Oxygen…THE DRUG!

DID YOU KNOW:

  • Hospital Oxygen is NOT FREE
  • At an SPO2 of 94%, additional oxygen is of NO BENEFIT. At this level, the standard dissociation curve is relatively flat, which means that the oxygen content of the blood does not change significantly even with large increases in oxygen.
  • Oxygen DOES NOT CURE DIFFICULTY IN BREATHING (DYSPNOEA), just HYPOXIA.
  • Oxygen should be delivered to achieve a target saturation of 94–98% for most acutely ill patients or 88–92% for those at risk of hypercapnic respiratory failure e.g. COPD
  • Humidification of supplemental oxygen commonly delivered by bubbling oxygen through either cold or warm sterile water before it reaches the patient should NOT be used because there is NO EVIDENCE of a clinically significant benefit but there is a risk of infection.

DOSE:

  • Nasal prongs delivers 4% additional oxygen per 1 litre of flow i.e. at 1L/min it delivers 24% (20% is already in the air), at 2L per min it delivers 28%, 3L/min 32%…and so on so at 6L/min it delivers 44%
  • A simple face mask should be used at a minimum of 6L/min (normal minute ventilation) to prevent the patient from breathing back their own CO2.
  • Application of a self inflating Bag-Valve-Mask on a patient’s face without compressing the bag is called suffocation. Due to the valves system, oxygen is only delivered ON COMPRESSING THE BAG
  • Pulse oximeters consist of two light-emitting diodes, one in the red range and one in the infrared range, and a detector.  Oxygenated and deoxygenated haemoglobin absorb light at different wavelengths differently. Deoxygenated or ‘‘blue’’ blood absorbs light maximally in the red band, whereas Oxygenated or ‘‘red’’ blood absorbs light maximally in the infrared band. The ratio of absorption of the two wavelengths of light are then compared with an algorithm in the microprocessor generated by empirically measuring the absorption in healthy volunteers at varying degrees of directly measured arterial oxygen saturation. The displayed value is usually an average based on the previous 3 to 6 seconds of recording.

HARMFUL EFFECTS:

  • Nonhypoxic heart attack victims treated with oxygen endure a 25 to 30% more heart damage than patients not given oxygen
  • Oxygen supplementation to nonhypoxic patients with mild or moderate strokes may increase mortality.
  • High-dose oxygen therapy to produce hyperoxaemia (above normal oxygen saturation) can cause absorption atelectasis
  • Oxygen is liberally administered to many critically ill patients, thereby exposing them to supranormal arterial oxygen levels.
  • Hyperoxia also results in the formation of reactive oxygen species, which adversely affect the pulmonary, vascular, cnetral nervous, and immune systems.
  • Though the optimal PaO2 remains unknown, recent evidence indicates that hyperoxia is associated with increased mortality in post-cardiac arrest, CVA, acute coronary syndrome, and traumatic brain injury patients.
  • Take Home Point: Carefully titrate oxygen to the lowest tolerable level to meet the patient’s needs.

Optimal Bag-Valve-Mask Ventilation

Sexy Bagging

 

  1. Remember to connect the device to an Oxygen Supply
  2. Use two providers wherever possible – one to maintain a good seal by lifting the face into the mask and applying a steady downward counter pressure to the mask using both hands (see image) and the other colleague squeezes the bag to ventilate.
  3. Don’t ‘bag’ too fast or hard – we recommend aiming for 1 breath every 6 seconds and just enough volume to make the chest rise (it’s a patient, not a balloon)
  4. Patients receiving BVM for cardiac arrest can do as well if not better than those who are intubated (there is NO EVIDENCE that use of an advanced airway in resuscitation saves lives)

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Emergency Ventilation

BMV is always a 2 person procedure (regardless of technique used) – Skilled person holds the mask and anyone else can provide the breaths + Consider the 2 thumbs down technique for BMV instead of the CE clamp. And Believe it or Not – Learning BMV is more important than mastering Laryngoscopy !!