Oxygen: Properties, Uses, and Importance

• Oxygen is considered a prescription drug.
• Oxygen is a colorless, odorless, and tasteless gas.
• Air contains about 20.9% oxygen, 78% nitrogen, and a small percentage (less than 2%) of other gases.
• Oxygen is a poor conductor of heat and electricity.
• Oxygen supports combustion but is not combustible itself; combustion requires fuel, heat, and oxygen.
• Oxygen forms compounds with almost all elements, except for inert gases.
• Oxygen unites with other elements to form oxides, such as carbon monoxide.
• Oxygen is the third most abundant element in the universe and the most abundant element in the Earth's crust.
• Oxygen makes up about 90% of water and two-thirds of the human body.

More on Oxygen

• Oxygen, water, and food are fundamental to life.
• Deprivation of oxygen leads to rapid death.
• Oxygen therapy is useful or necessary in several diseases or intoxications that interfere with normal blood oxygenation.
• Living cells must have access to oxygen to survive.
• The respiratory system supplies oxygen to cells and removes carbon dioxide from tissues.

External Respiration (Pulmonary Gas Exchange)

• External respiration involves the exchange of oxygen (O2) and carbon dioxide (CO2) between the external environment and the cells of the body.
• This process is efficient because alveoli and capillaries in the lungs have very thin walls and are abundant; there are approximately 300 million alveoli with a total surface area of 800 square feet.
• Oxygen moves down a stepwise series of partial pressure gradients from the alveoli to the body's cells and their mitochondria.
• Carbon dioxide is returned to the lungs through venous blood as bicarbonate or carbaminohemoglobin in the plasma. It crosses the alveoli and is exhaled, completing the cycle.

Partial Pressure and Pressure Gradients

• Total pressure exerted by any combination of gases equates to the sum of individual partial pressures of each gas in the mix.
• The pressure exerted by a single gas is its partial pressure.
• Partial pressure is measured in millimeters of mercury (mm Hg), with oxygen having a partial pressure of 160 mm Hg.
• Each gas exerts a pressure equivalent to its percentage of the total gas concentration.
• At sea level, the partial pressure of oxygen (PO2) is 20.9%.
• Hemoglobin carries about 98-99% of the oxygen breathed in the blood, while the remaining 1-2% is dissolved in the plasma.
• Sufficient oxygen amounts in the plasma result in increased hemoglobin transport, and vice versa.

Respiration and Oxygen

• Respiration involves in the exchange of oxygen and carbon dioxide.
• Oxygenation refers to how the concentration of oxygen increases.

Hemoglobin

• Hemoglobin is a protein making up about 35% of the red blood cell.
• Oxygenation is dependent on the relationship between partial pressure of oxygen and hemoglobin.
• Hemoglobin is about 98% saturated when air is breathed under normal circumstances.
• Hemoglobin levels are measured using a simple blood test.
• Low hemoglobin, or anemia, affects oxygen-carrying capacity and energy production on a cellular level.

(Internal) Cellular Respiration

• Mitochondria are intracellular power plants responsible for energy production in cells (require oxygen and glucose).
• Mitochondria are located in the cytoplasm outside the cell's nucleus and are the principal energy source, and contain enzymes for the critic acid cycle, ATP synthesis and the oxiditation of fatty acids.
• Mitochondria converts nutrients to energy and performs other specialized tasks.
• Mitochondrial chromosomes are inherited from the mother.
• Mitochondria is responsible for aerobic (oxygen dependent) metabolism of cells.

Breathing

• Breathing Process consists of the exchange of O2 upon inspiration and CO2 on expiration
• Normal breathing is initiated by the increase of CO2 in the lungs
• Hypoxemia describes insufficient oxygen levels in the blood
• Hypoxia describes insufficient oxygenation of the tissues.

Causes of Hypoxia

• Pulmonary Hypoxia - Abnormal pulmonary function impairs blood oxygenation.
  • Upper respiratory
  • Lower respiratory
  • Lung Tissue disease
  • Disordered breathing – neurogenic
• Post pulmonary Hypoxia - Oxygen isn't delivered to the tissues from the lungs.
  • Low cardiac output (disease of the heart tissue/pump)
  • Distribution issue (sepsis)
  • Hypovolemia – no blood to supply oxygen
  • Obstructive (tumor, pressure on the great vessels)
  • Inadequate concentration of oxygen in arterial blood (anemia, hemoglobinopathies, carbon monoxide poisoning)

Indications for O2 Therapy

• Respiratory arrest or difficulty breathing
• Shock
• Major blood loss
• Cardiac arrest/heart attack
• Lung disease
• Chest injuries
• Airway obstruction
• Stroke
• Seizures
• Trauma

Oxygen Safety: Always

• Follow the manufacturer’s guidelines for tank safety.
• Review procedures for transporting and storing tanks safely.
• Always store tanks securely, secured upright or lying on the side away from foot traffic and heat.

Oxygen Safety: Never

• Don't lubricate O2 tank of gauges with petroleum products
• Never roll a tank
• Never store in heat or in a closed vehicle in the sun.
• No smoking or open exposure to the open flame around O2
• No tape on tank/gauges
• O2 reacts with some adhesives
• An O2 tank that gets punctured, or the valves break off, turns the tank into a missile.
• Oxygen is a component needed to create combustion (heat, fuel, oxygen)

Oxygen Delivery Devices

• Nasal Cannula: O2 is delivered to nostrils via two small plastic prongs, delivering lower concentrations of O2.
• Simple Face Mask: Delivers moderate concentrations of O2.
• Non-Rebreather Mask: Delivers high concentrations of O2.

The Cannula

• Slightly curved prongs fit into the front of the nostrils.
• Tubing loops over the ears and connects under the chin with a sliding connector.

Nasal Cannula

• Delivers from 24% to 40% oxygen at a flow rate of 0.26-1.58 gal (1-6 liters per minute). -1 l/min: 24% oxygen -2 l/min: 28% oxygen -3 l/min: 32% oxygen -4 l/min: 36% oxygen

Simple Mask

• Delivers from 40% to 60% oxygen at 10-12 l per minute.
• An oxygen face mask is a plastic device that fits over the patients nose and mouth.
• Delivers oxygen as the patient breathes through the nose or mouth.
• Has open side ports that allow room air to enter and dilute oxygen as well as allowing exhaled carbon dioxide to leave containment space.
• A narrow tubing fixed to the bottom connects to an oxygen source.
• The adjustable elastic band is connected to each side of the mask. Slides over the head above the ears to hold the mask in place.

Partial Rebreather

• Used to deliver high concentrations of oxygen. It delivers from 70% to 90% oxygen at 6-15 I per minute.
• Like a simple face mask, but side ports are covered with one-way discus to prevent room air from entering the mask.
• A soft plastic reservoir is connected to the mask that conserves the first third of the patients exhaled air while the rest escapes through the side ports. The air gets inhaled along with the O2.
• Designed to make use of the carbon dioxide as a respiratory stimulant.

Non-Rebreather Mask

• High concentrations of oxygen
• Delivers 90% tp 100% oxygen at 15 liters per minute
• Contains a mask and reservoir bag
• Fill reservoir about 2/3 before applying
• Useful in acute situation
• Like a simple face mask buy has multiple one-way valves in the side ports.
• Prevents room air from entering the mask but allows exhaled air to leave the mask.
• Includes a reservoir bag with a one-way valve that prevents exhaled air from entering the reservoir.
• About 1/3 of the reservoir air is inhaled and replaced with oxygen. And the higher concentration of O2 is delivered.