The vascular-interstitial pH gradient during and after hemorrhagic shock

The interstitial fluid space (IFS) response to hemorrhagic shock (HS)-induced metabolic acidosis is reported. Prenodal skin lymph was used as a mirror of IFS changes. Twenty-three conditioned dogs had a reservoir HS insult followed by resuscitation with shed blood, crystalloid solution containing a total of 6.5 milliequivalents of sodium per kilogram of body weight and 250 milliliters of autologous banked blood. Prenodal skin lymph pH, oxygen tension (pO2), carbon dioxide tension (pCO2), bicarbonate level (HCO3) and flow rate measured before shock, during HS and in postresuscitation in 17 dogs in group 1 were compared with simultaneous samples of central venous blood. Peripheral venous values were not measured in dogs in group 1 to preclude any effects that local dissection might have on prenodal skin lymph. Six dogs in group 2 underwent the same HS and resuscitation model; the sequential changes in central mixed venous pH and lymphatic pH were compared with peripheral venous pH. HS caused metabolic acidosis; in group 1, the mixed venous pH decreased to 7.16 and in group 2, the peripheral venous pH decreased to 7.03. In contrast, the prenodal skin lymph pH in both groups was maintained at PS levels (7.51). Mixed venous pO2 decreased sharply with HS, whereas skin lymph pO2 was maintained. Maintained prenodal skin lymph pH and pO2 during HS-induced metabolic acidosis implies that the IFS undergoes stoichiometric changes. This facilitates the preferential adherence of highly charged proteins, like albumin, to the matrix to maintain cellular homeostasis.