Evaluation of baseline pathophysiological changes in patients with emergency abdominal pathology

Background. Acute surgical pathology is associated with high rates of postoperative complications and mortality. The aim is to determine baseline pathophysiological changes in patients with acute abdominal pathology and their dependence on the grade of surgical risk. Materials  and  methods. We examined 200 patients with urgency laparotomy. We have divided the patients into two groups (according to the surgical risk score — P-POSSUM), namely moderate (n = 100) and high (n = 100) surgical risk. We measured routine clinical laboratory characteristics, central hemodynamic state and fluid compartments of the body by the noninvasive bioelectric integral evaluation of the body structure with the Diamant monitor complex. Results. We found significant decrease of extracellular volume due to reduction of plasma volume (83 % of the norm (p < 0.05) in the 1st group, 86 % of the norm (p < 0.05) in the 2nd group); and dehydration was not defined. All patients had adaptive hemodynamic response. The 1st group was found to have decline in stroke volume by 10 % (p < 0.05) due to hypovolemia. We fixed a decrease of stroke volume index by 122 % of the norm (p < 0.05), which was compensated with moderate tachycardia and formed relative hyperdynamia (cardiac output was 107 % of the norm (p < 0.05)) for the 1st group. As a result, tissue perfusion complied with the standard rate. The relative hypodynamia was determined in the 2nd group (cardiac output was 84.6 % of the norm (p < 0.05)) despite tachycardia (heart rate was 45 % over the norm (p < 0.05)) and vasospasm (systemic vascular resistance was 184 % of the norm (p < 0.05)) while tissue perfusion decreased (peripheral perfusion index accounted for 81.3 % of the norm (p < 0.05)). Conclusions. Acute surgery pathology under II rate of dehydration forms the moderate vоlumе dеplеtion/hypovolemia, causes redistribution of extracellular fluid volume. Hypovolemia also deals with loss of plasma volume and causes development of hemodynamic disorder and water redistribution between body sectors. Severity of pathophysiological abnormality depends on the patient’s surgical risk degree. Compensatory raise of heart rate forms relative hyperdynamia and preserves tissue perfusion in patient of moderate surgical risk. Pathognomic development of tachycardia and vasospasm forms relative hypodynamic and tissue perfusion decrease, which is relevant for patient of high surgical risk.


Introduction
Acute surgical pathology is a condition including a large number of diseases [1][2][3][4][5][6][7][8]. The basic treatment method for it is emergency laparotomy. Emergency laparotomy is associated with a disproportionately high rates of postoperative complications and mortality in all age categories of patients [2,4]. This could be explained by the limited time of diagnosis, human factor and patho-physiological changes in patients. Hypovolemia is the most dangerous pathogenic cause of a patient's condition [3]. Hypovolemia is formed by pathological losses. Untimely and inadequate intensive therapy of hypovolemia goes with tissue perfusion and leads to the formation of multiple organ dysfunction/failure and seriously worsens the prognosis of life in patients with acute abdominal pathology [5,6]. UDC 616.381-083.98-036.2-092 DOI: 10.22141/2224-0586.4.99.2019 O.V. Kravets State Institution "Dnipropetrovsk Medical Academy of the Ministry of Health of Ukraine", Dnipro, Ukraine

Evaluation of baseline pathophysiological changes in patients with emergency abdominal pathology
Abstract. Background. Acute surgical pathology is associated with high rates of postoperative complications and mortality. The aim is to determine baseline pathophysiological changes in patients with acute abdominal pathology and their dependence on the grade of surgical risk. Materials and methods. We examined 200 patients with urgency laparotomy. We have divided the patients into two groups (according to the surgical risk score -P-POSSUM), namely moderate (n = 100) and high (n = 100) surgical risk. We measured routine clinical laboratory characteristics, central hemodynamic state and fluid compartments of the body by the noninvasive bioelectric integral evaluation of the body structure with the Diamant monitor complex. Results. We found significant decrease of extracellular volume due to reduction of plasma volume (83 % of the norm (p < 0.05) in the 1 st group, 86 % of the norm (p < 0.05) in the 2 nd group); and dehydration was not defined. All patients had adaptive hemodynamic response. The 1 st group was found to have decline in stroke volume by 10 % (p < 0.05) due to hypovolemia. We fixed a decrease of stroke volume index by 122 % of the norm (p < 0.05), which was compensated with moderate tachycardia and formed relative hyperdynamia (cardiac output was 107 % of the norm (p < 0.05)) for the 1 st group. As a result, tissue perfusion complied with the standard rate. The relative hypodynamia was determined in the 2 nd group (cardiac output was 84.6 % of the norm (p < 0.05)) despite tachycardia (heart rate was 45 % over the norm (p < 0.05)) and vasospasm (systemic vascular resistance was 184 % of the norm (p < 0.05)) while tissue perfusion decreased (peripheral perfusion index accounted for 81.3 % of the norm (p < 0.05)). Conclusions. Acute surgery pathology under II rate of dehydration forms the moderate vоlumе dеplеtion/hypovolemia, causes redistribution of extracellular fluid volume. Hypovolemia also deals with loss of plasma volume and causes development of hemodynamic disorder and water redistribution between body sectors. Severity of pathophysiological abnormality depends on the patient's surgical risk degree. Compensatory raise of heart rate forms relative hyperdynamia and preserves tissue perfusion in patient of moderate surgical risk. Pathognomic development of tachycardia and vasospasm forms relative hypodynamic and tissue perfusion decrease, which is relevant for patient of high surgical risk.

Keywords: emergency abdominal pathology; surgical risk; fluid compartments; central hemodynamics; hypovolemia
The purpose is to specify baseline pathophysiological changes in patients with acute abdominal pathology and their dependence on the grade of surgical risk and hypovolemia.

Methods and methods
We examined 200 patients with acute abdominal pathology and obtained the informed consents within local Ethics Committee approval. A prospective, observational study was performed in the period from January 2016 to December 2018. All patients undergoing emergency laparotomy (emergency laparotomy is an immediate lifesaving operation, which involves exploration of the abdomen usually within 2 hours), have potentially lifethreatening conditions that require prompt intervention. Acute cases of emergency laparotomy were: acute intestinal obstruction (n = 65), perforated gastric and duodenal ulcer (n = 51), strangulated hernia (n = 84). We examined 106 (53 %) men and 94 (47 %) women of mean age 61.1 ± 11.5 [45 : 75] years.
Inclusion criteria: the patient's age is more than 45 years and less than 75 years; emergency laparotomy, predicted intraoperative blood loss less than 500 ml; ASA IІІ E, diabetes mellitus at the stage of compensation, moderate dehydration (according to II grade by P. Shelestyuk [9]); surgical risk of patient ≥ 10 % (according to the surgical risk score P-POSSUM [8]).
Exclusion criteria: the patient's age is less than 45 years and more than 75 years; gastrointestinal bleeding; ASA І-ІІ-IV, diabetes mellitus at the stage of decompensation; pregnancy and lactation; allergic reactions to any component of drug therapy; mild/severe dehydration (according to I or III grades by P. Shelestyuk); surgical risk of patient ≤ 10 % (according to the score P-POSSUM); patient's refusal to participate in the study.
We examined all patients according to the protocol of the Ministry of Health of Ukraine No 297 (02.04.2010) [9]. Concomitant pathology was identified as: excessive body weight (obesity I-II stage) (n = 12), ischemic heart disease (n = 112), arterial hypertension (n = 89), atrial fibrillation (n = 52), chronic obstructive bronchitis in remission (n = 34), diffuse diabetes mellitus type II in remission (n = 22). All patients who were divided in two groups according to the surgical risk score P-POSSUM were treated in ICU before having surgery. Portsmouth Physiоlogical and Operative Severity Score for the enUmeration of mortality and Morbidity (P-POSSUM) is risk-adjusted score that predicts a patient outcome. P-POSSUM score calculation is based on usage of 12 physiological and 6 operative variables of a patient, which are graded as 1, 2, 4 or 8 relying on their magnitude then summed to form a physiological score and operative severity score. The physiological score and operative severity score predict the risk of mortality and morbidity [8,10].
We evaluated the clinical parameters of systemic hemodynamics: blood pressure, mean arterial pressure (MAP), heart rate (HR), central venous pressure, and routine clinical laboratory tests (general blood and urine analysis, coagulogram, biochemical blood test, acid-base status, plasma blood electrolytes, and lactate). We measured plasma, urine osmolarity and mean cell vo lume by calculation method [11]. The central and peripheral hemodynamic parameters were determined by the method of integral rheography with the apparatus Diamant: cardiac index (CI), stroke volume (SV), stroke volume index (SVI), systemic vascular resistance (SVR). Such indicators of the body fluid compartments as the extracellular fluid volume (ECF), intracellular fluid volume (ICF), the total volume of fluid, the plasma vo lume (PV), total volume of blood (TVB) were measured by the method of noninvasive bioelectric integral evaluation of the body structure with the Diamant monitor complex. We evaluated tissue perfusion by peripheral perfusion index (PI) with the apparatus +Biomed [12].
Scoring scales ASA and P-POSSUM were used for stratification of surgical risk.
Statistical analysis of the results was carried out with MS Excel 2007, Statistica 6 software package. The data are given in the form M ± m. Statistically significant values were p < 0.05.

Results
According to the preset principle, the patients of both groups were assigned as moderate grade of dehydration (according to II grade by P. Shelestyuk), which is associated with intrаvаsculаr vоlumе dеplеtion/moderate hypovolemia. Indeed, our results suggest that baseline pathophysiological changes in acute abdominal pathology are associated with hypovolemia, dehydration and central hemodynamic changes. In fact, our results revealed the redistribution of fluid between all of the fluid compartments (Table 1). There were no differences in absolute values of ECF and ICF. So, the ECF decreased consequently due to the volume of circulating № 4 (99), 2019 Медицина невідкладних станів, ISSN 2224-0586 (print), ISSN 2307-1230 (online) Оригінальні дослідження / Original Researches blood, namely by reducing the plasma volume (85.1 % of the norm (p < 0.05)) in the patients with moderate surgical risk. We did not identify intracellular dehydration (95.5 % of the norm (p > 0.05)), but decrease in circulating blood volume due to plasma volume reduction in the patients with high surgical risk, too. Ho wever, the absence of statistically significant difference in TVB and PV reduction in both groups did not cause the development of significant dehydration. No electrolyte abnormalities were observed in both groups of patients. Levels of sodium, potassium and chlorine were normal. Plasma osmolality coincided to reference range of 280 mmol/kg. Baseline volume status is a statistically significant variable of systemic hemodynamic parameters due to the initial vоlumе dеplеtion (Table 2). Moreover, clinical sign of groups seemed different. We determined decrease of SV (87 % of the norm; p < 0.05) and SVI (58 % of the norm (p < 0.05)) in the group of high surgical risk. It is associated with tachycardia (HR 145 % of the norm (p < 0.05)) and vasospasm (SVR 184 % of the norm; p < 0.05). Wherein MAP were above normal and formed relative hypodynamia (CI 84 % of the norm; p < 0.05). However, these mechanisms did not satisfy the adequate tissue perfusion -PI was significantly reduced (81.3 % of the norm; p < 0.05). The same hypovolemia asso ciated with relative hyperdynamia (CI 107 % of the norm; p < 0.05) and statistically nonsignificantly increased SVR (105 % of the norm; p < 0.05) and tachycardia (HR 122 % of the norm; p < 0.05) in patients of moderate surgical risk maintained satisfactory tissue perfusion. Nevertheless, level of lactate was within norm.

Discussion
It is known that acute surgical pathology is associated with hypovolemia and dehydration. We have determined moderate vоlumе dеplеtion/hypovolemia and its compliance to the II grade of dehydration (P. Shelestyuk) in surgical patient with acute pathology [4][5][6]. We have also found redistribution of fluid in all the fluid compartments almost to the same extent in both groups. To the best of our knowledge, this prospective, observational study is the largеst repоrtеd tо invеstigatе the hemodynamic response. So, hypovolemia is associated with relative hyperdynamia and statistically significant tachycardia in patients of moderate surgical risk. These compensatory reactions maintained satisfactory tissue perfusion. Another hemodynamic response was established in patients of high surgical risk. Relative hypodynamia is associated with tachycardia and vasospasm. The result of this investigation demonstrated over-normal MAP that disguises the clinical signs of patients' condition severity and gives impression of imaginary healthy living. However, these mechanisms did not satisfy the adequate tissue perfusion.

Conclusions
Acute surgical pathology in patients with moderate vоlumе dеplеtion/hypovolemia causes redistribution of extracellular fluid volume and hemodynamic response depending on surgical risk grade.