Background:

Pulmonary embolus (PE) secondary to deep vein thrombosis (DVT) continues to be a major source of morbidity and mortality in trauma populations. Patients with cervical spinal cord injury (SCI) are particularly susceptible to developing this complication. Non-invasive methods of preventing SCI, such as lower extremity compression devices and anticoagulation, do not confer complete protection against DVT. Retrievable inferior vena cava filters (IVCFs) offer the advantage of both providing protection against PE and avoidance of long-term complications such as DVT, if removed in a timely fashion. Our goals in this study were to identify complications related to IVCF insertion and also to determine if prophylactic insertion of IVCF is effective in preventing PE in spinal cord injured patients.

Methods:

This was a retrospective single center study that involved cervical SCI patients who were admitted to Parkview Hospital, a level II trauma center, from January 2003 to December 2009 and underwent placement of a prophylactic IVCF within 72 hours of admission. Patients were identified from a prospectively maintained trauma registry.

Results:

During a 6-year period, 45 spinal cord injured patients were identified, who underwent placement of a prophylactic IVCF. There were 37 men and 8 women. There were no short-term complications associated with peripheral intravenous catheter (PIVC) insertion. Seventeen of the 45 (37%) patients underwent successful removal of the filter within 6–8 weeks of insertion. Twenty patients did not return for removal during the 6–8 week period for removal and eight patients were lost to follow-up. None of the patients who underwent prophylactic IVCF placement sustained a PE.

Conclusion:

Our results suggest that the use of retrievable prophylactic IVCF is a safe procedure and has the added benefit of preventing the long-term lower extremity thrombotic complications associated with their use. Even though none of the patients sustained a PE, definitive conclusions regarding the efficacy of IVCF in preventing PE could not be made due to the small sample size of our study.

Background

Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age.

Methods

An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma.

Results

The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test).

Conclusion

An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging.

Background

Fractionated plasma metanephrine measurements are commonly used in biochemical testing in search of pheochromocytoma.

Methods

We aimed to critically appraise the diagnostic efficacy of fractionated plasma free metanephrine measurements in detecting pheochromocytoma. Nine electronic databases, meeting abstracts, and the Science Citation Index were searched and supplemented with previously unpublished data. Methodologic and reporting quality was independently assessed by two endocrinologists using a checklist developed by the Standards for Reporting of Diagnostic Studies Accuracy Group and data were independently abstracted.

Results

Limitations in methodologic quality were noted in all studies. In all subjects (including those with genetic predisposition): the sensitivities for detection of pheochromocytoma were 96%–100% (95% CI ranged from 82% to 100%), whereas the specificities were 85%–100% (95% CI ranged from 78% to 100%). Statistical heterogeneity was noted upon pooling positive likelihood ratios when those with predisposition to disease were included (p < 0.001). However, upon pooling the positive or negative likelihood ratios for patients with sporadic pheochromocytoma (n = 191) or those at risk for sporadic pheochromocytoma (n = 718), no statistical heterogeneity was noted (p = 0.4). For sporadic subjects, the pooled positive likelihood ratio was 5.77 (95% CI = 4.90, 6.81) and the pooled negative likelihood ratio was 0.02 (95% CI = 0.01, 0.07).

Conclusion

Negative plasma fractionated free metanephrine measurements are effective in ruling out pheochromocytoma. However, a positive test result only moderately increases suspicion of disease, particularly when screening for sporadic pheochromocytoma.