Oxygen Therapy & O2 Delivery Systems

Oxygen Therapy & O2 Delivery Systems
Dr. J. S Dali MAMC

Oxygen Therapy ?

Partial Pr of O2 in insp. gas
Oxygen Therapy Partial Pr of O2 in insp. gas (Pi o2)

Partial Pr of O2 in insp. gas
Oxygen Therapy Partial Pr of O2 in insp. gas (Pi o2) Conc. of O2 (Fi o2) (Orthobaric) Total Pressure (Hyperbaric)

Father of modern O2 Therapy
?

Father of modern O2 Therapy
O2 lack not only stops the machine, but totally ruins the supposed machinery J.S Haldane-1917

Aim of O2 Therapy ?

To restore tissue O2 towards normal
Aim of O2 Therapy To restore tissue O2 towards normal

O2 Cascade Air mitochondria

? O2 Cascade (dry) Atm. Air 159mm Hg (20.95 % of 760)
Lower Resp. Tract (moist 37oc) 149mm Hg (20.95 % of 713)

O2 Cascade (dry) Humidification 6 Vol % (47mm Hg) Atm. Air 159mm Hg
(20.95 % of 760) Atm. Air (dry) Humidification 6 Vol % (47mm Hg) Lower Resp. Tract (moist 37oc) 149mm Hg 20.95 % of 713 (760-47)

O2 Cascade ? ? Lower Resp. Tract 149mm Hg (20.95 % of 713) 101mm Hg
(moist 37oc) 149mm Hg (20.95 % of 713) ? ? 101mm Hg (14 % of 713) or (15 % of 673) 673 = 760 – 47 – 40 Alveolar air PA O2 = FI O2 (Pb – 47) – PaCo2 x F = PI O2 – PaCo2 = PI O2 – PaCo2 if breathing 100% O2 R.Q

O2 Cascade O2 consumption Alv. ventilation Lower Resp. Tract 149mm Hg
(moist 37oc) 149mm Hg (20.95 % of 713) O2 consumption Alv. ventilation 101mm Hg (14 % of 713) or (15 % of 673) 673 = 760 – 47 – 40 Alveolar air PA O2 = FI O2 (Pb – 47) – PaCo2 x F = PI O2 – PaCo2 = PI O2 – PaCo2 if breathing 100% O2 R.Q

? O2 Cascade A – a = 4 – 25 mmHg 101mm Hg Alveolar air Arterial blood
(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

O2 Cascade Venous admixture A – a = 4 – 25 mmHg 101mm Hg Alveolar air
(14 % of 713) or (15 % of 673) 673 = 760 – 47 – 40 Alveolar air Venous admixture Arterial blood 97mm Hg Pa O2 = 100 – 0.3 x age (years) mm Hg A – a = 4 – 25 mmHg

Venous admixture (physiological shunt)
O2 Cascade Venous admixture (physiological shunt) Low VA/Q Normal True shunt (normal anatomical shunt)

O2 Cascade Venous admixture (physiological shunt) Low VA/Q Normal True shunt (normal anatomical shunt) Pulmonary (Bronchial veins) Extra Pulm. (Thebesian veins)

O2 Cascade Venous admixture (physiological shunt) Low VA/Q Normal True shunt (normal anatomical shunt) Pulmonary (Bronchial veins) Extra Pulm. (Thebesian veins) Normal = upto 5 % of cardiac output

O2 Cascade ? ? Venous admixture Alveolar air Arterial blood
PA O2 = 101mm Hg (14 % of 713) or (15 % of 673) 673 = 760 – 47 – 40 Alveolar air ? Venous admixture ? Arterial blood Pa O2 = 97mm Hg Pa O2 = 100 – 0.3 x age (years) mm Hg A – a = 4 – 25 mmHg

O2 Cascade A – a = 4 – 25 mmHg Venous admixture Alveolar air PI O2
PA O2 = 101mm Hg (14 % of 713) or (15 % of 673) 673 = 760 – 47 – 40 Alveolar air PI O2 Venous admixture PV O2 Arterial blood Pa O2 = 97mm Hg Pa O2 = 100 – 0.3 x age (years) mm Hg A – a = 4 – 25 mmHg

Cell Mitochondria PO2 7 – 37 mmHg
O2 Cascade Arterial blood Pa O2 = 97mm Hg (Sat. > 95 %) Utilization by tissue Cell Mitochondria PO – 37 mmHg Mixed Venous blood PV O2 = 40mm Hg Sat. 75% – The critical level for aerobic metab. to continue

O2 Cascade Arterial blood Pa O2 = 97mm Hg (Sat. > 95 %) Utilization by tissue Cell Mitochondria PO – 37 mmHg 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)

Which patient is better placed – ?
A B Hb gm (normal) gm (Anaemic) C.O L (normal) 4 L (Low) PaO mm mm O2 Flux ml ml

A B Hb gm (normal) gm (Anaemic) C.O L (normal) 4 L (Low) SPO % % PaO mm mm O2 Flux ml ml Min. gradient for O2 transfer from cap. to cell (app. 20 mm Hg) = sat. 20 – 30% = 200 – 300ml O2 flux Critical Level for O2 delivery / critical O2 flux

O2 Cascade Arterial blood Pa O2 = 97mm Hg (Sat. > 95 %) Utilization by tissue Cell Mitochondria PO – 37 mmHg 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)

O2 Cascade Arterial blood Pa O2 = 97mm Hg (Sat. > 95 %) ? Utilization by tissue ? Cell Mitochondria PO – 37 mmHg 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)

O2 Cascade Arterial blood Pa O2 = 97mm Hg (Sat. > 95 %) Perfusion Utilization by tissue O2 content (Hb Conc.) Cell Mitochondria PO – 37 mmHg 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)

O2 content. Per 100 ml. Art. blood 14g x 1. 39 x 100% = 20 ml. Ven
O2 content Per 100 ml Art. blood 14g x 1.39 x 100% = 20 ml Ven. blood 14g x 1.39 x 75% = 15ml Tissue extraction % = 5ml

O2 content. Per 100 ml. Art. blood 14g x 1. 39 x 100% = 20 ml. Ven
O2 content Per 100 ml Art. blood 14g x 1.39 x 100% = 20 ml Ven. blood 14g x 1.39 x 75% = 15ml Tissue extraction % = 5ml % = 0.2ml Art. blood 7g x 1.39 x 100% = 10 ml Ven. blood 7g x 1.39 x 50% = 5ml Tissue extraction % = 5ml % = 0.1ml

PO2. O2 content. Per 100 ml 97mm. Art. blood 14g x 1
PO2 O2 content Per 100 ml 97mm Art. blood 14g x 1.39 x 100% = 20 ml 40mm Ven. blood 14g x 1.39 x 75% = 15ml Tissue extraction % = 5ml % = 0.2ml mm Art. blood 7g x 1.39 x 100% = 10 ml ? Ven. blood 7g x 1.39 x 50% = 5ml Tissue extraction % = 5ml % = 0.1ml

PO2. O2 content. Per 100 ml 97mm. Art. blood 14g x 1
PO2 O2 content Per 100 ml 97mm Art. blood 14g x 1.39 x 100% = 20 ml 40mm Ven. blood 14g x 1.39 x 75% = 15ml Tissue extraction % = 5ml % = 0.2ml mm Art. blood 7g x 1.39 x 100% = 10 ml 27mm Ven. blood 7g x 1.39 x 50% = 5ml Tissue extraction % = 5ml % = 0.1ml

Oxygen Therapy Indications

Oxygen Therapy Indications
FIO2 Barometric Pressure PIO2

FIO2 FIO2 during anaes. - Rebreathing Barometric Pressure - High altitude PIO2

FIO2 FIO2 during anaes. - Rebreathing Barometric Pressure - High altitude PIO2 O2 Consumption Alveolar Ventilation PAO2

FIO2 FIO2 during anaes. - Rebreathing Barometric Pressure - High altitude PIO2 O2 Consumption convulsions thyrotoxicosis -shivering -pyrexia Alveolar Ventilation resp. depression Resp. muscle paresis resp.effort (trauma) airway obstruction PAO2

FIO2 FIO2 during anaes. - Rebreathing Barometric Pressure - High altitude PIO2 O2 Consumption convulsions thyrotoxicosis -shivering -pyrexia (7 % / o C) Alveolar Ventilation resp. depression Resp. muscle paresis resp.effort (trauma) airway obstruction PAO2

Low VA/Q Normal Anat. shunt PaO2

Low VA/Q Abn. Pulmonary shunt - pneumonia lobar atelectasis ARDS Normal Anat. shunt Abn.extra Pulm. Shunt cong. heart disease (R L ) PaO2

Low VA/Q Abn. Pulmonary shunt - pneumonia lobar atelectasis ARDS Normal Anat. shunt Abn.extra Pulm. Shunt cong. heart disease (R L ) PaO2 Hypoxic hypoxia

Simple Rule 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

Low VA/Q Abn. Pulmonary shunt - pneumonia lobar atelectasis ARDS Normal Anat. shunt Abn.extra Pulm. Shunt cong. heart disease (R L ) PaO2 Perfusion Hb concentration Cell PO2

Low VA/Q Abn. Pulmonary shunt - pneumonia lobar atelectasis ARDS Normal Anat. shunt Abn.extra Pulm. Shunt cong. heart disease (R L ) PaO2 Perfusion local - PVD, thrombosis gen – shock, Hypovol., card. Failure cardiac arrest Hb concentration Anaemia CO poisoning Cell PO2

A B Anaemic patient Patient with Hb 14gm% Hb = 7gm % Normal Hb 7gm% Hb Co gm%

A B Anaemic patient Patient with Hb 14gm% Hb = 7gm % Normal Hb 7gm% Hb Co gm% 2,3 DPG Shift to R Shift to L unloading of O2 unloading of O2 (blood tissue) (blood tissue) PVO2 – ? PVO2 – ?

A B Anaemic patient Patient with Hb 14gm% Hb = 7gm % Normal Hb 7gm% Hb Co gm% 2,3 DPG Shift to R Shift to L unloading of O2 unloading of O2 (blood tissue) (blood tissue) PVO2 – 27 mm Hg PVO2 – ?

A B Anaemic patient Patient with Hb 14gm% Hb = 7gm % Normal Hb 7gm% Hb Co gm% 2,3 DPG Shift to R Shift to L unloading of O2 unloading of O2 (blood tissue) (blood tissue) PVO2 – 27 mm Hg PVO2 – 14mmHg

Hypoxia in co poisoning is out of proportion to degree of anemia

A B Anaemic patient Patient with Hb 14gm% Hb = 7gm % Normal Hb 7gm% Hb Co gm% 2,3 DPG Shift to R Shift to L unloading of O2 unloading of O2 (blood tissue) (blood tissue) PVO2 – 27 mm Hg PVO2 – 14mmHg Cardiac Output

Dissolved O2 in plasma 0.003ml / 100ml of blood / mm PO2
Breathing Air (PaO2 100mm Hg) 0.3ml / 100ml of blood

Breathing Air (PaO2 100mm Hg) 0.3ml / 100ml of blood Breathing 100% O2

Breathing Air (PaO2 100mm Hg) 0.3ml / 100ml of blood Breathing 100% O2 (PaO2 600mm Hg) 1.8ml / 100ml of blood

Breathing Air (PaO2 100mm Hg) 0.3ml / 100ml of blood Breathing 100% O2 (PaO2 600mm Hg) 1.8ml / 100ml of blood Breathing 100% O2 at 3 Atm. Pressure

Breathing Air (PaO2 100mm Hg) 0.3ml / 100ml of blood Breathing 100% O2 (PaO2 600mm Hg) 1.8ml / 100ml of blood Breathing 100% O2 at 3 Atm. Pressure 5.4ml / 100ml of blood

Basis of Hyperbaric O2 therapy
Dissolved O2 in plasma 0.003ml / 100ml of blood / mm PO2 Breathing Air (PaO2 100mm Hg) 0.3ml / 100ml of blood Breathing 100% O2 (PaO2 600mm Hg) 1.8ml / 100ml of blood Breathing 100% O2 at 3 Atm. Pressure 5.4ml / 100ml of blood Basis of Hyperbaric O2 therapy

Benefit of O2 therapy in Hypoxia
Hypoxic hypoxia (gas phase) Anaemic hypoxia (fluid phase – const.) + Stagnant hypoxia (fluid phase – flow) + Histotoxic hypoxia (tissue phase) -

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)

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) 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

Physical effects of O2 “Air in the body – where it should not be”

Physical effects of O2 “Air in the body – where it should not be” Surgical emphysema Pneumothorax Air embolism Bowel decompression

Gas Tensions mmHg Art. blood Ven. blood Breathing air PO2 100 40 PCo2
46 PN2 570 Breathing 100% O2 600 ?

Gas Tensions mmHg Art. blood Ven. blood Breathing air PO2 100 40 PCo2
46 PN2 570 Breathing 100% O2 600 50

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 – ?

O2 stores in the body Breathing air Breathing 100% O2 Lungs (FRC)
450 ml 3000 ml Blood 1000 ml 1090 ml Tissue fluids / myoglobin +

O2 Delivery systems

O2 Delivery systems Ambient pressure Variable performance devices
Fixed performance devices

O2 Delivery systems Ambient pressure Positive pressure ventilation
Variable performance devices Fixed performance devices Positive pressure ventilation Non invasive (BIPAP, CPAP) Invasive

O2 Delivery systems Ambient pressure Positive pressure ventilation
Variable performance devices Fixed performance devices Positive pressure ventilation Non invasive (BIPAP, CPAP) Invasive ECMO

O2 Delivery systems 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 system Low flow system
The gas flow is sufficient to meet all inspiratory requirement Low flow system The gas flow is insufficient to meet all inspiratory requirement. Part of tidal volume is provided by room air.

Variables O2 flow rate Patient factors Device factors

Variables O2 flow rate Patient factors Device factors
Inspiratory flow rate Expiratory time (active exp. flow + exp. pause) Device factors

Variables O2 flow rate Patient factors Device 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 FICO2 O2 flow rate + –
+ = – = No cap. Devices Capacity devices FIO2 FICO2 O2 flow rate + – Patient Factors Insp. Flow rate Exp. time Device Physical volume Vent resistance

Nasal Catheter O2 Flowrate (L/min) 1 2 3 4 5 6 Fi O2 0.24 0.28 0.32
0.36 0.40 0.44

Normal Anatomic Reservoir
(50ml) 6 Ltr/min = 100ml/sec = 50ml/1/2 Sec

Nasal Catheter 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.

Nasal Catheter Merits Demerits 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 Mask – ? Simple face mask

Simple Face Mask Simple face mask NO YES

Simple face mask O2 Flowrate (L/min) 5-6 6-7 7-8 Fi O2 0.40 0.50 0.60

Partial Rebreathing mask (polymask)

Partial Rebreathing mask (polymask)
O2 Flowrate (L/min) 6 7 8 Fi O2 0.60 0.70 0.80

What type of circuit it is – ?
Poly mask What type of circuit it is – ?

What type of circuit it is – ? Modified T – Piece
Poly mask What type of circuit it is – ? Modified T – Piece

Non Rebreathing mask Non Rebreathing Mask

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

Face Masks Merits Demerits Higher Oxygen Conc.
Rebreathing (if O2 flow is inadequate) Interfere with further airway care Proper fitting is required Uncomfortable (sweating, spitting)

Bag – Valve – Mask assembly (Ambu Resuscitator)

Delivers O2 during BOTH spont. & artf. Vent O2 concentration 30 – 50% (without reservoir) 80 – 100% (with reservoir) To deliver 100% O2

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 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) 5 10 15 Fi O2 0.40 0.50 (Spont.) (M - mask)

Incubator Small infants – not on ventilator Works on venturi principle
Complete air change – 10 times / hour Control of humidity & temperature O2 conc. falls rapidly when access ports are open

O2 tents For children – not tolerating mask / catheter
Large 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 ? What precaution to be taken for humidification of gases while using this device ?

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

Simple Face Mask Simple face mask NO YES

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 O2 which a patient is getting is not known then the situation is similar to a drug being administered without knowing the dose which can do harm if given more or provide insufficient effect if given less

O2 Toxicity 100% - not more than 12hrs 80% - not more than 24hrs 60% - not more than 36hrs

Rest (read it yourself)

Thank you & Best of Luck

Oxygen Therapy & O2 Delivery Systems

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