BiPAP và CPAP Theory and Uses (Chế độ BiPAP và CPAP và cách sử dụng trong gây mê hồi sức)

CPAP and BiPAP
Theory and Uses
By Rudy Koch BSRT,RRT
Adult Clinical Coordinator
Respiratory Care Department
Strong Memorial Hospital


What is CPAP?
• CPAP delivers a continuous positive air
pressure
• This is delivered throughout the respiratory
cycle
• designed to deliver a positive pressure of
between 4 and 25 cm H2O
• been described as being similar to
breathing with your head stuck out of a
moving car


multiple reasons why CPAP
might improve breathing.
• Counteract intrinsic PEEP (autonomic
PEEP)
• decrease preload and afterload in
CHF ( not totally proven why yet)
• improve lung compliance in CHF
• decrease the work of breathing
(increasing FRC)
• helps treat obstructive sleep apnea

BiPAP
• BiPAP delivers CPAP but also senses
when an inspiratory effort is being
made and delivers a higher pressure
during inspiration. When flow stops, the
pressure returns to the CPAP level.
This positive pressure wave during
inspirations unloads the diaphragm
decreasing the work of breathing.


BiPAP Terms
• EPAP- expiratory positive airway
pressure.
• This is the CPAP level and the end of
expiration.
• IPAP- inspiratory positive airway pressure.
• This is the pressure given during the
inspiratory cycle.


If you think about it…..
• CPAP is for oxygenation-to
increase the PaO2/SpO2
• BiPAP is for ventilation- to
decrease the PaCo2


Indications for BiPAP

• Obstructive sleep apnea
• Nocturnal hypoventilation
• Chronic ventilator muscle dysfunction
accompanied by CO2 retention
• Post extubation difficulty in whom
reintubation may be avoided
• Impending respiratory failure
• CHF after diagnosis is confirmed


Contraindications for BiPAP
• Patients with altered level of
consciousness ( not hypercapnia)
• Head gear cannot be secured secondary
to the extent of their injury
• Patients with respiratory rates greater
than 30 breaths per minute
• Patients who has a history of vomiting.
• Patients who have high FiO2 needs.


WHAT TO ORDER!!
•
•
•
•

Mode of BiPAP( CPAP or BiPAP)
EPAP level
IPAP level

O2 saturation goal/or specified O2 flow
rate
• Duration/circumstances of use


Initial settings on BiPAP
a common technique is begin with the
expiratory level(EPAP) at 5 and the
inspiratory level(IPAP) at 15. The
levels are adjusted based on patient
comfort tidal volume achieved and
blood gases.


• The use of BiPAP machines has
increased over the last several years.
• There are also more types of masks
available and this has improved patient
comfort and compliance.
• The patient must always be shown
how to remove it in case of panic or
vomiting. If the patient has a
decreased level of consciousness,
copious secretions, can not protect his
airway or is unstable
hemodynamically, then intubation is
warranted.

I MEAN
NEVER………
TRANSPORT A PATIENT ON
BiPAP!!!!!!
The BiPAP has no battery backup
So the patient cannot clear
Their CO2


SOMETHING TO NOTE
• Patient understanding and
cooperation is important for the
success of this modality
• Proper mask sizing is a crucial
component of success. Mask comfort
is often the limiting factor to success.
• select the smallest mask possible for
the patient's nasal contour


NOTE……….
• Patients placed on NIPPV or BiPAP for
acute respiratory distress or for
conditions in which inadvertent cession
of support would produce an immediate
life threatening risk are to be considered
as if on full mechanical ventilatory
support. These patients may be
considered to be placed into the ICU.

Adjustments
• Increasing IPAP in increments of 2 cmh2o
provides a "pressure boost" on inspiration
that may provide an increase in alveolar
ventilation and/or decrease the work of
breathing.
• Increasing EPAP in increments of 2 cm H2O
may result in some increase in FRC and
along with manipulations in FiO2 improve
oxygenation.


REMEMBER!!!!
• BiPAP settings are manipulated based on
the patient's physiologic response. Failure
to see an improvement in the patient's
respiratory status within hours of
implementing BiPAP is an indication to
discontinue and evaluate other supportive
options.


Monitoring:
Things that should be assessed
• Neuro assessment
• Respiratory assessment (R.R., breath
sounds, resp. pattern etc.)
• BiPAP settings
• O2 liter flow, SaO2 and vitals

• Any adverse effects/response


New study
• Latest studies have show that placing
people with COPD or Asthma early in their
exacerbation can prevent them from being
intubated and increase their mortality.
• But almost 100 % of patients with
advanced pneumonia ended up intubated!!


• There is still controversy on how and why
CPAP works in CHF. There is no dispute
that it reduces the work of breathing by
improving atelectasis and V/Q ratios. Some
studies have suggested it also improves
preload and afterload and that there is
actually an improvement in cardiac index.
Of even more interest, studies out of
Toronto by Bradley suggest that up to 50%
of patients with CHF have sleep apnea. It is
possible that obstructive sleep apneas can
put a severe strain on the heart by
markedly increasing afterload and leading
to hypertension.


• In conclusion, for those patients who
present to the on the floors with acute

respiratory failure but with normal levels
of consciousness, no major secretion
problems and who are hemodynamically
stable, a trial of BiPAP or CPAP should
be attempted prior to considering
intubation and a mechanical ventilator.
• Any questions please contact the
respiratory supervisor or clinical
coordinator.