mechanical ventilation

Question 1

perfusion

Answer 1

blood supply

Question 2

shunt

Answer 2

normal perfusion but decreased or no ventilation
physiological eg: normal shunting from pleural coronory circulation, dormant alveoli

pathologic: atelectasis secretion
emphysema

Question 3

dead space

Answer 3

ventilation but no perfusion

Question 4

partial pressure

Answer 4

partial pressure is the individual pressure exerted independently by a particular gas within a mixture of gases

Question 5

oxygen saturation

Answer 5

oxygen saturation measures the percentage of hemoglobin bound to oxygen in the blood.

At low partial pressure of oxyegen most hemoglobin is deoxygenated

Question 6

how many o2 molecule carry haemoglobin?

Answer 6

4

Question 7

mechanical ventilation or assisted /artificial ventilation

Answer 7

term used when mechanical means are used to assist or replace spontaneous breathing

Question 8

what is respiratory failure?

Answer 8

inability to maintain p02 of more than 60 mmhg &

pco2 of less than 45 mmhg

Question 9

what are type of respiratory failure?

Answer 9

hypoxemic (type 1) - pa02 <60 mmhg with normal or subnormal paco2

hypercapnic (type 2): paco2 >50 mmhg

Question 10

hypoxemia

Answer 10

lung failure 
(gas exchange failure manifested by hypoxaemic)

occur at lung

Question 11

hypercapnia

Answer 11

pump failure

ventilatory failure manifested by hupercapnia

occur outside a lung

Question 12

what baro receptor do?

Answer 12

sensing the pressure

Question 13

chemoreceptors & baroreceptor?

Answer 13

baroreceptor (sense the increase & decrease pressure of o2 level)

chemoreceptors (check the saturation ) send signal to brain send to respiratory muscle

then muscle are work harder

Question 14

causes of respiratory failure?

Answer 14

failure of lung caused by a variety of lung disease (e.g pneumonia, ild & emphysema) leads to hypoxaemia with normal normocapnia or hypocapnia

failure of pump (e.g drug overuse) results in alveolar hypo ventilation & hypercapnia
although there is coexistence hypoxaemia the hallmark
if ventilatilatory failure is the increase in pa co2

Question 15

indication of mechanical ventilation?

Answer 15

loss of airway anatomy- edema , direct/indirect trauma, burns , infection

loss of protective airway mechanisms-intoxicants, brain injury, stroke

expected clinical course or prophylactic ventilatory support- e.g post anaesthesia recovery, muscle fatigue

inability of oxygenate appropriately (hypoxaemic respiratory failure)
-shunt ,alveoli filled with anything apart from air like secretion, infection etc (condition like ARDS , COPD , cardiac disease etc)

inability to ventilate appropriately (hypercapnia respiratory failure)
cns disease e.g head injury, cerebral hemorrhage , drug overuse (decreased central respiratory drive)

neuromuscular disease e.gbs, poliomyelitis etc (impaired mechanical performance of inspiratory muscle)

musculoskeletal disease e.g chest wall trauma (mechanical defect in chest wall)

Question 16

goals of mechanical ventilation

Answer 16

relive respiratory distress
decrease work of breathing 
improve pulmonary gas exchange 
reverse respiratory muscle fatigue 
permit lung healing 
avoid complications

Question 17

criteria for starting mechanical ventilation

Answer 17

respiratory rate >35 or <5 breath/ min

exhaustion with laboured pattern of breathing

hypoxia- central cyanosis, sa02 <90% on oxygen or pa02 <80 mmhg

hypercarbia -paco2 >50 mmhg
decreasing conscious level
significant chest trauma
tidal volume <5ml/kg or vital capacity <15ml/kg

control of intracranial pressure in head injury

airway protection following drug overdose

following cardiac arrest

for recovery after prolonged major surgery or trauma

Question 18

how normal breathing happens?

Answer 18

when the pressure in the lung di decreases the outside air come inside

when the pressure in the lungs more than atmospheric pressure
air goes out

Question 19

physical breathing

Answer 19

• movement of air in & out of the lungs by respiratory muscle depending on the body requirements
• initiation & termination of breath, rate & depth of breathing are partly voluntary & depand on level of pco2 , p02 and lung inflation
• air is sucked into lungs during inspiration because of negative pressure

increase in pulmonary pressure is minimal between -3 to +5 cm of water

venous return increase during inspiration

Question 20

mechanical ventilation ?

Answer 20

work of respiratory muscle carried out by ventilator

initation & termination of breath rate and depth of breathing are machine /clinical determined

air is sucked into lungs during inspiration because of positive pressure

increase in pulmonary pressure is high between 15 to 40 cm of water

venous return decrease during inspiration

Question 21

dead space

Answer 21

normal ventilation but decreased or no perfusion

physiologic e.g peripheral airway like trachea, bronchi

pathologic: pulmonary embolism

Question 22

mechanical ventilation classification

Answer 22

invasive

ventilatory support given through ETT(endo tracheal tube) or tracheotomy

NON invasive

ventilatory support given without establishing ETT or tracheotomy, generally given through maks

Question 23

where tube coke ate end?

Answer 23

carina where bifurcate into two bronchioles

Question 24

invasive positive pressure ventilation types

Answer 24

volume cycle
pressure cycle
time cycle

Question 25

what is volume cycle?

Answer 25

a pre determined & pre set volume (on completion of its delivery)terminate inspiration.
volume is constant & pressure is variable

Question 26

what is pressure cycle?

Answer 26

a pre determined & pre set pressure terminates inspiration.

pressure is constant & volume is variable

Question 27

what is time cycle?

Answer 27

delivers air /gas over a set time after which inspiration ends

Question 28

pressure depand on?

Answer 28

Volume of air
condition of lungs
if there is same amount of volume goes into the 2 lungs (but one is elastic & 2nd one is in elastic)

the inelastic lung will be required more pressure
why?
becoz effort requires more in the inelastic lungs as compared to elastic lungs

Question 29

mechanical ventilation breath types

Answer 29

controlled breathing
assisted breathing
supported breathing

Question 30

what is controlled breathing?

Answer 30

breath are completely “controlled “ by the breathing.

Question 31

what is assisted breathing?

Answer 31

breath will deliver to the pt. id they attempt to trigger breath .Machine will support u full.

Question 32

what is supported breathing?

Answer 32

these type of breathing triggered by pt. effort . but it will give u some support not fully like assisted breathing