Outcome / PredictionThe prognostic value of the strong ion gap in acute pancreatitis
Introduction
Acid-base disorders are common in critically ill patients and associated with high mortality [1], [2], [3]. In patients with acute pancreatitis (AP), such disorders are often present on admission to the intensive care unit (ICU) [4], [5]. The epidemiology and clinical significance of such disorders in AP, however, are poorly understood.
The traditional method for interpreting acid-base disorders is based on the Henderson-Hasselbalch equation [6], which is then coupled with the anion gap (AG) [7] and clinical assessment to define the presence of specific metabolic or respiratory acid-base states. However, the traditional method has been criticized for not taking into account the impact of hypoalbuminemia, disorders of phosphatemia, and the presence and impact of unmeasured anions when used improperly (without correction for hypoalbuminemia) [8], [9], [10]. Stewart's approach offers an alternative paradigm for the interpretation of acid-base disorders and allows for quantification of the effects of changes in strong ion difference (SID), albumin and phosphate levels, and unmeasured anions (strong ion gap [SIG]).
Two studies have shown that SID and SIG correlate with hospital mortality in trauma patients [11], [12]. Moreover, the prognostic value of SIG was also confirmed in other critically ill patients [13]. More recently, Sharma et al [5] also found that arterial pH, bicarbonate levels, and base deficit at presentation were early markers for predicting adverse outcome in AP. However, no information exists on the predictive value of acid-base variables as estimated by the Stewart approach in patients with AP.
The purpose of our investigation was to evaluate how acid-base variables obtained at the earliest stages of AP and analyzed according to the Stewart model may help predict subsequent AP severity and AP-related mortality.
Section snippets
Patients and materials
We conducted a retrospective, cohort study in the surgical ICU of Jinling Hospital, Nanjing, China, a tertiary referral center for the treatment of AP. The data collection for this study was approved by the institutional review board of Jinling Hospital. Patients with a primary diagnosis of AP admitted to our center from September 2010 to June 2014 were screened for potential inclusion. Diagnosis of AP required 2 of the 3 following criteria: (1) abdominal pain consistent with the disease, (2)
Results
During the study period, 980 patients with AP were screened and 794 were excluded (see the details in Fig. 1), leaving 186 consecutive patients for analysis. Their demographic data are shown in Table 1. The study patients had an overall mortality of 17.7%. In total, 24 (72.7%) patients died of septic shock and multiple-organ failure, 4 (12.1%) died of uncontrolled intra-abdominal hemorrhage, 2 (6.1%) died of tracheal hemorrhage, and the last 3 died of middle cerebral artery aneurysm rupture
Key findings
We conducted a retrospective observational study to identify predictors of severity and outcome in a large cohort of AP patients from a tertiary referral center for pancreatitis in China before fluid resuscitation. We aimed to evaluate whether the Stewart analysis might help predict severity, mortality, and AKI in adult AP patients with simple and routine clinical tests. Our results suggested that SIG was an accurate predictor of severity of AP and a moderate predictor of mortality and
Conclusions
In this study, we assessed the predictive value of the SIG in patients with AP. Our study demonstrated that an elevated SIG was a common phenomenon at the early stage of severe AP, that it was independently correlated with adverse outcomes, and that it was an accurate predictor of subsequent severity and mortality, suggesting that it could be used in the triage, risk stratification, management, and prognosis of such patients in the future.
Acknowledgments
This study was supported by the National Science Foundation of China (81300360). The funding agency had no role in study design, the collection of data, in the interpretation of data, in the writing of the article, or in the decision to submit the article for publication.
References (37)
- et al.
Strong ion gap: a methodology for exploring unexplained anions
J Crit Care
(1995) - et al.
Strong ions, weak acids and base excess: a simplified Fencl-Stewart approach to clinical acid-base disorders
Br J Anaesth
(2004) - et al.
Unmeasured anions account for most of the metabolic acidosis in patients with hyperlactatemia
Clinics (Sao Paulo)
(2007) - et al.
Diagnosis and treatment of acute pancreatitis
Surg Clin North Am
(1951) - et al.
Base deficit correlates with mortality in pediatric abusive head trauma
J Pediatr Surg
(2013) - et al.
Stewart analysis of apparently normal acid-base state in the critically ill
J Crit Care
(2013) - et al.
Acid-base and electrolyte analysis in critically ill patients: are we ready for the new millennium?
Curr Opin Crit Care
(2003) - et al.
Acid-base disorders evaluation in critically ill patients: we can improve our diagnostic ability
Intensive Care Med
(2009) - et al.
Unmeasured anions in critically ill patients: can they predict mortality?
Crit Care Med
(2003) - et al.
Changes in acid-base equilibrium in acute pancreatitis
Khirurgiia (Mosk)
(1968)
Arterial pH, bicarbonate levels and base deficit at presentation as markers of predicting mortality in acute pancreatitis: a single-centre prospective study
Gastroenterol Rep (Oxf)
A balanced view of balanced solutions
Crit Care
Diagnosis of acid-base derangements and mortality prediction in the trauma intensive care unit: the physiochemical approach
J Trauma
Serum proteins and acid-base equilibria: a follow-up
J Lab Clin Med
Initial pH, base deficit, lactate, anion gap, strong ion difference, and strong ion gap predict outcome from major vascular injury
Crit Care Med
Anion gap as a predictor of trauma outcomes in the older trauma population: correlations with injury severity and mortality
Am Surg
Classification of acute pancreatitis—2012: revision of the Atlanta classification and definitions by international consensus
Gut
Multiple organ dysfunction score: a reliable descriptor of a complex clinical outcome
Crit Care Med
Cited by (0)
- 1
These authors contribute equally to the paper.