Oxygen TherapyOxygen Therapy

Dr Surinder SinghDr Surinder Singh

IGMC ShimlaIGMC Shimla

Basic Concepts:Basic Concepts:

Oxygen CascadeOxygen Cascade: :

Inspired = 150 mmHg at Inspired = 150 mmHg at Sea Level Sea Level SML120SML120

↓ ↓ Alveolar POAlveolar PO22= 103= 103 ↓↓ Arterial=100Arterial=100

↓↓ Capillary= 51Capillary= 51 ↓↓ Mitochondrial= 1-10Mitochondrial= 1-10

(FiO(FiO2 2 expressed as 0.21-1.0 or 21- 100%)expressed as 0.21-1.0 or 21- 100%)

Oxygen Availability: NormalOxygen Availability: Normal

Oxygen Flux or OOxygen Flux or O22 availability/min availability/min::= (Hb content+ Plasma content) x Q= (Hb content+ Plasma content) x Q

= (= (1.39x Hb x SaO1.39x Hb x SaO2 2 + 0.003 x PaO+ 0.003 x PaO22 ) x ) x Q mlQ ml

100100 100 100

= (= (1.39 X 14.5 X 97.51.39 X 14.5 X 97.5+.003 X 100) X +.003 X 100) X 50005000

100100 100100

= 985+ 15 = 1000ml= 985+ 15 = 1000ml

Coefficient of Oxygen utilisation: OCoefficient of Oxygen utilisation: O2 2 consumed/ Oconsumed/ O22

availableavailable

= = 250250 =25% =25% Safety margin= 75%Safety margin= 75%

10001000

Oxygen Availability: Disease stateOxygen Availability: Disease state

Low CO eg. 50%+ Normal Hb = 500 ml Low CO eg. 50%+ Normal Hb = 500 ml Safety=50%Safety=50%

Low CO eg 50%+ Low Hb 7gm= 250 ml Low CO eg 50%+ Low Hb 7gm= 250 ml Safety=??Safety=??

Hemorrhagic Shock= Hemorrhagic Shock= ↓CO+↓Hb=↓↓↓↓ O↓CO+↓Hb=↓↓↓↓ O22

MS+Anemia= ↓CO+↓Hb=↓↓↓↓ OMS+Anemia= ↓CO+↓Hb=↓↓↓↓ O22

Critical Flux= 500ml Critical Flux= 500ml

Last 250ml can’t be extractedLast 250ml can’t be extracted

The narrow safety margin is further reduced if The narrow safety margin is further reduced if oxygen demand increases in such patientsoxygen demand increases in such patients

Perioperative State:Perioperative State:

↑ ↑ Oxygen Oxygen demanddemand due to shivering, due to shivering, fever, sepsis, fever, sepsis, hypercatabolic state.hypercatabolic state.

Patients may be Patients may be unable unable to increaseto increase cardiac cardiac output or Voutput or VE E or bothor both

A A vicious cycle of vicious cycle of hypoxemia hypoxemia may startmay start

..

Factors Factors ↓ O↓ O22 Availability: Availability:

A.A. Low arterial OLow arterial O2 2 content:content: ↓ ↓ FiOFiO2, 2, ↓PaO↓PaO22

↓ ↓ Diffusion eg ARDS, CPE Diffusion eg ARDS, CPE ↓ ↓ pH or acidosispH or acidosis

B.B. Low Hemoglobin:Low Hemoglobin: ↓ ↓ HbHb ↑ ↑ COHbCOHb MetHbMetHb

C.C. Low cardiac output statesLow cardiac output states

Factors Factors ↑ O↑ O22 Requirement: Requirement:

Pregnancy: Pregnancy: ↑ 7-8 ml/kg/min ↑ 7-8 ml/kg/min Normal=4-5 ml/kg/minNormal=4-5 ml/kg/min

Sepsis , Hypercatabolic stateSepsis , Hypercatabolic state

Shivering= Shivering= ↑ ↑ 500% 500% of the Normal requirements of the Normal requirements

Fever: 7% increase /Fever: 7% increase /ooC rise of body temperatureC rise of body temperature

↑ ↑ Work of breathingWork of breathing

↑ ↑ Myocardial work: TachycardiaMyocardial work: Tachycardia

How to How to ↓O↓O22 Consumption: Consumption:

Minimize exertionMinimize exertion Digitalize, treat cardiac failureDigitalize, treat cardiac failure Prevent & Treat feverPrevent & Treat fever Under extreme circumstances: Under extreme circumstances:

Paralysis and IPPV Paralysis and IPPV Induce hypothermiaInduce hypothermia ECMOECMO CPB CPB

How to How to ↑ O↑ O22 availability: availability: Raise Arterial PaORaise Arterial PaO2 2 && SaOSaO22

Oxygen TherapyOxygen Therapy Treat Bronchospasm/ respiratory lesions Treat Bronchospasm/ respiratory lesions Ventilation, PEEP, CPAPVentilation, PEEP, CPAP

Raise Hemoglobin:Raise Hemoglobin: Hb: BT, Pack cell transfusionHb: BT, Pack cell transfusion

Raise Cardiac Output:Raise Cardiac Output: Correct AcidosisCorrect Acidosis Correct Hypovolemia Correct Hypovolemia Inotropic SupportInotropic Support Treat Cardiac Lesions/ ShuntsTreat Cardiac Lesions/ Shunts

Efficacy of oxygen therapyEfficacy of oxygen therapy

∆∆ OO22 /100 ml Art. Blood/percent /100 ml Art. Blood/percent ↑↑ FiO2FiO2 Diffusion Hypoxia & High AltitudeDiffusion Hypoxia & High Altitude 3 ml 3 ml Respiratory depressionRespiratory depression 3 ml3 ml ARDS/CPEARDS/CPE AnemiaAnemia 0.03 ml0.03 ml Shock, Valve defectsShock, Valve defects 0.03 ml0.03 ml MetHbMetHb 0.03 ml 0.03 ml Cytotoxic HypoxiaCytotoxic Hypoxia 0.03 ml0.03 ml

BTS Indications: High BTS Indications: High concentrationconcentration

Indication Additional CommentsTarget Sp O2 94 - 98%

Grade of Recommendation

Cardiac arrest or resuscitation

Bag- valve- mask D

Shock, sepsis, major trauma, near drowning,

Target maximal SpO2

Add other treatments

D

Major Head Injury Early intubation and ventilation if needed

D

Carbon monoxide poisoning

Bag valve with high flow to avoid rebreathingSpO2 will be high

PaO2 will be normal

Patient will be hypoxic

C

BTS Indications: Medium BTS Indications: Medium concentrationconcentration

Indication Additional comments Evidence grade

Asthma Supplement oxygen CPneumonia Supplement oxygen CLung cancer Supplement oxygen CPostop breathlessness Treat underlying cause, CPAP, BiPAP CAcute Heart failure Consider CPAP, NIV Intubation and

ventilation+PEEPD

Pulmonary embolism Most do not require Severe ones not benifitted DPleural effusions Drainage of effusion D

Pneumothaorax Drainage/ aspiration of pneumothorax D

ILD (Ac deterioration) Bag valve mask if SpO2 < 85% D

Severe anemia Transfuse and correct anemia B& D

Sickle cell crisis Useful in hypoxemia; treat aggravating factors BNasal cannulae 2- 6 LPM or simple mask 5-10 LPM Target 94-98% SpO2

Reservoir mask if no improvement. If high risk hypercapnea; target 88-92% SpO2

BTS Indications: Low BTS Indications: Low ConcentrationsConcentrations

COPD and other conditions requiring low dose oxygen therapy (2 – 6 LPM)

COPD 24- 28% oxygen, 88-92% SpO2 ABG to assess PaCO2 D

If normocapnea target SpO2 of 94-98% D

If below 88% despite 28% FiO2 switch over from ventimask to nasal cannula 2-6 LPM

D

Repeat ABG after 30-60 min or on deterioration for PaCO2

D

LTOT > 17 hour/day improved quality of life and survival A

Oxygen Alert card for Hypercapnic respiratory failure patients should guide oxygen therapy

Chronic NM disorders eg MND, LAS

Chronic and subacute conditions require nocturnal CPAP, NIV and eventually end of life care

C

Acute neuromuscular disorders

Rapidly progressing LGBS and Myasthenia gravis often require tracheal intubation and ventilatory supportNeurotoxins also fall in this category

A& B*

Specific conditionsSpecific conditionsSpecific conditions

MI, ACS Not hypoxic, benefits/harms of oxygen therapy unknown D

Stroke Harmful in nonhypoxemic mild to moderate stroke patients B

Pregnancy& Obstetric patients

Major trauma, sepsis, shock states give oxygen to target 94-98% SpO2

Harmful to fetus in nonhypoxemic mothers causes, Fetal acidosis Use left lateral tilt in POG > 20wks

A – D

Hyperventilation& dysfunctional breathing

Oxygen not justifiedRebreathing may cause hypoxia thus not recommended

C

Drug poisoning, overdose

Hypoventilation if present, treat with antidotes e.g. naloxoneAvoid hyper-oxygenation as hypercapnea may be presentPerform ABG

D

Paraquet/ bleomycin

Avoid oxygen C

General considerationsGeneral considerations

PIFR:PIFR:

Low: Respiratory Low: Respiratory depressiondepression

V High: Tachypnea, ARDSV High: Tachypnea, ARDS

Expiratory pauseExpiratory pause

Longer: Resp depressionLonger: Resp depression

Shorter: Tachypnea ARDSShorter: Tachypnea ARDS

General considerationsGeneral considerations Use mask in distress :Mouth breathing Use mask in distress :Mouth breathing Humidification not useful < 10LPMHumidification not useful < 10LPM Use upright posture to the extent permissibleUse upright posture to the extent permissible Appropriate FiOAppropriate FiO2 to achieve Target SPO22 to achieve Target SPO2

Confirm oxygen delivery to the patient Confirm oxygen delivery to the patient Prescribe& document oxygen therapyPrescribe& document oxygen therapy Monitor SpOMonitor SpO22 ABG, Vitals, Narcosis ABG, Vitals, Narcosis Diagnose and treat the underlying cause Diagnose and treat the underlying cause

MOST INDICATIONS FALL IN EVIDENCE LEVEL-D OR MOST INDICATIONS FALL IN EVIDENCE LEVEL-D OR CC

Devices for oxygen :HistoryDevices for oxygen :History

BLB Mask 1938BLB Mask 1938

BoothbyBoothby

LovelaceLovelace

Bulbulian Bulbulian

Nasal mask with Nasal mask with reservoirreservoir

Devices Devices Nasal Catheters:Nasal Catheters: : : No/ low capacity No/ low capacity Variable performanceVariable performance

2-4 LPM (BTS 2-6)2-4 LPM (BTS 2-6) Upto 35% FiOUpto 35% FiO22

Advantages: Advantages: Economical, Gas Economical, Gas

economyeconomy No VNo VDD/ rebreathing/ rebreathing Eating, drinking, Eating, drinking,

speaking possiblespeaking possible Useful for low FiOUseful for low FiO22

Can be used in Can be used in Tracheal/ Tracheal/ Tracheostomy tubeTracheostomy tube

Disadvantages:Disadvantages: Irritation, No Irritation, No

humidificationhumidification Encrestations, Encrestations,

UlcerationUlceration

Nasal Prongs/ oxyarm: Nasal Prongs/ oxyarm: No/ Low capacity No/ Low capacity Variable performanceVariable performance

Nasal Prongs:Nasal Prongs: Better toleranceBetter tolerance Performance same as Performance same as

nasal cathetersnasal catheters Reservoir 20-30mlReservoir 20-30ml ETCO2 samplingETCO2 sampling

Oxyarm: Oxyarm: Cloud of 28-35% FiOCloud of 28-35% FiO22 in in

front of nose& mouthfront of nose& mouth

Simple Mask: Simple Mask: Low capacity Variable Low capacity Variable performanceperformance

Simple Face MaskSimple Face Mask:: No limit of ONo limit of O2 2 flowflow Usually 4-6 LPMUsually 4-6 LPM FiOFiO2 2 ≈≈ oxygen flow oxygen flow Usually 2- 4%/ LPMUsually 2- 4%/ LPM-1-1

AdvantagesAdvantages:: Simple, No Flow limit/ Simple, No Flow limit/

FiOFiO22 limit limit

DisadvantagesDisadvantages:: ? FiO? FiO2, 2,

Cross InfectionCross Infection No HumidificationNo Humidification

Ventury masks: Ventury masks: Fixed performance High Fixed performance High flowflow

Medium Conc. MaskMedium Conc. Mask:: Comes with one Comes with one

adapter set at 35%adapter set at 35% Required 5 LPMRequired 5 LPM Set of adaptersSet of adapters

Multi VentMulti Vent: : One or two adjustable One or two adjustable

adapters adapters

Anaesthesia Breathing Anaesthesia Breathing Circuits: Low flow Circuits: Low flow

Fixed performanceFixed performance

Devices:Devices: High capacity Reservoir mask High capacity Reservoir mask

60 – 95% FiO60 – 95% FiO2 2

FiOFiO2 2 dependant on FGFdependant on FGF

Inversely related toInversely related to VVËË

Rebreathing directly Rebreathing directly related torelated to VVË Ë and and inversely related to FGFinversely related to FGF

Valve between the Valve between the reservoir & mask reservoir & mask prevents rebreathingprevents rebreathing

Requires continued Requires continued flow and observationflow and observation

Hood, tent and IncubatorHood, tent and Incubator

Large capacity for Large capacity for oxygen and COoxygen and CO22

Unpspecified FiOUnpspecified FiO22

Ambulatory devicesAmbulatory devices

.. ..

Oxygen Toxicity:Oxygen Toxicity:

Described by Sir joseph PriestleyDescribed by Sir joseph PriestleyGeneration of Superoxide radicals O - Generation of Superoxide radicals O - Absorption atelectasisAbsorption atelectasis↓↓ Surfactant productionSurfactant productionDrying of mucosal epithelium and secretionsDrying of mucosal epithelium and secretionsROPM, Fibrocystic dysplasia, ARDS ROPM, Fibrocystic dysplasia, ARDS ↑ ↑ PCOPCO 2 2 in COPD patients: Narcosisin COPD patients: Narcosis

FiOFiO 2 2 100%= 4 hrs FiO100%= 4 hrs FiO 2 2 80%= 8 hrs80%= 8 hrs FiOFiO 2 2 70%= 12 hrs FiO70%= 12 hrs FiO 2 2 60%= 24 hrs60%= 24 hrs FiOFiO 2 2 ≤≤ 50%= Indefinite 50%= Indefinite

Choose wisely - live wellChoose wisely - live well

THANKS FOR YOUR PATIENT LISTENINGTHANKS FOR YOUR PATIENT LISTENING