22 09-12 how do i ventilate normal lung
DESCRIPTION
Ventilation,Normal lung,more art than scienceTRANSCRIPT
How do I ventilate normal lung?
Dr Anand.TiwariF.N.B Critical care medicine.
Consultant neuro-intensive careRuby hall clinic
History
2012
1950
When do I ventilate a normal lung?
BrainstemSpinal cordNerve root
Airway
Nerve
Neuromuscular junction
Respiratory muscle
Lung
Pleura
Chest wall
EXTRAPULMONARYComponents
Choosing the interface
Increased vascular
resistance
Decreased venous return
Decreased distensibility
Decreased distensibility
Decreased venous return
Alveoli
Septal displacement
Heart- Lung Interaction Physiology
Volume / Compliance
Flow x Resistance
Pressure=flow x resistance
Alveolar pressure=volume/compliance + PEEP
Airway pressure=Flow x Resistance + volume/compliance + PEEP
Flow=volume/time
B (P A LV)A (P AW)
Physics of Positive pressure ventilation
3 key ventilator phase variables
When the breath is delivered What limits gas delivery what end the gas delivery
Trigger
Limit
cycle
Assisted Mode(Volume-Targeted Ventilation)
Assisted Mode(Volume-Targeted Ventilation)
Time (sec)Time (sec)
Flow(L/m)
Pressure(cm H2O)
Volume(mL)
Preset VT
Volume Cycling
Patient triggered, Flow limited, Volume cycled Ventilation
Assisted Mode (Pressure-Targeted Ventilation)
Assisted Mode (Pressure-Targeted Ventilation)
Pressure
Flow
Volume
(L/min)
(cm H2O)
(ml)
Set PC level
Time (sec)Time (sec)
Time-Cycled
Patient Triggered, Pressure Limited, Time Cycled Ventilation
SIMV +PS
Pressure support
Physiological PEEP
Case scenario!!
• 25 yr old female admitted with history of BZD and antidepressant,no past medical history in. Registrar calls you in evening 7p.m patient is unwell gurgling sounds, mild airway obstruction drowsy .Respiration appears shallow ?
• U advise -ABG ?• NIV ? Invasive ventilation.?
Goals during Positive pressure ventilation
• Adequacy of ventilation• Oxygenation• Decreased work of breathing• Patient comfort• Synchrony with ventilator• Avoiding complication-VILI,VAP• Early wean ability
What mode ??Which setting ??
Settings
• Fio2• R.r• Tidal volume• I:E ratio• Trigger• Peep• Set alarms
Monitoring during ventilation• Pulse oximetry - 95 % • ABG
– pH. 7.32– PCO2- 55– Po2 414– HCO3 28
• EtCo2 -50• Chest x ray Vitals- P-120/min B.p- 90/60
Note—no replacement to a vigilant Intensivist bedside
Hypovolemia
What next?
• Wake up call for consultant?
• Registrar reports increase in pressure alarm repeatedly ? U Advice
• A)Suction• B)Nebulization• C) Chest X ray
PIP vs PplatPIP vs Pplat
NormalNormal High RHigh Rawaw
High FlowHigh FlowLow ComplianceLow Compliance
Time (sec)Time (sec)
Paw
(c
m H
Paw
(c
m H
22O)
O)
PIPPIP
PPPlatPlat
PIPPIP
PIPPIP PIPPIP
PPPlatPlatPPPlatPlat
PPPlatPlat
Interpretation of Ventilator Graphics v.1 ©2000 RespiMedu
Complications
• Related to intubation and extubation.
Ventilator related
• Extra pulmonary – gut ischemia, Water ADH +
• F• A• S• T• H• U• G
anand tiwari
Ancillary care
Give your patient a fast hug (at least) once a day*Jean-Louis Vincent, MD, PhD, FCCM
Day 3 patient start to wake up trigger ventilator frequently some breath stacking,vitals stable
• Restless ,bites the tube intermittently restless• As reported by the nurse and physiotherapist.• You suggest—• A)weaning• B) Sedate and ventilate
ABCDE bundle
Mechanical VentilationWeaning: Predictors (Parameters)
• Respiratory Rate < 30/min• Spontaneous Vt > 4 ml/kg
• Inspiratory Pressure > - 20 cm H2O
• Breathing Index (f/Vt) < 105
• PEEP < 8 cmH2O
• PaO2/FIO2 > 200
• FIO2 < .50
Winning modes
Esteban, N Engl J Med 1995; 332:345
Summary of recommendations of weaning
• Protocol-directed - favorable outcome• SBT or PS trials than-- SIMV• 30min and 120min trials are equally successful• Twice daily SBT no advantage over once daily• Sedation vacation better outcome.• Early compared to late tracheostomy leads to
better outcomes
So mechanical ventilation of normal lung should not end up in an abnormal lung… think & act!!!!!!!!