Indications and Modes of Mechanical Ventilation

Acute Respiratory Failure
ICU
Mechanical Ventilation
Indications of mechanical ventilation
Modes of mechanical ventilation
Setting of mechanical ventilation

1. Waheed Shouman
Professor of Chest Medicine
Zagazig University

3. Clinical examination and MV are both science and ART.
But Georges Braque (French Cubist) says:
“The only thing that matters in art can’t be explained”

5. Indications of MV :
They are wide, from frank apnea to just
signs of increased WOB without ABG
evidence of abnormal gas exchange

6. Clinical picture of Increased WOB:
•Nasal flaring,
•Accessory muscle recruitment,
•Expiratory muscle recruitment,
•Tracheal tug,
•Tachypnea,
•Adomenal Paradox
•Tachycardia,
•Hypo/Hypertension,
•Sweating,
•Chnages in mental status
In norms: Respiratory O2 consumption is 1-3% of
total, Here it may reach 20%

8. Indications for MV:
•Apnea
•Severe respiratory distress
•PaO2< 60 on FiO2 0.6 or maximum permitted
•Worsening CO2 endangering pH
•Managing pH

9. Indications of MV:
•RR> 30
•Vt less than 4 ml/kg IBW
•VC< 15 ml/kg

11. •Shallow breathing (when measure by instrument)
is common
•When clinically judged, it is unreliable.
•This clinical skill is not improved by years of
experience
•Patients with impending RF or ARF have NO
uniform presenion
•Imending or eminent respiratory failure has NO
clear defintion

12. Indications of MV:
•Correct, Reverse, Stabilize O2
•Correct, Reverse, Stabilize CO2
•Decrease WOB (Respiratory O2
consumption)
•Support apneic patients
•Prevent or reverse atelectasis (post-op)
•Prevent eminent respiratory failure

13. Indications of MV:
•Fighters in agony (severe distress)
•The lazy (CO2 confusion and more)
•The silent (apnea)

14. Indications for MV:
•When the patient needs (he may not
seem)
•When you feel the patient need (you
may not )
•MV is NOTthe 1st choice in treating
respiratory failure (It may be)
•Do not rush,but earlier is better!!
•MV can be LETHAL, (mostly life saving)

15. Indication for MV:
HOPE

16. Contraindications for MV:
•Absolute:
Pneumothorax without drain
•Relative:
Informed consent,
Medical futility

17. NIV use :
COPD: Sure
OSA OHS: Sure
ACPE: Sure
Slow NMD: Sure
Postoperative: Preferred
Trauma: Try (need research)
Altered mentality : May be Yes (need research)
Pneumonia: May be No (need research)
Br Asthma: No (need research)
ARDS: No (Research may fail)

18. Avoid NIV
Seizures
Inability to clear secretions or protect airways
Hemodynamic instability
Upper airway obstruction
Severe Upper GIT bleeding
Recent gastroesophageal surgery
Recent facial surgery, trauma or burn
Deformity preventing fit mask
Undrained pneumothorax
Vomiting
Bello et al 2016

19. Mode

20. Modes of MV

22. Ventilator settings
1.Ventilatormode
2.Respiratoryrate
3.Tidal volume or pressure settings
4.Inspiratory flow
5.I:E ratio
6.PEEP
7.FiO2
8.Inspiratory trigger
9.Flow pattern
10.Rise time

23. Inspiratory Triggering:
•Pressure (Patient)
•Flow (Patient)
•Time (Machine/Operator)
•Neurally (Patient)
•Manual (Operator)

25. Flow Rate / I:E Ratio
•Flow Rate:
A measure of the rate of delivery of air through the
system to the patient.
(usually 60 liters per minute) IN OBSTRUCTIVE
DISEASES and 40-45 in others
•I:E Ratio:
Ameasure of total inspiratory time to expiratory
time.
(1:3) is ideal IN OBSTRUCTIVE DISEASES and
1:1.5-2 in others may e reverse (1:1 or less)

26. Flow Pattern

27. Oxygen (FiO2)
•Start with 100%
then taper

28. Vt
•4-8 ml/kg IBW

31. V-SIMV
•PSV is almost combined with it (to decrease
WOB)
•Set(RR, Vt, Flow rate, PEEP, FiO2, Rise Time,
Insp Pause, Ti, I:E ratio, Duty Cycle)
•Inbetween mandatory breath, patient can
breathe freely (controlled, assisted or
spontaneous)

33. SIMV

34. Pressure Controlled Ventilation
(PCV) (P-SIMV):
•Set Pressure not Exceeded
•Vt variable according to compliance and resistance
from breath to breath
•Alarm: Vt and minute volume
•Set (Pressure, PEEP, PSV, Ti, Rise time, I:E ration,
FiO2, RR)
•Time cycled
•Time or Patient triggered

36. Assist/Control Ventilation (ACV):
•Mostly Volume , may be Pressure
•Machine or patient triggered
•twin breaths
•PEEP may be added
•Decrease WOB but may cause dynamic hyperinflation or
respiratory alkalosis
•The set rate is at least maintained
•Set (RR, PEEP, Rise, I:E ratio, FiO2, Waveform, Vt, Flow rate)

37. A/CV

38. Pressure Support Ventilation (PSV):
•Not pressure controlled but Pressure
assist or Boost ventilation
•Decrease WOB
•Exclusively; patient triggered
•Flow Cycled

40. POSITIVE END EXPIRATORY
PRESSURE (PEEP):
•This is NOT a specific mode, but is rather an
adjunct to any of the vent modes.
•PEEP is the amount of pressure remaining in
the lung at the END of the expiratory phase.
•Utilized to keep otherwise collapsing lung
units open while hopefully also improving
oxygenation.

41. Major indications of PEEPe:
•Intrapulmonary shunt and refractory
hypoxemia
•Decreased FRC
•PEEPi

44. BIPAP:
•PSV Plus PEEP (CPAP)
•The PSV value + PEEP value during
inspiration is IPAP
•PEEP alone during expiration is EPAP

45. HFOV:
RR 180-900
Vt up to 3ml/kg only
In ARDS only

46. Dual Modes:
•Volume Assured Pressure Support
(VAPS)
•Pressure Regulated Volume Controlled
(PRVC)
•etc.......

47. PRESSURE REGULATED
VOLUME CONTROL (PRVC):
•This is a volume targeted, pressure
limited mode. (available in SIMV or
AC)
•Each breath is delivered at a set
volume with a variable flow rate and
an absolute pressure limit.
•The vent delivers this pre-set volume
at the LOWEST required peak
pressure and adjust with each breath.

49. APRV

50. PAV:
•PAV is an accessory muscle of inspiration
•No set target for flow, volume or pressure
•Differ from PSV as it changes from breath to
breath according to patient effort
•Available in: Puritan Bennett 840, and Drager
Evita 4 and XL

52. PAV setting:
•Enter IBW
•Enter Tube size
•Set expiratory sensivity (3L/min default)
•Set flow trigger (3 L/min)
•Set humidifier volume if applicable
•Set high Vt limit
•Start assist at 70%
•Set PEEP
•Acivate PAV

53. Neurally Adjusted Ventilatory Assist
(NAVA):
The pressure assist is proportional the the degree of
diaphragmatic electrical activity

57. Previous simple days