title: Skin perfusion pressure of the foot is a good substitute for toe pressure in the assessment of limb ischemia.
abstract: OBJECTIVE
  Noninvasive measurements of limb systolic pressures are used routinely in the assessment of the severity of peripheral arterial disease, including the evaluation for critical limb ischemia. However, ankle pressures cannot be measured reliably in patients with medial calcification, which is especially common among patients with diabetes. Skin lesions on the toes or previous digital amputations may preclude the measurement of toe pressures. Measurements of skin perfusion pressure (SPP) are not subject to such limitations and were shown to be useful in the assessment of the severity of peripheral arterial disease. Because toe pressure is often used in the evaluation of severity of arterial disease and in the assessment for critical ischemia, we undertook to study whether there is a sufficient correlation between toe pressure and foot SPP that would allow the use of SPP measurements when toe pressures cannot be measured.
  
  
  METHODS
  Measurements were carried out in 85 limbs of 71 patients referred to the vascular laboratory for evaluation for peripheral arterial disease. Diabetes mellitus was present in 43 patients. Each patient had foot SPP and toe pressure measurements. Toe pressures measured with photoplethysmography were correlated with foot SPP measured with laser Doppler scanning.
  
  
  RESULTS
  There was a strong linear correlation between SPP and toe pressure (r = 0.87; P <.01). Also, significant correlation was found in both the patients with diabetes and the patients without diabetes (r = 0.85 and 0.93, respectively; P <.01 in both cases).
  
  
  CONCLUSIONS
  We concluded that SPP measured in the foot correlates well with toe pressure and can be substituted for toe pressure measurement in patients in whom toe pressures cannot be measured.
authors.affiliation: Morristown Memorial Hospital, the University of Colorado Health Services Center, Denver, CO, USA.
authors.forename: F W
authors.initials: FW
authors.lastname: Tsai
authors.forename: N
authors.initials: N
authors.lastname: Tulsyan
authors.forename: D N
authors.initials: DN
authors.lastname: Jones
authors.forename: N
authors.initials: N
authors.lastname: Abdel-Al
authors.forename: J J
authors.initials: JJ
authors.lastname: Castronuovo
authors.forename: S A
authors.initials: SA
authors.lastname: Carter
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003925:Diabetic Angiopathies / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D005528:Foot / Q000098:blood supply*; D006801:Humans; D007511:Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply; D014034:Toes / Q000098:blood supply