Download New technologies in ventilator management and other strategies

New technologies in ventilator
management and other strategies
Objectives
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NAVA (Sevo I)
Pulmo Vista 500 (Drager Evita)
Liquid Ventilation
Positive Pressure effects on Hemodynamic
Neurally Adjusted Ventilatory Assist
(NAVA)
NAVA
• Normal ventilation varies considerably from
breath to breath, but this is lost with traditional
positive pressure ventilation
• Neurally adjusted ventilatory assist (NAVA)
uses diaphragmatic electromyography to trigger
ventilation in a more natural manner
NAVA
• NAVA is described as a mechanical ventilation
method, controlled by brain signals (i.e. vagus
nerve stimulation of the diaphragm), that might
help patients in critical conditions by improving
the interaction between the patient and the
ventilator. The technology might also have the
potential to avoid diaphragm disuse atrophy in
critically ill patients.
NAVA
• The act of breathing depends on rhythmic
discharge from the respiratory center of the
brain.
• This discharge travels along the phrenic nerve,
excites the diaphragm muscle cells, leading to
muscle contraction and descent of the
diaphragm dome.
• As a result, the pressure in the airway drops,
causing an inflow of air into the lungs.
NAVA
• Conventional mechanical ventilators sense a patient
effort by either a drop in airway pressure or a
reversal in flow.
• NAVA created and used exclusively on the Servo I
ventilator
•
With NAVA, the electrical activity of the diaphragm
(Edi) is captured, fed to the ventilator and used to
assist the patient’s breathing. As the ventilator and
the diaphragm work with the same signal,
mechanical coupling between the diaphragm and
the ventilator is practically instantaneous
NAVA
• NAVA created to increase triggering by
enhancing sensitivity to hyperinflation, intrinsic
PEEP and secondary triggering problems.
• No current evidence to show NAVA increases
clinical outcomes
• Increased adaptation to varying patient trigger
demands has been shown
NAVA
• SOME OF THE POTENTIAL BENEFITS
Improved synchrony: In NAVA the ventilator is
cycled-on as soon as neural inspiration starts.
The level of assistance provided during inspiration is
determined by the patient’s own respiratory center
demand.
The same applies for the cycling-off phase – the
ventilator cycles off inspiration the instant it is
alerted to the onset of neural expiration. By utilizing
the Edi signal, maintenance of synchrony between
the patient and the ventilator is improved.
• Lung protection: With NAVA the patient’s own
respiratory demands determine the level of assistance.
NAVA gives the opportunity to avoid over or under assistance
of the patient.
• Decision support for unloading and extubation: The
Edi signal can be used as an indicator to set the support level
• from the ventilator, and to optimize unloading. As the
• patient’s condition improves, Edi amplitude decreases,
• resulting in a reduction in ventilator-delivered pressure.
• This pressure drop is an indicator to consider weaning and
• extubation.
• Patient comfort: With NAVA, the respiratory muscles
and the ventilator are driven by the same signal.
• The delivered assistance is matched to neural demands. This
synchrony between patient and ventilator helps minimize
patient discomfort and agitation, promoting spontaneous
breathing and possible reduced sedation.
NAVA
• With NAVA the patient’s own respiratory demands
determine the level of assistance. NAVA gives the
opportunity to avoid over or under assistance of the
patient.
•
The Edi curve and its associated value can thus be
used as a powerful monitoring tool in all ventilation
modes, providing information on Respiratory Drive,
Volume requirements and the effect of the
ventilatory settings, and to gain indications for
sedation and weaning.
NAVA
• Edi signal (Electrical activity of diaphragm) can
be used in any mode
• Can be used to assess respiratory drive, volume
requirements and the effects of the vent settings
• The Edi catheter picks up an esphageal ECG
which can be displayed on the Servo I screen
Servo I with ECG reading
The decrease in pressure in this particular patient is clearly
visible when switching from Pressure Support to Nava (shown
in red). The green value shows respiratory rate.
NAVA
• NAVA is as straightforward to use
• The only equipment required in addition to a
• SERVO-i ventilator is NAVA software, an Edi
module with cable and an Edi catheter. The same
module can be used interchangeably with different
SERVO-i units.
• The Edi Catheter also functions as a
nasogastric feeding tube, and comes in
dimensions ranging from 6Fr–16Fr to cover all
patient categories from neonatal to adult.
The NAVA upgrade kit
installs simply on all
SERVO-I ventilator
configurations and is
fully interchangeable
with all SERVO-i
units.
A range of Edi catheter sizes
ensures optimized signal
quality across all patient
categories.
NAVA
• The NAVA Edi catheter is as simple to apply as
any standard nasogastric tube.
• However, positioning of the Edi catheter takes on
added importance to ensure a strong Edi signal and
accurate readings.
• With the Edi catheter inserted and positioned, all
that remains is to plug the Edi module into the
SERVO-i and connect the Edi catheter to its outlet.
The esophageal ECG now showing on the SERVO-i
screen can help confirm proper Edi catheter
positioning.
The Edi catheter is inserted to the measured
depth and positioned correctly.
With the catheter properly positioned, a prominent Pwave should be visible in the uppermost channel with a
continued decline of P-wave amplitude in the lower
leads.
• http://www.youtube.com/watch?v=QMWGYtxZ
dM0
• http://vimeo.com/48398681
PuloVista 500
Electrical Impedance Tomography
(EIT)
http://www.youtube.com/watch?v=tSnRZZYIJPg
PulmoVista 500
• EIT monitoring involves the application of a
small current and measurement of resulting
voltages to determine the ventilation related
impedance changes that occur in a thoracic
cross-section.
PulmoVista 500
• Enables the assessment of regional ventilation
distribution as well as short-term changes in
end-expiratory lung volumes. You can see the
effects of therapeutic manoeuvres and monitor
the results over time. PulmoVista 500 helps you
assess conditions such as atelectasis, overinflation, air trapping, pleural effusion or
pneumothorax may have on ventilation.
PulmoVista® 500 offers:
– Continuous information about regional
distribution of ventilation, displayed as images,
waveforms and parameters
– Trend display of regional distribution of
ventilation
– Trend display of changes in end-expiratory lung
volume
Prior to recruitment maneuver
10 mins after recruitment
4 hrs after recruitment
The same tidal volume setting was used pre and post
recruitment.
PulmoVista® 500 offers:
• Non-invasive tomographic monitoring
• The regional ventilation monitoring provided by
PulmoVista 500 is non-invasive and without any
side-effects. Unlike chest x-rays or CT, there’s no
ionizing radiation involved. EIT involves
minimal preparation so monitoring is
established in just a few minutes.
• Patient preparation only requires the positioning
of a flexible non-adhesive belt around the
patient’s chest.
liquid-assisted ventilation (LAV)
http://www.youtube.com/watch?v=1NAU8Iz6aXE
Liquid Ventilation
• Liquid ventilation (LV) is a technique of
mechanical ventilation in which the lungs are
insufflated with an oxygenated
perfluorochemical liquid rather than an oxygencontaining gas mixture. The use of
perfluorochemicals, rather than nitrogen, as the
inert carrier of oxygen and carbon dioxide offers
a number of theoretical advantages for the
treatment of acute lung injury,
Liquid Ventilation
• Reducing surface tension by maintaining a fluid
interface with alveoli
• Opening of collapsed alveoli by hydraulic pressure
with a lower risk of barotrauma
• Providing a reservoir in which oxygen and carbon
dioxide can be exchanged with pulmonary capillary
blood
• Functioning as a high efficiency heat exchanger
• Despite its theoretical advantages, efficacy studies
have been disappointing and the optimal clinical use
of LV has yet to be defined
Liquid Ventilation
• Although total liquid ventilation (TLV) with completely
liquid-filled lungs can be beneficial, the complex liquid-filled
tube system required is a disadvantage compared to gas
ventilation - the system must incorporate a membrane
oxygenator, heater, and pumps to deliver to, and remove from
the lungs tidal volume aliquots of conditioned
perfluorocarbon (PFC).
• One research group led by Thomas H. Shaffer has maintained
that with the use of microprocessors and new technology, it is
possible to maintain better control of respiratory variables
such as liquid functional residual capacity and tidal volume
during TLV, than with gas ventilation
• Consequently, the total liquid ventilation necessitates a
dedicated liquid ventilator similar to a medical ventilator
except that it uses a breatheable liquid. (NON EXIST in USA)
Positive Pressure effects on
Hemodynamics
Positive Pressure effects on
Hemodynamics
• Right heart effects of positive-pressure
ventilation
• During inspiration, the positive intrathoracic
pressure produced by a mechanical breath
decreases venous return.
• An increase in intrathoracic pressure as small as
4 mm Hg is associated with a reduction in
venous return by 50% for a transient period of
time
Positive Pressure effects on
Hemodynamics
• In individuals with normal cardiac function, venous
return and subsequent cardiac output may be
dramatically reduced with the institution of mechanical
ventilation,
• particularly in individuals with coexisting hypovolemia
or states that produce systemic vasodilation or relative
hypovolemia, like septic shock
• In most instances, the consequences of reduced venous
return are alleviated by intravenous fluid administration
and adequate augmentation of blood volume
• Aggressive hydration during continuous positivepressure ventilation restores atrial transmural pressure,
plasma atrial natriuretic peptide concentrations, and
renal function.
Positive Pressure effects on
Hemodynamics
• Natural compensation for this hemodynamic
response includes catecholamine release and
secretion of arginine vasopressin and renin with
subsequent increases in angiotensin II and
aldosterone
• Natriuretic peptide hormone secretion is reduced
with less cardiac chamber volume to stimulate
hormone release. The net effect of these responses is
sodium and water retention to support adequate
preload and vasoconstriction to increase blood
pressure.
Positive Pressure effects on
Hemodynamics
• Angiotensin, a peptide hormone, causes blood
vessels to constrict, and drives blood pressure
up. It is part of the renin-angiotensin system,
which is a major target for drugs that lower
blood pressure. Angiotensin also stimulates the
release of aldosterone, another hormone, from
the adrenal cortex. Aldosterone promotes
sodium retention in the distal nephron, in the
kidney, which also drives blood pressure up.
Positive Pressure effects on
Hemodynamics
• Patients with heart failure may actually improve cardiac function
with the application of mechanical ventilation
• Reduction in venous return
• Unless optimally managed, patients with heart failure have a
chronic increase in preload because of persistent stimulation of the
renin angiotensin aldosterone system, reduction in natriuretic
peptide release, and secretion of arginine vasopressin.
• Patients with heart failure also exhibit a perpetually elevated
systemic vascular resistance partly because of chronic sympathetic
nervous system activation.
• Application of mechanical ventilation reduces venous return and
moderates the ventricular volume load. This reduced volume load
will decrease ventricular wall tension and support the mechanical
efficiency of the heart. Thus, in patients with heart failure, cardiac
function may dramatically improve with the application of
mechanical ventilation.
Positive Pressure effects on
Hemodynamics
• Left heart effects of positive-pressure ventilation
• Several of the left ventricular effects of mechanical
ventilation are directly attributed to alterations in right
ventricular function, particularly the effects on left
ventricular preload or end-diastolic volume
• Reduced venous return subsequently decreases the
volume of blood the left ventricle receives. Thus, left
ventricular preload is decreased and subsequent stroke
volume and cardiac output are less. Increased right
ventricular afterload and right ventricular dilation with
shift of the interventricular septum reduces left
ventricular chamber size, compliance, and filling, which
also leads to reduced left ventricular preload
Positive Pressure effects on
Hemodynamics
• Left ventricular preload may also be influenced
by increased pericardial pressure
• Hyperinflated lungs directly compress the heart,
reduce cardiac compliance, and lessen
ventricular filling and end-diastolic volumes.
These responses to mechanical ventilation all
reduce left ventricular preload.
Positive Pressure effects on
Hemodynamics
• Positive pressure mechanical ventilation also reduces left
ventricular afterload or transmural pressure on inspiration and
throughout the ventilatory cycle with the application of PEEP
• Transmural pressure is the pressure inside the ventricular chamber
minus pressure outside the ventricle (intrathoracic pressure).
• Left ventricular transmural pressure is an indication of the pressure
the ventricle must overcome to eject blood into the aorta.
• Positive intrathoracic pressure actually unloads the left ventricle by
reducing transmural pressure. Consequently, the left ventricle is
able to eject a greater stroke volume of blood with less pressure
generation. Thus, myocardial oxygen demand is reduced and
cardiac output improves. Patients with heart failure particularly
benefit from mechanical ventilation by significantly increasing
cardiac output with less myocardial oxygen consumption because of
the combination of a reduction in ventricular volumes and a
decrease in left ventricular afterload