Rapid-Shallow-Breathing Rsb; Negative Inspiratory Force Nif - Dräger Evita 2 dura Instructions For Use Manual

Description
Measurements

Rapid-Shallow-Breathing RSB

The Rapid Shallow Breathing index (RSB)* is the quotient of
the spontaneous breathing frequency (spontaneously
breathed breaths per minute) and the tidal volume
f [1/min]
spn
RSB [1/(min x L)] =
V [L]
T
The lower the RSB index for a patient with spontaneous
breathing, the more probably he or she can be weaned
successfully. The significance of the RSB index is due to the
fact that patients who can be weaned successfully tend to
have a lower spontaneous breathing frequency and a higher
tidal volume than those who are not yet ready to be weaned.
In their 1991 study*, Yang and Tobin showed that the
RSB index is an effective instrument for predicting the
success of an attempt to wean the patient. Patients with an
RSB index <100 1/(min x L) were weaned with a probability
of 80 %, while 95 % of those with an RSB index > 100 were
not yet ready to be weaned. Evita 2 dura indicates the
RSB index in CPAP/ASB and PPS modes.

Negative Inspiratory Force NIF

The Negative Inspiratory Force index (NIF)** measures the
patient's maximum inhalation effort after exhaling. The patient
system is closed during measurement of the NIF. This value is
also known as the Maximum Inspiratory Pressure (MIP).
As a result of the inhalation effort during manually extended
expiration, the patient generates a negative pressure in
relation to PEEP. The probability that the patient can be
weaned successfully increases with the magnitude of this
negative pressure. Patients with a NIF < –30 mbar can in all
probability be weaned successfully, while those with a NIF of
up to –20 mbar will most probably prove unsuccessful.
Evita 2 dura determines the NIF value during manually
extended expiration. The patient system closes following
expiration by the patient while the »Exp. hold« key is held down
and Evita 2 dura measures the maximum inhalation effort
made by the patient. The NIF is measured as a pressure
against PEEP. The measuring procedure is ended when the
»Exp. hold« key is released or after not more than 15 seconds.
The last measured NIF value and the time of measurement are
shown in Table 2 on the screen.
* Bibliography (8), page 131
** Bibliography (9), (10), page 131
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