What would the nurse monitor frequently to ensure that the prescribed amount of oxygen is being delivered to a client?

Based on Nicol: Essential Nursing Skills 4E
Adapted by: Mary Nevin BNS(Hons) MSc RGN RNT
Updated by: Sue Faulds BSc (Hons) MA(ed) RN 
Last updated: February 2017

Oxygen cylinder. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)

Oxygen flow meter set at 2 l/min. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)

Mask with venturi system. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)

Learning Objective

After reading the skill overview, watching the video, following up some of the references/web sites and completing the self-test quiz you should be ready to be assessed in practice in the skill of giving oxygen therapy using the venturi system.

Introduction

Patients may require oxygen when the level of oxygen they have in their blood is insufficient for normal functioning.  At the same time, they may be experiencing shortness of breath but it is the low level of oxygen rather than the breathlessness that is the reason for oxygen administration.  The aim of administering oxygen is to achieve a normal or near normal oxygen saturation.  What is normal will depend on the individual but for those without chronic respiratory conditions, such as Chronic Obstructive Pulmonary Disease (COPD), it may be as low as 88–92% when monitored with an oxygen saturation probe (pulse oximeter).  For those without chronic respiratory conditions the normal oxygen saturation level is 94–98% (BTS 2008).

Oxygen delivery devices fall into two main categories: low flow delivery systems or high flow delivery systems (McGloin 2008). The use of a venturi oxygen mask to deliver oxygen is an example of a high flow oxygen delivery system.High flow delivery systems are also known as fixed performance systems. These systems will deliver fixed oxygen rates above the normal inspiratory flow rate (BTS 2008). Venturi system masks can deliver between 24% and 60% oxygen, depending on the connector used. They are generally used for patients requiring a high concentration of oxygen; however, the British Thoracic Society recommends the use of venturi masks for acutely breathless patients requiring low doses of oxygen, because they deliver a more reliable oxygen concentration than nasal cannulae or simple face masks (Henderson 2008).

A venturi oxygen mask incorporates an interchangeable venturi connector for the mask (Esmond 2008). Each connector is designed so that precise proportions of room air are mixed to deliver a specific percentage of oxygen (Table 1). The concentration of oxygen delivered depends on the flow of oxygen via the inlet and the size of the holes through which the air is entrained, therefore the larger the hole on the venturi connector, the greater the volume of air entrained into the mask, and the lower the concentration of oxygen delivered to the patient (BTS 2008). The venturi mask with the prescribed venturi connector is placed over the patient’s nose and mouth, with the elastic strap over the ears to the back of the head. The nose section and the length of the strap are adjusted to ensure the mask fits comfortably on the patient.

Table 1 Flow rate and percentage of inspired oxygen of different venturi valves

As well as ensuring that the oxygen is given at the prescribed flow rate, the nurse must also consider the comfort of the patient. Oxygen therapy via a face mask can cause oral and nasal mucosal drying, along with skin redness or ulceration where the mask touches the face and the elastic strapping sits behind the ears and head. To prevent damage, the nurse must regularly check the patient’s condition and document findings.  If there is evidence that the patient's skin is becoming damaged they must act accordingly.  The nurse must perform regular mouth care and offer the patient frequent sips of fluid (if appropriate for the patient’s condition) in order to prevent the oral mucosa drying and cracking. Humidified oxygen may also be used which will reduce the mucosa from drying and provide additional comfort for the patient.  Humidified oxygen may either be delivered at room temperature of warmed using the appropriate equipment (Woodrow 2016).

Henderson (2008) states that the key to successful oxygen therapy is careful monitoring of the patient in order to recognise and treat complications in a timely manner.

Oxygen therapy via a venturi system can be delivered from an oxygen cylinder or via a piped source. The oxygen cylinder has a black base with white shoulders and has ‘oxygen’ written on it (Figure 1). For safety purposes, if using an oxygen cylinder, the nurse must ensure that a replacement cylinder is available when the volume indicator gauge shows approximately one quarter full. The nurse must also ensure that patients and visitors are made aware of the dangers of smoking when oxygen is being administered as it is highly inflammable. The use of paraffin or other flammable substances should not be used around the patient due to the fire risk (NPSA 2009).

Preparation and safety

• Explain the procedure, to gain consent and cooperation.
• Prepare the patient preoperatively if oxygen therapy is planned postoperatively.
• Patients and visitors must be made aware of the dangers of smoking when oxygen is being administered, because it is highly inflammable. Patients must be made aware of the risks of using products such as paraffin containing emollients due to their flammable nature.
• The nurse’s hands should be clean and an apron should be worn.
• Additional protective clothing may be necessary if indicated by the patient’s condition.

Procedure

If you are in the Republic of Ireland this skills needs to be read in conjunction with the latest advice from PHECC

1. Perform hand hygiene and explain the need for oxygen. Wear additional personal protective equipment where necessary. 
   Rationale – Hand hygiene is essential to prevent the spread of infection. Patients should be fully informed as to the reasons for initiating oxygen therapy.
2. Check the patient’s identity and the prescription.
   Rationale – Oxygen therapy is a medication and therefore must be prescribed, except in respiratory emergency situations (BTS 2008). In order to ensure that administration of medication is safe, the nurse must remember the ‘6 rights’, i.e., right patient, medicine, dose, route, time, and documentation (Brooker & Nicol 2011).
3. Check the percentage of oxygen that has been prescribed matches what is written on the venturi connector.
   Rationale – To ensure that the correct percentage of oxygen will be administered to the patient.
4. Connect the oxygen tubing to the oxygen flow meter.
   Rationale – Ensure that the oxygen tubing is secured firmly to both the flow meter and mask. Also, that the length of the oxygen tubing will allow freedom of movement for the patient but is not so long that it is a tripping hazard or touches the floor (Brooker & Nicol 2011).
5. Set the centre of the ball in the flow meter to the rate shown on the mask before putting the mask on. It is vital that it is exactly the number of litres shown on the mask, because the flow of oxygen draws air in through the holes in the connector to dilute it to the required percentage.
   Rationale – It is important that the flow is set at the rate indicated to achieve the prescribed percentage of oxygen (Figure 2).
6. Place the mask over the patient’s nose and mouth, with the elastic strap over the ears to the back of the head. Adjust the nose section and the length of the strap to ensure the mask fits snugly but is not tight (Figure 3).
   Rationale – The mask should fit comfortably on the patient. A tightly fitting mask can cause significant patient discomfort and skin redness or ulceration on the face or behind the ears.
7. Document oxygen administration procedure according to local policy.
   Rationale – In order to comply with local policy requirements.
8. If 24% oxygen is required, use a white connector and set the oxygen flow to 2 l/min.
   Rationale – The size of the air entrainment ports on a blue venturi connector, with an oxygen flow of 2 l/min, is designed to deliver 24% oxygen.
9. If 28% oxygen is required, use a white connector and set the oxygen flow to 4 l/min.
   Rationale – The size of the air entrainment ports on a white venturi connector, with an oxygen flow of 4 l/min, is designed to deliver 28% oxygen.

10. If 35% oxygen is required, use a yellow connector and set the oxygen flow to 8 l/min. 

    Rationale – The size of the air entrainment ports on a yellow venturi connector, with an oxygen flow of 8 l/min, is designed to deliver 35% oxygen (Figure 3).

11. If 40% oxygen is required, use a red connector and set the oxygen flow to 10 l/min. 

    Rationale – The size of the air entrainment ports on a red venturi connector, with an oxygen flow of 10 l/min, is designed to deliver 40% oxygen.

12. If 60% oxygen is required, use a green connector and set the oxygen flow to 15 l/min. 

    Rationale – The size of the air entrainment ports on a green venturi connector, with an oxygen flow of 15 l/min, is designed to deliver 60% oxygen.

13. Assess the patient after a few minutes and continue to observe in accordance with patient’s condition and local policy.
    

    Rationale – Oxygen is prescribed when the patient has a need and therefore the patient must be monitored to ensure that it is achieving the goal.

Ongoing care, monitoring and support

• Observe the patient’s colour and perfusion and respiratory pattern.
• Offer drinks or mouth washes. Oxygen therapy dries the mucous membranes of the mouth. Frequent drinks should be provided if the oxygen is not being humidified.
• Humidification should always be considered if oxygen therapy is required for prolonged periods and if patients with respiratory infections have difficulty expectorating sputum (Perry et al. 2016).
• Tubing and masks may be reused several times for the same patient, as long as they are kept dry and free from dust. They should be disposed of in the clinical waste when no longer required. If using an oxygen cylinder, ensure that a replacement cylinder is available when the volume indicator gauge shows only one quarter full.
• The centre of the ball in the flow meter must sit at the level of the flow rate prescribed.
• Monitor the patient’s respiratory pattern and rate.

Documentation and reporting

• Document oxygen administration procedure and the prescribed percentage of oxygen according to local policy.
• Report any abnormalities or complications so that appropriate interventions can be initiated.

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