PS#1: Thickened Liquids in the Management of Oropharyngeal Dysphagia

Position Statement: 

 SA Swallowing Services recommends minimal use of thickened liquids with patients with dysphagia. 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 

Benefits: Thickened liquids may reduce the risk of laryngotracheal aspiration during drinking. Newman et al. (2016) provides the rationale for use of thickened liquids. Use of thickened liquids helps improve swallowing safety by (a) increasing oral transit time; (b) normalizing swallow patterns; (c) enhancing sensory input; and (d) allowing more time for airway closure. Subacute phase postradiation head and neck cancer patients were reported to have less aspiration using minimally thickening of liquids, like smoothies. However, residue was common but not necessarily worsened with slightly or mildly thick liquids (Barbon et al., 2021)

Risks: 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).  There is no convincing evidence to suggest that modified liquid consistencies prevent pneumonia in adults with dysphagia (O’Keeffe, 2018).  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, Prass et al., (2006) 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. 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, 2005).

Thickened liquids carry an innate risk of dehydration due to a variety of factors: patients are typically offered fewer thickened liquids throughout the day, there is less 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 empty 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). 

 Other known risks associated with thickened liquids not discussed previously: decreased quality of life, increased institutional cost to provide thickened liquids, awkward social situations, interference with absorption of medications, and silent aspiration (O’Keefe, 2018).

 References

 Ashford, J. R. (2005). Pneumonia: Factors beyond aspiration. Perspectives on Swallowing and Swallowing Disorders (Dysphagia), 14(1), 10-16.

Barbon, C. E., Chepeha, D. B., Hope, A. J., Peladeau-Pigeon, M., Waito, A. A., & Steele, C. M. (2022). Determining the Impact of Thickened Liquids on Swallowing in Patients Undergoing Irradiation for Oropharynx Cancer. Otolaryngology–Head and Neck Surgery, 166(3), 511-514.

Cichero, J. A. (2013). Thickening agents used for dysphagia management: effect on bioavailability of water, medication and feelings of satiety. Nutrition Journal, 12(1), 1-8.

Dickson, R. P., Erb-Downward, J. R., Martinez, F. J., & Huffnagle, G. B. (2016). The microbiome and the respiratory tract. Annual review of physiology, 78, 481-504.

Feinberg, M. J., Knebl, J., & Tully, J. (1996). Prandial aspiration and pneumonia in an elderly population followed over 3 years. Dysphagia, 11(2), 104-109.

Langmore, S. E., Terpenning, M. S., Schork, A., Chen, Y., Murray, J. T., Lopatin, D., & Loesche, W. J. (1998). Predictors of aspiration pneumonia: how important is dysphagia? Dysphagia, 13, 69-81.

Lee, A. S., & Ryu, J. H. (2018, June). Aspiration pneumonia and related syndromes. In Mayo Clinic Proceedings (Vol. 93, No. 6, pp. 752-762). Elsevier.

Logemann, J. A., Gensler, G., Robbins, J., Lindblad, A. S., Brandt, D., Hind, J. A., ... & Gardner, P. J. M. (2008). A randomized study of three interventions for aspiration of thin liquids in patients with dementia or Parkinson’s disease.

Mukand, J. A., Cai, C., Zielinski, A., Danish, M., & Berman, J. (2003). The effects of dehydration on rehabilitation outcomes of elderly orthopedic patients. Archives of physical medicine and rehabilitation, 84(1), 58-61.

Nadel, E. R., Fortney, S., & Wenger, C. B. (1980). Effect of hydration state of circulatory and thermal regulations. Journal of Applied Physiology, 49(4), 715-721.

Newman, R., Vilardell, N., Clavé, P., & Speyer, R. (2016). Effect of bolus viscosity on the safety and efficacy of swallowing and the kinematics of the swallow response in patients with oropharyngeal dysphagia: white paper by the European Society for Swallowing Disorders (ESSD). Dysphagia, 31, 232-249.

O’Keeffe, S. T. (2018). Use of modified diets to prevent aspiration in oropharyngeal dysphagia: is current practice justified?. BMC geriatrics, 18, 1-10.

Prass, K., Braun, J. S., Dirnagl, U., Meisel, C., & Meisel, A. (2006). Stroke propagates bacterial aspiration to pneumonia in a model of cerebral ischemia. Stroke, 37(10), 2607-2612.

Wotton, K., Crannitch, K., & Munt, R. (2008). Prevalence, risk factors and strategies to prevent dehydration in older adults. Contemporary nurse, 31(1), 44-56.

Begum, M. N., & Johnson, C. S. (2010). A review of the literature on dehydration in the institutionalized elderly. e-SPEN, the European e-Journal of Clinical Nutrition and Metabolism, 5(1), e47-e53.