Recommendation and Use of Thickened Liquids in the Management of Oropharyngeal Dysphagia
Among clinical decisions, the recommendation to use thickened liquids to reduce or prevent laryngeotracheal aspiration in the management of oropharyngeal dysphagia should be made with extreme caution and within limits. Decisions for the proper and safe use of thickened liquids to reduce aspiration potential must be made in the context of (1) potential effectiveness determined from instrumental assessments (VFSS or FEES), (2) the presence of and severity of co-morbidities such as documented dehydration, renal disease, respiratory infection and disease, nervous system impairment, reflux and gastroparesis, and potentially how thickened liquids could impact these conditions, (3) potential medication alterations and effectiveness, and (4) the potential impact on the patient’s quality of life.
Position Clinical Evidence Support:
Thickened Liquids: Benefits and Risks
Thickened liquids may reduce the risk of laryngotracheal aspiration during drinking. While aspiration may be mitigated with an increase in liquid viscosity, rates of pneumonia and respiratory complications have been shown to increase with the use of thickened liquids (Logemann et al., 2008; Wotton, 2008). While the rate of pneumonia associated with prandial aspiration—outside of acute CVA—ranges from 1-12% (Feinberg, Knebl, & Tully, 1996; Logemann et al., 2008). Even with acute CVA, it has been demonstrated that aspiration alone is insufficient for the development of pneumonia; rather, it is the activation of the parasympathetic nervous system that inhibits the immune response to pathogens in the lungs (Prass, et al., 2006). Indeed, the pathogenesis of pneumonia from aspiration of food and liquid remains poorly understood, and misconceptions about the development of nosocomial pneumonia still abound (Dickson, Erb-Downard, & Huffnagle, 2014). Yet, decades of research consistently demonstrate that aspiration alone will not result in the development of pneumonia (Langmore et al., 1998; Feinberg, Knebl, & Tully, 1996; Ashford, 2001; Brock et al., 2017).
Thickened liquids also carry an innate risk of dehydration due to a variety of factors: patients are typically offered fewer thickened liquids throughout the day, there is reduced desire to drink thickened liquids, and they cause an increased feeling of satiety (Cichero, 2013). While aspiration may lead to pneumonia, the systemic effects of dehydration can be devastating—especially with medically fragile, chronically ill, or geriatric populations. Dehydration can lead to: renal failure, constipation, urinary tract infections, hypotension, confusion/delirium, poor recovery from illness, and respiratory infections (Cichero, 2013; Wotton, 2008; Nadel, 1980; Begum, 2010; Mukand, 2003).
Further consideration is warranted for patients with reflux and gastroparesis, because thickened liquids can delay gastric emptying and slow digestion. Any treatment option that further slows digestion in these patients is particularly problematic as it could aggravate the underlying condition—placing the patient at higher risk for aspiration of gastric contents. While prandial aspiration may result in pneumonia (or may be harmless), aspiration of gastric contents can have dramatic and dire consequences—including pneumonitis, bronchospasm, bronchitis, lung fibrosis, and ARDS (Lee & Ryu, 2018).
For patients with bacterial infections, convulsions, Type 2 Diabetes, angina, hypertension, and heart and blood circulation disorders, thickened liquids have been shown to delay bioavailability of some medications. With increased liquid viscosity, delay in medication dissolution and disintegration in the gut increases (Cichero, 2013, Manrique et al., 2016). Of primary concern is the delaying effects for those medications that have narrow windows of required therapeutic levels, such as anti-convulsives and blood-thinners (O’Keeffe, 2018; Nissen et al., 2009).
Other known risks associated with thickened liquids not discussed previously: decreased quality of life, increased institutional cost to provide thickened liquids, awkward social situations, and silent aspiration.
Thickened Liquids: Considerations for Recommendation after FEES
Thickened liquids present quite a clinical conundrum. They have the ability to reduce aspiration in some patients. However, a significant body of literature, spanning at least two decades, demonstrates that prandial aspiration of liquids is insufficient to cause pneumonia without other factors (impaired immune response and poor oral care). Surprisingly, the possibility of reducing aspiration appears to trump all other concerns. Yet, thickened liquids carry significant health risks, increase cost of care, and reduce quality of life. Hence, they should be recommended only when absolutely necessary. That is, when they are shown to directly improve airway protection (visualized on VFSS or FEES) significantly over thin liquids. Contraindications for use—even with improved airway protection—would include: chronic dehydration, renal failure, gastroparesis, reflux, and patient inability to intake enough fluids to maintain hydration. Additionally, consultation with a pharmacist would be warranted to determine if they would interfere with medication absorption. In summation, thickened liquids carry multiple risks that could negatively impact the overall health of patients, and the recommendation to consume thickened liquids should be made with extreme caution.
(Ward, M., & Ashford, J.)