Intensive care medicine was born along with art and science of positive pressure ventilation. Started with polio epidemic in 1952,denmark,3000 patient required critical care and 1/3 had paralysis had 10 % had respiratory insufficency,ventilation done with –negative pressure bulk flow mobilization in patient lung by cyclically creating sub atmospheric pressure around the chest or cuirass ventilator rigid shell around the chest,logistic problems of nursing care, mortality was 87% dr Lassen and dr Bjorn Ibsen invented tracheotomy and positive pressure ventilation and mortality dropped to 40%
CNS- depressant drug,structural brain damage, spinal cord disease above c5,GBS,MG,Critical illness poly neuropathy,organophosphates,amytropic lateral sclerosis, anterior horn cell disease,ms dytrophy,periodic paralysis,myopathy dyselectrolemia,ks.120,cardiac support in shock,as part of general anesthesia,marked airway or facial odema
The first positive-pressure ventilators were designed to inflate the lungs until a preset pressure was reached. This type of pressure-cycled ventilation fell out of favor because the inflation volume varied with changes in the mechanical properties of the lungs. In contrast, volume-cycled ventilation, which inflates the lungs to a predetermined volume, delivers a constant alveolar volume despite changes in the mechanical properties of the lungs. For this reason, volume-cycled ventilation has become the standard method of positive-pressure mechanical ventilation
22 09-12 how do i ventilate normal lung
How do I ventilate normal lung?
F.N.B Critical care medicine.
Consultant neuro-intensive care
Ruby hall clinic
Pressure=flow x resistance
Alveolar pressure=volume/compliance + PEEP
Airway pressure=Flow x Resistance + volume/compliance + PEEP
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
• 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
• U advise -ABG ?
• NIV ? Invasive ventilation.?
Goals during Positive pressure
• Adequacy of ventilation
• Decreased work of breathing
• Patient comfort
• Synchrony with ventilator
• Avoiding complication-VILI,VAP
• Early wean ability
What mode ??
Which setting ??
• Tidal volume
• I:E ratio
• Set alarms
Monitoring during ventilation
• Pulse oximetry - 95 %
– pH. 7.32
– PCO2- 55
– Po2 414
– HCO3 28
• EtCo2 -50
• Chest x ray Vitals- P-120/min
Note—no replacement to a vigilant
• Related to intubation and extubation.
• Extra pulmonary – gut ischemia, Water ADH +
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—
• B) Sedate and ventilate
Esteban, N Engl J Med 1995; 332:345
Summary of recommendations of
• 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
So mechanical ventilation of normal lung should
not end up in an abnormal lung… think &