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Reconstructive Options Following Flap Failure


Introduction

A failed free flap is a challenge for every microsurgeon no matter how experienced. When a flap is lost, the patient and family are disappointed, and disturbed over the need for additional surgery. The clinical support staff share a sense of responsibility and discouragement. The surgeon must make difficult clinical decisions. There are often several reconstructive surgical options, the array seems confusing – simpler methods (skin graft) seem “second-choice” (though there is a great desire and hurry to get the patient healed and discharged), while more complex options (another free flap) seem daunting and fraught with a second loss. Although the rates of failure are low, every microvascular case can potentially succumb to the “perfect storm.” An array of reasons for failure exist, and vary depending upon anatomic region and types of reconstruction – and have been elucidated in this book as well elsewhere. To be fully prepared with an alternative “plan B” – a well-defined post-failure strategy is essential for every microsurgeon and for every case. It is a sure-footed approach, which greatly reduces the stress of decision-making. It has a redeeming, confidence-boosting effect for both the patient and the surgeon. For a patient who has undergone flap failure, partial or complete, either immediately after surgery or following what might have appeared to be a successful flap transfer, the following reconstructive questions bear discussion:

  • When is a conservative reconstructive approach (potentially associated with a suboptimal result yet ensuring a safer recovery) justifiable?

  • Can less than optimal methods of reconstruction, ones that were thought to be inadequate when the first procedure was performed, treat these problems successfully?

  • Does the overwhelming concern about another potential free flap failure deter surgeons from taking a hard decision of performing another free flap?

  • When is it justifiable to undertake another free flap to replace the previously failed one and risk another possible failure?

  • What specific flap must be selected as the mode of a secondary reconstruction?

    • If free flap, then what are the metrics that decide the selection of recipient vessels?

    • What adjunctive treatments are deployed to ensure survival after one failed flap chemotherapeutic interventions (heparin, dextran, and aspirin), to improve the outcome of these flaps?

In order to address these questions, we describe a framework that comprises three aspects:

  • 1.

    Patient-centered decision-making : A sensitive patient-centered five-step decision-tree based firmly on the patient's condition and need and a root cause analysis of flap failure

  • 2.

    Reconstructive choices : A matched-list of available flap reconstructive options (both free and non-microsurgical) – to help proper selection of a reliable secondary reconstructive strategy

  • 3.

    Pearls and pitfalls that help survival of the second flap.

In this chapter we will consider each of these issues in detail.

Patient-Centered Decision-Making

Patient-centered decision-making involves five steps ( Fig. 30.1 ).

Figure 30.1, Patient-centered decision-making tree.

Step One: Clinical Status of the Patient

An honest appraisal of the patient's medical status is a critical component of the way forward. Typically, the patient has undergone one long primary operation (a resection with a microsurgical reconstruction), an arduous recovery (punctuated with the sentinel event of flap failure), and then a re-exploration for salvage (which has also failed). At this stage, the patient could be quite compromised, and undertaking another long procedure right away may be ill-advised. If the patient is medically unstable, then repeat surgery must be deferred. Even a totally failed flap can serve as a biological dressing for 10 days or more. Most often, this is not necessary, and emergency re-exploration confirms irreversible pedicle thrombosis. At this time, immediate repeat reconstruction is usually performed, especially if loss of the flap results in exposure of vital structures. If, for some reason, repeat major surgery is not advisable, then the necrotic portions of the flap can be debrided and the wound temporarily dressed until a repeat reconstruction can be performed under more suitable circumstances. This course is indicated when the patient's general medical condition is unfavorable or if preferable for the patient to have an opportunity to participate in a complicated decision-making process. If ultimate failure of all or a portion of the flap would result in an unacceptable recurrent defect, then early debridement of all compromised tissue and repeat reconstruction offers a speedy recovery. If it appears likely that critical portions of the flap have a good chance of survival, then surgery can be delayed to allow maximal tissue salvage and clear delineation of the remaining defect.

Step Two: Root Cause Analysis of Flap Failure

If you don't ask the right questions, you don't get the right answers. (EDWARD HODNETT)

When analyzing the causes of free flap failure, a thorough review of microsurgical principles coupled with a candid effort to identify possible breaches in technique is mandatory. This not only helps one to decide whether it is prudent to attempt another free tissue transfer, but it is a discipline that improves the technical abilities of the surgeon.

A root cause analysis (RCA) provides the tools for a systematic approach. Root cause analysis is a structured method used to analyze serious adverse events. Initially developed to analyze industrial accidents, RCA is now widely deployed as an error analysis tool in health care. A central tenet of RCA is to identify underlying problems that increase the likelihood of errors, while avoiding the trap of focusing on mistakes by individuals. RCA thus uses the systematic approach to identify both ACTIVE ERRORS (errors occurring at the point of interface between humans and a complex system) and LATENT ERRORS (the hidden systemic problems that contribute to adverse events). This step is critical to decision-making for the secondary reconstruction.

Pearl

If failure is attributable to a clearly avoidable cause, then undertaking a second free flap reconstruction is feasible. In sharp contrast, if the cause is an unavoidable problem, a more conservative approach may be the only way the defect can be reconstructed.

In order to help elucidate the issue of avoidable versus unavoidable causes of failure, a brief synopsis of the common causes is presented.

All free flap failures ultimately result from platelet aggregation at the microvascular anastomosis (in patients with normal clotting function). The list of factors that lead to this sentinel event is classified into three main categories ( Box 30.1 ).

Box 30.1
Causes of Flap Failure

Systemic Factors

  • Low flow states

  • Drugs

  • Hypoxia

  • Comorbid disease

  • COPD

  • Hypercoagulable states

  • Impaired wound healing state

    • Diabetes

    • Renal failure

    • Stroke

    • Steroid use

Extraluminal Factors

  • Pressure

  • Hematoma

  • Postop positioning

  • Dressings, tapes, masks

  • Catheter drains

  • Edema

  • Fibrosis

  • Twist/kink

  • Tissue tension

Intraluminal Factors

  • Intimal inversion

  • Atherosclerosis

  • Rheologic currents

  • Embolism

  • Suture exposure

  • Radiation

  • Vascular malformations

  • Thrombophilia

Systemic Factors

Typically, the systemic factors are directly related to comorbid conditions that the patient suffers and which adversely affect flap survival. Low-flow states , such as cardiac disease, labile hypertension, dehydration, renal failure, and perioperative hypovolemia, vasoactive medications, or recreational drugs that result in vasoconstriction, hypotension, or altered flow to the flap; hypoxia (from COPD), or restrictive pulmonary disease, are possible causes.

Usually they constitute unavoidable causes of flap failure (an exception being perioperative hypovolemia and dehydration, which are correctable) – and steer decision-making away from another free flap reconstruction that could fail again. In most patients with systemic causes of failure, it is safer to choose a non-microsurgical simpler reconstructive strategy and return for a more definitive reconstruction after the factors that led to flap failure have been mitigated. Systemic disorders are associated with poor wound healing or the unacceptable risks of morbidity such as myocardial infarction, stroke, respiratory failure, etc. Flap failure is related to conditions that cannot be immediately reversed such as severe malnutrition or morbid obesity pose a circumstance in which a non-microsurgical alternative may be most prudent. Each patient must be individually assessed for the possible effect of comorbid conditions and the risk and benefits of repeat microsurgery must be thoughtfully weighed. Equally important is to consider the patients' functional recovery in the setting of comorbid conditions that the patient has inherently.

Extraluminal Factors

Even a technically perfect microanastomosis will thrombose if flow is reduced in the hours and days following surgery. The most common cause of reduced flow is mechanical compression of the vascular pedicle . Largely, these factors arise from the local tissues directly adjacent to the flap, and cause vascular compromise. They typically include external pressure from catheters, tape, dressings, tissue edema, improper positioning, and hematoma formation adjacent to the vascular pedicle. Last but not the least, prolonged surgery may add to the risks of complications.

Intraluminal Factors

Vascular disease involving the donor or recipient vessels may render them prone to thrombosis, despite optimal microsurgical technique and postoperative management. Intima-media thickening, the precursor lesion of atherosclerosis, may begin in adolescence, but definite atherosclerosis tends to appear after the age of 40 in men, and the onset of menopause in women. In the carotid system, a common recipient vessel location for head and neck free flaps, the incidence of asymptomatic atherosclerosis can be as high as 80%, depending on patient age, gender, and associated hypertension, cigarette smoking, and diabetes mellitus. Incidence in the lower extremities is similar. Radiotherapy increases the risk of vascular disease in vessels located in the treatment fields. Patients with vascular malformations can also pose problems due to abnormal local vasculature and clotting abnormalities. Performing microvascular surgery on diseased vessels requires meticulous attention to technical details. When a flap fails despite proper technique and adjuvant systemic anticoagulation, then it is usually prudent to salvage the reconstruction using non-microvascular methods.

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