Gradual sucrose gastric loading test: Does it really matter?

Abstract

Measuring gastric residual volume (GRV) is a standard practice during enteral nutrition (EN) in the Intensive Care Units (ICU). However this practice though customary is marred due to several postulations. It is assumed that GRVs in critically ill patients is a well-standardized practice, GRVs consistently and precisely measures gastric contents, they adequately indicate normal from abnormal emptying. A host of intraluminal and extraluminal causes influences gastric emptying (GE), which may be endogenous or exogenous, and can be modulated by neural and hormonal factors. Factors that may alter GE include osmolarity, volume of feeds, composition of feeds, caloric density, temperature, nature of nutrients, and systemic parameters such as blood sugar levels.[1] The definition of “high” GRV is extremely variable. One survey revealed that GRV definitions ranged from values as low as 50-400 mL.[2] The assumption that high GRV is synonymous in delayed GE is not well supported by evidence.[3] In critically ill patients specified groups are more likely to have delayed GE, these include patients with multitrauma (60%), traumatic brain injury (57%) and sepsis (42%).[4] Feeding intolerance is also related to the severity of illness. Opioids and catecholamines that are widely used in the critically ill will influence GE. A protocol of EN management without GRV monitoring is not inferior to a similar protocol, including GRV monitoring in terms of protection against ventilator associated pneumonia as demonstrated by the CRICS study.[5] Other methods of determining GE is Scintigraphy (which is considered to be a gold standard consists of recording GE by a γ-scintillation camera), paracetamol absorption test (since paracetamol is not absorbed in the stomach), breath tests using nonradioactive isotope, carbon-13 (13C), refractometry (model requires measurement of the Brix value), ultrasound to measure cross-sectional scans of a defined portion of the stomach, Gastric impedance monitoring is based on modifications of electrical resistivity (or impedance) for the estimation of GE and using magnetic resonance imaging. Most of these methods may not be practical to implement in the critically ill.[6]