Intramucosal pH as a criterion for the organism emergency from hepatospanchnic ischemia, or centralization of blood flow

In critical conditions, despite the restoration of systemic hemodynamics and overall oxygen delivery, tissue hypoxia and reduced oxygen extraction remain. One of the important tasks of intensive care for critical conditions is the early diagnosis of tissue perfusion disorders. In clinical circumstances, signs of hypoperfusion are arterial hypotension, tachycardia, oliguria, encephalopathy, low body temperature, the disappearance of skin capillary pattern, metabolic lactate acidosis. However, blood pressure is an insensitive indicator of tissue hypoperfusion itself. Experimental clinical trials have repeatedly documented that local perfusion pressure in critical conditions does not directly depend on systemic blood pressure. Lactate is not a specific marker of anaerobic metabolism, but rather impaired microcirculation seems to be one of the possible mechanisms of hyperlactatemia. Reliable markers of tissue perfusion and the effectiveness of early targeted therapy are regional capnometry (gastric intramucosal pH, sublingual pCO2), a saturation of mixed venous blood, etc. Intramucosal pH is of particular practical importance as a marker of regional capnometry. The aim of the study is the analysis of literature sources devoted to the effectiveness and diagnostic significance of intramucosal pH as a marker of regional perfusion. The value of intramucosal pH was evaluated: 1) during abdominal operations and the development of postoperative complications in comparison against IL-6 and IL-8; 2) during and after surgical interventions in conditions of prolonged cardiopulmonary bypass to assess the adequacy of blood supply to the abdominal organs; 3) in experimental septic shock compared to the values of lactate and hypoxanthine concentration in the liver and arterial blood; 4) the correlation between intramucosal pH va-lues, indices of the pediatric mortality risk scale, forming of great (cardiac arrest, shock) and minor (hypotension, hypovolemia, arrhythmia) hemodynamic complications and duration of staying in intensive care unit and intensive therapy; 5) during laparoscopic cholecystectomy in apparently healthy patients with the simultaneous calculation of the difference between arterial and intramucosal pH. Intramuscular pH-controlled intensive therapy is a separate fragment: an intramucosal pH of less than 7.3 reflects splanchnic hypoperfusion and is an indicator of the unfavorable outcomes; intramucousal pH of more than 7.3 is a criterion for the emergency of the organism from hepatosplanchic ischemia, i.e. centralization of blood circulation. Therefore, the intramucosal pH is valuable in the clinical picture of critical conditions as a marker of regional perfusion measured by capnometry, which allows monitoring that reflects the perfusion of the intestinal wall. The lower threshold is 7.35 (the sensitivity of the method is 67 %, specificity is 74 %). An intramucosal pH of < 7.3 reflects splanchnic hypoperfusion and is an indicator of an adverse outcome. An alternative measurement of intramucosal pCO2, pCO2 in arterial blood and the difference [P (1-a) CO2] is a more reliable index of intestinal oxygenation than single intramucosal pH, but rather pH (1-a) makes it possible to adequately assess the acid-base state of arterial blood. The improvement and widespread use of capnometry and capnography for monitoring during general anaesthesia and intensive care, on the one hand, and modern knowledge of the pathophysiology of gas exchange, on the other hand, stimulate the wider use of less invasive and more affordable methods of regional capnometry and aerial tonometry.

The effectiveness of hepatosplanchnic ischemia treatment monitored with intramucosae pH in polytrauma

The study aimed to substantiate and introduce the empirical oxygenation of general and local action into intensive care for heptosplanchnic ischemia during polytrauma. The study included 85 patients with polytrauma with the brain injury of mild to moderate severity according to the modern clinical classification. The conditions for inclusion in the study were as follow: Injury Severity Score (ISS) more than 32 points, Acute Physio­logy and Chronic Health Evaluation (APACHE II) — 25 points or more. Clinical and biochemical studies were carried out at the following stages: upon admission (stage 1), 12–24 hours after the start of intensive care (stage 2), in 3, 5, 7 days (stages 3, 5, 7, respectively). The clinical observation was carried out up to 32 days from the time of the injury. The manifestations showed certain differences depending on the outcome of the disease. Victims with a subsequent fatal outcome had higher blood loss (by 27.65 %, p < 0.05), blood volume deficiency (by 33.42 %, p < 0.05), more severe hypotension, tachycardia; increased arterial hypoxemia; the indicator of venous blood shunting in the lungs significantly exceeded the normal values and those of the group of survivors. With sigmoidal gas tonometry in survivors, the intramucosal pH ranged 6.88–7.0; pCO2 from 85.6 to 118.38 mmHg. In the dead, the intramucosal pH ranged from 6.79 to 6.9 units; pCO2 from 95.61 to 121.71 mmHg. In 85 % of cases of endoscopic visuali­zation, erosive-ulcerative changes in the mucous membrane of the antrum were determined. Gastrointestinal insufficiency in patients with subsequent fatal outcome clinically corresponded to II–III stages; according to the manifestations of histological changes in the mucous membrane of the antrum of the stomach to the III–IV stages. The described features are based on the prevalence of 11.77 % ISS scales in deceased victims, APACHE II by 20.78 %, and SOFA by 71.52 %, which determines the severity of the damage, the condition of the victims, and the severity of organ damage. Starting from the 1st day of intensive care, the differences between the studied parameters in survivors and deceased victims continued to worsen. In surviving patients, oxygenation of arterial blood was restored from the first day to the physiological values due to the elimination of venous bypass blood in the lungs, and the transition to normodynamic blood circulation. Then on the 3rd day, the intramucosal pH was 99.59 % of the norm. In the dead, the restoration of the oxygenation index on the 1st day was combined with a decrease in tissue oxygen extraction, hypovolemic shock, refractory to vasopressor therapy from the 3rd day of the study. The pH values exceeded 7.35 only by the 5th day, while clinically the digestive function did not recover on the 7th day of the study. The data of the clinical evaluation of gastroenteric insufficiency were confirmed in the endoscopic picture, the data of histological and histochemical studies of the mucous membrane of the antrum. High, positive, reliable correlations between intramucosal pH and the outcome of the disease have been established. The actual mortality rate at the intermediate points was 20 %: 3 victims died on the 3rd day, 2 victims — on the 5th day. Before the 28th day of clinical observation, the actual mortality rate was 44 % (the rest 6 victims died from the 7th day to the 28th day). After 28 days to 32 days, death was not registered.