Title:
THE NEED FOR MORE DETAILED CHARACTERIZATION OF THROMBUS IN THE PULMONARY ARTERIAL
SYSTEM
Authors:
T. Shane Hester, DO - University of Florida College of Medicine - Jacksonville
James Dennis, MD - University of Florida College of Medicine - Jacksonville
Jon Allmon, MD - University of Florida College of Medicine - Jacksonville
Joseph Habib, MD - University of Florida College of Medicine - Jacksonville
Background:
Venous thromboembolic (VTE) events are a major contributor to the morbidity and mortality of severely injured
trauma patients.1,2 Over the past two decades, significant research has been done to identify the appropriate
methods of deep venous thrombosis (DVT) prophylaxis and specific high-risk groups especially vulnerable for DVT
and pulmonary embolism (PE).1,2,3 Current guidelines recommend routine low-molecular weight heparin for VTE
prophylaxis in the trauma population, but in many cases, chemical prophylaxis cannot be administered or can only
be given intermittently between procedures; which continues to expose trauma patients to a high risk of VTE
following their injury.4,5,6 Trauma patients may also have other contributing factors to pulmonary arterial
thrombosis such as the injury itself or other factors resulting from prolonged lengths of stay in the ICU.7,8,9,10 The
use of prophylactic inferior vena cava (IVC) filter placement in patients with high risk injuries and/or inability to use
VTE prophylaxis has been one measure utilized in these selected high-risk trauma patients, but its routine use has
been controversial.11,12,13,14,15
Over the study time period, there has also been significant improvement in the quality of radiographic imaging,
which has significantly improved the ability to identify smaller pulmonary emboli. 4 The recognition of VTE as a
significant contributor to the morbidity and mortality of trauma patients by physicians during this time has also led
to an increase in the number of CT scans utilized to evaluate trauma patients for pulmonary embolism. 2 In
addition, quality assurance measures by the medical center continuously monitor the incidence of VTE, which also
increases overall awareness. All of these factors may have contributed to an increase in the identification of
pulmonary emboli, thus distorting the data collected and the effectiveness of standard prophylaxis and IVC
filters.16
In effort to better characterize the incidence, etiology, and distribution of VTE in multi-system trauma patients, the
medical record of trauma patients in the last 15 years were reviewed to determine the use of VTE prophylaxis,
presence of previously identified high-risk criteria, timing and location of the PE, and other factors that may have
increased the patient’s risk for PE. Improved characterization of VTE events should lead to more specific directed
treatment and prophylactic measures.
Methods:
T. Shane Hester, DO
University of Florida – College of Medicine - Jacksonville
653 West 8th Street, Box FC12 Jacksonville, FL 32209
timothy.hester@jax.ufl.edu PH: 904/244-3903 FX: 904/244-3020
The trauma registry at a level I trauma center was utilized to collect data retrospectively on all trauma patients
from January 1999 to June 2013 who were diagnosed with a pulmonary embolism during the initial hospitalization.
Multiple data points were collected including age, sex, injuries, operations, type of DVT prophylaxis used, date of
IVC filter placement, specific CT findings of pulmonary embolism, septic episodes and amount of blood products
administered. During this time a protocol for placement of a prophylactic IVC filter placement was in place which
included patients with spinal cord injuries resulting in loss of function, complex pelvic fractures with associated
long bone fracture, multiple long bone fractures with inability to maintain consistent anticoagulation, brain injury
with contraindication to anticoagulation greater than 48 hours, major venous injury, and major eye injury with
multi-system trauma. Data was analyzed and patients were grouped into 4 groups. Group 1 was composed of
patients with classic PE where the institutional protocol for prophylactic IVC filters in specific high risk patients was
not followed. Group 2 was classified as pulmonary thrombosis resulting directly from the injury. These patients
were diagnosed with a “pulmonary embolism” by a radiologist within 48 hours of admission, had no evidence of
DVT and the thrombosis corresponded with rib fractures and/or pulmonary contusions. Group 3 was composed of
patients with classic PE with no high risk injuries and as per the protocol did not meet criteria for prophylactic IVC
filter placement. Group 4 was defined as pulmonary thrombosis not as a result of the initial direct trauma. All of
these patients had no defined high risk injuries, no evidence of DVT and the CT revealed thrombosis of small,
segmental vessels. These patients also had prolonged length of stay in the ICU and had a septic episode prior to
the diagnosis of PE.
Results:
During the time of January 1999 to June 2013 there were 77 patients with a diagnosis of “pulmonary embolism”.
Twelve patients had incomplete data or previous underlying diseases that affected their VTE risk. A total of 65
patients were analyzed and placed into the four categories. Twenty-nine (45%) of patients were categorized into
group 1, which represented cases where the protocol for prophylactic IVC filter placement was not followed.
Trend analysis indicated that over the 14 year study period, the protocol became more established in this
institution and the incidence of patients in this category has significantly decreased. Eleven patients (17%) were in
group 2, which represents direct pulmonary thrombosis from injury. All of these patients were diagnosed with a
pulmonary embolism within 48 hours of admission, had no evidence of DVT and the thrombosis correlated with
chest trauma. Nineteen patients (29%) were in group 3 who had no high risk injuries which would have initiated
an evaluation for prophylactic IVC filter placement yet failed routine VTE prophylaxis. A majority of these patients
had prolonged immobilization as well as other risk factors including advanced age and obesity. Six patient (9%)
were assigned to group 4, which appears to represent primary pulmonary thrombosis. None of these patients had
any defined high risk injuries or evidence of DVT. All had thrombosis of segmental vessels and all had a septic
episode prior to the diagnosis of pulmonary embolism.
Conclusion:
VTE remains a significant contributor to the morbidity and mortality of the trauma patient. The increased
awareness of VTE along with the increasing quality of CT imaging performed have led to an increase in the
diagnosis of PE, however, it is likely that the overall number of pulmonary embolisms has remained constant over
this time. Close analysis indicates approximately one fourth of radiographic diagnosed “pulmonary emboli” can
actually be classified as pulmonary thrombosis and not emboli. These VTE events are likely in situ pulmonary
arterial thrombosis secondary to the patient’s injury itself or a result of sepsis-induced hypercoagulability. Careful
consideration must be used in these two groups of patients before initiating systemic anti-coagulation or IVC filter
placement.
T. Shane Hester, DO
University of Florida – College of Medicine - Jacksonville
653 West 8th Street, Box FC12 Jacksonville, FL 32209
timothy.hester@jax.ufl.edu PH: 904/244-3903 FX: 904/244-3020
References:
1. Dennis JW, Menawat S, Von Thron J, Fallon Jr WF, Vinsant GO, Laneve LM, Jagger C, Frykberg
ER. Efficacy of deep venous thrombosis prophylaxis in trauma patients and idenification of
high-risk groups. Journal of Trauma 1993;35:132-9.
2. Netto FS, Tien H, Ng J, Ortega S, Scarpelini S, Rizoli SB, Geerts W. Pulmonary emboli after
blunt trauma: Timing, clinical characteristics and natural history. Injury 2012;43:1502-6.
3. Sekharan J, Dennis JW, Miranda FE, Hertz JA, Veldenz HC, Dovgan PS, Frykberg ER. Longterm follow-up of prophylactic greenfield filters in multisystem trauma patients. Journal of
Trauma 2001;51(6):1087-91.
4. Knudson MM, Gomez D, Haas B, Cohen MJ, Nathens AB. Three thousand seven hundred thirtyeight posttraumatic pulmonary emboli: A new look at an old disease. Ann Surg 2011;254:62532.
5. Knudson MMM, Morabito DR, MPH, Paiement GDM, Shackleford SR. Use of low molecular
weight heparin in preventing thromboembolism in trauma patients. Journal of Trauma-Injury
Infection & Critical Care 1996;41(3):446-59.
6. Malinoski D, Ewing T, Patel MS, Jafari F, Sloane B, Nguyen B, Barrios C, Kong A, Cinat M,
Dolich M, et al. Risk factors for venous thromboembolism in critically ill trauma patients who
cannot receive chemical prophylaxis. Injury 2013;44(1):80-5.
7. Geerts WH, Jay RM, Code KI, Chen E, Szalai JP, Saibil EA, Hamilton PA. A comparison of lowdose heparin with low-molecular-weight heparin as prophylaxis against venous
thromboembolism after major trauma. N Engl J Med 1996;335:701-7.
8. Shackford SR, Dennis JW, Hollingsworth-Fridlund P, Brewer NS, Hoyt DB, Mackersie RC.
Venousthromboembolism in patients with major trauma. The American Journal of Surgery
1990;159:365-9.
9. Velmahos G, Nigro J, Tatevossian R, Murray JA, Cornwell EEI, Belzberg H, Asensio JA, Berne
TV, Demetriades D. Inability of an aggressive policy of thromboprophylaxis to prevent deep
vein thrombosis in critically injured patients: Are current methods of DVT prophylaxis
insufficient? Journal of the American College of Surgeons 1998;187(5):529-33.
10. Van Gent JD, Zander ALD, Olson EJM, Shackford SRM, Dunne CEM, Sise CBM, Badiee JM,
Schechter MSM, Sise MJM. Pulmonary embolism without deep venous thrombosis: De novo or
missed deep venous thrombosis? 2014;76(5):1270-4.
11. Kidane B, Madani AM, Vogt K, Girotti M, Malthaner RA, Parry NG.
The use of prophylactic inferior vena cava filters in trauma patients: A systematic review
Injury 2012;43:542-7.
12. McMurtry AL, Owings JT, Anderson JT, Battistella FD, Gosselin R. Increased use of prophylactic
vena cava filters in trauma patients failed to decrease overall incidence of pulmonary
embolism. Journal of the American College of Surgeons 1999;189(3):314-20.
13. Khansarinia S, Dennis JW, Veldenz HC, Butcher JL, Hartland L. Prophylactic greenfield filter
placement in selected high-risk trauma patients. Journal of Vascular Surgery 1995;22(3):2316
14. Rogers FB, Cipolle MD, Velmahos G, Rozycki G, Luchette FA. Venous thromboembolism: Role
of vena cava filter in the prophylaxis and treatment of PE. Journal of Trauma 2002;53(1):14264.
15. Velmahos G, Kern J, Chan LS, Oder D, Murray JA, Shekelle P. Prevention of venous
thromboembolism after injury: An evidence-based report - part I: Analysis of risk factors and
evaluation of the role of vena caval filters. Journal of Trauma 2000;49:132-9.
16. Menaker J, Stein D, Scalea T. Pulmonary embolism after injury: More common than we think?
J Trauma 2009;67(6):1244-9.
T. Shane Hester, DO
University of Florida – College of Medicine - Jacksonville
653 West 8th Street, Box FC12 Jacksonville, FL 32209
timothy.hester@jax.ufl.edu PH: 904/244-3903 FX: 904/244-3020