Respiration represents the exchange of gaseous molecules between cellular membranes and the circulation. Ventilatio…
VOL: 102, ISSUE: 44, PAGE NO: 28
Brendan Docherty, MSc, PGCE, RN, is nurse manager, patient access and nursing services
Steven Coote, MN (Critical Care), BN, RN, is advanced practice nurse, after hours nursing services; both at The Prince of Wales Hospital, Sydney, Australia
Respiration represents the exchange of gaseous molecules between cellular membranes and the circulation. Ventilation refers to the movement of air between the atmosphere and the lungs, so in fact when you observe a patient’s ‘respiratory rate’ you are in fact measuring their ventilation rate.
The ventilation rate is regulated through the complex interplay of processes that ensure adequate oxygenation of tissues, removal of the by-product of respiration, carbon dioxide, and the maintenance of the acid-base balance of the blood (Tortora and Grabowski, 2002).
Respiratory rate should be between 10 and 20 breaths per minute and the peripheral oxygen saturation (SpO2) should be 95% or above (Docherty, 2002). Respiratory rate should be counted while the patient is settled and at rest. It is also an opportunity to assess ‘work of breathing’, evidence of orthopnoea, dyspnoea and audible respiratory cues such as wheeze and stridor (Bickley, 2005, Docherty, 2002).
Count the respiratory rate for a full 60 seconds as this provides the most accurate value, especially in paediatric patients (Adam and Osborne, 2005).
Bedside nursing respiratory assessment and documentation should include respiratory rate per minute; rhythm of the respiratory effort; regularity of the respiratory effort; chest expansion and symmetry; recording of any abnormal sounds heard audibly or on auscultation; oxygen therapy, inhaler or nebuliser therapy and peripheral saturation if indicated (Bickley, 2005). Auscultation of the lung fields with a stethoscope to check for good air entry and to identify any additional respiratory problems should be undertaken by an experienced practitioner.
The patients should be reviewed by a senior practitioner/doctor as a matter of priority if they have a respiratory rate under eight or above 30 breaths per minute, acute onset of dyspnoea, acute changes in work of breathing or if they simply state: ‘I can’t breathe’ (Smith, 2000).
Oxygen is a therapeutic drug and needs to be respected as such. Local institutional protocols should help direct the nurse in the specific uses of the various forms and delivery systems of oxygen therapy.
Nurses must be wary when administering oxygen to patients with the potential for chronic hypercarbia such as patients with chronic obstructive pulmonary disease (COPD). Oxygen therapy for this vulnerable group should still be aimed at preventing hypoxaemia, usually with a less aggressive programme and a more flexible clinical end-point such as SpO2 levels rising above 90%.
This considered, a patient who is experiencing difficulty breathing or is in respiratory distress needs to be started on high-flow oxygen via a non-rebreathing mask at 10-15l per minute as soon as possible. Untreated hypoxaemia will cause irreversible cellular and cerebral damage (Bickley, 2005; Adam and Osborne, 2005). Other adjuncts that may be required are a chest X-ray, arterial blood gas sampling and chest physiotherapy (Docherty, 2002; Smith, 2000).
A slow breathing rate (eight breaths per minute or below), low tidal or minute volume of air exchange in the lung can lead to hypoxaemia (reduced blood oxygen levels) and hypercarbia (high levels of carbon dioxide in the blood) (Tortora and Grabowski, 2002). In patients with chronic airway diseases with a complication such as pneumonia, the lungs have to work harder to exchange gases so that the patient becomes tired very easily. Respiratory collapse can occur due to the brittle nature of the patient’s lungs (Docherty and Foudy, 2006).
Other common clinical scenarios where hypoventilation can occur include (Adam and Osborne, 2005)
- Over-sedation with relaxant agents or pain relief (for example post-operatively);
- Pre- or peri-cardiac arrest where the patient is becoming hypoxaemic;
- In neurological conditions where the cardiorespiratory centre in the medulla oblongata is temporarily not functioning;
- Neuromuscular diseases where the respiratory support musculature and diaphragm are unable to support ventilation.
Hyperventilation is often related to anxiety or occurs after strenuous or prolonged exercise (Tortora and Grabowski, 2002) and is a normal mechanism in these situations in order to increase oxygenation of the body tissues.
Fast breathing rates in the acute setting is normally defined as above 30 breaths per minute (RCUK, 2005).
There are other situations where hyperventilation occurs as an indication of compensation to a clinical respiratory issue, for example (Adam and Osborne, 2005; Tortora and Grabowski, 2002; Smith, 2000):
- Diabetic ketoacidosis - blood acidosis caused by metabolic disrpution related to hyperglycaemia. The body’s response is to create blood alkalosis to counteract the blood acidosis by breathing faster;
- Hypoxaemia - consider the circulation volume, rate and haemoglobin quality in this scenario. When receptors in the brain are stimulated by low levels of circulating oxygen, a neurological feedback mechanism will initiate faster and deeper breathing in the lungs in an attempt to correct the hypoxia;
- Pain - untreated and undertreated pain mounts the body’s stress response and as a result the patient’s respiratory effort will increase. Check that your patient’s analgesia is adequate;
- Sepsis - endotoxins produced by gram-negative bacteria act as a potent breathing stimulus, along with a rise in the body’s temperature as it attempts to battle the systemic infection. Patients with sepsis will have an elevated rate of breathing and an element of hypoxaemia.
- Define respiratory rate and the factors that influence it
- Identify hypoventilation, the causes and the nursing care required
- Identify hyperventilation, the causes and the nursing care required
- Reflect on this article and develop a systematic problem-solving approach to the care of patients with respiratory rate abnormalities
- Outline your place of work and why you were interested in this article
- Detail the last time you encountered a patient with hypoventilation or hyperventilation
- Write about a piece of information in the article that could have helped in your care of that patient
- Explain how you intend to disseminate what you have learnt among your colleagues
This article has been double-blind peer-reviewed