Oxygen delivery-systems

transcript

Oxygen Therapy & OOxygen Therapy & O22

Delivery SystemsDelivery Systems

Dr. J. S Dali

www.anaesthesia.co.in anaesthesia.co.in@gmail.com

Oxygen TherapyOxygen Therapy

Oxygen TherapyOxygen TherapyPartial Pr of O2 in insp. gas

(Pi o2)

Conc. of O2 (Fi o2)

(Orthobaric)

Total Pressure

(Hyperbaric)

Partial Pr of O2 in insp. gas

(Pi o2)

Father of modern OFather of modern O22 Therapy Therapy

J.S Haldane-1917

O2 lack not only stops the machine,

but totally ruins the supposed machinery

Aim of OAim of O22 Therapy Therapy

To restore tissue O2 towards normal

OO2 2 CascadeCascade

mitochondria

Atm. Air

Lower Resp. Tract

(moist 37oc)

159mm Hg

(20.95 % of 760)

149mm Hg

(20.95 % of 713)

Atm. Air

Lower Resp. Tract

(moist 37oc)

159mm Hg

(20.95 % of 760)

149mm Hg

20.95 % of 713 (760-47)

Humidification

6 Vol % (47mm Hg)

149mm Hg

(20.95 % of 713)

Lower Resp. Tract

(moist 37oc)

Alveolar air

101mm Hg

(14 % of 713) or (15 % of 673)

673 = 760 – 47 – 40

PA O2 = FI O2 (Pb – 47) – PaCo2 x F

= PI O2 – PaCo2

= PI O2 – PaCo2 if breathing 100% O2

149mm Hg

(20.95 % of 713)

O2 consumption

Lower Resp. Tract

(moist 37oc)

Alv. ventilation

Alveolar air

101mm Hg

(14 % of 713) or (15 % of 673)

673 = 760 – 47 – 40

PA O2 = FI O2 (Pb – 47) – PaCo2 x F

= PI O2 – PaCo2

= PI O2 – PaCo2 if breathing 100% O2

101mm Hg

(14 % of 713) or (15 % of 673)

673 = 760 – 47 – 40

Alveolar air

Arterial blood 97mm Hg

Pa O2 = 100 – 0.3 x age (years) mm Hg

A – a = 4 – 25 mmHg

Venous admixture

101mm Hg

(14 % of 713) or (15 % of 673)

673 = 760 – 47 – 40

Alveolar air

Arterial blood 97mm Hg

A – a = 4 – 25 mmHg

Venous admixtureVenous admixture((physiological shunt)physiological shunt)

Low VA/Q Normal True shunt

(normal anatomical shunt)

Pulmonary

(Bronchial veins)

Extra Pulm.

(Thebesian veins)

Pulmonary

(Bronchial veins)

Extra Pulm.

(Thebesian veins)

Normal = upto 5 % of cardiac output

Venous admixture

PA O2 = 101mm Hg

(14 % of 713) or (15 % of 673)

673 = 760 – 47 – 40

Alveolar air

Arterial blood Pa O2 = 97mm Hg

A – a = 4 – 25 mmHg

Venous admixture

PA O2 = 101mm Hg

(14 % of 713) or (15 % of 673)

673 = 760 – 47 – 40

Alveolar air

Arterial blood Pa O2 = 97mm Hg

A – a = 4 – 25 mmHg

Utilization by tissue

Arterial blood

Pa O2 = 97mm Hg

(Sat. > 95 %)

Mixed Venous blood

PV O2 = 40mm Hg

Sat. 75%

Cell Mitochondria PO2 7 – 37 mmHg

– The critical level for aerobic metab. to continue

Arterial blood

Pa O2 = 97mm Hg

(Sat. > 95 %)

Mixed Venous blood

PV O2 = 40mm Hg

Sat. 75%

Pasteur point – The critical level for aerobic metab. to continue (1 – 2 mmHg PO2 in mitochondria)

A B Hb 14gm (normal) 7gm (Anaemic)

C.O. 5 L (normal) 4 L (Low)

PaO2 23 mm 60 mm

O2 Flux 375ml 350ml

Which patient is better placed – ?Which patient is better placed – ?

A B Hb 14gm (normal) 7gm (Anaemic)

C.O. 5 L (normal) 4 L (Low)

SPO2 40 % 90 %

PaO2 23 mm 60 mm

O2 Flux 375ml 350ml

Min. gradient for OMin. gradient for O22 transfer from cap. to cell (app. 20 mm Hg) transfer from cap. to cell (app. 20 mm Hg) == sat. 20 – 30% sat. 20 – 30% == 200 – 300ml O 200 – 300ml O22 flux flux

Critical Level for OCritical Level for O22 delivery / critical O delivery / critical O22 flux flux

Arterial blood

Pa O2 = 97mm Hg

(Sat. > 95 %)

Mixed Venous blood

PV O2 = 40mm Hg

Sat. 75%

Pasteur point – The critical level for aerobic metab. to continue (PO2 1-2 mmHg in mitochondria, 22mmHg in capillary)

Arterial blood

Pa O2 = 97mm Hg

(Sat. > 95 %)

Mixed Venous blood

PV O2 = 40mm Hg

Sat. 75%

Arterial blood

Pa O2 = 97mm Hg

(Sat. > 95 %)

Mixed Venous blood

PV O2 = 40mm Hg

Sat. 75%

PerfusionO2 content (Hb Conc.)

OO22 content content Per 100 mlPer 100 ml

Art. blood 14g x 1.39 x 100% = 20 mlArt. blood 14g x 1.39 x 100% = 20 ml Ven. blood 14g x 1.39 x Ven. blood 14g x 1.39 x 75% = 15ml75% = 15ml Tissue extraction Tissue extraction 25% = 5ml 25% = 5ml

OO22 content content Per 100 mlPer 100 ml

Art. blood 14g x 1.39 x 100% = 20 mlArt. blood 14g x 1.39 x 100% = 20 ml Ven. blood 14g x 1.39 x Ven. blood 14g x 1.39 x 75% = 15ml75% = 15ml Tissue extraction Tissue extraction 25% = 5ml 25% = 5ml 1% = 0.2ml 1% = 0.2ml

Art. blood 7g x 1.39 x 100% = 10 mlArt. blood 7g x 1.39 x 100% = 10 ml Ven. blood 7g x 1.39 x Ven. blood 7g x 1.39 x 50% = 5ml50% = 5ml

Tissue extraction Tissue extraction 50% = 5ml 50% = 5ml 1% = 0.1ml 1% = 0.1ml

POPO22 OO22 content content Per 100 mlPer 100 ml

97mm97mm Art. blood 14g x 1.39 x 100% = 20 mlArt. blood 14g x 1.39 x 100% = 20 ml 40mm 40mm Ven. blood 14g x 1.39 x Ven. blood 14g x 1.39 x 75% = 15ml75% = 15ml Tissue extraction Tissue extraction 25% = 5ml 25% = 5ml 1% = 0.2ml 1% = 0.2ml

97mm 97mm Art. blood 7g x 1.39 x 100% = 10 mlArt. blood 7g x 1.39 x 100% = 10 ml ? ? Ven. blood 7g x 1.39 x Ven. blood 7g x 1.39 x 50% = 5ml50% = 5ml

POPO22 OO22 content content Per 100 mlPer 100 ml

97mm97mm Art. blood 14g x 1.39 x 100% = 20 mlArt. blood 14g x 1.39 x 100% = 20 ml 40mm 40mm Ven. blood 14g x 1.39 x Ven. blood 14g x 1.39 x 75% = 15ml75% = 15ml Tissue extraction Tissue extraction 25% = 5ml 25% = 5ml 1% = 0.2ml 1% = 0.2ml

97mm 97mm Art. blood 7g x 1.39 x 100% = 10 mlArt. blood 7g x 1.39 x 100% = 10 ml 27mm 27mm Ven. blood 7g x 1.39 x Ven. blood 7g x 1.39 x 50% = 5ml50% = 5ml

Indications

Oxygen TherapyOxygen Therapy IndicationsIndications

Barometric Pressure

- FIO2 during anaes.

- Rebreathing

Barometric Pressure

- High altitude

- Rebreathing

Barometric Pressure

- High altitude

O2 Consumption Alveolar Ventilation

- Rebreathing

Barometric Pressure

- High altitude

O2 Consumption

-convulsions

-thyrotoxicosis

-shivering

-pyrexia

Alveolar Ventilation

-resp. depression

-Resp. muscle paresis

- resp.effort (trauma)

-airway obstruction

- Rebreathing

Barometric Pressure

- High altitude

O2 Consumption

-convulsions

-thyrotoxicosis

-shivering

-pyrexia

(7 % / o C)

Alveolar Ventilation

-resp. depression

-Resp. muscle paresis

- resp.effort (trauma)

-airway obstruction

Low VA/Q Normal Anat. shunt

Low VA/Q

Abn. Pulmonary shunt

- pneumonia

-lobar atelectasis

Normal Anat. shunt

Abn.extra Pulm. Shunt

•cong. heart disease

(R L )PaO2

Low VA/Q

- pneumonia

-lobar atelectasis

Normal Anat. shunt

(R L )PaO2

Hypoxic hypoxia

Hypoxia due to hypoventilation

Slight increase in O2 conc.

(Thus the importance of ventimask)

Higher O2 conc.– –

Simple Rule

Hypoxia due to hypoventilation

Slight increase in O2 conc.

(Thus the importance of ventimask)

Higher O2 conc.– hypercapnoea– absence of cynosis

Simple Rule

Low VA/Q

- pneumonia

-lobar atelectasis

Normal Anat. shunt

(R L )PaO2

Hb concentration Perfusion

Low VA/Q

- pneumonia

-lobar atelectasis

Normal Anat. shunt

(R L )PaO2

Hb concentration

-Anaemia

-CO poisoning

Perfusion

local - PVD, thrombosis gen – shock, Hypovol., card. Failure cardiac arrest

A BAnaemic patient Patient with Hb 14gm%

Hb = 7gm % Normal Hb 7gm%

Hb Co 7gm%

2,3 DPG

Shift to R Shift to L

unloading of O2 unloading of O2

(blood tissue) (blood tissue)

PVO2 – ? PVO2 – ?

Hb Co 7gm%

2,3 DPG

PVO2 – 27 mm Hg PVO2 – ?

Hb Co 7gm%

2,3 DPG

PVO2 – 27 mm Hg PVO2 – 14mmHg

Hypoxia in co poisoningHypoxia in co poisoning

is out of proportion is out of proportion

to degree of anemiato degree of anemia

A BAnaemic patient Patient with Hb 14gm% Hb = 7gm % Normal Hb 7gm% Hb Co 7gm% 2,3 DPGShift to R Shift to L

PVO2 – 27 mm Hg PVO2 – 14mmHg

Cardiac Output

Dissolved ODissolved O22 in plasma in plasma

0.003ml / 100ml of blood / mm PO2

Breathing Air (PaO2 100mm Hg)

0.3ml / 100ml of blood

Breathing 100% O2

Breathing 100% O2 (PaO2 600mm Hg)

Breathing 100% O2 at 3 Atm. Pressure

Basis of Hyperbaric O2 therapy

Benefit of OBenefit of O22 therapy in Hypoxia therapy in Hypoxia

Hypoxic hypoxia (gas phase) + + +

Anaemic hypoxia (fluid phase – const.) +

Stagnant hypoxia (fluid phase – flow) +

Histotoxic hypoxia (tissue phase) -

Normal Person (breathing 100% O2)

14gm x 1.34ml = 18.7ml + 1.8ml = 20.5ml (1.8 is 9% 20.5)

Normal Person (breathing 100% O2)

14gm x 1.34ml = 18.7ml + 1.8ml = 20.5ml (1.8 is 9% 20.5)

Anaemic patient (breathing 100% O2)

4gm x 1.34ml = 5.4ml + 1.8ml = 7.2 ml (1.8 is 25% of 7.2)

Physical effects of O2

“Air in the body – where it should not be”

Surgical emphysema

Pneumothorax

Air embolism

Bowel decompression

Art. blood Ven. blood

Breathing air

PO2 100 40

PCo2 40 46

PN2 570 570

Breathing 100% O2

PO2 600 ?

PCo2 40 46

PN2 0 0

Gas Tensions

Art. blood Ven. blood

Breathing air

PO2 100 40

PCo2 40 46

PN2 570 570

Breathing 100% O2

PO2 600 50

PCo2 40 46

PN2 0 0

Gas Tensions

Tissue requirement per 100ml = 5ml

Dissolved Fraction = 1.8 ml

Balance = 3.2 ml

0.2ml x 16% = 3.2ml

84% saturation = PO2 50mm Hg

Pre oxygenation / ?

Pre oxygenation / denitrogenation

To the O2 reserve in the body – ?

OO22 stores in the body stores in the bodyBreathing

Breathing 100% O2

Lungs (FRC) 450 ml 3000 ml

Blood 1000 ml 1090 ml

Tissue fluids / myoglobin + +

OO22 Delivery systems Delivery systems

Ambient pressure– Variable performance devices– Fixed performance devices

Positive pressure ventilation– Non invasive (BIPAP, CPAP) – Invasive

Ambient pressure– Variable performance devices (Pt. dependent) low flow

No capacity system – no rebreathing

nasal catheter / cannulae Capacity system – chance of rebreathing

– Small – (mass shell only)

– Large – (with reservoir bag)

– Fixed performance devices (Pt. independent) high flow HAFOE (ventimask) Anaesthesia circuits

High flow systemThe gas flow is sufficient to meet all inspiratory

requirement

Low flow systemThe gas flow is insufficient to meet all inspiratory

requirement.

Part of tidal volume is provided by room air.

VariablesVariables

O2 flow rate

Patient factors– –

Device factors– –

VariablesVariables

O2 flow rate

Patient factors– Inspiratory flow rate– Expiratory time (active exp. flow + exp. pause)

Device factors– –

VariablesVariables

O2 flow rate

Patient factors– Inspiratory flow rate– Expiratory time (active exp. flow + exp. pause)

Device factors– Physical volume (capacity)

– Vent resistance (tight fit)

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Variable+ =

No cap.

Devices

Capacity devices

FIO2 FIO2 FICO2

O2 flow rate +

Patient

Factors

Insp. Flow rate

Exp. time

Device

Factors

Physical volume

Vent resistance

Nasal CatheterNasal Catheter

O2 Flowrate (L/min)

Normal Anatomic Reservoir

(50ml)

6 Ltr/min

= 100ml/sec

= 50ml/1/2 Sec

Merits Easy to fix Keeps hands free Not much interference with further airway care Useful in both spont. breathing and apnoeic

10-15 Ltr/min flow rate ----------- 50-60 % O2 conc.

Merits Easy to fix Keeps hands free Not much interference with further airway care Useful in both spont. breathing and apnoeic Small but definite rise in FiO2 (dose not critical)

Demerits Mucosal irritation (uncomfortable) Gastric dilatation (especially with high flows)

For higher O2 Concentration

gadgets with storage capacity (reservoir)

problem of re-breathing

minimized / avoided by higher flows

Simple face maskSimple face mask

Simple Face Mask – ?

NO YES

Simple Face Mask

O2 Flowrate (L/min)

Partial Rebreathing mask (polymask)Partial Rebreathing mask (polymask)

Partial Rebreathing maskPartial Rebreathing mask(polymask)(polymask)

O2 Flowrate (L/min)

Poly mask Poly mask

What type of circuit it is – ?

Poly mask Poly mask

What type of circuit it is – ?

Modified T – Piece

Non Rebreathing maskNon Rebreathing mask

Non Rebreathing Mask

10 – 15 Ltr/min flow rate – 50-100 O2 conc.

Face MasksFace MasksMeritsHigher Oxygen Conc.

DemeritsRebreathing (if O2 flow is inadequate)

Interfere with further airway careProper fitting is requiredUncomfortable (sweating, spitting)

Bag – Valve – Mask assemblyBag – Valve – Mask assembly(Ambu Resuscitator)(Ambu Resuscitator)

Delivers O2 during BOTH spont. & artf. Vent

O2 concentration – 30 – 50% (without reservoir)– 80 – 100% (with reservoir)

To deliver 100% O2

Bag – Valve – Mask assemblyBag – Valve – Mask assembly(Ambu Resuscitator)(Ambu Resuscitator)

Delivers O2 during BOTH spont. & artf. Vent

O2 concentration – 30 – 50% (without reservoir)– 80 – 100% (with reservoir)

To deliver 100% O2 – Reservoir – as large as bag vol

– O2 flow rate > minute volume (10 l/m)

Drawback – keeps rescuer’s hands engaged

Pocket MaskPocket Mask

Delivers O2 in BOTH spont. & aponeic

Allows use of both hands – for maintaining airway Upto 4 ltr reserve vol. (rescuer’s vital capacity)

O2 Flowrate (L/min)

0.80 (Spont.)

0.54 (M - mask)

IncubatorIncubator

Small infants – not on ventilatorWorks on venturi principle Complete air change – 10 times / hourControl of humidity & temperature O2 conc. falls rapidly when access ports are open

OO22 tents tents

For children – not tolerating mask / catheterLarge capacity system Upto 50% O2 concentration

Large tent cap. and leak port – limited CO2

build up.Disadvantage

– Limited access – Risk of fire

– Conflict in O2 therapy / nursing care

Can You name the device ?

Written over it – 28 % @ 4 L P M – ?

If flow is doubled (8 LPM) – what will the %age of O2 delivered by the device ?

If flow is halved (@ 2 LPM) – what will be the %age of O2 received by the patient ?

What is the likely entertainment ratio of this device ?

1 2 4 8 16

What precaution to be taken for humidification of gases while using this device ?

F ixe d P e rfo rm an ce D e v ice

R o om

A p p. D e a d S pa ceR e bre a th ing

A n . C ircu itw ith co lla s ib le re se rvo ir

In sp ira to ry f lo w w ave fo rm

K n o w n , fixe d & se le cta b le

H A F O EV e n tu ri

C o n tin ou s f lo w > P IFR

C o n s ta n t Insp ira to ry m ix tu re

•Works on principle of constant pressure jet – mixture.

•O2 jet entrains air as per entrain. ratio.

•Total flow > PIFR (30 – 35 L/min)

•Eliminates the problem of dead space & leak free connection.

Ventimask

NO YES

Simple Face Mask

•Works on principle of constant pressure jet – mixture.

•O2 jet entrains air as per entrain. ratio.

•Total flow > PIFR (30 – 35 L/min)

•Eliminates the problem of dead space & leak free connection.

•Upper limit is 60 %.

•Humidification of O2 supply is not sensible.

If conc. of OIf conc. of O22 which a patient is getting which a patient is getting

is not known is not known then the situation is similar to then the situation is similar to

a drug being administereda drug being administered without knowing the dose without knowing the dose

which can do harm if given morewhich can do harm if given more or provide insufficient effect if given less or provide insufficient effect if given less

100% - not more than 12hrs100% - not more than 12hrs 80% - not more than 24hrs 80% - not more than 24hrs 60% - not more than 36hrs 60% - not more than 36hrs

OO2 2 ToxicityToxicity

Rest Rest

(read it yourself)(read it yourself)

www.anaesthesia.co.in anaesthesia.co.in@gmail.com

Oxygen delivery-systems

Education