Blood Congestion Can Be Rescued by Hemodilution in a Random-Pattern Skin Flap

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We read with interest the article entitled “Blood Congestion Can Be Rescued by Hemodilution in a Random-Pattern Skin Flap” by Kanayama et al.1 Despite several studies on microcirculatory physiology, the effect of hemodilution is still extremely controversial.2–4
We would like to congratulate the authors for the study. In a clear and scientific way, they demonstrated how in the random skin flaps the hemoconcentration favors necrosis, whereas hemodilution reduces blood viscosity and improves tissue blood flow. We believe that this is true for random flaps, but especially for free flaps. We would like to know whether the authors have experience in clinical practice and in microsurgery.
In our clinical practice, we carry out a preoperative intravenous infusion (12 hours before surgery) of 500 cc of sodium chloride in all patients in whom a blood loss is expected. This slightly hypervolemic hemodilution has allowed us to significantly limit the percentage of postoperative blood transfusions and has improved the survival rate of the flaps, especially microsurgical flaps (>97 percent). The use of colloids in preoperative therapies, as indicated by the authors, is not indicated, also because of adverse reactions.
In microsurgical patients, we usually apply a specific protocol: 12 hours before surgery, we administer 500 ml of sodium chloride with 40 mg of pantoprazole, 100 mg of salicylic acid (Flectadol; Maggioni Winthrop Italia, Milan, Italy), and 500 mg of methylprednisolone.
The pharmacologic cocktail acts in multiple ways. The lower blood viscosity caused by the reduction of hematocrit together with reduced platelet aggregation (induced by low-dose salicylic acid) improves perfusion of the tissues. Methylprednisolone acts by improving cardiac performance (mild increase in perfusion pressure) and by a protective effect on the vessels.
Our experience, especially in patients who have not been given Flectadol for salicylate allergy, suggests that probably the most beneficial effect of preoperative therapy is attributable to the infusion of crystalloids. Simple preoperative hemodilution does not expose the patient to additional risks, and even in the absence of prophylactic antithrombotic drug therapy, the failure rate of the flap for thrombotic complication has dropped from 8 percent to 3 percent, and the percentage of patients undergoing blood transfusion has decreased considerably.
Transfusion is limited only to patients with hemoglobin values below 7 mg/dl. In the postoperative period, unless there is a serious risk (hemoglobin <7 mg/dl), we prefer to administer crystalloid liquids rather than transfusion to maintain a hematocrit less than 30 percent and to support flap circulation from a hemorheologic point of view.
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