A retrospective cohort study of perioperative prognostic factors associated with intra-abdominal sepsis.

CONTEXT: Intra-abdominal sepsis following laparotomy for acute abdomen remains still a challenging condition. The understanding of various perioperative risk factors by anesthesiologists are crucial in optimum management these patients. AIMS: The objective of this study is to assess the perioperative risk factors, which predicts the outcome of treatment. SETTINGS AND
DESIGN: This retrospective observational study of 603 patients who underwent Laparotomies between March 2012 and March 2015 at our University Medical College. Of 603 patients, 52 consecutive patients with intra-abdomen sepsis who underwent surgical procedures and admitted in Intensive Care Unit (ICU) were selected and analyzed for prognostic risk factors in relation to severity of the disease. SUBJECTS AND METHODS: 52 consecutive patients who developed intra-abdominal sepsis following laparotomy was allocated one of two groups; Group Sepsis, patients with peritonitis without systemic hypotension (mean arterial pressure [MAP] >60 mm of Hg); and Group septic shock, patients with peritonitis with systemic hypotension (mean arterial pressure [MAP] <60 mm of Hg) and patients were analyzed for prognostic risk factors. STATISTICAL ANALYSIS USED: Categorical variables were analyzed by using Fisher's exact (two-tail) test and continuous variable were analyzed by using Mann-Whitney (two-tail) U-test.
RESULTS: Out of 603 patients who underwent laparotomy 52 patients developed an intra-abdominal septic complication. Of these 52 cases studied 28 patients developed septic shock and required a longer duration of admission in ICU and more inotropic support. Preoperative albumin and hematocrit level were significantly low in septic shock patients as compared to the patients with sepsis without systemic hypotension. PaCO2: FiO2 was also significantly low in these patients.
CONCLUSIONS: Preoperative low hematocrit, low albumin level, and delay in laparotomy more than 72 h were also associated with adverse outcome in the patients with intra-abdominal sepsis. Clinicians should maintain equipoise on this topic pending prospective randomized clinical trials.

INTRODUCTION

Sepsis following laparotomy is one of the common condition encountered by an anesthesiologist in surgical Intensive Care Units (ICUs), intra-abdominal sepsis is associated with significantly increased mortality, and morbidity in spite of advances in diagnosis and management.[1]

Despite the advances, antimicrobial therapy and ICU support the mortality due to intra-abdominal sepsis remains significantly high. The pathogenesis of intra-abdominal sepsis is dependent on bacterial load, virulence and synergy between bacterial species and promotional growth of bacteria by the presence of intestinal contents. In addition to this host defense mechanism and appropriate medical intervention contribute to the successful outcome.[2]

In this study, we have studied various prognostic risk factors in the patients with severe abdominal sepsis requiring intensive care therapy. The primary aim was to compare risk factors among septic shock patients with sepsis without systemic hypotension in terms of their clinical, laboratory, microbiological, and therapeutic data. It was hoped that by identifying and addressing these factors it might be possible to identify poor prognostic factors and ultimately improve outcome.

SUBJECTS AND METHODS

This was a retrospective observational study of adult patients with intra-abdominal sepsis admitted to ICU of University Medical College from March 2012 to March 2015. This study was approved by Intuitional Ethical Committee.

Data were collected from registered files at the Department of Surgery. For the purpose of patients selection, we defined intra-abdominal sepsis with shock as patients with peritonitis or localized abscess at laparotomy associated with systemic hypotension (mean arterial pressure [MAP] <60 mm of Hg) and intra-abdominal sepsis without shock in the patients with peritonitis or localized abscess at laparotomy without systemic hypotension (MAP > 60 mm of Hg) who subsequently required admission to ICU.

During this study, we reviewed the ICU chart, treatment strategy, investigation, and mortality.

Following data were collected for analysis of risk factors. Age and gender, co-morbid illness, duration of ICU stay, time duration between onset of symptoms and time of surgery, preoperative steroid use, whether the initial surgery was elective or an emergency, whether mechanical ventilation was required, coagulation profile, preoperative hematocrit and albumin, requirement for and duration of inotropic support, dialysis, corticosteroids, and blood transfusions.

Statistical analysis

Statistical analysis were has done by SPSS version 13 software (SPSS South Asia Pvt. Ltd., Bengaluru, Karnataka, India), where categorical variables were analyzed by using Fisher's exact (two-tail) test and continuous variable, were analyzed by using Mann–Whitney (two-tail) U-test.

RESULTS

Demographic variables were represented in Table 1. There were no differences between genders in this severity of sepsis. The median age of patients with septic shock was 49 years ranges from 31 to 88 years as compared 28 years in the patients with sepsis without hypotension which was statistically significant. Twelve patients older than 65 years developed septic shock as compared to only 4 patients with sepsis without shock which was statistically significant. There was no difference in the severity of sepsis among male and female gender though there was more male in both the groups.

Table 1

Age group and gender distribution

Co-morbid illnesses were present in both groups as shown in Table 2. Thepatients in septic shock group had higher co-morbid illness and 8 patients aged more than 65 years developed septic shock had more than 2 co-morbidities as compared to only 1 patient in sepsis group.

Table 2

Co-morbid illnesses in study group

Forty-four percent (23 patients) of the patients who developed intra-abdominal sepsis surgery was done as an emergency procedure. Out of these 69.5% of patients, 16 patients developed septic shock as compared to 27% in patients who have undergone elective surgical producers (29 patients) [Table 3]. Table 4 shows preoperative albumin and hematocrit levels were significantly low in the patients with septic shock. Mean preoperative albumin level was 18 g/L as compared to 27 g/L in the patients with sepsis without systemic hypotension. Mean preoperative hemoglobin level was 28.1% in case of sepsis as compared to 21.6% in the patients with septic shock. This was statistically significant.

Table 3

Urgency of surgery

Table 4

Preoperative investigations

According to Table 5, the mean duration of ICU stay of patients with septic shock was 13 days as compared to 4 days in the patients with sepsis. 70% of patients with septic shock patients required more than 10 days ICU admission as compared to 18% of patients with sepsis. Out of these 78% of the patients with a septic shock, 6 patients died in ICU. All these patients had multi organ dysfunction syndrome. 40% of these patients with sepsis shock required renal replacement therapy.

Table 5

ICU stay

The septic shock patients had a significantly longer stay in the ICU than the sepsis group patients (13 days vs. 4 days; P = 0.022), all the patient required mechanical ventilation as compared to only three patients in sepsis group (P = 0.024), septic shock patients had significantly more blood transfusions (6 vs. 0.5; P = 0.001), they required more inotropic support and corticosteroids.

DISCUSSION

This is the retrospective consecutive cohort study to investigate the perioperative prognostic risk factors associated with severe sepsis and septic shock. The current study confirmed that the proportion of the patients with preoperative low albumin level, low hematocrit, more than 2 co-morbidity increases the risk of septic shock after surgery. Co-morbid illnesses were present in both the sepsis and septic shock patients. The common co-morbidities were mainly risk factors for systemic vascular diseases such as hypertension, chronic obstructive pulmonary disease, ischemic heart disease, and diabetes mellitus.

In our study, the albumin and hematocrit levels on admission were low in both the septic shock and sepsis without hypotension patients. The presence of a low serum albumin and hematocrit has been shown to be an important risk factor for perioperative septic shock[3] and for treatment failure in patients with bacterial peritonitis. Preoperative correction of hypoalbuminemia and anemia may reduce these complications.

It is well-known that hypotension is associated with an increased risk of sudden and unexpected death in the patients admitted to hospital with nontraumatic diseases;[4] identifying patients with severe sepsis early and correcting the underlying micro vascular dysfunction may improve patient outcomes. If not corrected, micro vascular dysfunction can lead to global tissue hypoxia, direct tissue damage, and ultimately, organ failure.[5]

In this study, the most important factors related to the severity of septic shock were the inability to gain early source control, as determined by the ongoing need for surgery, delay in surgery, the number of blood transfusions, and dialysis. The timing and adequacy of source control are of most importance in the management of intra-abdominal sepsis, as late and/or incomplete procedures may have severely adverse consequences on the outcome.

Source control encompasses all measures undertaken to eliminate the source of infection, reduce the bacterial inoculum and correct or control anatomic derangements to restore normal physiologic function.[67]

Renal failure requiring continuous renal replacement therapy (CRRT) in abdominal sepsis appears to be a poor prognostic factor. In our patients, none of those with sepsis without systemic hypotension required CRRT, whereas 25% of patients with septic shock required renal replacement therapy. In patients with sepsis, attention should always be paid to acute kidney injury (AKI). Patients with AKI had lesser ventilator-free and ICU free days and a decreased likelihood of discharge to home. Morbidity and mortality increased with severity of AKI, and AKI of any severity was found to be a strong predictor of hospital mortality.[89]

In our study, age more than 65 years increases the risk of septic shock and mortality, some reports have also noted that mortality is higher in those aged >60 years.[101112]

The first-line management of the septic shock patients is the administration of intravenous antimicrobial therapy. Antimicrobials play an important role in the management of intra-abdominal sepsis, especially in the patients with severe shock who require immediate empirical antibiotic therapy.

An insufficient or otherwise inadequate antimicrobial regimen is one of the variables more strongly associated with unfavorable outcomes in critical ill patients.[13] Empiric antimicrobial therapy should be started as soon as possible in the patients with severe sepsis with or without septic shock.[141516]

Considering recent trials with novel treatment, it will be important to delineate the risk factors that reflect septic processes that are potentially modifiable. We have found that preoperative low albumin and hematocrit, increases the risk of perioperative septic shock, correcting these may reduce perioperative mortality and morbidity due to sepsis.

Our results should be considered in light of several limitations. First, data used in this study are subject to possible inaccuracies inherent in administrative datasets. Further prospective randomized studies will mitigate the shortcoming of this retrospective study.

CONCLUSIONS

We conclude that the patients with abdominal sepsis are at increased risk severe sepsis with systemic hypotension if preoperative albumin and hematocrit are low, and there is inadequate initial source control. Additionally, the outcome is worse if the patient required renal replacement therapy. The requirement for inotropes, longer ICU stays, and the requirement for blood transfusion also significantly increases the severity of sepsis.

Financial support and sponsorship

Subbaiah Institute of Medical Sciences, Shimoga, Karnataka, India.

Conflicts of interest

There are no conflicts of interest