Procedures and ETF testing Measurements
Eustachian tube function (ETF) was measured in each ear using a modified
pressure-equilibration test. An earplug containing two probes was
introduced into the ear canal. One probe was connected to a constant
flow pump at a speed of 25ml/min, the other probe was coupled to a
high-resolution manometer and data of MEP was obtained from a computer
which showed the MEP-time curve. The ME was inflated and positive
pressure was applied. When the ET spontaneously opened, the pump was
manually stopped and air was discharged through the ET until the latter
closed passively. The pressure at which the ET opened passively was the
opening pressure(Po) and the pressure at which it closed passively was
the closing pressure(Pc). We restricted the upper limit of positive
pressure to
700
daPa because some patients felt uncomfortable when the pressure exceeded
the above level. If the ET remained closed when the pressure reached the
upper limit, we defined it as negative passive opening function. The
active opening function test was then carried out (Fig.
1),7 the ME was first inflated to +200 daPa following
which the patient was instructed to swallow at least ten times. The
residual pressure(Pr) remaining in the ME after swallowing was recorded.
The number of swallows and number of times the ET opened (judged by the
appearance of the swallow waveform) were also noted down. Each time the
ET opened, the MEP change was recorded as ΔP and the duration of ET
opening was recorded as Δt (Fig. 2). Next, similar testing was carried
out at a MEP of -200 daPa. To improve accuracy and misjudgment of ET
opening, ET opening was only defined when ΔP>3daPa and
Δt<1.5s.8 Patients were classified into four
types according to the test results: 1. with both active and passive ET
opening function; 2. with only passive opening function; 3. with only
active opening function; 4. without active or passive opening function.