Hypoxia and Home Oxygen Therapy

hypoxia

What is hypoxia?

Hypoxia is a condition that results from not enough oxygen supply to tissues in the body. This can be caused by inadequate delivery or the tissues using more oxygen.  1 

The air we breathe contains 21 percent oxygen. The level of oxygen in our body is a measure of oxygen the red blood cells are carrying. In adequate oxygenation, the blood contains normal concentrations of haemoglobin.  2

Oxygenation can be measured with:

Oxygen saturation (SaO2) – using a pulse oximeter to measure haemoglobin bound to oxygen compared to haemoglobin not bound to oxygen. 3  4

Partial pressure of oxygen (PO2) arterial blood gas analysis to determine the amount of oxygen gas dissolved in the blood. 1 

In most people the percentage of oxygen in the blood is above the SpO2 level of 92 per cent and the PO2 is 75 to 100 mmHg.  3 

Hypoxia can result from hypoxaemia (low oxygen levels in the blood), anaemia, and/or inadequate oxygen delivery. If the body compensates with an increase in haemoglobin and cardiac output, hypoxaemia can occur without hypoxia. 1 

Sometimes medical conditions affect the body’s ability to compensate for this short fall. In these cases home oxygen therapy is prescribed home oxygen therapy can ensure enough oxygen gets to the vital organs. 

The aim is to achieve normal oxygen levels in the blood. Depending on the medical condition, home oxygen therapy can improve quality of life. 5 

What are the symptoms indicating the need for home oxygen therapy?

Symptoms most common with hypoxia are shortness of breath with hypoxaemia. Others symptoms include coughing, wheezing and changes in skin colour. More dangerous symptoms are drowsiness, loss of memory, tachycardia (fast heart rate); and bradycardia (slow heart rate). 6  7

What conditions with hypoxia need oxygen home therapy?

The indications for home oxygen therapy are based on the medical condition and tests to determine oxygen measurements in the blood. These can be due to the presence of arterial blood gases (at rest/night/exertion) with room air, cardiac disease or because the patient is in palliative care.  2  8

Symptoms of hypoxia can be caused by respiratory medical conditions such as asthma, sleep-related breathing disorders having pulmonary hypertension or interstitial pulmonary fibrosis or malignancy. 

It can also be caused by cardiac conditions such as  chronic obstructive pulmonary disease; ischaemic heart disease, cardiac failure or other conditions (terminal illness and cluster headache).  2  4   6  8

What are the complications of hypoxia?

The three main complications associated with hypoxia are difficulty converting energy without (anaerobic metabolism), cellular acidosis or cell death and the main one, organ failure1

Continued hypoxia leads to anaerobic metabolism, cell damage and lactic acid release. The lactic acid can injure tissues in the lungs, liver, kidneys, heart and brain. 1 

What are the tests for home oxygen therapy?

INDICATION FOR HOME OXYGEN THERAPY

TESTDESCRIPTION
Chronic hypoxia PO2  pH
PCO2
  Partial pressure of oxygenAmount of oxygen dissolved in arterial blood. Potential of hydrogenMeasure of hydrogen ions determining acidity and alkalinity in arterial blood. Partial pressure of carbon dioxideMeasure of carbon dioxide dissolved in arterial blood.
Nocturnal or exertional hypoxia Oxygen saturation Per cent fraction of oxygen-saturated haemoglobinMeasure of haemoglobin bound to oxygen compared to haemoglobin not bound to oxygen. 
The indications for home oxygen therapy. 3  7

The prescription

 If the criteria is met for home oxygen therapy the prescription will include rate of flow of oxygen, duration for use, oxygen supply equipment; and respiratory home therapy appliances.

The prescription for the type of oxygen therapy tank depends on a person’s mobility, strength, breathing preference (nose or mouth) and the oxygen flow required. 7

What are the types of oxygen equipment?

 Compressed oxygen gas cylinder (OGC) for stationary use only – contains a purity level of oxygen (no less than 99.5 per cent). The gas from the cylinder can be used for a ‘home-fill’ of a smaller portable cylinder. They vary in different sizes.

Home oxygen concentrator (HOC) – draws in room air (21 percent oxygen and 79 percent nitrogen) and processes it to 90 – 95 percent oxygen. The two types of oxygen concentrators are stationary and portable. They need a power source or battery. 2

Accessories

  • Nebuliser
  • Humidifier/vaporiser
  • Peak flow meter
  • Volumatic spacer
  • Respiratory suction apparatus
  • Oxygen consumables and accessories (masks, cannula, tubing, swivels, ear protectors, key wheel and carry bag)  7

Oxygen therapy machines

  • Continuous Positive Airway Pressure (CPAP)
  • Bilevel Positive Airway Pressure (BiPAP)
  • Automatic Positive Airway Pressure (APAP)  2

Management to improve oxygen therapy

Raising the head of the bed can improve oxygenation, reduce acid reflux, lower pressures in the brain and prevent obstructive sleep apnoea.  9  10

Deep breathing techniques increase oxygen saturations and lung capacity.

What type of health professional can prescribe home oxygen therapy?

In Australia a registered nurse, a physiotherapist or a general practitioner the following health professionals can prescribe/order home medical oxygen therapy, along with a local medical officer, respiratory physician an Oncologist and a Cardiologist  11

Oxygen safety precautions

  1. Fire prevention
  • Smoking is not permitted in a room with medicinal oxygen.
  • Heating equipment with an open flame must not be in the same room with medical oxygen.
  • Flammable items are not to be near the oxygen.
  • Smoke detectors are  to be installed and operating on each level of home.
  1. Personal safety
  • Ensure the flow rate is the prescribed rate. 
  • Oxygen equipment used must only be products the medical specialist prescribes. 
  • All oxygen therapy must use the correct regulator to reduce cylinder pressure to a usable level for delivery via cannula or mask.
  • Gas cylinders and oxygen tubing are to be secured safely and positioned to prevent falls.
  • Back-up cylinder must be present.
  • When the cylinder is almost empty, it is to be stored in a separate place to full cylinders in a clearly marked area.
  • No extension cords are to be used with oxygen concentrators. 
  • Surge protector should be installed at the service panel.
  • Preventative maintenance should be kept up to date (12 monthly). 
  • Have an emergency plan for the event of a power failure.
  1. Infection control
  • Nasal cannula and oxygen tubing are to be changed as advised. 
  1. Important contacts
  • List phone numbers of the oxygen supplier, specialist and General Practitioner.

Support for oxygen therapy at home

Lung Foundation Australia

Heart Foundation

Community Health Centre

References

  1. Considine J. Emergency assessment of oxygenation. Acute Care Testing. Published January, 2017. Accessed March 24, 2021.

https://acutecaretesting.org/en/articles/emergency-assessment-of oxygenation#:~:text=Untreated%20hypoxia%20results%20in%20anaerobic,oximetry%20and%20arterial%20blood%20gases

  1. O’Driscoll BR, Howard LS, Earis J, Mak V. British Thoracic Society Guideline for Oxygen use in Adults in Healthcare and Emergency Settings. Br Med J Open Respir Res. 2017;4(1):170. doi:10.1136/bmjresp-2016-000170. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5531304/
  1. Hafen B, Sharma S. Oxygen saturation. National Center for Biotechnology Information. Updated August 12, 2020. Accessed March 24, 2021. https://www.ncbi.nlm.nih.gov/books/NBK525974/
  1. The Royal Australian College of General Practitioners. Home-Care Guidelines for Adult Patients With Mild COVID-19. The Royal Australian College of General Practitioners. August, 2020. Accessed March 24, 2021. https://www.racgp.org.au/FSDEDEV/media/documents/Clinical%20Resources/Guidelines/Home-care-guidelines-for-adult-patients-with-mild-COVID-19.pdf

Home-care guidelines for adult patients with mild COVID-19

  1. Suntharalingam J, Hippolyte S, Knowles V. et al. When should I be considering home oxygen for my patients? Nat Partner J Prim Care Resp Med. 2016;26(15074):1-4. doi:10.1038/npjpcrm.2015.74. https://www.nature.com/articles/npjpcrm201574
  1. Web MD. Hypoxia and Hypoxemia. Updated June 14, 2020. Accessed March 24, 2021. https://www.webmd.com/asthma/guide/hypoxia-hypoxemia
  1. Thomas P. ‘I can’t breathe’ – Assessment and emergency management of acute dyspnoea. Aust Fam Physician. 2005;34(7):523-529. Accessed March 24, 2021. https://www.racgp.org.au/afpbackissues/2005/200507/200507thomas.pdf
  1. Hattle A. How to get and use oxygen to treat your cluster headaches. National Headache Foundation. Date unknown. Accessed March 24, 2021. https://headaches.org/2018/04/10/how-to-get-and-use-oxygen-to-treat-your-cluster-headaches/
  1. Altun Uğraş G, Yüksel S, Temiz Z, Eroğlu S, Şirin K, Turan Y. Effects of different head-of-bed elevations and body positions on intracranial pressure and cerebral perfusion pressure in neurosurgical patients. J Neurosci Nurs. 2018;50(4):247-251. doi:10.1097/JNN.0000000000000386. https://www.researchgate.net/publication/326370019_Effects_of_Different_Head-of-Bed_Elevations_and_Body_Positions_on_Intracranial_Pressure_and_Cerebral_Perfusion_Pressure_in_Neurosurgical_Patients
  1. De Barros Souza B, Genta R, de Souza Filho A, Wellman A, Lorenzi-Filho G. The influence of head-of-bed elevation in patients with obstructive sleep apnea. Sleep Breath. 2017;21(4):815-820. doi:10.1007/s11325-017-1524-3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5700252/
  1. Australian Government – Department of Veterans’ Affairs. Home medical oxygen therapy and/or respiratory home therapy appliances. Published September 1, 2012. Accessed March 24, 2021. https://www.dva.gov.au/sites/default/files/dvaforms/d0804.pdf
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