![]() ![]() Gagging seems evolutionarily designed to prevent choking on large pieces of food, not to prevent liquid aspiration. ![]() No statistically significant relationship was found between gag reflex and aspiration.Ī poor relationship between gagging and aspiration may seem counterintuitive, but this is easily explained. McCullough 2001 prospectively evaluated the gag reflex in sixty patients with stroke who were undergoing videofluoroscopic examination. ![]() The authors concluded that there was no relationship between the gag reflex and aspiration. Alternatively, among patients with a normal gag reflex, half had evidence of aspiration (11/21). Among patients without a gag reflex, most patients had no aspiration (6/7). Leder 1997 prospectively evaluated the gag reflex in a mixed population of patients undergoing a videofluoroscopic examination with modified barium swallow procedure.Several studies have found that the gag reflex has little relationship to aspiration, for example: The greatest amount of evidence about the gag reflex regards its ability to predict aspiration. Performance of the gag reflex for predicting aspiration Regardless, the specificity is poor and non-reproducible. It may also partially reflect different techniques used to elicit the reflex. This may partially reflect different patient populations, with gag reflex less common among the elderly or patients with sleep apnea ( Valbuza 2011). There is enormous variability in the frequency of absent gag reflex. The table below shows the frequency of absent gag reflex among neurologically normal individuals (1): However, healthy people frequently lack a gag reflex. If it were perfectly specific, the gag reflex would be present in 100% of patients without neurologic disease. In clinical practice reproducibility is probably even worse, because clinicians use a variety of different techniques. Some sources recommend shaking the endotracheal tube, whereas others recommend inserting a tongue depressor or suction catheter into the posterior pharynx.ĭavies 1995 found that inter-observer agreement was poor even within a single research study using a standardized protocol (agreement in only 10/15 patients, which isn't much better than pure chance). The technique for testing a gag reflex in an intubated patient is even murkier.Since the gag reflex may be stimulated by both touch and pressure, more aggressive probing of the pharynx is probably more likely to elicit a gag. The instrument used and amount of pressure applied to the pharynx isn't standardized.Among 104 medical students, touching the posterior pharynx was far more likely to stimulate a gag response than the posterior tongue (91% vs. Most texts recommend touching the posterior pharynx, but some recommend touching the back of the tongue.There is no standardization of how the gag reflex is tested: However, the gag reflex is more dramatic and thus has received far more attention. The palatal reflex is probably a better indicator of true pathology. The palatal reflex seems to be more hard-wired, whereas the gag reflex may be more susceptible to influence from higher brain centers (e.g. However, normal patients often lack a gag reflex, despite retaining a palatal reflex ( Lim 2009). The gag reflex appears to always be accompanied by the palatal reflex. This component is unpleasant and obvious from across the room. Gag reflex: Retching (which may rarely progress to vomiting).This component is subtle, requiring continuous attention to the soft palate. Palatal reflex: Upward movement of the soft palate.The pharyngeal reflex should be dissected into two components: More sensitive patients also gag in response to stimulation of the soft palate, which is enervated by cranial nerve V (trigeminal). However, this division isn't absolute in particular, the pharyngeal muscles are enervated by both nerves. Sensation is predominantly due to CN IX (glossopharyngeal nerve), whereas the pharyngeal musculature is mostly controlled by CN X (vagus nerve). The pharyngeal reflex involves stimulating the posterior pharynx, which will usually elicit a reflexive constriction of the pharynx with elevation of the uvula. This post pushes back against the practice of gagging patients by proposing an extreme viewpoint: this test should be abandoned in living patients. Despite evidence that it's unhelpful, it continues to be commonly performed. Thankfully, this practice has fallen out of favor.Ĭhecking gag reflexes seems like a similar practice: an uncomfortable test which is engrained in our practice during training. Eventually, the utility of digital rectal examination as a cancer-screening tool was debunked. The rationale was to avoid ever missing a case of rectal or prostate cancer. As a medical student I rotated through an elite hospital where it was believed that every patient admitted to the medicine service needed a rectal exam. ![]()
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