After an oral dose of paracetamol, serum concentrations of paracetamol can be measured in the blood at increasing time points to assess gastric emptying [1]. This test is dependent on gastric emptying as well as intact resorption, it therefore combines properties of motility and gastrointestinal barrier. Paracetamol is absorbed rapidly if given post-pyloric [1].
Feasibility/Equipment: Paracetamol is available in all ICUs. Measurements of paracetamol levels in the blood may not be available at all sites. No specific training for ICU personnel is necessary.
Scoring information: Area under the curve is calculated from the absorption time, which then allows assessment of gastric emptying [2].
Cost: Multiple blood samples are necessary, which may be expensive.
Evidence: Paracetamol absorption tests have been shown to correctly identify post-pyloric tube placement [1]. It has been used to identify patients with delayed gastric emptying [3] and was used in the assessment of sedation strategy on gastric emptying [2]. A prospective study of 27 patients assessed the incidence of delayed gastric emptying using paracetamol absorption test [4]. In COVID-19 patients, paracetamol absorption test identified patients with delayed gastric emptying [5].
Accuracy / measurement properties: No differences were found between sedation strategies of dexmetonidine and propofol in gastric emptying time (AUC120 894.53 +/- 499.39 vs. 1113.46 +/- 598.09 propofol and dexmedetomidine groups, respectively) [2]. Paracetamol absorption test may be normal in patients even with high GRV (> 150ml) [3]. If given post-pyloric, Paracetamol concentrations peak were significantly higher with 42.6 +/- 13.5 versus 20.5 +/- 7.5 mg/L (p < .0001) [1]. In a retrospective cohort of 20 COVID-19 patients, when comparing those with a detectable paracetamol level to those with an undetectable level, there was a lower frequency of radiologic evidence of ileus (20% vs 88%; P =.03), higher tolerated tube-feed rates (40ml/h vs 10ml/h; P =.01), and a trend towards lower gastric residual volumes (45ml vs 830ml; P =.11) [5].
References
1. Berger MM, Werner D, Revelly JP, Cayeux MC, Tappy L, Bachmann C, Chiolero RL: Serum paracetamol concentration: an alternative to X-rays to determine feeding tube location in the critically ill. JPEN J Parenter Enteral Nutr 2003, 27(2):151-155.
2. Memiş D, Dökmeci D, Karamanlioğlu B, Turan A, Türe M: A comparison of the effect on gastric emptying of propofol or dexmedetomidine in critically ill patients: preliminary study. Eur J Anaesthesiol 2006, 23(8):700-704.
3. Cohen J, Aharon A, Singer P: The paracetamol absorption test: a useful addition to the enteral nutrition algorithm? Clin Nutr 2000, 19(4):233-236.
4. Tarling MM, Toner CC, Withington PS, Baxter MK, Whelpton R, Goldhill DR: A model of gastric emptying using paracetamol absorption in intensive care patients. Intensive Care Medicine 1997, 23(3):256-260.
5. Southren DL, Nardone AD, Haastrup AA, Roberts RJ, Chang MG, Bittner EA: An examination of gastrointestinal absorption using the acetaminophen absorption test in critically ill patients with COVID‐19: A retrospective cohort study. Nutrition in Clinical Practice 2021, 36(4):853-862.