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 a s a mirror of IFS changes. Twenty-three conditioned dogs had a reservo ir HS insult followed by resuscitation with shed blood, crystalloid so lution containing a total of 6.5 milliequivalents of sodium per kilogr am of body weight and 250 milliliters of autologous banked blood. Pren odal skin lymph pH, oxygen tension (pO2), carbon dioxide tension (PCO2 ), bicarbonate level (HCO3) and flow rate measured before shock, durin g HS and in postresuscitation in 17 dogs in group 1 were compared with simultaneous samples of central venous blood. Peripheral venous value s were not measured in dogs in group 1 to preclude any effects that lo cal 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 periphe ral venous pH. HS caused metabolic acidosis; in group 1, the mixed ven ous pH decreased to 7.16 and in group 2, the peripheral venous pH decr eased 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 s kin lymph pH and pO2 during HS-induced metabolic acidosis implies that the IFS undergoes stoichiometric changes. This facilitates the prefer ential adherence of highly charged proteins, like albumin, to the matr ix to maintain cellular homeostasis.