An area of the parietal and visceral peritoneum that is inflamed, or the entire area, is said to have peritoneitis. Acute or chronic, septic or aseptic, primary or secondary, localised or generalised peritonetitis are all possible. The most typical type of peritonitis that develops after an intra-peritoneal source, typically from the puncture of hollow viscera, is secondary peritonitis [1-2].

Elevated blood lactate levels have been used to define the prognostic value of occult hypoperfusion in critically ill patients without signs of clinical shock [3-4] reported a specificity of 74.3% for mortality with lactate levels of ≥ 4 mmol/l in patients with sepsis. Mikkelsen [5] reported that intermediate and high lactate levels are independently associated with mortality in severe sepsis, independent of organ failure and shock. Nichol [6] performed both - static and dynamic measurements of plasma lactate in critically ill patients (36,673 lactate measurements in 5,041 patients) and found that dynamic lactate measurement was most predictive of mortality.        

In 2001 at the International Conference on Definitions of Sepsis, pro-calcitonin was recognized as the most important marker for the diagnosis in the initial stages of the inflammatory response to infection, and enumerating its severity of sepsis [7]. Procalcitonin (PCT) is a prohormone of protein origin, similar to calcitonin, of which it is the precursor peptide.  Under normal conditions, it is produced and secreted by C cells in the thyroid gland. It is also secreted by neuroendocrine cells in the lung and intestine; these last two sources of PCT provide its true clinical utility, since they increase its production in response to a pro-inflammatory stimulus. Procalcitonin is a biomarker of sepsis, whose concentrations increase when some endotoxin enters the bloodstream. It is used, among other things, to discriminate the etiology of infections, increase or decrease the antibiotic spectrum, and predict mortality. The diagnostic value of markers of inflammation could differentiate infectious processes that are not, and predicting the severity of a disease process or condition, which would initiate appropriate therapeutic and measure its response [7-8].

The aim of this study is to evaluate the serum lactate, pH and procalcitonin level as a prognostic indicator for mortality among secondary peritonitis patients in a tertiary care Hospital.

Aims And Objectives

To evaluate the serum lactate, pH and procalcitonin level as a prognostic indicator for mortality among secondary peritonitis patients in a tertiary care Hospital.

This study was conducted in the Department of Surgery IGMC, Shimla over a period of twelve months from January 2021 – December 2021. 

Inclusion Criteria

• All adult patients (> 18 years of age) presenting with the clinical diagnosis of perforation peritonitis of either sex

• All Patients willing to participate in the study

Exclusion Criteria

• Patients operated elsewhere before presentation

• Patients unwilling to participate in the study

• Patients on drugs which alter the level of arterial lactate

Study Methodology

• The proposed study was a longitudinal, prospective study with two-time measurement of arterial lactate levels at24 hours interval

• All patients presenting to the Department of Surgery, IGMC, Shimla with a diagnosis of secondary peritonitis and fulfilling the inclusion and exclusion criteria were recruited

• The diagnosis of secondary peritonitis was established based on clinical examination, investigations and operative findings

• Informed and written consent was taken from the patient / relative

• Resuscitation, preoperative and postoperative treatment was performed according to the established protocol for perforation peritonitis

• Relevant information was collected as per study performa

• ABG analysis was performed twice to assess arterial lactate levels and pH, once initially, on admission (preoperative), and the other, 24 hours after surgery (postoperative)

• 2 ml of blood sample drawn for ABG sampling from either the radial or femoral arteryin a pre-heparinized syringe

• Arterial Blood Lactate level and pH measured by using Siemens Rapid Point 500 e Analyzer which is available in the hospital and estimates the whole blood lactate level based on potentiometric measuring principles

• AL_I was the preoperative reading of arterial lactate levels

• AL₂₄was postoperative reading and absolute clearance as well as percentage lactate clearance calculated using the formula –

Absolute lactate clearance (mmol/L) = AL_I -AL₂₄

Percentage of lactate clearance (%) = (AL_I -AL₂₄) x 100

AL_I

• Serum procalcitonin estimation of the patient was done at the time of admission into hospital

• For the determination of change in lactate level following peritonitis, preoperative and post-operative lactate values were statistically compared and Correlation of these values measured with t-test and Chi-square test

• For the determination of correlation between PCT and outcome t-test and Chi-square test were performed

• For the determination of change in pH following peritonitis, preoperative and postoperative pH values were statistically compared and Correlation of these values measured with t-test and Chi-square test

Statistical Analysis

Data compiled in the excel sheet and further analyzed by using IBM SPSS Statistics 28 and result displayed in number and percentage. To access the relationship between parameters under study outcome various hypothesis was designed and results were compiled in results and observation section using t-test and Chi-square test.

In this retrospective study total 250 patients with diagnosis of perforation peritonitis were evaluated. Among the total Males were 205 (82%) and Females were 45 (18%). Mean age of the patients was 47.28±17.34 years with range from 18 to 87 years. Among the total, 99(39.6%) patients were age < 40 years while 151(60.4%) patients were aged > 40 years. Among the total, 32(12.80%) were expired while 218(87.20%) were discharged after treatment (Figure 1).

Figure 1: Age and gender Distribution of Study Participants

In the present study, mean Pre (AL1), Postoperative (AL24) lactate level and Absolute lactate clearance (AL1 - AL24) was 2.48±1.42 and 1.74±1.52 and 0.74 mmol/L respectively. There was significant difference in the Pre (AL1) and Postoperative (AL24) lactate level (Table 1).

Table 1: Comparison Between Pre and Postoperative Lactate Level

In the present study, mean pre-operative lactate level (AL1) in expired patients was 3.78±2.24 mmol/L while among discharged patients it was 2.29 ±1.15 mmol/L and its increased level was significantly associated with mortality. The mean post-operative lactate level (AL24) in expired patients was 3.67±3.18 mmol/L while among discharged patients it was 1.45 ±0.76 mmol/L and its increased level was significantly associated with mortality. The mean Absolute lactate clearance (AL1 - AL24) in expired patients was 0.11±2.79 mmol/L while among discharged patients it was 0.84 ±1.1- mmol/L and its decreased level was significantly associated with mortality (Table 2).

Table 2: Mean Comparison of AL1, AL24 And AL1-AL24 Between Outcomes

In the present study, mean Pre (pH1), Postoperative (pH24) pH level and Procalcitonin was 7.33±0.10 and 7.35±0.11 and 0.88±0.80 ng/ml respectively (Table 3).

Table 3: Minimum, Maximum, Mean and SD Values of Ph1, Ph24 and Procalcitonin (Ng/Ml)

In the present study, mean pre-operative pH level (pH1) in expired patients was 7.16±0.09 while among discharged patients it was 7.36 ±0.08 and its decreased level was significantly associated with mortality (Figure 2). 

Figure 2: Distribution of Outcome of the Study Participants

The mean post-operative pH level (pH24) in expired patients was 7.17±0.13 mmol/L while among discharged patients it was 7.38±0.07 and its decreased level was significantly associated with mortality. The mean Procalcitonin level in expired patients was 2.58±1.26 ng/ml while among discharged patients it was 0.63±0.18 ng/ml and its increased level was significantly associated with mortality (Table 4).

Table 4: Mean comparison of PH1, PH24 and Procalcitonin (ng/ml) with Outcome

In the gastrointestinal tract, lactate is increased in acute abdominal conditions such as bowel perforation, gangrene, acute pancreatitis, intestinal obstruction and appendicular perforation. Although increased blood lactate levels have been documented as a risk factor for mortality in peritonitis [9].

Lactate levels are routinely used to assess circulatory function and tissue perfusion. Higher levels are thought to be associated with circulatory dysfunction and impaired tissue perfusion. But there are no clear-cut relationship and interpretation of results should be performed cautiously. Persistent hyperlactatemia may be result of decreased clearance instead of increased production. Also, when adrenalin is administered to the patients, production of lactate can be increased in the presence of adequate tissue oxygenation. Lactate may be a substrate for metabolism, may be increased in liver dysfunction and finally, may persist with or without tissue hypo perfusion [10]. Lactate levels were statistically significantly higher in non-survivors on the 3rd day and at that time-point demonstrated statistically significant discriminative power regarding outcome; lactate levels higher than cut-off values were good predictors of lethal outcome. These results are in accordance with other similar studies [11-14] reported that in postoperative period whenever lactate level rise above 2.0 mmol/L increased admission to the intensive care unit. The present study was prospective and purely observational, relying upon two measurements of arterial lactate (once on admission i.e. preoperative and the other 24 h post-operatively), to establish lactate values that could prognosticate mortality exclusively in secondary peritonitis.

The two static values of preoperative lactate and 24 h post-operative lactate were used to calculate lactate clearance to give a dynamic value of percent lactate clearance that was an indicator of trend or change in lactate value over the first 24 h after surgery. A fall in post-operative lactate and increased percent lactate clearance can be perceived as successful management of the patient, indicative of good resuscitation, source control, management of peritonitis and reversal of organ dysfunction, whereas a rise indicates the opposite or worsening of condition. In the present study, percent lactate clearance increase was reported. SPSS analysis reported there was difference in the lactate levels of survivors and non-survivors indicating significant role in prediction of mortality in case of secondary peritonitis. According to the present study lactate level is directly related to the change in the pH. 

In present study it was reported that there was significant elevation of percent lactate clearance levels on obstruction patients and secondary peritonitis and has significant role in the prediction of mortality. However, it was studied in literature that percent lactate clearance levels are more related with the prediction of sepsis instead of morbidity in case of secondary peritonitis. Harindranath et al. [8] reported elevated percent lactate clearance levels in patients with bacterial infection. Role of procalcitonin can also be explained by understanding the Patho physiology of ischaemia. Ischaemia is defined as decreased blood flow through the vessels inflammatory reaction then triggers the release of reactive oxygen species which in turn promotes the releases of inflammatory mediators like interferon. Interleukins, resulting oxidative stress damage the mucosa of intestine increasing the permeability of the intestinal wall then indigenous bacteria then proliferate and produce the endotoxins that ultimately promote the release of procalcitonin from the liver.

The study concluded that increased Pre (AL1), Postoperative (AL24) lactate and Procalcitonin level while decreased Absolute lactate clearance (AL1 - AL24), Pre (pH1) and Postoperative (pH24) pH level was significantly associated with mortality. 

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