Methodological Studies

6.2.1 A Comparison of Low- and High-resolution Pharyngeal Manometry

Research question: The advent of HRM overcame many of the limitations of low-resolution

manometry. However, there was a discrepancy in the literature when comparing normative pharyngeal pressure data, with variable temporal data and markedly increased standard deviations using HRM instrumentation (Lamvik et al., 2014; Mielens et al., 2012). How do low- and high-resolution manometry compare in a within-subject investigation of amplitude and latency of pharyngeal pressure?

Objective: To evaluate timing and amplitude of swallowing pressure by comparing two

methods of recording pharyngeal pressure generation: unidirectional, low-resolution manometry and circumferential, high-resolution manometry.

Hypothesis: There would be no significant difference in the peak or nadir amplitude between

the two sensor types. There would be no significant difference in the duration of UES relaxation.

Significance: Advancements in the development of HRM have largely replaced a long

history of manometric data collected with standardized, unidirectional low-resolution catheters. Understanding differences in measurement between these two intraluminal pressure measurement devices was critical to explain the variability in normative data collected by these instruments. This may aid in improving diagnostic specificity.

Proposed Study (see Chapter 11): Low- and high-resolution manometry measurements

were investigated using a within-subject design, with order of evaluation equal across two counter-balanced groups. Participants were evaluated under four conditions with low- resolution manometry, specifically with the unidirectional sensors recording in one of four directions intraluminally to mimic circumferential evaluation. In each condition, the participant performed five dry swallows and five 10 mL liquid bolus swallows. During HRM, participants performed the same protocol of ingestion, including dry and liquid swallows in one recording condition. Amplitude and latency of pressure were directly compared in corresponding sensors within each participant and across conditions with repeat-measures ANOVA (see section 11.2.3 for further details).

6.2.2 Characterization and Correction of Measurement Error in Low- and High-resolution Manometry: In-Vitro and In-Vivo

Research question: Valid investigation of timing and amplitude of pharyngeal pressure is

reliant on instrumental measurement accuracy. However, a substantial pressure drift in the ManoScan™ HRM system has been reported (Babaei et al., 2015; Robertson et al., 2012) and similar investigations of measurement consistency in low-resolution manometry are not evident in the literature. What measurement error is evidenced pharyngeal manometry and with what accuracy do possible error corrections perform?

Objective: To explore measurement error and subsequent compensation with low-resolution

manometry and HRM in-vitro and in-vivo, in both abbreviated and extended-length recordings.

Hypothesis: Due to the differences in sensor composition, measurement would be

significant measurement error would be documented in HRM. It is hypothesized the available correction methods will appropriately compensate for the measurement error.

Significance: This study was the first to analyse possible measurement error both in-vitro

and in-vivo in low- and high-resolution manometry. Controlled in-vitro studies are robust for investigating system faults and comparison to in-vivo data was critical for both clinical use and future research of HRM. Thus, identification and characterisation of measurement error in pharyngeal manometry can have a substantial impact in clinical diagnosis and utility of existing normative data.

Proposed Study (see Chapter 12): Short and extended duration studies were completed with

low-resolution manometry and HRM. Studies were performed in-vitro using a water bath at 37°C and in-vivo studies will be performed with healthy participants. Two correction methods – TC and interpolated thermal compensation (ITC) – were tested (see section 12.2.3 for further details).

6.2.3 The Effect of Topical Nasal Anaesthetic on Tolerability and Pharyngeal Pressure in Healthy Adults: A Double-Blind Study

Research question: Topical nasal anaesthetic (TNA) is used in research and clinical

examinations with pharyngeal HRM and recommended in clinical HRM protocols (Knigge et al., 2013). However, it was unclear if desensitizing the nasal mucosa improves procedure tolerability or affects pharyngeal swallowing.

Objective: To evaluate the effect of TNA on participant perception of procedure comfort,

as well as timing and amplitude of pharyngeal swallowing using pharyngeal HRM.

Hypothesis: There would be no significant differences in the participant report of procedure

comfort between the two TNA and placebo test conditions. Further, healthy participants will demonstrate no difference in amplitude and timing of pharyngeal pressure under the TNA and placebo conditions.

Significance: Results from this study may allow refinement of published protocols for

conducting this examination and offer further information to guide best practice of pharyngeal HRM and similar trans-nasal intubation techniques.

Proposed Study (see Chapter 13): A double-blind study was conducted with healthy

participants, who received two examinations counter-balanced under placebo (lubricant) and anaesthetized (0.4 ml of 2% viscous lidocaine hydrochloride) conditions. Procedural comfort was rated using a 100-mm visual analog scale and comparisons were made using paired samples t-tests (see section 13.2.3 for further details).

6.2.4 Reliability of Clinical Analyses of Swallowing using Pharyngeal High-resolution Manometry

Research question: Knigge et al. (2014) provide the only published clinical protocol for

analysis of HRM spatiotemporal plots using existing system-based technologies (e.g., ManoScan™ HRM systems). The reliability of this technique was unknown.

Objective: To evaluate the reliability of clinical swallowing measurements made using the

analysis protocol described by Knigge et al. (2014).

Hypothesis: Raters would demonstrate sufficient inter-rater reliability and intra-rater

reliability (ICC > 0.75; Portney & Watkins, 2008) consistent with similar prior research (Jones et al., 2014).

Significance: The anatomic and measurement definitions proposed by Knigge et al. (2014)

have been used in the majority of pharyngeal HRM studies and are being utilized in ongoing development of automated software programmes (Jones et al., 2015). Therefore, understanding the reliability of this technique is imperative to appreciate the consistency of this system-based measurement for clinical use. This would likely have an impact on diagnostics and best practice, as further research is needed to standardize measurement of pharyngeal swallowing using HRM.

Proposed Study (see Chapter 14): Clinical researchers participated in a 20 min training

(2014) protocol. Raters analysed 3 individual swallows from 3 healthy participants and 3 patients, with one repeated swallow from each sample for intra-rater analysis. Swallows were coded for blinding and randomized within and across raters. Statistical analysis included ICC to assess intra- and inter-rater reliability, interpreted with Portney et al. (2009) criterion (see section 14.2.3 for further details).