William L. Fan
Clinically Appraised Topic
July 20, 2001
Pulmonary
Embolism in Patients with Upper Extremity DVT Associated to Venous Central
Lines
A patient on the Hem/Onc service has a PICC line and a documented upper extremity DVT.
Is the risk of having a pulmonary embolus negligible in this patient?
“Pulmonary Embolism in Patients with Upper Extremity DVT Associated to Venous Central Lines- A Prospective Study.” Monreal M. et al. Thrombosis and Hemostasis. 1994, 548-50.
This is a prospective cohort study of 86 consecutive patients with central venous catheters that developed upper extremity DVT in a referral hospital in Barcelona Spain. Patients were all treated with IV heparin and all underwent a V/Q scan within 48 hours of diagnosis.
I. Are the results valid?
1. Was a defined, representative sample of patients assembled at a similar point in the course of the disease?
For a small study, it does contain a fair representative sample. There were 49 males and 37 females; aged 25-82, mean age 55y. Most common underlying diseases were malignancy in 27 patients, AMI 13; AIDS 7, pneumonia 6; acute pancreatitis 5; CHF 5. Various catheters were used (61 were PICC lines.). These patients were all from one referral based hospital.
The inclusion criteria included patients with indwelling catheters that had radiographic evidence of upper extremity DVT. No exclusion criteria were published.
It is unclear how long the DVT was present with each patient.
2. Was a follow-up sufficiently long and complete?
V/Q scans were done on 85 patients (1 patients was too unstable for the study). The scan was done within 48 hours of diagnosis of DVT regardless of symptoms. 6 patients with intermediate prob scans were excluded and 1 patient with documented LE DVT was also excluded.
3. Were objective and unbiased outcome criteria used?
High prob V/Q scans were used to define evidence of PE. The scans were interpreted by two physicians who had no knowledge of the clinical history. In order to reduce observer bias, and additional series of 20 normal lung scans were included in the sample.
II. What are the results?
1. How large is the likelihood of the outcome event in a specified period of time?
The diagnosis of PE was made during a 48 hour window. 13/79 (16.5%) had a high prob scan. Remember, this does not even include the patients with intermediate prob scans. 66/79 (83.5%) had low or neg scans.
2. How precise are the estimates of likelihood?
There was no range of results. No Confidence intervals were calculated.
III Will the results help me in caring for my patients?
25 out of 79 patients had a malignancy. 61 out of 86 catheters were PICC lines.
The paper does not address mortality, but it does demonstrate that a catheter related DVT may pose a higher risk of PE. We must consider that the V/Q scan was use as the “gold standard”. The study did not routinely r/o LE DVT in each patient.