ASSISTED VENTILATION

By:

Dr.SaifAssistant Professor Of Paediatrics

Allied Hospital Faisalabad.

Definition

“Movement of gas into and out of lungs by an external source connected to the patient”

History

Hipocrates (400 B.C) work ignored for next 1000 years.

Paracealsus (1493-1541) Bellow and oral tube.

Vide Chaussier and his successors (1879). Aerophore pulmonare.

Fell-O’Dwyer apparatus (1887)

Alexander Graham Bell’s Negative Pressure Ventilator(1889)

Five Ws of assisted ventilation

WHOWHEN WHATWHEREWHY

Types of ventilators

Negative pressure ventilators

e.g, Airshield “Isolette respirator”

• Advantages:

o Less oxygen toxicityo Less pulmonary infectiono Less chances of atelectasiso Less pulmonary air leakso Less airway trauma

• Disadvantages: o Patient inaccessible for

routine investigationso Hypothermiao Neck abrasionso o Not effect for V.L.B.W

Negative Pressure Ventilator

Positive pressure ventilators:

Classification (by cycling mode);

• Time cycled: o Electrical e.g; Sechrist, Bourns BP 200, o Healthdyne 100,Bear Cub, o Pneumatic e.g; Baby bird

• Volume cycled:o e.g.; Siemens,Bourns LS-104-150, Bonnett,Emerson

• Pressure cycled

• Flow cycled

• Mixed cycling

Positive Pressure Ventilator

High Frequency Ventilators: Delivers small gas volumes at high frequency.

Classification of positern press ventilatoron (by cyclic mod)

Volume cycledPressure cycledTime cycledMined cycled

Satisfactory ventilator

All models of ventilation, should be Simple, Reliable, Small, Inexpensive, Wide range of respiratory rate upto 150, FiO2 21 to 100%, Alarm system etc.

“IT IS NOT THE GUN BUT MAN BEHIND THE GUN”

1965 Lancet editorial: • The tedious argument about the virtues of

respirators not invented over those readily available can be ended now that it is abundantly clear that the success of such apparatus depends on the skill with which it is used.

Mode control mode

Control mode: Ventilator will take total control Assist mode Ventilator initiate inspiration when

pt generates sub base line pressure trigger level

Asst/cont. Mode: Vent is set at certain level and its

responds to all breathing efforts by the patient reaching trigger level. If patients rate falls below preset rate it will automatically enter control mode.

IMV: Control mode + unhandled

spontaneous ventilation by the pt. SIMV: CPAP: Maintain increased transpulomanary

pressure during expiratory phase of respiration.

Ventilation settings Flow Rate:• 7L/min (4-10L/min)• High flow rate when inspiratory time shortened • A minimum flow of at least two times the infant

calculated minute ventilation (tidal Volume * RR) e.g. 10 Kg 70 50/3.50L/min 1:E Ration 1:1: to 1:2

2. Oxygen Con (FiO2: 50-70%

3. Peak Inspiratory pressure (PIP) 20-25cmH2O range (5 to 10 cm H2O)

4. Respi ratory rate frequency (f): varies 2-150/min range

5. Positive end expiratory pressure (PEEP): 4-7 cm/H2O

6. Wave form range: taper(sin) to square

Mean air way pressure 5.0 to 80 cm H2O the mean of installations readings of press with in the air way

Bar graph patient pressure display

Breath status indicator

D/C power indicator

Battery power indicator

Visual Alarm indicator

Message display

Alarm setting indicator

Alarm Delay setting /display

Means R/R

Trigger/Sensor sensitivity setting display

Set respiratory display.