o2 therapy in nicu by dr. tareq rahman

DR. TAREQ RAHMAN

&

Dr. CHANDRA

Resident of phase B, Neonatology

BSMMU

What is Oxygen?

• Oxygen is a chemical

element with symbol “O”

and atomic number “8”. It

is a highly reactive non

metalic element and

oxidizing agent .

• O2 or dioxygen is the

most stable form of

oxygen

Characteristics:

• Colorless, Odorless, Tasteless.

• Non-flammable, accelerates combustion.

• Condenses(Liquid) at –182.95 ° C,

Freezes(Solid) at – 218.79 ° C.

• Atmospheric air contains 20.946% O2.

History

Joseph Priestley discovered element of oxygenin 1774

In 1783 French physician Dr Caillens first time used oxygen therapy as a remedial measure in disease

Paul Bert

Oxygen toxicityin 1878

Why we need Oxygen ?

1. Regulation of breathing process.2.Regulation of metabolic processes.3.90% of our energy comes from O2.4.Phagocytosis5. Assimilation of nutrients.6. Elimination of metabolic wastes.7. Maintain a strong immune system.8. Heightens concentration, alertness and

memory.

Metabolic processes

Electron transport chain and oxidative phosphorylation

Phagocytosis

Oxygen cascade

Oxygen transport in the body

Oxygen transport in the body

• O2 enters into blood from alveoli by simple diffusion.

• In blood oxygen transported in two forms

1. Dissolved state (3%).

2. Oxyhaemoglobin (97%).

From blood O2 enters into tissue due

to pressure gradient.

Oxyhemoglobin Dissociation Curve

• Definition : A relationship between the amount of oxygen dissolved in the blood and the amount attached to the hemoglobin. This is called the normal Oxyhemoglobin dissociation curve.

Normal Oxyhemoglobin Dissociation Curve

97% saturation = 97 PaO2 (normal)90% saturation = 60 PaO2 (danger)80% saturation = 45 PaO2 (severe hypoxia)

SHIFT TO LEFT

• Increase in pH

• Decrease in CO2

• Decrease in 2.3-DPG

• Decrease in temperature

SHIFT TO RIGHT

• Decrease in pH

• Increase in CO2

• Increase in 2,3-DPG

• Increase in temperature

Oxygen dissociation curve

Shift to the left in O2 curveO2 affinity } {

1. Causes: pH, CO2, 2-3 DPG, Temp.

O2 sat. for any pao2 but resulting in less gradient to move O2 to tissue. (Carries moreO2 but more difficult to release it at tissue level)

3. Examples: stored blood loses 2-3 dpg a shift to the left results from this. Hyperventilation, Hypothermia.

2. Results:

Shift to the right in O2 curve

O2 affinity }{

1. Causes: pH , CO2 , 2-3 DPG, Temp.

2. Results: O2 sat for any PaO2 but resultingin more gradient to move o2 into the tissues.

3. Examples: hypoventilation, fever, metabolic acidosis.

Oxygen therapyOxygen therapy• Oxygen Therapy is usually defined as

the administration of oxygen at concentrations greater than those found in ambient air

• The purpose of oxygen therapy is to achieve adequate tissue oxygenation using the lowest possible FiO2.

Goals of O2 therapy

1. Treat hypoxemia

2. Decrease work of breathing (WOB)

3. Decrease myocardial Work

Oxygen saturation is a relative measure of the amount of oxygen that is dissolved or carried in a given medium

• SpO2 = oxygen saturation as measured by pulse oximeter

• SaO2 = oxygen saturation as measured by blood analysis (e.g. a blood gas) ; the degree to which oxygen is bound to hemoglobin.

PaO2 is a measurement of the partial pressure of oxygen dissolved in the plasma only. It is measured in mm Hg.

• It is not the body's total oxygen content, but it does indicate how much oxygen is available in the alveoli to dissolve in the blood.

Indications of OIndications of O22 therapy : therapy :

• Hypoxia: (In neonate SpO2 < 88% , PaO2 < 50 mmHg) Acute respiratory failure. Cardiac failure. Shock. Severe anaemia. Hyper metabolic state.

• During CPR. • During anaesthesia for surgery and Post operative state• Seizure.• Transport of sick patient• Cyanide poisoning and Carbon monoxide poisoning.

• Hypoxia: is an abnormally low oxygen content in any tissue or organ, or the body as a whole.

• Hypoxemia: is usually defined in terms of reduced partial pressure of oxygen in arterial blood, but also in terms of reduced content of oxygen or percentage saturation of hemoglobin with oxygen, which is either found singly or in combination.

• Hyperoxia: occurs when tissues and organs are exposed to an excess supply of oxygen or higher than normal partial pressure of oxygen.

Hypoxia

• Five types of hypoxia: – Anemic– Hypoxemic– Histotoxic– Circulatory– Hypermetabolic

Anemic Hypoxia

• Having a decreased carrying capacity for oxygen, the pt with decreased or abnormal Hb

• Treatment involves blood transfusions, hyperbaric chamber, bone marrow transplant

Hypoxemic Hypoxia

• Low PaO2 due to the atmosphere

• Hypoventilation – PCO2 is rising• Diffusion Defects

• The PaO2 will be lower in all cases, but the PCO2 may or may not be increased.

• Treatment: Compensatory actions to reduce inequalities, supplemental oxygen

Circulatory Hypoxia

• A decrease in cardiac output results in a low BP and a prolonged systemic transit time

• The PaO2 can be high, but because of the time it takes to get to the tissues, the pt is hypoxic

• Cardiovascular instability or failure• Shock• Arrhythmias

• Treatment include increasing cardiac output with use of cardiovascular drugs and therapy, supplemental oxygen

Hypermetabolic Hypoxia

• In some disease states the body requires a slight increase in metabolism (i.e. – wound healing requires 5% increase)

• Extensive burns and some cancers will cause large increases metabolism to the point that supplemental O2 is required

• Treatment: Supplemental O2 or FiO2

Histotoxic Hypoxia

• Inability for tissues to utilize oxygen available

• Cyanide Poisoning will inhibit cellular metabolism from occuring; the cells can not process the O2

• Treatment: Reversal of poisoning, supplemental oxygen and/or ventilation

CONTRAINDICATION :

• In patient with chronic CO2 retention.

• Paraquat poisoning.

COMPLICATIONS :COMPLICATIONS :

• Induced hypoventilation

• Absorption atelectasis.

• Hyperoxemia.

• Skin irritation.

• Nasal obstruction.

• Drying of nasal and pharangeal mucosa.

Cont…

• Some neonate on hypoxic drive may go to apnea.

• ROP – Persistent PaO2 .

• CLD and HIE due to free radical damage .

• Home O2 dependence and rehospitalisation.

• Nosocomial Infection.

• This follows after This follows after prolonged Oprolonged O22 therapy therapy..

1.Intraalveolar hemorrhage.1.Intraalveolar hemorrhage.

2. Lung fibrosis.2. Lung fibrosis.

3. Decreased lung compliance.3. Decreased lung compliance.

• So So ≥24 hours and 100% oxygen should be ≥24 hours and 100% oxygen should be

avoidedavoided..

Oxidative Stress :

• Imbalance between pro-oxidant and anti-oxidant forces in the body.

• Pro-oxidants include oxygen radicals or reactive oxygen species, which can be cytotoxic because of their ability to alter cellular components and function

• Reactive oxygen species are generated as a result of normal mitochondrial respiration, reperfusion phase of hypoxic tissue injury , infection and inflammation.

• Oxygen is “toxic” because of the production of reactive oxygen species; thus oxygen administration increases oxidative stress.

• Antioxidant defenses include the enzymes superoxide dismutase, catalase, and glutathione.

• Nonenzymatic antioxidants start to cross the placenta in late gestation, and include vitamins A, C, E, and ubiquinone.

• Premature baby particularly are in risk of oxidative stress injury because their both endogenous and passively acquired exogenous anti-oxidant defense system are not mature

Pathology in neonate :• Retinopathy of prematurity• Bronchopulmonary dysplasia,• Necrotizing enterocholitis• Intraventricular hemorrhage

Figure 2. Revised Two-Phase Hypothesis of Retinopathy of Prematurity.In retinopathy of prematurity, there is initially delayed physiologic retinal vascular development, resulting in a peripheral avascular areaof the retina (phase 1). Later, vasoproliferation in the form of intravitreal angiogenesis can occur at the junction of avascularized andvascularized retina (phase 2). As shown in the lower panel, increased vascular endothelial growth factor (VEGF) induced by hypoxiadelays physiologic retinal vascular development by interfering with ordered vascular development; decreased VEGF in high oxygen alsodelays physiologic retinal vascular development by reducing developmental angiogenesis. EPO denotes erythropoietin, ERK extracellularsignal-regulated kinase, HIF hypoxia-inducible factor, IGF-1 insulin-like growth factor 1, MEK mitogen-activated protein–ERK, O2 oxygen,pAKT phosphorylated protein kinase B, PI3 phosphatidylinositol 3, pJAK phosphorylated Janus kinase, pSTAT3 phosphorylated signaltransducer and activator of transcription 3, ROS reactive oxygen species, and VEGFR vascular endothelial growth factor receptor.

Effects on lungs(lorrain-smith effect) :• Protein modification, DNA base modification, and strand

scission

• Increased proliferation of type II pneumocytes and fibroblasts

• Alterations in the surfactant system• Stimulation of inflammatory cells and cytokines• Increased collagen deposition, endothelial cell damage,

and apoptotic cell death

• Elevations of growth factors and increasing matrix metalloproteinases

Effects on Brain( Paul bert effect) :• Oxidative damage to premyelinating oligodendrocytes in

cerebral white matter is proposed as a mechanism of periventricular leukomalacia

• Reduces cerebral blood flow velocity

• Intracranial hemorrhage

How much oxygen is safe ?

• 100% not more than 12 hours

• 80% not more than 24 hours

• 60 % not more than 36 hours

Goal should be to use lowest possible FiO2 compitable with adequate tissue oxygenation

• FiO2: Fraction Of Inspired Oxygen

• 100% = FiO2 is 1.00

• Each 1L/min flow increment = 4% (0.04)

• Low Flow O2 : 21-50% (FiO2 0.21-0.5)

• High Flow : 50-100% (FiO2 0.5-1)

Oxygen delivery Method

• All system requireSource of oxygenOxygen tubingFlow meter HumidifierDelivery devices

humidifer

• In small hospital,O2 may be supplied to the piped medical gas and vaccum system.

• Larger hospitals, pipeline O2 originates from a liquid O2 .

• Oxygen is stored at a temperature of approximately -165 ˚C at 10.5 bar in a giant thermas flask .

Sources of oxygen• Compressed gas cylinders

• Liquid oxygen in cryogenic containers

• Oxygen concentrators for medical use.

Factors to Consider for the selection of oxygen delivery :

• size and weight of the device;

• storage capacity; and

• cost and the ability to fill the device.

Compressed Gas Cylinders :

Compressed Gas Cylinders :

• Oxygen is packaged under high-pressure gas in seamless steel or aluminum cylinders.

• In cylinders charged with gaseous oxygen , where Full high-pressure cylinders normally contain gas at 15169 kPa (2200 psig) at 21 °C (70°F)

• large sized cylinders are linked together to supply medical oxygen to medical gas pipelines which then lead directly to the bedside in hospitals.

Liquid Oxygen in Cryogenic Containers :

• Cryogenic containers store liquefied oxygen and vapor

• Liquid oxygen manufactured by fractional distillation of air at an oxygen manufacturing plant and then delivered and stored on site to supply the healthcare facility.

• The liquid oxygen passes through warming coils and is allowed to evaporate, the gas is delivered to a medical gas pipeline system and then directly to the bedside

Oxygen Concentrators

• Supplies oxygen to their medical gas pipelines systems which is then delivered directly to the bedside.

• Separates and concentrates oxygen from the air through molecular sieves or semi-permeable membranes.

• Smaller individual concentrators can provide oxygen at a hospital bedside, in the home or on the transport.

• Deliver up to 90-95 % O2 at the flow rate 3-5L/min

Medical Oxygen

Storage

Cylinder

Concentrator

Pipe line Oxygen Supply

Humidification

• Humidification: Addition of heat and moisture to a gas

• Rationale:– Cold, dry air increases heat and fluid loss– Medical gases including air and oxygen have a

drying effect on mucous membranes resulting in airway damage

– Secretions can become thick & cause airway obstruction

• Indications:– Patients with thick copious secretions– Non-invasive and invasive ventilation– Nasal prong flow rates of greater than 2 L/min (<2

years) or 4 L/min (>2 years)– Facial mask flow rates of greater than 5 L/min– All high flow systems require humidification– Patients with tracheostomy

Humidification…

• Invasive Mode: Delivers saturated gas as close to body temperature (37 degrees, 44mg/L) as possible. Suitable for patients with:

• Nasal Prongs • Invasive Ventilation• Tracheostomy attachment or mask

• Non-Invasive Mode: Delivers gas at a comfortable level of humidity (31-36 degrees, >10mg/L). Suitable for patients receiving:

• Face mask therapy• Non-invasive ventilation (CPAP)

• Should be written in treatment order• Mention Flow rate• Mention device• Mention duration of therapy• Mention mode of flow(continuous or SOS)

• Example: O2 inhalation by nasal catheter @ 2L/min ---continuous until next order

How to prescribe

O2 delivery methods

• Low flow oxygen delivery system

( variable performance )

• High flow oxygen delivery system

( fixed performance )

low flow devices include:

Nasal Cannula Nasal Catheter Transtracheal Catheter Simple Mask Partial Rebreather Mask Non-Rebreather Mask

Nasal Catheter

Nasal Prong

High Flow Oxygen Delivery Devices

Air Entrainment Mask (Venturi) Air Entrainment Nebulizer Nasal High Flow Oxygen Therapy Mechanical Ventilators (invasive Non-invasive) CPAP Machines Resuscitation Bags and Hyperbaric Oxygen Chambers

Oxygen Hood

• Deliver 80-90% O2 at 5-10 L/min

• Used in <1 year of age

Oxygen tent

• Clear plastic sheet that cover child’s upper body

• FiO2 50%

• Not reliable

• Limit access to patient

• Not useful in emergency situations

Continuous positive airway pressure

• By applying underwater expiratory resistance• Indicated

– When oxygen requirement >40% Fio2

– Significant respiratory distress with Silverman or Downe’s score >4

CPAP reduce work of breathing, increases FRC and helps maintain it, recruit alveoli, increase static compliance, and improve ventilation perfusion ratio

Continuous positive airway pressure…

• Used in– RDS, acute bronchiolitis, pneumonia– It should be tried in spontaneously

breathing child who does not require emergency intubation prior to conventional ventilation

– Can be used in early, incipient or frank respiratory failure

Mechanical Ventilator

Oxygen Delivery Devices • Nasal prongs : 1-2L/min up to 4L/min

• Nasal catheter : 1-2L/min up to 4L/min

• Nasopharyngeal catheter : 1-2L/min up to 4L/min

• Simple Mask : 5L/min

• Venturi Mask : 5-8L/min

• Head Box : 5-10L/min

• CPAP : 8-10 L/min

• Ventilator : As much as

Specialized form of O2 therapy

1. Nitric Oxide mixed O2 2. Prone position. 3. Hyperbaric oxygen. 4. Extracorporeal membrane

oxygenation(ECMO). 5. Ambulatory O2 Therapy. 6. Home oxygen therapy. 7. Trans tracheal oxygen

Hyperbaric oxygen chamberHyperbaric oxygen chamber

PEDIATRICS 2004, 114:2;555

Hyperbaric oxygen• The goal is to deliver extremely high partial pressure of

oxygen, >760 mmHg

• Indications:– Smoke inhalation– CO poisoning– CN poisoning– Thermal burns– Air embolism– Clostridium myenecrosis– Osteomyelitis (refractory)– Compromised skin grafts– Radiation injury– Acute traumatic ischemia/acute crush injury– Severe decompression sickness– Necrotizing fasciitis

ECMO

• Extracorporeal Membrane Oxygenation is a possible final option if other conventional technique failed.

• Cardiopulmonary venous bypass is initiated using heparin- bonded catheter and extracorporeal oxygenation and CO2 removal are achieved using membrane oxygenator.

ECMOECMO

Ambulatory OAmbulatory O22 therapy therapy

Home OHome O 22 therapy therapy

Measurement of delivered oxygen• Oxygen analyzer or FiO2

meter • Sensor digitally convert sensed

concentration into reading• Quality and accuracy of sensor

is most important• Calibration with every use• The oxyhood is ideal place, can

be used within masks held at moth or nose

Monitoring

• Clinical improvement(Cyanosis, BP or

CRT)

• SpO2

• ABG

Monitoring…• Document

– Day and time oxygen started– Method of delivery– Oxygen concentration and flow– Patient observation– Oronasal care and nursing plan

Clinical monitoring

• Vital signs (hourly)– HR– RR (including level of distress)– BP– Temperature– SpO2

• Breathing pattern• Level of consciousness and responsiveness • Color

HbO2 absorbs more Infrared light wave and Hb absorbs more Red light wave

Monitor

Range of spo2

• Preterm : 88-92%

• Term : 93-97%

ABG

Normal value

pH 7.35-7.45

(PaO2) 11-13 kPa or 75-100mmHg

(PaCO2) 4.7-6.0 kPa or 35-45mmHg

HCO3− 22–26 mEq/L

total CO2 (tCO2) 23-30mmol/L

ABG and SPO2

SpO2 PaO2

92% 65 mmHg

93% 65 mmHg

94% 75 mmHg

95% 95 mmHg

96% 125 mmHg

97% 140 mmHg

Weaning

• After clinical and laboratory improvement

• Normal SpO2 and ABG

• Gradual weaning (FiO2 @ 0.05 in each F/U)

• In CPAP pressure with previous flow then O2 flow.

• Low flow and concentration can be continued without ill effects for long time

1. Oil and grease around connections should be

avoided.

2. Alcohol, ether and inflammatory liquids

should be kept separate from o2.3 No electrical devices near 02 tent.

4. No smoking.

5. Fire Extinguisher needs to be available.

Precautions

Cont…3. No electrical devices near 02 tent.

4. No smoking.

5. Fire Extinguisher needs to be available.

6. Care with using defibrillator near high oxygen concentrations.

7.When not in use it must be kept off.

8.Do not store oxygen cylinders in hot place

9.Do not drag or roll cylinders

10.Do not carry a cylinder by the valve or regulator

11.Do not attempt to mix gases in an oxygen cylinder or transfer oxygen from one cylinder to another

Low concentration oxygen therapy

• Reserved for children at risk of hypercapnic respiratory failure– Advanced cystic fibrosis and non cystic fibrosis

brochiectasis – Severe kyphoscoliosis or severe ankylosing spondylitis – Severe lung scarring caused by TB – Musculoskeletal disorders with respiratory weakness – Overdose of opioids, benzodiazepines, or other drugs

causing respiratory depression. – Uncorrected cardiac defects.

• Until blood gases can be measured, initial oxygen should be given using a concentration of 28% or less, titrated towards a SpO2 of 88-92%