Oxygen and its basic concepts

In this webinar we will learn about the following– What is oxygen? What is its role in body function? How is oxygen transported in the body? What is hypoxia and hyperoxia? What are the harms / potential toxicities of hypoxia and hyperoxia?
Oxygen is expressed as O2. It is a colorless / odorless gas which is essential for normal body functions. Oxygen is available to us from the atmospheric air. Normal oxygen concentration in the air is 21%. Oxygen is absorbed in to our body from the air which we breathe in.
Oxygen is essential for normal functioning of each and every cell, the functional unit of our body. Primarily it is required for energy synthesis (ATP). This energy form (ATP) is used for synthesis of proteins / enzymes and to carry out normal cellular functions. Lack of oxygen results in inefficient energy synthesis and depletion of ATP eventually leading to cell death.
Oxygen delivered to baby is expressed as fraction of inspired oxygen concentration (FiO2) Oxygen is transported bound to Hb and in dissolved form Oxygenation can be expressed as Partial pressure of oxygen (PO2) – which is the pressure exerted by the oxygen dissolved in blood. Normal PaO2 in arterial blood is 50-70 mm Hg in neonates. Percentage saturation of oxygen (SpO2)- which is percentage of oxygenated Hb . Normal SpO2 is 90-95%.
• Hypoxia and hyperoxia are terms used to describe low or high levels of oxygen in blood. • It can be defined based on arterial PO2 Normal PaO2: 50-70 mmHg Hypoxia: PO2 <50 mmHg from arterial blood sample Hyperoxia: PO2 >70 mmHg It can also be defined based on SpO2 Normal saturation targets: 90-95% Hypoxia: <90% Hyperoxia: >95%
Severe hypoxia developing over short time (acute hypoxia) affects almost all organ systems immediately particularly brain resulting in poor activity or lethargy progressing to loss of consciousness. Baby also develops shock, decreased urinary output, bradycardia and can progress to cardiac arrest if not attended to. Intermittent or prolonged hypoxia increase the risk of death and NEC in preterm infants. Hypoxia also causes periventricular leukomalacia in preterm infants resulting in neurodevelopmental impairment. It also results in pulmonary hypertension.
Hyperoxia causes free radical injury resulting in increased risk of Bronchopulmonary dysplasia Retinopathy of prematurity Brain damage in an infant with birth asphyxia
Clinical identification of hypoxia or hyperoxia is not possible. If not identified early will result in complications described earlier Continuous monitoring with pulse-oximeter is essential Oxygen saturation >95% may correspond to very high PaO2 values and thus relying only on SpO2 may fail to detect hyperoxia Maintaining strict oxygen saturation targets is advisable to avoid both hypoxia and hyperoxia. Desired oxygen saturation target is 90-95%
To conclude: Oxygen is essential for normal function of the body. Both hypoxia and hyperoxia are harmful to preterm babies. Monitoring by pulseoximetry is essential. Maintaining optimal oxygen saturation targets is essential to prevent harmful effects of hypoxia or hyperoxia.
  • Introduction...
  • 1. Learning object...
  • 2. Oxygen...
  • 3. Oxygen- its rol...
  • 4. Oxygenation- Ho...
  • 5. Hypoxia & Hyper...
  • 6. Effects of hypo...
  • 7. Effects of hype...
  • 8. Monitoring oxyg...
  • 9. Key messages...
 

Introduction

DR. N. CHANDRA KUMAR NATRAJAN
MD, DM (Neonatology)

Consultant Neonatologist
Cloudnine Hospital
Chennai

1. Learning objectives

â–º What is oxygen? What is its role in body function?

â–º What is hypoxia and hyperoxia?

â–º What are the harms / potential toxicities of hypoxia
    and hyperoxia?

2. Oxygen

â–º Oxygen, expressed as O2, is a colorless, odorless gas

â–º Oxygen is available to us from atmospheric air

â–º Normal concentration in air - 21%

â–º O2 is absorbed in to our body from the air we breathe in

3. Oxygen- its role in normal body function

â–º Essential for functioning of each and every cell of the body

â–º Energy synthesis (ATP)- cellular respiration

â–º This energy is required for normal functioning of the cell
    ♦ Synthesis of structural proteins
    ♦ Synthesis of functional proteins
    ♦ Other metabolic reactions

â–º Lack of oxygen- depletion of energy- CELL DEATH

4. Oxygenation- How to measure?

â–º Oxygen delivered is expressed as FiO2

â–º Oxygen is transported
    ♦ Bound to hemoglobin
    ♦ As dissolved oxygen

â–º Oxygenation can be expressed as
    ♦ PaO2 (partial pressure of oxygen)- Pressure exerted by
       dissolved oxygen
    ♦ SpO2 (% saturation of oxygen)-% of Hb totally bound to
       oxygen

5. Hypoxia & Hyperoxia

â–º Hypoxia and hyperoxia are terms used to describe low or
    high levels of oxygen

â–º Based on PaO2:
    ♦ Normal PaO2: 50-70 mm Hg
    ♦ Hypoxia: PO2 <50 mmHg from arterial blood sample
    ♦ Hyperoxia: PO2 >70 mmHg

â–º Based on SpO2:
    ♦ Normal saturation targets: 90-95%
    ♦ Hypoxia: <90%
    ♦ Hyperoxia: >95%

6. Effects of hypoxia

7. Effects of hyperoxia

8. Monitoring oxygen status

â–º Clinical identification - Not possible

â–º Continuous monitoring with pulse - Oximeter is essential

â–º At higher oxygen saturation ranges SpO2 is not reliable
    – Fails to detect hyperoxia

â–º Desired oxygen saturation target is 90-95%

9. Key messages

â–º Oxygen is essential for normal function of the body

â–º Both hypoxia and hyperoxia are harmful to preterm babies

â–º Monitoring by pulse oximetry is essential

â–º Maintaining optimal oxygen saturation targets is essential
    to prevent harmful effects of hypoxia or hyperoxia