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Discussion
Assessing the neurological integrity of the LCR after a neurological event is essential to determining the appropriate clinical treatment plan for prescription of food, fluids, and medications. The RCT helps to stratify pneumonia risk and improves outcomes through decreased morbidity, mortality, and cost.
The function of the LCR may or not mirror the degree of dysphagia present in a stroke patient. The term silent aspiration, as interpreted clinically, may be used as a negative description of a normal physiological process. Everyone aspirates his or her own secretions to some degree, which necessitates the need for throat clearing, a voluntary clearing cough and natural pulmonary ciliary cleansing system. An intact LCR involuntarily clears abnormal boluses of food, fluids, secretions, or medications that enter the airway. What these receptors recognaize as normal or abnormal is not entirely clear, and there are probably different degrees of reflex response depending on the stimulant.
A chemoirritant such as tartaric acid stimulates an abrupt, forceful, and involuntary LCR in normal patients without neurological impairment. This same response was seen in all of the normal RCT stroke patients regardless of the degree of hemiparesis, dysphagia, dysarthria, or cognitive deficits. Many of the normal LCR patients had wet voice qualities or severe dysphagia but were fed on the basis of experienced speech pathologist’ bedside evaluations, using the RCT response as a pivotal factor indicating airway protection. Many were started on modified diets or placed in a supervised dining setting, with diet advancement based on clinical examination and improvement. Videofluoroscopic examination was used only to evaluate structural problems such as fistula, tracheostomy, or tumor and only if the patient had a normal LCR.
If the neurological airway protection mechanism, ie , LCR, functions normally, then patients may be fed on the basis of the bedside physiological findings and diet may be advanced on the basis of improvement with therapeutic swallow exercise treatments. An abnormal LCR (weak or absent) should be viewed as a warning signal. Patients with abnormal LCR require close attention and planning to prevent aspiration pneumonia. In patients with poor caloric intake, lethargy, or significant aphasia, a PEG may be warranted. This would allow no food, fluids, or medications by mouth. In cases of a neurologically unprotected airway, this would help to decrease the production of oral secretions that may be aspirated in volumes that could cause pneumonia. Nasogastric tubes were avoided because of the development of increased secretions and decreased pharyngeal proprioception caused by prolonged use.
Patients with an abnormal LCR were observed clearing their throats less often and did not as readily initiate a voluntary crearing cough as those with a normal LCR.
Surprisingly, many patients with severe dysarthria, dysphagia, and dense hemiparesis have a normal cough reflex and are able to take in adequate calories and medications. Conversely, other stroke patients, who historically would be classified as low risk (because of few physical deficits), have no response to the chemoirritant. These patients were not fed by mouth initially and received PEG placement. While in rehabilitation, these patients had recovered their LCR as determined by RCT, and they were then fed by mouth. The PEG was safely removed no earlier than 4 weeks after insertion. It is likely that patients in this category previously developed “silent aspiration pneumonia” despite being at a high functional level. Twenty-five patients with abnormal RCTs did not receive PEGs and were eventually retested as before admission to the rehabilitation setting. During rehabilitation, 20 PEGs were inserted ; 7 of these patients had a normal RCT, and 13 had an abnormal RCT. Seven of the 20 PEGs were removed before the patients were discharged from the rehabilitation setting, and 13 were still in place 3 months after stroke onset.
The neurology of airway protection and the physiology of swallowing are separate processes. The neurological examination of the LCR and airway protection is more important in regard to pneumonia risk than the physiological examination of dysphagia. If the neurological protection of the airway is intact, the physiological deficit of swallowing may be more aggressively treated, and diet may be more readily advanced with a reduced risk of pneumonia development. An abnormal LCR gives rise to further discussion and treatment plan modification.
Routinely, families are included in the decision-making process regarding whether or not the patient should have a PEG or should be fed orally, despite the risk of pneumonia development, on the basis of living wills or healthcare surrogates. Many of these patients receive a PEG for the bulk of their caloric and medication intake and are then fed the safest consistencies orally for quality of life and pleasure. Having informed knowledge of adverse risk helps families and patients to make difficult decisions about feeding, which affects quality of life.
The RCT is a safe, reliable, and cost-effective procedure for testing the LCR. Additionally, other medical conditions may require the need to assess the reflex cough. This procedure is currently under review for approval by the Food and Drug Administration.