1. “Respiratory equipments”
Supply
Delivery
Piping
Regulation

2. Mechanisms of Filters Interception Inertial impaction
Gravitational settling - large particles
Diffusion - small particles
Electrostatic attraction - charged particles
Most-penetrating-particle size = um
“bacteria” - 1μm; “virus” μm

3. Types of filters Mechanical (e.g. glass fibres) High fibre density
High resistance to airflow
Electrostatic (e.g. polypropylene)
Lower fibre density
Lower resistance to airflow

4. Filters Dead space inevitable
Resistance increases as dead space decreases
Occlusion can occur with excessive sputum/water

5. “Respiratory equipments”
Supply
Delivery
Piping
Regulation
H2O
Heat

6. The dilemma Upper airway Ventilator circuit/storage Warm Humid
Filtered
To allow mucociliary elevator functioning
Room temperature
Humid Free
To protect cylinders, pipes and valves

7. Relationship between the humidity and temperature of inspired gas and the function of the airway mucosa, CCM 1996

8. Solutions Passive (Heat Moisture Exchanger) Active (Humidifier)
Circle breathing system

9. HMEs Transparent housing
Rely on chemical to trap heat and moisture in exhaled gas (e.g. Calcium chloride)
Variable and unadjustable performance

10. Active humidification
Bottle humidifier
Active heat and moisture exchanger
Heated humidifier
Nebulizer

11. Bottle humidifier Driven by airflow
Gas blown over water surface - inefficient
Gas blown through water - more efficient but increased resistance, water-bound infections
Maximal level of humidity limited by ambient temperature

12. Heated humidifier Vapor provided by heated water reservoir
Heated tubing to prevent condensation
Temperature of reservoir and tubing adjustable to control humidity and temperature of inspired gas

13. Active HME

14. Nebulizers
Gas powered
Ultrasonic
May be used for medication delivery

15. Which one better? VAP risk
AARC Evidence-Based Clinical Practice Guidelines - Care of the ventilation circuit and its relation to VAP. Respiratory Care 2003

16. Which one better?
Mechanical effects of Heat-moisture exchangers in ventilated patients. Critical Care 1999

17. “Respiratory equipments”
Supply
Delivery
Patient
Exhaust
Suction
Piping
Regulation
H2O
Heat

18. Suction - behind wall
Pump
Pump
Vacuum Tank
Filter

19. Suction - Patient end Catheters Narrowest point at tip
Smooth surface to avoid trauma
Maybe designed as close system
Collecting system
Cut off overflow valve
Foam prevention

20. “Respiratory equipments”
Supply
Monitor
Delivery
Patient
Exhaust
Suction
Piping
Regulation
H2O
Heat

21. Pulse oximetry

22. Pulse Oximetry Motion Tissue perfusion Venous pulsation/engorgement
Ambient Light
Intravascular dye
Abnormal hemoglobin

23. Waveform
Jubran, Critical Care 1996

24. Oxygen Toxicity Retrolental fibroplasias in premature babies
Acute lung injury, ?related to oxygen free radical production
Absorption atelectasis
high FiO2 may cause increased peripheral vascular resistance in congestive heart failure
CO2 narcosis in chronic lung disease

25. Capnograph
Graphical display of expired CO2 concentration (y) against time (x)
IR spectrometry
Affected by
Pulmonary blood flow (cardiac output)
pCO2 (metabolism)
Alveolar ventilation

27. Clinical use Confirmation of artificial airway placement
Early detection of disconnection/kinking within breathing circuit
Estimate adequacy of ventilation
Specific patterns in different pathologies

29. Thank you