1. Monitoring Ventilated Patients
Dr.T.Sureshkumar MD, IDCCM, EDIC
Consultant Intensivist
Kovai Medical Center and Hospitals

2. SCOPE OF THIS TALK
The aim is not to make anybody expert but to guide safe and efficient practice.
Narrowed down to avoid major catastrophe
Focused on graphics and hemodynamics as time limits
Language is not a barrier here & I am not the best in English.
My intention is not delivery but reach, so please come close to me.

3. Five Monitors Three Phases Patient Induction Ventilator Maintenance
Vitals
Images
Labs
Three Phases
Induction
Maintenance
Weaning

4. Why Ventilation ?? Need for Ventilation Pulmonary Extra Pulmonary
Abnormal lung
Pulmonary
Extra Pulmonary
Normal lung
Air way issues
Parenchymal issues
High resistance
Poor Compliance

5. Start with…Intubation
1st - Look your Patient
Look & check air entry
Abnormal breathing
Abdomen distending
Irregular chest rise
Hear
Five point auscultation
Abnormal sounds –wheeze, crepts
And Yes your tube in right place…

6. Patient Disease worsening During Weaning :
At induction phase Pt will be in control ventilation
During maintenance Pt will trigger and may attempt his own breath
Care should be taken whether he tolerates ventilator
Our settings adequate for him
Asynchrony
Disease worsening
During Weaning :
Important to communicate with Patient
Don’t ignore his needs

7. 2nd – Check Ventilator Two important things
What the ventilator gives to the patient
How the lung accepts it.

8. Basic setup Scalars and loops Parameters Alarm settings
Oxygenation ( FiO₂)
Ventilation (RR, Vt)
Desired mode
Recruitment (PEEP) if needed.
Scalars and loops
Parameters
Alarm settings

9. Ventilator Graphics
Scalar and Loops are windows to Lung-Ventilation Mechanics
So all modern ventilators equipped with Graphical representations.
Gives a quick clue for problem even from a distance.
On evaluation can diagnose specific disorder and helps in preventive measures.

10. Scalars and Loops:
Scalars: Plot pressure, volume, or flow against time. Time is the x-axis.
Loops: Plot pressure or flow against volume. (P/V or F/V). There is no time component.

11. Volume Modes Pressure Modes Pressure Control PRVC SIMV (PRVC)
SIMV (Press. Control)
Volume Control
SIMV (Vol. Control)
Pressure Support
Volume Support

12. Pressure Time

13. Plateau Pressure
Airway Pressure
Mean airway Pressure

14. Increased Airway Resistance Decreased Compliance
PIP
PIP
Raw
Pplat
Pplat
•A -Increase in airway resistance (Raw) causes the PIP to increase, but Pplat pressure remains normal.
•B-A decrease in lung compliance causes the entire waveform to increase in size. (More pressure is needed to achieve the same tidal volume). The difference between PIP and Pplat remains normal.

16. Air-Trapping (Auto-PEEP)
•An acceptable amount of auto-PEEP should be < 5cm H2O

17. Flow Time

18. Volume
Pressure

20. Wheeze & Bronchodilator Response
Improved Peak Flow

21. The area of no flow indicated by the red line is known as a “zero-flow state”.
This indicates that inspiratory time is too long for this patient.

22. Is it Inadequate insp. Time??
No . In spontaneous mode it is decided by the patient

23. Volume Time

24. Air-Trapping or Leak

25. Pressure / Volume loops
Dynamic
Compliance

26. Over distention/DHI

27. •As airway resistance increases, the loop will become wider.
•An increase in expiratory resistance is more commonly seen.

28. Increased Compliance Decreased Compliance Example: Emphysema
Example: ARDS, CHF, Atelectasis

29. Lung Compliance Changes and the P-V Loop
Volume Targeted Ventilation
Preset VT
COMPLIANCE
Increased
Normal
Decreased
Volume (mL)
Paw (cm H2O)
PIP levels

30. Lung Compliance Changes and the P-V Loop
Increased
Normal
Decreased
VT levels
Pressure Targeted Ventilation
Volume (mL)
Paw (cm H2O)
Preset PIP

31. A Leak
The expiratory portion of the loop doesn’t return to baseline. This indicates a leak.

32. Pressure / Volume Loop

33. The shape of the inspiratory portion of the curve will match the flow waveform.

34. A Leak
Normal
If there is a leak, the loop will not meet at the starting point where inhalation starts and exhalation ends. It can also occur with air-trapping.

35. Airway Obstruction

36. Flow Starvation
The inspiratory portion of the pressure wave shows a “dip”, due to inadequate flow.

37. Hemodynamics
Important to understand Thoracic physiology – Heart & Lung.
Normally the Negative Plural Pressure augments the venous return to RA and thus increases CO
So Output increases during Inspiration than Expiration.
But in case of Positive Pressure it differs

38. The systolic pressure and the pulse pressure are maximum (SPmax and PPmax) during inspiration and minimum (SPmin and PPmin) during the expiratory period.

39. In hypovolemic conditions
(1) RV preload decreases because
the increase in pleural pressure induces a compression of the
superior vena cava
(2) an increase in intramural right atrial pressure
(3) RV afterload increases because pulmonary capillaries are compressed.
(4) The increase in alveolar pressure squeezes out the blood contained in the capillaries toward the left side of the heart.
(5) The increase in pleural pressure induces a decrease in left ventricular afterload

40. In hypervolemic conditions
The vena cava and right atrium are poorly compliant and compressible and hence relatively insensitive to changes in pleural pressure
(4) Each mechanical breath increases pulmonary venous flow and left ventricular preload
(5) The increase in pleural pressure induces a decrease in left ventricular afterload .

41. Capnography Measures End-tidal CO2 (EtCO2) Monitors changes in
Ventilation - asthma, COPD, airway edema, foreign body, stroke
Diffusion - pulmonary edema, alveolar damage, CO poisoning, smoke inhalation
Perfusion - shock, pulmonary embolus, cardiac arrest, severe dysrhythmias
Gold Standard for confirming Intubation
Reports quality of CPR

42. Normal range is 35-45mm Hg (5% vol)

43. Waveform D C E B End-tidal Alveolar Plateau Ascending Phase
of Exhalation A
Descending phase of Inhalation E
Baseline B

44. Normal 4 5
Hyperventilation 4 5
Hypoventilation

45. Normal
Bronchospasm 4 5

46. SPO₂
Works at two different wavelengths absorbed by oxy and deoxy Hb and the gradient is used to calculate Hb saturation.
Different models of probes available.
Very useful to pick Pt deterioration.
Pros :
Mobile
All time wearable
Real time monitor
Cheap
Cons :
Sats < 85 % are unreliable
Impedance disturbances
Picks little late
Cannot measure MetHb, SulHb
Altered with shock state, nail polish, dyes etc

47. CXR Useful for properly locating the ET Diagnosing issues.
Follow Up of Disease.

48. ABG Its out of scope for this Session. Check Ph
Metabolic side(HCO3) / Respiratory Side(PCO2)
Compensated/ Uncompensated
Any ventilator change can alter it.

49. Charting Even the best handing over cannot replace charting
Reviewing trends helps in Pt Dx & Mx.

50. Language is not a barrier here & I am not the best in English.