Objective: Safe swallowing may be achieved in most patients with neurogenic dysphagia by manipulating the viscosity of ingested fluids. However, in clinical practice fluids are thickened using subjective judgement. This may lead to errors in the preparation of drinks to the prescribed viscosity. The aim of the present study is to examine whether the use of a viscometer improves the dietary management of dysphagic stroke patients.

Study design: A randomized controlled study design was used. The speech and language therapist determined the optimal fluid thickness for each patient. The prescribed fluid viscosity for the study group was obtained using a viscometer. Patients in the control group received fluids prepared according to current practice, i.e. the amount of thickener required to produce the prescribed viscosity was judged subjectively by the nursing staff. The two methods of fluid thickening were used for seven consecutive days. Assessment was made blind to randomization.

Main outcome measure: Pulmonary aspiration, assessed clinically and with pulse oximetry. If the patient did not drink all the fluid that was offered the residue was measured.

Results: Ten patients in the study group (n = 23) and nine in the control group (n = 23) aspirated. The mean viscosity of fluids offered to patients in the control group was significantly higher than that of the study patients. There was a statistically significant correlation between the viscosity and the residual volume of fluid (Pearson's test: r = 0.7, p <0.02). The findings of the study suggest that fluids prepared by subjectively assessing the amount of thickener required to produce a given consistency tend to have a higher viscosity than those prepared using the viscometer. However, the higher viscosity does not appear to protect against pulmonary aspiration and may lead to a reduced fluid intake.

Conclusion: Manipulation of fluid thickness using objective measurements with a viscometer may improve the dietary management of dysphagic stroke patients.