2. Reliable lip force measurement in healthy controls and in patients with stroke. A methodological study.

A prefabricated oral screen has shown promising results as a muscle self-training device to improve the lip function of stroke patients affected by oropharyngeal dysphagia. However, a technique for the measurement of lip muscle force, whether in healthy individuals or in stroke patients, is lacking. The present study was designed to (1) test the intra- and inter-reliability of lip force measurements by means of a newly devised Lip Force Meter, LF100, (2) determine a normal lower limit for lip force in Newtons (N), and (3) ascertain the instrument’s sensitivity and specificity. LF100 is a modified strain gauge for recording the ability of lips to withstand pressure from a pre-dentally placed oral screen. Forty-two healthy controls and 22 stroke patients agreed to participate in the trial. The controls and patients were examined three times with the LF100, with 2-min rest intervals, twice by investigator MH and once by investigator MO. Intra-investigator reliability with the LF100 proved excellent in both controls and patients: ICC was 0.83 and 0.90, respectively. Inter-investigator reliability was good or excellent in both groups: ICC was 0.71 and 0.91. There was a significant difference in lip force between controls and stroke patients (mean = 24.7 ± 6.3 N and 9.5 ± 5.5 N, p < 0.001). The sensitivity of LF100 was 91 % and the specificity 95 %. The cut-off level for normal lip force was 15 N. The LF100 showed itself to be a suitable and reliable instrument for measuring lip force.

Dysphagia: Proof of effective measurement of pharyngeal sling competence. And the existence of a lower normal limit.

Peer reviewed. Methodological study.

To (i) test the intra- and inter-reliability of pharyngeal sling force measurements by means of a newly devised Lip Force Meter, LF100, (ii) determine a normal lower limit for this, and (iii) determine the instrument’s sensitivity and specificity.

• 64 patients: 22 with stroke, F=13, M=9, mean age 77 years (range 38 – 90)
• 42 healthy controls, F=27, M=15, mean age 57 years (range 25 – 87).

Test for intra- and inter-reliability of pharyngeal sling force by means of so-called lip force measurements (LF100). Determine a normal lower limit for pharyngeal sling force measured in Newtons. Determine LF100 instrument’s sensitivity and specificity.

Pharyngeal sling competence (using Lip Force meter – LF100), Inter Class Coefficient (ICC).

Intra-investigator reliability with the LF100 ICC was 0.83 – 0.90. Inter-investigator reliability ICC was 0.71 – 0.91. Significant difference in pharyngeal sling competence between controls and stroke patients (mean = 24.7 ± 6.3 N and 9.5 ± 5.5 N, p < 0.001). The sensitivity of LF100 was 91 % and the specificity 95 %. The lower cut-off level for pharyngeal sling force was 15 N.

(p < 0.001) difference in pharyngeal sling competence between controls and stroke patients.

The LF100 showed itself to be a suitable and reliable instrument for measuring pharyngeal sling competence. The Kappa coefficient of Intra-investigator reliability is rated as ‘almost perfect agreement’ and the inter-investigator reliability as ‘substantial agreement’.