Feeding difficulties in children encompass a wide spectrum including delayed feeding skills development, disordered sensory processing, preferences for a limited range of food types or textures, aversive feeding behaviours resulting in food refusal and/or difficulty with swallowing (oropharyngeal dysphagia) . Oropharyngeal dysphagia is the term used to define dysphagia involving the oral and/or pharyngeal phases of swallowing. Oropharyngeal dysphagia is clinically important in children as its consequences may include inadequate nutritional intake, dehydration and oropharyngeal aspiration (OPA) . OPA is defined as the entry of fluids, food particles and/or oral secretions into the airway below the level of the true vocal cords . OPA is associated with acute respiratory sequelae such as apnea, tachypnea and pneumonia and chronic sequelae such as chronic cough and bronchiectasis [3, 4]. Thus, early detection and appropriate management of OPA is important to prevent chronic pulmonary disease and poor growth in children.
Proving the diagnosis of recurrent OPA as the reason for persistent or chronic respiratory systems remains elusive in respiratory medicine . The first step in evaluating a child for oropharyngeal dysphagia is often a clinical feeding examination (CFE) conducted by a speech pathologist. It is subjective [5, 6] but inexpensive, non-invasive, time efficient and repeatable. The CFE involves a case history and mealtime observations of the child’s oral sensorimotor, feeding and swallowing skills [5, 7–9]. However, the examination only provides an estimation of the co-ordination and movement of food/fluids through the pharyngeal phase. This is determined through visual observation of laryngeal movement , palpation of laryngeal movement  and listening to clinical features (e.g. cough [12, 13], wet voice [5, 14], choking, voice change) [12, 14]. In particular, clinical features such as wet voice and wet breathing have been significantly associated with OPA detected on MBS . In children, high sensitivity (92%) on fluids but low sensitivity (33%) on solids for the detection of OPA via CFE has been documented in comparison to MBS findings . Similarly, the CFE in adults is limited by low sensitivity and specificity values for the identification of OPA when compared with MBS [9, 15, 16]. This limitation to the accurate identification and assessment of OPA means many children require further objective assessment, such as a MBS or fiberoptic endoscopic evaluation of swallowing (FEES), to more accurately detect and identify OPA on a variety of food textures and fluid consistencies.
MBS and FEES have comparable sensitivities [17, 18] and reliably detects OPA [15, 17, 19–22], especially when the Penetration-Aspiration Scale (PAS) is used [21, 23]. However, both procedures are usually limited to specialist paediatric tertiary centres, are expensive, and require the expertise of a paediatric speech pathologist and radiologist or an otolaryngologist. These may not be readily available because of scheduling requirements of personnel, suites and equipment. Furthermore, MBS involves radiation although at acceptable levels .
To improve the diagnostic accuracy of the CFE for detecting OPA, several approaches to the examination have been studied. These include combining the CFE with water swallow challenges [7, 25–27], trial swallows using different viscosities [8, 13], pulse oximetry  and using cervical auscultation (CA). CA is a portable, non-invasive technique that uses a stethoscope to detect cervical sounds generated during the swallow and breath sounds pre- and post-swallow. It is based on the premise that fluid flow through the upper oesophageal sphincter can be heard by listening to the cervical neck region. Higher OPA agreement between CFE + CA (76%), rather than CFE only (42%), when compared to MBS results have been reported in separate adult studies [16, 28]. Further, unpublished data titled “Impact of cervical auscultation on accuracy of clinical evaluation in predicting penetration/aspiration in a paediatric population” by Eicher et al. presented at a CA workshop in Virginia (1994) compared CFE (n = 15) and CFE + CA (n = 41) with MBS findings in 56 children (aged 1–312 months) and found that CFE + CA had a higher agreement with MBS results than CFE only (83% vs. 76%) . CFE + CA had 89% sensitivity and 83% specificity in detecting OPA/penetration compared to MBS. Other adult studies on CA used to accurately identify OPA have described sensitivities of 62-94% and specificities of 66-70% when compared to MBS [30, 31]. Current studies documenting the validity of CA in conjunction with the CFE are limited to the adult population [28, 30–33] and have methodological limitations such as small subject numbers [30, 31, 33], observational study designs [28, 30–33], clinician bias , selection bias with large age differences between comparative groups [30, 31], and undefined abnormal swallowing sound parameters [31, 32]. As such, there are no randomised controlled trials that have examined the utility of CA in adults and children. Hence, a better understanding of the diagnostic value of this technique for improving OPA detection is required before it can be used routinely in the clinical setting.
Aims of the study
Our study investigates the utility of cervical auscultation (CA) in the assessment and diagnosis of OPA in children. The primary aim is to determine whether the CFE combined with CA increases the detection of OPA determined by MBS, compared to the CFE only. We hypothesise that the use of CA (compared to not using CA) as an adjunctive clinical tool to assess oropharyngeal dysphagia improves the detection of OPA in children as assessed with the current gold standard, MBS.
Our secondary aim is to determine the perceptual characteristics of common typical respiratory and swallow sound patterns and/or descriptors pre- and post-swallow in children with OPA.