getemed VitaGuard VG2100, Руководство по эксплуатации

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106 Algorithms and measuring principles
AVERAGING N whereby
1
60
1
0
) (
=
=
∑
−
=
N
n
n
HR
MAX AC
HR
T
The higher the value selected for RR
Averaging
, the longer VitaGuard®
needs before the displayed heart rate
reflects the patient’s actual heart rate.
When, for example, a value N = 16 is chosen, the actual heart rate is
not displayed until after sixteen heartbeats.
The longest alarm condition delay for the heart rate therefore occurs
when it is at its lowest. When, for example, the heart rate suddenly
drops to thirty beats a minute, a beat is detected every two seconds.
When RR
Averaging
is set to 16, a heart rate of thirty is not displayed
until after thirty-two seconds.
10.1.2 Alarm condition delay for respiration
The impedance pneumography used to monitor apnea must rule out
cardiac artifacts as the source of changes to measured impedance.
When central apnea has occurred the applied algorithm detects
cardiac artifacts after max four heartbeats.
The alarm condition delay for respiration depends in addition on the
signal amplifier’s recovery time. When in the worst case the amplifier
is saturated owing to sudden, violent movements by the patient
directly before the occurrence of apnea, the zero line is reached in six
seconds. From then, again in the worst case, a period of four beats is
needed before any cardiac artifacts can be detected.
10.1.3 Alarm report delays
The alarm report delays for bradycardia and tachycardia can be set
within certain limits.
TA
(max)
for bradycardia: ....... set
Bradycardia delay
+ 2 s
TA
(max)
for tachycardia: ....... set
Tachycardia delay
+ 2 s
seconds) in ime recovery t max s amplifier' (6 6
60
4
) (
= +






=
HR
T
apnea
MAX AC