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Evaluation of the pH-stat modified approach for the treatment of non-respiratory (lactic) acidosis and vascular hyporeactivity caused by hemorrhagic shock in dogs

Rojas, Jesus Antonio, Sr.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1063035811

Abstract Details

2003, Doctor of Philosophy, Ohio State University, Veterinary Clinical Sciences.
The objective of this dissertation was to determine if the pH-stat modified therapy is more effective than the pH-stat therapy in treating hemorrhagic shock and vascular hyporeactivity in dogs. The specific aims were to compare the effectiveness of these two treatments on systemic hemodynamics and acid-base balance and to evaluate their efficacy in preventing vascular hyporeactivity in dogs with hemorrhagic shock. Twenty-three anesthetized dogs were randomly assigned to four groups: I: One (1) dog included as control to provide baseline and control data; II: Seven (7) hemorrhaged, hypothermic [HT] (32° C) dogs received lactated Ringers solution (LRS); III: Seven (7) hemorrhaged, HT dogs received LRS and were subjected to the pH-stat therapy; IV: Eight (8) hemorrhaged, HT dogs received LRS and underwent the pH-stat modified therapy. Dogs were intubated and mechanically ventilated on room air and end tidal CO2 of 35-40 mm Hg. Approximately 40% of each dogs blood volume was removed until mean arterial pressure (MAP) reached 50 mm Hg. MAP was held constant for 60 minutes. After bleeding, all dogs were treated with LRS. Dogs in group II received LRS. Dogs in group III and IV received LRS and either pH-stat or pH-stat modified therapies. pH-stat keeps arterial pH at 7.40 and PCO2 at 40 mm Hg regardless of body temperature. PaO2, PCO2 and pH were corrected for body temperature. pH-stat modified maintains a fixed PCO2 of 60 mm Hg and a pH of 7.30. Hemodynamics and acid-base data were measured at baseline, through hemorrhage, end of treatment, and at 60, 120 and 180 minutes post-resuscitation. Vascular reactivity to norepinephrine infusion and blood flow to the hind limb and small intestine were determined. Through bleeding, heart rate increased insignificantly in all groups and returned to values not different from baseline. None of the treatments was superior in sustaining left ventricular systolic pressure and preload. The 3 methods produced transient improvements in physiological variables that did not persist with time. All systemic arterial pressures behaved nearly identically during hemorrhage and subsequent fluid resuscitation. They fell at the end of hemorrhage due to reduced preload, returned to normal at the end of resuscitation and drifted to subnormal values consistent with venous pooling. Blood flow was better with pH-stat modified than with the other 2 interventions. Blood flow was also superior with pH-stat-modified when animals received norepinephrine and when occlusion was applied. High lactate levels leading to both low arterial pH (pHa) and bicarbonate were seen in all groups 3 hours after resuscitation, confirming the presence of non-respiratory acidosis. The lowest lactate concentration was seen with pH-stat modified therapy. Nonetheless, differences among groups were not significant. Animals which received pH-stat modified exhibited lower pHa levels than animals with other interventions. Apparently, there were no significant differences produced by one volume replacement over another, with the exception of flow improvement to tissues in animals which received pH-stat modified therapy.
William Muir (Advisor)
262 p.
Biology, Veterinary Science
HEMORRHAGIC SHOCK; hemorrhage; Hypothermia; pH-STAT MODIFIED

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Citations

  • Rojas, Sr., J. A. (2003). Evaluation of the pH-stat modified approach for the treatment of non-respiratory (lactic) acidosis and vascular hyporeactivity caused by hemorrhagic shock in dogs [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1063035811

    APA Style (7th edition)

  • Rojas, Sr., Jesus. Evaluation of the pH-stat modified approach for the treatment of non-respiratory (lactic) acidosis and vascular hyporeactivity caused by hemorrhagic shock in dogs. 2003. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1063035811.

    MLA Style (8th edition)

  • Rojas, Sr., Jesus. "Evaluation of the pH-stat modified approach for the treatment of non-respiratory (lactic) acidosis and vascular hyporeactivity caused by hemorrhagic shock in dogs." Doctoral dissertation, Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1063035811

    Chicago Manual of Style (17th edition)

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