The importance of early detection of vascular compromise in the presence of an extremity injury cannot be understated. A prolonged tissue perfusion deficit can lead to irreversible ischemia, myonecrosis, fibrosis, severe functional loss, and nonviability of the involved extremity (Figure 9.5
). Furthermore, the metabolic results (myoglobinuria and metabolic acidosis) of prolonged ischemia can be life threatening
(renal failure). For these reasons, any vascular abnormality in the setting of extremity trauma should be considered an emergency and dealt with promptly and with the appropriate support of vascular surgeons or those trained in microvascular techniques when needed. One must also be aware of those fractures in children that are commonly associated with vascular disruption, occlusion, or spasm and be vigilant for any vascular differences on examination. Such fractures include displaced extension supracondylar humerus fractures (brachial artery injury) (Figure 9.7
), fractures through the distal femur and proximal tibia (popliteal artery injury), and knee dislocations (popliteal artery injury) (Figure 9.8
Examination begins with inspection of the extremity for pallor and temperature. In the presence of arterial insufficiency, the skin is often cool, pale, and occasionally has a bluish hue or patchy areas of purple overlying otherwise white pale skin (mottling). In the setting of vascular congestion due to disruption of venous outflow, the extremity may appear swollen and dark purple in color, which may improve somewhat with elevation. In the setting of penetrating trauma, the presence of an expanding or pulsatile hematoma should raise concern about an active arterial bleed.
Capillary refill time (CRT) is easily assessed by manually compressing a distal phalanx to effectively exsanguinate the tip of the digit than observing for the duration of time before the end of the digit becomes pink and reperfused ( Video 9.2
). This is oftentimes best observed through the nail plate. CRT of 2 seconds or less is commonly considered normal, although results should always be compared with the uninvolved extremity to identify differences.
The presence and quality of distal pulses must be documented and compared with the uninjured extremity. In the upper extremity, the radial pulse is usually easiest to assess. In the lower extremity, the posterior tibial artery (posterior to the medial malleolus) and the dorsalis pedis pulse (dorsum of the foot
in the region of the medial midfoot) should be examined. A palpable pulse that is diminished in comparison with the contralateral extremity can be indicative of vascular compromise and merits concern. In the absence of a palpable pulse or in the setting of a barely palpable pulse, Doppler examination of the pulses is useful ( Video 9.3A
). Dopplerable pulses are described as monophasic, biphasic, or triphasic (Table 9.6
). Triphasic flow is normal ( Video 9.4
), while a monophasic flow often represents partial occlusion of flow or even complete arterial occlusion with the signal resulting from retrograde flow.
FIGURE 9.7 Clinical (A) and radiographic (B) presentation of an open supracondylar humerus fracture with brachial artery laceration. C, Arterial bypass grafting using saphenous vein (white arrows) was performed once the supracondylar humerus fracture was reduced. (Courtesy: Kevin Little, MD.)
FIGURE 9.8 The popliteal artery is in close relationship to the posterior aspect of distal femur and proximal tibia. Displaced fractures of distal femur or proximal tibia can cause popliteal artery injury.
In the setting of a side-to-side difference in the peripheral pulse examination, a more objective assessment can be obtained by determining the ankle brachial index (ABI) or arterial pressure index (API) (Figure 9.9
). The ABI is obtained using a blood pressure cuff and stethoscope or Doppler to record the systolic pulse at the ankle and brachial artery ( Video 9.5
). A patient’s ABI is calculated by dividing the systolic blood pressure at the ankle by the pressure obtained at the arm. An ABI of less than 0.9 is considered abnormal and is commonly used as the threshold to perform more advanced diagnostics to assess for a vascular injury. The API is calculated by comparing the systolic pressure in the injured extremity with the systolic pressure in the contralateral uninjured extremity. As with the ABI, an API less than 0.9 should raise concern for a vascular insult and consideration of more advanced vascular assessment.
Table 9.6 Arterial Waveforms on Peripheral Pulse Doppler Examination
Forward flow (systole); reverse flow (early diastole); forward flow (late diastole)
Forward flow (systole); reverse flow (diastole)
Single phase with muted/absent acceleration or deceleration of flow
FIGURE 9.9 Determination the ankle brachial index (ABI).