VEGETACIÓN

During execution of the behavioural studies in Part II, it became apparent that existing diagnostic methods were inadequate for understanding the rapid sensorimotor swallowing response. Pharyngeal manometry is the only method of quantifying pressure in the pharynx during swallowing, therefore a comprehensive understanding of the reliability and validity of this technique is critical for clinical cross-over. Therefore, these methodological studies provide preliminary evidence to further understand the measurement accuracies and best practices in use of both low- and high-resolution pharyngeal manometry.

Chapter 11 is the first study to have compared low- and high-resolution manometry. 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 is critical to explain the variability in normative data collected by similar intraluminal instruments. Significant differences in pressures were recorded between low- and high-resolution manometry. Importantly, there were significant differences in the measurement of peak-to-peak latency in dry swallowing conditions between low- and high- resolution manometry, both when using posterior-oriented unidirectional measurement or when averaging the low-resolution manometry data to approximate a circumferential recording. Further, there were significant differences between the duration of UES relaxation between conventional posterior-oriented low-resolution manometry to HRM in liquid swallowing, and with averaged low-resolution radial pressures and HRM in dry swallowing. It is unclear if these differences result from the increased diameter of the HRM catheter, or inherent differences in measurement. Ongoing research is critical to understand these measurement differences, as they are likely exacerbated in patient cohorts who present with unilateral asymmetries, for example. At the present time, it is unclear which manometric tool offers more accurate measures, thus it is clear both techniques warrant continued use in clinical practice and research of dysphagia.

Chapter 12 analysed possible measurement error in low- and high-resolution manometry. While low-resolution manometric measurements were stable over time, the substantial drift in

corrected via standard operating instructions. This HRM drift can have a substantial impact in clinical diagnosis and research. For example, when evaluating function of the UES, normative data indicate that average nadir UES pressure of -4 mmHg has a narrow standard deviation of only 7 mmHg (Mielens et al., 2012). With a possible pressure drift of 6.5 mmHg in 15 min found in Chapter 12, caution is needed when interpreting acquired data and forming subsequent diagnoses. The standard TC process did not correct the error associated with the drift. ITC is able to correct the error associated with baseline drift, but requires communication with the manufacturer to enable this option. Overall pressure drift can have a

substantial impact in clinical diagnosis and research of pharyngealand oesophageal function

and caution should be taken when referencing previously reported normative data. Published

research using ManoScanTM HRM instrumentation need to report what type of correction is

implemented, if any, for accurate interpretation and replication of findings. Further research is indicated to evaluate if this measurement error is an inherent feature of other HRM measurement systems across manufacturers and thus pervasive across this technology. Chapter 13 investigated the effects of TNA on tolerability and pharyngeal pressure using HRM. Results indicate TNA offered no difference in procedure comfort while affecting swallowing physiology; however, further research is warranted using larger diameter HRM catheters and oral (gargled) applications of anaesthetic. Larger diameter catheters may predispose the participant to increased discomfort, yet using additional anaesthetic, such as oral applications, may alter swallowing sensorimotor function to a greater degree. 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. Given the cost, possible effect on swallowing sensorimotor function and limited improvement in procedure comfort, TNA is not essential in a procedural protocol for clinical manometric studies using 2.75-mm diameter catheters.

Lastly, Chapter 14 found the reliability of clinical swallowing measurements derived using the Knigge et al. (2014) protocol is substandard for clinical use. This is concerning given that the anatomic and measurement definitions proposed by Knigge et al. (2014) have been used in the majority of pharyngeal HRM studies to date. Further, the definitions in this protocol are being utilized in ongoing development of automated software programmes (Jones et al., 2015). Although intra-rater reliability was almost perfect after training, the majority of

measures had unacceptable inter-rater reliability. Users of pharyngeal HRM should therefore consider not only the limitations in reliability but the validity of measurements as well.

In conclusion, low- and high-resolution manometry have been further characterised with regard to reliability and validity. Low-resolution manometry appears reliable in terms of consistency across recording directions of unidirectional sensors and no apparent measurement error in response to temperature shock or study duration, unlike HRM. While advancements in HRM have overcome limitations in use of three-sensor low-resolution manometry, the results of the present work highlight ongoing limitations of HRM. Notably, there is a marked absence in analysis tools for HRM, with the only currently available published protocol demonstrating poor and variable reliability. Paired with the measurement

error seen in the ManoScanTM system, HRM should not be seen as the gold-standard as yet.

There is a great need for ongoing research to further understand differences and indications for use of unidirectional versus circumferential catheters, differences in HRM systems and best-practice for analysis of pharyngeal swallowing on HRM. While manometry provides critical objective data at higher temporal resolutions than the widely-used technique of VFSS, a stringent review of reliability and validity of this technique is essential. In the short-term, further research is needed to improve the consistency of this system-based measurement for clinical use. Long-term research is needed for optimisation of novel analysis programmes that are specific to pharyngeal swallowing. This will likely have a substantial impact on diagnostics and best practice, as inclusion of pharyngeal manometry is key to comprehensive diagnostic assessment of oropharyngeal swallowing.