Interstitial gel swelling pressure in human subcutaneous tissue measured with a cotton wick.

1. A cotton wick probe has been used to measure the pressure in subcutaneous interstitial tissues of man. 2. The probe was inserted with minimal trauma into a plane of natural dissection at the level of the deep fascia in three sites: dorsum of the hand and foot, and the forearm. 3. The pressure was subatmospheric on every occasion (mean pressure : hand, -3-015SD 0.50 cmH,O; foot, -3.545SD 1-74 cmH,O; forearm, -2*41+SD 0.85 cmH,O). 4. Taking the three sites together, there was a positive correlation between wick pressure and locally measured tissue temperature (r = 0.55; P<O-Ol), but when each site was analysed separately the relationship was significant only in the hand. 5. Wick pressure rose when the subcutaneous tissues were warmed. 6. A negative correlation was observed between wick pressure from the forearm and the subject’s plasma colloid osmotic pressure (r = 0.73; P<O.OI), but no such relationship was observed in the hand or foot.