture and said that they could be compared

• Manco-Johnson, et all (2000) provided the protocol for the study– Method determines results– CVL should be flushed w/ 10 ccs NS, then

10ccs of blood wasted before specimen is drawn

– All CVL specimens should be treated with heparinase

– With this method inhibitor titers drawn from CVLs are accurate

Maximum Blood Draw Volumes for Pediatric Patients

• Policy is 2.5% total blood volume, can be increased with MD approval.

Adapted from Children’s Hospital and Regional Medical Center Lab, Seattle, WA. 2001.

Body Wt. Kg Body Wt. lbs Max Volume (ml)

1 2.2 2.5

5 11 10

10 22 20

21-25 45-55 42-50

Preliminary Results

Subject Veni Fac Veni Inh CVL Fac CVL Inh

#1 FVIII 1% 0.09 BU FVIII 1% 0 BU

#2 FVIII <1% FVIII <1%

#3 FVIII 1% 0 BU FVIII 1% 0 BU

#4 FVIII 7% 0BU FVIII 7% 0 BU

#5 FVIII <1% 47.2 BU FVIII <1% 47 BU

#6 FVIII 62% 0 BU FVIII 48% 0 BU

#7 FIX 7% 0 BU FIX 5% 0 BU

Outlier

• Peripheral Draw– 1:10= 48%– 1:20= 62%– Low 1:10= 59%

• CVL Draw– 1:10= 47%– 1:20= 48%– Low 1:10= 54%

Subject Veni Fac Veni Inh CVL Fac CVL Inh

#6 FVIII 62% 0 BU FVIII 48% 0 BU

Goal of Study

• To show whether factor levels and inhibitor titers can be accurately drawn from CVLs

• Will need to expand this pilot study to enroll enough subjects to achieve significance

• Might be a good multi-center study?