For the reconstructive surgeon the use of grafts and flaps has become an important tool in the ever-growing resources available for patient treatment. Proper planning and surgical judgment are critical to the ultimate success of these procedures as well as an improved quality of life for the graft/flap patient.

Situations can arise, however, when grafts and/or flaps become compromised and require urgent intervention for salvage. These instances can include irradiated or otherwise hypoxic wound beds, excessively large harvested grafts, random flap ischemia, venous or arterial insufficiency, and ischemia-reperfusion injury.

Compromised grafts and flaps

can be inadvertently created secondary to trauma as well. It is in all these types of cases that hyperbaric oxygen (HBO2) treatment can serve as a useful adjunct to help salvage compromised flaps and grafts.

 
The most effective solution includes planning, prevention and judgment.

And sometimes it calls for

hyperbaric medicine.

Grafts
First, the graft surgeon must check the fit. For example, a compromised graft can be avoided by ensuring an appropriate recipient bed for a given graft size. Issues can arise, however. Large composite grafts are often required after traumatic avulsions of the soft tissues of the nose, ear and fingertips. Poor surgical planning/judgment can affect the quality of the procedure. For example, a questionable recipient bed may go unrecognized; or the size of the harvested graft may be too large to be sustained by the recipient bed. Whatever the cause, these grafts can become compromised.

Grafts are avascular tissues that rely on the recipient bed for revascularization and ultimate survival. When grafts fail they become hypoxic, but these tissues can be salvaged with prompt treatment using hyperbaric medicine. Hyperbaric oxygen can help maximize the viability of the compromised graft while revascularization takes place, reducing the need for repeat grafting procedures that require further surgeries and increase donor site morbidity.

Flaps
Flaps differ markedly from grafts. While flaps are frequently grouped together with skin grafts and composite grafts, these two sets of disorders are physiologically distinct. All flaps have an inherent blood supply, while graft tissue must integrate into the wound bed for vascularization. When the remaining tissue cannot support a graft a surgical flap is used to treat a wound. Flaps are also used to rebuild more complex anatomic structures such as the breast or jaw.

Despite meticulous harvest and inset, many etiologies can cause flap compromise, ranging from random ischemia, to venous congestion/occlusion, to arterial occlusion harvest and inset. Similarly, traumatic accidents can result in significant avulsion of soft tissues, extensive degloving injuries, and open fractures with poorly perfused skin flaps.

In addition, free tissue transfers – flaps in which the arterial and venous blood supply is divided and reattached to another location by microsurgical anastomosis – can have their own special problems. Free flaps can be exposed to both ischemia-reperfusion injury and secondary ischemic insults, which can compromise the viability of the flap.

In many cases surgical re-exploration will identify and treat the etiology of flap compromise. In other instances there is no correctable mechanical cause of decreased flap perfusion. Moreover, in skin flaps created by trauma the compromised perfusion is typically the result of crush injury or the development of exceptionally large random flaps that do not follow the classic 3:1 length-to-width ratio. Both conditions result in poor perfusion to the distal flap.

Hyperbaric medicine can help

Hyperbaric medicine can play an important role in both flap and graft salvage. The key to successful salvage is the prompt application of

hyperbaric oxygen treatment,

which can help maximize tissue viability while perfusion is restored. As with its use in compromised grafts, hyperbaric oxygen can reduce the need for repeat flap procedures, thus decreasing overall patient morbidity.

Evidence-based review
With the current emphasis on evidence-based medicine and practice, the clinical data available in the literature plays a tremendous role in the decision to recommend or institute a treatment. The levels of evidence according to the Oxford Oxford Centre for Evidence-Based Medicine are outlined in Figure 1. A review of the literature examining the clinical evidence available for the use of hyperbaric oxygen treatment for compromised flaps and/or grafts reveals no less than 23 studies involving more than 2,200 different flaps or grafts, with the available clinical evidence ranging from level 1 to level 4 type studies.

An evidence-based review of the benefits of HBO2 treatment for compromised grafts and flaps encompasses a variety of experimental trials. These studies can be classified into animal studies and clinical studies. A more in-depth review of the current literature, including a breakdown of the various trials and studies, is in the full version of this paper.

Clinical management
The hyperbaric oxygen treatments are given at a pressure of 2.0-2.5 atmospheres absolute (ATA) and range from 90 to 120 minutes, depending on the type of HBO2 therapy facility available, patient status, and other factors. Mechanical causes of flap compromise that can be treated surgically should be addressed prior to initiation of hyperbaric treatment.

Currently, there is no consensus as to the optimal HBO2 treatment regimen for compromised flaps and grafts. One study cited in the original paper (Weber et al. [86]) used the rat random flap model to compare the efficacy of daily to twice-daily (BID) HBO2 treatment. Results of this study suggest no additional benefit when performing BID hyperbaric treatment. If the compromised graft or flap fails, daily hyperbaric treatments may be continued to prepare the compromised wound bed for a salvage graft or flap reconstruction.

To be maximally effective HBO2 treatment should be started as soon as signs of flap or graft compromise appear. Flap viability can be assessed by clinical judgment as well as by a variety of non-invasive and invasive techniques, including transcutaneous oximetry and laser Doppler studies. The diagnosis of graft/flap compromise and evaluation of the subsequent response to HBO2 treatment should be a multidisciplinary effort between the hyperbaric physician and plastic surgeon. Objective measures should be used to assess and monitor the compromised flap or graft whenever possible.

Utilization review
Utilization review is required after 20 treatments when preparing a recipient site (such as a radiated tissue bed) for a flap or graft, although the indication for HBO2 may be better classified by the underlying cause of wound healing compromise – i.e., soft tissue radionecrosis, osteoradionecrosis, chronic osteomyelitis, diabetic foot ulcer – unless treatments are continued immediately following compromised graft or flap failure. Utilization review should also be employed following 20 treatments after a flap or graft has been placed into its recipient site.

It can be noted that a variety of types of grafts and flaps has been investigated in animal and human studies. Results of the preponderance of work in the literature clearly show the efficacy of hyperbaric medicine in the enhancement of skin graft and flap survival. Of importance is that different types of flaps have been analyzed in these studies, including free skin grafts, pedicle flaps, random flaps, irradiated wounds and flaps, composite grafts, as well as free flaps. Although each flap problem is unique, a key factor to flap necrosis is tissue hypoxia. The results indicate that viability of flaps can be enhanced by HBO2 treatment through a reduction of the hypoxic insult. Other mechanisms of action whereby HBO2 enhances flap survival include the enhancement of fibroblasts and collagen synthesis, creation of neovascularity, the possibility of closing off arteriovenous shunts, and favorable effects on microcirculation.

Cost impact
Failed flaps are extremely expensive and result in significant morbidity and distress for both the patient and the surgeon. Adjunctive hyperbaric can reduce these financial, physical, and mental costs by salvaging skin grafts, pedicle flaps, random flaps, composite grafts, as well as free flaps and thus eliminating or minimizing the need for secondary surgeries and alternate donor sites.

Taken from:
Kleban S, Baynosa RC. The effect of hyperbaric oxygen on compromised grafts and flaps. In: Moon RE, ed. Hyperbaric Oxygen Therapy Indications, 14th ed. Undersea and Hyperbaric Medical Society, 2019: 117-134.

Kleban S, Baynosa RC. The effect of hyperbaric oxygen on compromised grafts and flaps. Undersea Hyperb Med. Fourth-Quarter 2020;47(4):635-648.