Weaning from mechanical ventilation in 21 st century
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Transcript of Weaning from mechanical ventilation in 21 st century
Weaning from mechanicalventilation in 21st century
Dr P K DashSCTIMST, Trivandrum
Aim of ventilatory care
Goals of mechanical ventilation
Discontinuing ventilation
• Easy• Quick• May not be controversial
Initiating ventilation
• Difficult• Time consuming• Controversial
Do Not Wait
Weaning from ventilationvs
Discontinuation of ventilation
Most accepted method
• Spontaneous breathing trials–T Piece–Pressure Support–CPAP
Pressure Support
CPAP
T Piece
Most commonly used
• Partial ventilatory support– SIMV– SIMV with PS
• Less Tried– NIV– BIPAP
SIMV with pressure support
Evolution of Modes
• Volume control
• Pressure control
• Pressure support
• Dual control
• Algorithm based
• Knowledge based
Considerations for Knowledge based weaning
Knowledge based weaning
1992
2005
2006
1994
What we need
Adaptive support ventilation
Adaptive support ventilation
Adaptive support ventilation
ASV settings
ASV monitoring
Smart care
Smart care• It is a knowledge based automated weaning system.• It contains an automated clinical weaning guideline • Based on recognised medical expertise and research.
Preconditions• patient body weight 35-200 kg• ventilator in adult mode• CPAP/ASB mode• automatic tube compensation deactivated• invasive ventilation via ETT or tracheostomy• apnoea ventilation on and properly set• end tidal CO2 monitoring through the ventilator• flow monitoring activated• ΔPASB should be between ΔPASB goal+5 and 35• PEEP 0-20
Ventillatory setting
Smart Care
• Zone of Respiratory Comfort– Spontaneous breathing frequency (fspn) 15-30 cycles/min, – up to 34 in patients with neurologic disease
– Spontaneous tidal volume (VT) Vt > 300 ml– 250 if weight < 55 Kg,
– Endtidal CO2 (etCO2)PetCO2< 55mmHg – 65mmHg if COPD
Decision Tree
Change in severity of lung illness
Smart care working principle
• Step 1: Stabilizing within a respiratory comfort zone
• Step 2: Reducing invasiveness
• Step 3: Testing readiness for extubation
Smart care Weaning
Contraindications to smart care
Neurally adjusted ventilator assist
Trigger pointN
euro
-Ven
tilat
ory
Cou
plin
g Central Nervous System
Phrenic Nerve
Diaphragm Excitation
Diaphragm Contraction
Chest Wall and Lung Expansion
Airway Pressure, Flow and Volume
New
Technology
IdealTechnology
CurrentTechnology
VentilatorUnit
Conventional triggering
Conventional ventilator technology uses a pressure drop or flow reversal to provide assistance to the patient.
This is the last step of the signal chain leading to inhalation.
This last step is subject to disturbances such as intrinsic PEEP, hyperinflation and leakage.
Nava triggering
• The earliest signal that can be registered with a low degree of invasivity is the excitation of the diaphragm.
• The excitation of the diaphragm is independent of pneumatic influence and insensitive to the problems with pneumatic triggering technologies.
• By following diaphragm excitation and adjusting the support level in synchrony with the rise and fall of the electrical discharge, the ventilator and the diaphragm will work with the same signal input.
• In effect, this allows the ventilator to function as an extra muscle, unloading extra respiratory work induced by the disease process.
Components
Catheter
Signal capture
• All muscles (including the diaphragm and other respiratory muscles) generate electrical activity to excite muscle contraction.
• The electrical activity of the diaphragm is captured by an esophageal catheter with an attached electrode array. The signal is filtered in several steps and provide the input for control of the respiratory assist delivered by the ventilator.
Catheter verification• P and QRS waves are present on the top leads and the P-
waves disappear on the lower leads and with a decrease of the QRS-amplitude on the lower leads.
• When an Edi waveform is present, observe which leads are highlighted in blue. If the leads highlighted in blue are in the center (i.e. second and third leads), secure the Edi Catheter in this position.
• To finally verify correct positioning of the Edi Catheter press the Exp. Hold and keep the button depressed until a breathing effort is registered. A negative deflection in the pressure curve with a simultaneous positive inflection in the Edi curve verifies correct position of the Edi Catheter.
Catheter verification
Setting the NAVA levelNAVA preview is a help tool to set the NAVA level to reach an estimated NAVA
On the uppermost waveform (the pressure curve), there are two curves presentedsimultaneously. The gray curve shows the estimated pressure, Pest, based on theEdi signal and the set NAVA level.
NAVA preview is available in all invasive modes of ventilation except NAVA.
Setting the Ventilator
Benefits of NAVA
Reintubation and Steroids
A reintubation rate of 10% is acceptable. Patients deserve a trial of extubation, and many will do well in spite of poor mechanics A high-risk population to develop post-extubation stridor and reintubation can be identified by a cuff-leak test (a low level of leak less than 110 ml or less than 25%).There is convincing evidence for giving steroid therapy at least four hours before extubation to prevent stridor and reintubation in a high-risk population.The steroid benefit remains unclear when patients are not selected.
Thanks for your attention