# Can Arterial Blood Gas, Electrolyte and Acid–Base Analysis at Admission be Used to Predict Survival to Hospital Discharge for Different Causes of Colic?

## TL;DR

This study shows that arterial blood tests on admission can predict survival in horses with different types of colic.

## Contribution

The study identifies specific arterial blood parameters that correlate with survival in various colic types in horses.

## Key findings

- Arterial blood measures like PaO2 and Na+ are associated with survival in non-strangulating and strangulating small intestinal colic.
- Calcium and bicarbonate levels are significant predictors for large colon non-volvulus colic.
- Arterial blood analysis shows good sensitivity but poor specificity in predicting survival.

## Abstract

Predicting outcome in horses presenting with colic remains challenging.

To test whether arterial blood samples in horses admitted for colic predict outcome to hospital discharge for different colic types.

Arterial blood samples collected on admission from 358 horses undergoing medical or surgical management of colic were evaluated for pH, PaO2, PaCO2, Na+, K+, iCa2+, Cl−, HCO3
− (P), HCO3
− (P, set), Base (B), Base (ecf) and anion gap. Categories were small intestinal non‐strangulating (SINS) or strangulating (SIS) lesions, large colon non‐volvulus (LCNV) or volvulus (LCV), small colon non‐strangulating (SCNS) or strangulating (SCS) lesions, viscus rupture or other. Multivariable logistic regression models were developed based on survival, or not, to hospital discharge. Odd ratios (ORs) with 95% confidence intervals (95%CI) and area under the curve receiver operator characteristics (AUROC), sensitivity, specificity and positive and negative predictive values were calculated at a cut‐off value of p = 0.5.

A total of 295/358 (82.4%) horses survived to hospital discharge. Variables retained as significantly associated with survival were PaO2 for SINS (OR 1.15, 95%CI 1.04–1.27), PaO2 (OR 1.06, 95% CI 1.01–1.11) and Na+ (OR 1.24, 95% CI 1.02–1.52) for SIS, Ca2+ (OR 175.1, 95% CI 2.20–13958) and HCO3
− (P) (OR 1.18, 95% CI 1.01–1.37) for LCNV and PaCO2 (OR 1.47, 95% CI 1.05–2.06) for LCV. AUROCs showed acceptable‐excellent discrimination (range: 0.7–0.9), excellent sensitivity (range: 91%–100%) but poor–fair specificity (range: 8%–50%).

Arterial blood is good at predicting survival based on colic type but less accurate at predicting those horses which do not survive to hospital discharge.

This study used arterial blood analysis taken on admission to determine which measures were associated with survival to hospital discharge in a cohort of horses presenting to a single clinic for medical and surgical management of colic. Specific arterial blood measures were found to be associated with survival in non‐strangulating and strangulating small intestinal and in large colon volvulus and non‐volvulus conditions
.