The success rate of arterial revascularization is inversely proportional to the duration of the ischemic time. According to the histological studies of Malan [26], the critical warm ischemic time for striated muscle is 6–8 h. Blood flow must be reestablished within this time to avoid irreversible muscle and nerve damage. The presence of soft tissue loss, disruption of arterial and venous collateral vessels, or hypotension may further decrease the length of this critical period. After vascular shunts have been inserted, potentially life-­threatening injuries to the head, chest, or abdomen can be diagnosed and treated in a more orderly fashion. Similarly, use of these vascular shunts can prevent the need for the amputation of potentially salvageable extremities because of the prolonged ischemic time during other operative procedures. Therefore, the amount of time the intravascular shunt can maintain patency is of importance to the trauma surgeon.

The reported shunt times in the literature ranged from a couple of minutes to as long as several days. The longest shunt time of up to 10 days occurred in a civilian case (David V. Feliciano, Atlanta, GA, 2009 personal communication). But the longest dwell time recorded in the literature was reported by Granchi [25], who demonstrated that shunts could be left in place and maintained distal perfusion for up to 52 h without systemic anticoagulation in complex extremity injuries. Although Rozycki et al. [24] reported a dwell time of 54 h for a Pruitt-Inahara shunt left in the brachial artery, this shunt was occluded at reoperation, resulting amputation in the end. Intravascular shunts have been used to maintain the vascular patency of the extremities, with times ranging from 12 to 17 h in three patients undergoing air transfer to a level I trauma center for definitive care [27]. No evidence of shunt thrombosis or distal emboli was observed. However, Rasmussen et al. [19] argued that in war time maintaining the shunt patency for 2 h is sufficient because of fast evacuation patterns and relatively fewer shunt-related complications.

Experimentally, Ding compared four different shunt indwelling times in previously established superior mesenteric artery (SMA) injury models [28] and aimed to determine the safest duration in the setting of DCS. Their study suggested that TIVS can be used as an important DCS adjunct to maintain patency safely for 6 h (Fig 18.1); however, prolonged duration of an indwelling vascular shunt (over 9 h) caused endothelial injury in such SMA injuries in the setting of DCS [29]. Their recent study [30] showed that prolonged indwelling time of temporary vascular shunts is associated with increased endothelial injury, and, when possible, ­vascular reconstruction following the use of shunts should include an interposition graft after debridement of the arterial edges that interfaced with the shunt. Finally, to minimize intimal injury to the native vessel, this model suggests that the indwell times of shunts should be <9 h.

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