title: Hypothermic, initially oxygen-free, controlled limb reperfusion for acute limb ischemia.
abstract: BACKGROUND
  Controlled limb reperfusion has been shown to prevent the deleterious effects of ischemia-reperfusion (IR) syndrome following revascularization of acute limb ischemia (ALI). To reduce the production of cell-toxic oxygen-free radicals, we have established a new initially oxygen-free, hypothermic, heparin-coated perfusion and hemofiltration system and report on our first results.
  
  
  METHODS
  In a retrospective single-center study, controlled limb reperfusion was applied in 36 patients (64.7 ± 15 years) with ALI of category IIA to III (33.7 ± 20.7 hr ischemic time). 52.8% had central (aortic and bifurcation) and 47.2% had peripheral (common iliac artery and distal) vascular occlusions. The common femoral artery and vein were cannulated, and a hypothermic (22°C), initially oxygen-free, potassium-free ringer's solution was perfused using a heparin-coated extracorporeal membrane oxygenation (ECMO) and hemofiltration system with low-dose heparinization. Thirty-day mortality, clinical recovery of neurological dysfunction, limb amputation, and fasciotomy rate were analyzed. Laboratory parameters associated with ischemia and IR injury were determined.
  
  
  RESULTS
  Average perfusion time was 94 ± 35 min. Thirty-day mortality was 27.8%. 55.5% of patients showed complete recovery of motor and sensory dysfunction. A total of 27.8% of patients developed a compartment syndrome and required fasciotomy. Lower leg amputation was necessary in 11.1% of patients. Lactate levels were reduced in ischemic limbs by 25.3% within 60 min (P < 0.05). Preoperative negative base excess of -1.96 ± 0.96 mmol/L was equalized after 12 hr (P < 0.05), while pH stayed balanced at 7.4. Serum potassium stayed within normal limits throughout 24 hr, and therefore systemic hyperkalemia was prevented and imminent metabolic acidosis was corrected.
  
  
  CONCLUSIONS
  An initially oxygen-free, hypothermic, heparin-coated ECMO counteracts local and systemic effects of IR injury. Reduced mortality and morbidity might result from this new treatment, although this could not be conclusively proven in our study. A prospective, randomized controlled trial is needed to prove superiority of this new concept.
authors.affiliation: Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland; Vein Clinic Bellevue, Kreuzlingen, Switzerland. Electronic address: c.schmidt@venenklinik.ch.
authors.forename: Christian A P
authors.initials: CA
authors.lastname: Schmidt
authors.affiliation: Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Zoran
authors.initials: Z
authors.lastname: Rancic
authors.affiliation: Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Mario L
authors.initials: ML
authors.lastname: Lachat
authors.affiliation: Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Dieter O
authors.initials: DO
authors.lastname: Mayer
authors.affiliation: Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland; The Cleveland Clinic, Cleveland, OH; New York University Medical Center, New York, NY.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Veith
authors.affiliation: Clinic for Cardiovascular Surgery, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Wilhelm
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000671:Amputation, Surgical; D000925:Anticoagulants / Q000008:administration & dosage; D020099:Coated Materials, Biocompatible; D003161:Compartment Syndromes / Q000209:etiology / Q000601:surgery; D019299:Decompression, Surgical / Q000379:methods; D004867:Equipment Design; D015199:Extracorporeal Membrane Oxygenation / Q000009:adverse effects / Q000295:instrumentation / Q000401:mortality; D000071938:Fasciotomy; D005260:Female; D006440:Hemofiltration / Q000009:adverse effects / Q000295:instrumentation / Q000401:mortality; D006493:Heparin / Q000008:administration & dosage; D017052:Hospital Mortality; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects / Q000401:mortality; D007511:Ischemia / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D023821:Limb Salvage; D035002:Lower Extremity / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D010477:Perfusion / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods* / Q000401:mortality; D020127:Recovery of Function; D012189:Retrospective Studies; D012307:Risk Factors; D012677:Sensation; D013557:Switzerland; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000925:Anticoagulants; D020099:Coated Materials, Biocompatible; D006493:Heparin