Discussion
With the incidence rate of laryngeal cancer increasing year by year in
China,15 more and more patients undergo partial
laryngectomy.5 After partial laryngectomy, the
structure、local nerve、muscle and coordination function of larynx and
pharynx are affected, resulting in dysphagia.16 The
most serious dysphagia occurs weeks after the surgery, and most patients
could get different degrees of improvement through oral intake training,
but the remaining problems of swallowing would affect the long-term life
of patients, such as repeated pneumonias, change of eating habits and
reducing or even refusing of social intercourse.2Therefore, it is imperative to evaluate and rehabilitate the swallowing
abilities of the patients after partial laryngectomy, especially in
early postoperatively period.5
VFSS is the gold standard for swallowing
examinations.4, 7, 17 Traditional VFSS usually uses
barium as contrast agent that has some drawbacks. Once the barium is
aspirated into the trachea and lung, it will be difficult to remove and
absorb, and may cause damages of the lung function. Ioiohexol solution
is a non-ionic contrast agent, which has the advantages of high-water
solubility, low viscosity, low osmotic pressure and low
toxicity.18 Therefore, we improved VFSS using
Iohexol Injection to instead of barium.
However, VFSS also has some disadvantages and it is necessary to develop
new evaluation tools. So far, almost all swallowing assessment tools
require patients to swallow liquid food directly,19while ignoring the swallowing ability of food of other
characteristics.20, 21 GUSS chose three kinds of food
to complete the test sequentially, but the evaluation sequence was not
suitable for patients with partial laryngectomy. This was based on the
following observation: the risk of aspiration of swallowing solid food
was lower than that of swallowing semisolid food, and the risk of
aspiration of swallowing semisolid food was lower than that of
swallowing liquid food. Therefore, we modified the sequence of food
trails to minimize the risk of aspiration during the examination and to
identify patients who could intake solid, semi-solid or liquid food
respectively. This point is important because it guides the
rehabilitation.
In our research, we classified modified GUSS into 4 grades according to
the severity rating of GUSS, and corresponded to 4 grades of risks of
aspiration. The benefit was that both dysphagia and aspiration were
evaluated at the same time. And we reported that the severity rating and
grades of risks of aspiration assessed by modified GUSS were excellent
consistent by comparing with VFSS. It indicated that modified GUSS could
distinguish patients suffering from dysphagia with varying degrees of
risks of aspiration and even recommend food of different
characteristics. Although the recommendations were not drafted by us,
they must be dissimilar to those of GUSS because of the modified
sequence.
Moreover, we demonstrated that modified GUSS had substantial to
excellent interrater reliability for all classification categories. The
predictive values were also acceptable. For the chosen no dysphagia
grade, it had 100.0% sensitivity and 100.0% specificity VFSS; for the
chosen moderate and severe dysphagia grade, it had 90.0% sensitivity
and 100.0% specificity; for the chosen severe dysphagia grade, it had
84.2% sensitivity and 100.0% specificity. The all 100.0%
specificities meant extremely low misdiagnosis rates, and the high
sensitivities meant very low missed diagnosis rates. However, the
results revealed that some patients with severe or moderated dysphagia
were graded with a lower severity degree, and also indicated that these
patients were particularly difficult to swallow semi-solid food and
liquid food, while relatively easy to swallowing solid food. In order to
adjust this result and identify the false negative patients, daily
evaluation by modified GUSS was recommended.
In addition, we revealed that the higher the modified GUSS scores, the
less the days from oral feeding to gastric tube extubation. Although we
did not set objective criteria for removing the gastric tube, just based
on the subjective assessment of the patients by the doctors, we
confirmed that the modified GUSS scores could predict the time to remove
the gastric tube generally.
In summary, on the basis of GUSS, we introduced a bedside evaluation
tool that had good reliability and validity for assessment of swallowing
function and risks of aspiration before oral feeding in early period
after partial laryngectomy. However, there is still a lot of work to be
done according to modified GUSS, such as swallowing
rehabilitations、food recommendations、long term evaluation
effectiveness and standards for gastric tube extubation.