Patients and the Nursing and Midwifery Council (NMC) (2018) expect nurses to use their knowledge and skills, to identify when their patients are unwell and to act on the information received. Respiratory rate is part of the holistic assessment of a patient, and careful monitoring should be used if the respiratory rate changes put it outside the patient's normal range (Kelly, 2018). Respiratory rate is a non–invasive and useful assessment tool and abnormalities in respiratory rate have been shown to indicate patient deterioration and should be managed accordingly (Cooper et al, 2014). However, evidence suggests that nurses may fail to take an accurate respiratory rate (McGain, 2008; Semler et al, 2013; Flenady et al, 2017).
Changes and anomalies in respiratory rate are not simply associated with respiratory conditions—they are a good indicator that a patient is struggling to maintain homeostatic control (the body's internal environment). Respiratory rate is an early, extremely good indicator of physiological conditions such as hypoxia (low levels of oxygen in the cells), hypercapnia (high levels of carbon dioxide in the bloodstream), metabolic and respiratory acidosis.
Cretikos et al (2008) showed that respiratory rate is a strong and explicit forecaster of events such as cardiac arrest and unexpected intensive care admissions. Dougherty and Lister (2015) discussed how respiratory rate can help identify patient deterioration, assess response to treatment, and help identify when a patient requires an escalation in care. Actions taken when indicators suggest that a patient is deteriorating improve patient outcomes and evidence suggests that the respiratory rate is one of the first vital signs to change when the body has a problem (Cretikos et al, 2008).
Anatomy and physiology of breathing
The body requires oxygen as an important part of its energy provision process. The respiratory system provides the body with oxygen and removes carbon dioxide as a waste product. This is the process of respiration. Respiration is then classified into two types: internal and external. External respiration is the exchange of gases at alveolar and capillary level; internal respiration is the metabolism of gases at cellular level, and where the body combines the oxygen with carbohydrates to create energy, producing carbon dioxide as a waste product of the body's metabolic process (Porth, 2015).
Breathing or pulmonary ventilation is the increase of alveolar pressure created by inspiration, where the thorax expands by the movement of the rib cage equally and bilaterally upwards and outwards by the external intercostal muscles. At the same time the diaphragm, the other main breathing muscle, contracts downwards; this reduces the pressure within the lungs to less than that of the atmosphere and therefore draws air into them (Higginson and Jones, 2009). Expiration is the relaxation of the intercostal and diaphragm muscles and the expelling of the oxygen and carbon dioxide.
Normal breathing is regular with even chest expansion and deflation; normal breathing is also an unconscious process. The main respiratory centre is within the medulla oblongata and pons, and these are responsible for controlling the rate and depth of breathing. Tidal volume (the volume of air transferred during inhalation and exhalation) and respiratory rate together generate alveolar ventilation. These are usually controlled by the central and lung receptors and peripheral chemoreceptors (Marieb and Hoehn, 2013). Ventilation is determined by both arterial partial pressure of oxygen and partial pressure of carbon dioxide. The medulla oblongata houses chemoreceptors that monitor the carbon dioxide levels within the cerebral spinal fluid; a rise in the carbon dioxide level (the partial pressure of carbon dioxide) will cause the receptors to increase messages to the diaphragm and intercostal muscles to increase their contractions, thus increasing the number of breaths per minute (Nair and Peate, 2013).
The body endeavours to correct hypoxaemia (low oxygen levels in the blood) and hypercapnia by increasing tidal volume and respiratory rate (Cretikos et al, 2008). In normal breathing an inspiratory breath should be half as long as an expiratory breath (Higginson and Jones, 2009).
In some conditions—for example, chronic obstructive pulmonary disease (COPD) and neurological conditions—breathing will change. This might be through the use of sternomastoid muscles (accessory muscles) during an exacerbation of COPD, or paroxysmal breathing in neurological disorders, where the chest and diaphragm move in different directions during tidal breathing (Higginson and Jones, 2009). Observing how a individual is breathing alongside the rate of breathing is therefore important.
Conditions that cause metabolic acidosis, such as abdominal pathology or sepsis, will precipitate an increase in tidal volume and respiratory rate through an increased concentration of hydrogen ions, which leads to increased carbon dioxide production. In addition, any other condition that causes hypercapnia or hypoxia will increase alveolar ventilation. In essence, the respiratory rate is an important indicator of a severe derangement in many body systems, not just the respiratory system, and it is therefore a key predictor of adverse events (Cretikos et al, 2008).
Respiratory rate or the number of breaths per minute is defined as one breath to each movement of air in and out of the lungs. In general, the respiratory rate for an adult sits between 12 and 20 breaths per minute (Royal College of Physicians (RCP), 2017), but there will be some variation depending on age and medical condition. An increase or decrease in the respiratory rate indicates the requirement for more or less oxygen or carbon dioxide in the body. It is accepted that a respiratory rate of above 25 breaths per minute or an increasing respiratory rate can indicate that a patient could be deteriorating (Resuscitation Council UK (RCUK), 2015). A reduction in respiratory rate to 8 or fewer breaths per minute is also indicative of patient deterioration. The significance of this assessment should not be underestimated because ineffective breathing negatively impacts on effective gas exchange (Flenady et al, 2017).
How to measure respiratory rate
Evidence suggests that health professionals do not prioritise the measurement of respiratory rate; this is observed as being down to poor knowledge, lack of time or lack of prioritisation (Mok et al, 2015; Philip et al, 2013; Kelly, 2018). Flenady et al (2017) suggested that lack of knowledge and understanding of the significance of recording an abnormal respiratory rate are issues for some nurses; Cooper et al (2014) suggested in their work that the measurement of respiratory rate is not perceived as important as recording other vital signs. The lack of reliable equipment to measure respiratory rate has been cited as a possible reason for poor monitoring (Hogan, 2006; Philip et al, 2013). Evidence suggests that health professionals often rely on pulse oximetry to assess respiratory function, failing to take into consideration the work and rate of breathing (Cretikos et al, 2008).
Measurement of respiratory rate is acknowledged to be a core nursing skill (Hogan, 2006). There is, however, evidence to suggest that respiratory rate is estimated by nurses or under-reported (Flenady et al, 2017; Kelly, 2018). McGain et al (2008) identified that respiratory rate was not well documented in a significant number of areas; evidence also emerged of differences between an individual patient's respiratory rate and the one recorded (Semler et al, 2013).
The other challenge to measuring respiratory rate is that drawing the patient's attention to their breathing may disrupt the automatic regulation of breathing, creating conscious control rather than unconscious, thus disrupting the patient's breathing pattern (Hill et al, 2018). Hill et al (2018) also identified that nursing texts give numerous ideals for the monitoring of respiratory rate—ranging from counting breaths for 15 seconds and multiplying by 4 to counting for a full minute—this poor provision of information, given the high significance of respiratory rate, is challenging. Underestimation of respiratory rate, especially when a reduced length of time is taken to observe the rate or if patient becomes aware of respiratory rate observation, is especially important in critically/unwell patients and patients with poor regularity of respiratory rate/breathing (Hill et al, 2018).
Measuring respiratory rate is often not perceived as an important element of the nursing assessment, with poor monitoring still raising concerns (Philip et al, 2013; Cooper et al, 2014) with reductions in time taken to complete the assessment, such as 15 or 30 seconds rather than a full minute (Semler et al, 2013). Evidence suggests that this reduces the respiratory rate by one or two breaths each minute (Semler et al, 2013). Health professionals need awareness that even small changes in respiratory rate have the potential to be a sign of deterioration (Dougherty and Lister, 2015). Cooper et al (2014) suggested that the most commonly recorded respiratory rate is 18 breaths per minute, and that health professionals make quick estimates of respiratory rate based on previous recordings for the patient. The RCP (2017) has promoted use of the National Early Warning Score (NEWS) 2 to encourage the monitoring of trends, but its utility will be limited if the respiratory rate sits at a single figure.
Although the rate at which a person breathes is extremely important, monitoring of respiratory rate should also include an observational exercise. While monitoring respiratory rate the practitioner should be observing how the patient is breathing. This includes the depth to which the patient is breathing, what muscle groups they are using—for example, the sterno-mastoid (accessory muscles) and abdominal muscles—the movement of the chest wall in terms of symmetry, the regularity of breathing and any discomfort that the patient is experiencing while breathing (Table 1). The inability to speak in full sentences or increased effort to speak is an indicator of discomfort when breathing (Higginson and Jones, 2009). All these elements help the practitioner assess and understand the patient in terms of monitoring and improvement of their condition.
| Condition | Changes in breathing |
|---|---|
| Pleural effusion | Dyspnoea—difficulty breathing |
| Pneumothorax | Asymmetrical chest expansion |
| Exacerbation of asthma | Dyspnoea—difficulty breathing, wheeze |
| Exacerbation of chronic obstructive pulmonary disease | Dyspnoea—difficulty breathing, wheeze |
How to use respiratory rate to detect deterioration
The trend of increasing respiratory rate is suggestive that a patient is becoming unwell, because the body responds by trying to maintain the correct amount of oxygen to the tissues (Kelly, 2018). Failure to recognise early signs of deterioration has the potential for patients to have a poor clinical outcome (Kelly, 2018). Cretikos et al (2008) reviewed the outcomes of a group of patients, identifying that their outcomes could have been improved if the respiratory rate had been used as an indicator for detecting earlier deterioration. Evidence has also emerged that early detection and documentation of vital signs monitoring, especially respiratory rate, could help detect respiratory failure, a prime reason for admission to high-dependency and intensive care areas (Jonsson et al, 2011). Studies have also shown that respiratory rate can help predict patients who are at high risk of cardiac arrest (Cretikos et al, 2008).
It is important to note that not all causes of hypoxia and hypercapnia result in an increase in tidal volume and respiratory rate. Medications such as opiates, which are commonly used in hospitals, depress the respiratory drive and the respiratory response to hypoxia and hypercapnia. In these circumstances, the respiratory rate can still be a useful tool to monitor for an adverse event, as the respiratory rate may be lowered, often in association with a reduced level of consciousness.
Best practice
Good monitoring of respiratory rate gives the opportunity to reduce the incidence of severe illness and improve the clinical response for patients (Flenady et al, 2017) (Box 1).
The use of technology and advances in technology have not clearly provided good equipment to measure respiratory rate. Mok et al (2015) found a significant number of nurses in their survey suggested that they could replace respiratory rate with pulse oximetry recordings. Health professionals need to understand that pulse oximetry and respiratory rate are monitoring two different elements of the patient's homeostatic balance (Mok et al, 2015), and pulse oximetry measurement should not be seen as a replacement for measuring respiratory rate. Pulse oximetry monitors the amount of oxygen saturation, and oxygen saturations at an early stage in a patient's deterioration journey are likely to be normal as the body compensates by changing the respiratory rate to maintain oxygenation (Mok et al, 2015). Pulse oximetry is not shown to be an indicator of either ventilation or a measurement of respiratory rate (Cretikos et al, 2008).
The use of NEWS and subsequently NEWS 2 has helped standardise the healthcare approach and understanding of observation monitoring. Monitoring of vital signs throughout an acute hospital episode and during a hospital stay is important as evidence shows that significant numbers of patients continue to have mortality associated with abnormal vital signs throughout their hospital stay, with mortality figures as high as 40% (Bleyer et al, 2011). Evidence suggests that the presence of three or more critically abnormal vital signs is a significant indicator of high mortality and early recognition is an early opportunity to reduce this incidence (Bleyer et al, 2011).
McBride et al (2005) suggested that the introduction of modified early warning scores improved the documentation of respiratory rate. Obviously, NEWS is at its optimum when the information gathered and transcribed is at its most accurate (Flenady et al, 2017) because it is an extremely good predictor of clinical deterioration; but is only as good as the data health professionals gather. A scoring system such as NEWS helps map trends, indicating the clinical status of the patient and their response to treatment (Philip et al, 2013; RCP, 2017). It is important for the multidisciplinary team to regularly review the frequency of vital signs monitoring, particularly as the patient improves (Mok et al, 2015).
Conclusion
Vital signs are an important indicator of the patient's clinical condition of which the respiratory rate is one of the most sensitive and accurate. The UK move towards the use of NEWS and now NEWS 2 scoring is designed to support nurses and health professionals to respond appropriately to the patient's clinical condition, especially where the ‘abnormal score, generates a high score and therefore a referral on to further review’ (Philip et al, 2013).
More importantly health professionals need to recognise the significance of accurate vital sign monitoring especially in terms of the respiratory rate. Accurate measurement and recording of respiratory rate over 1 minute and the use of observational skills during the respiratory assessment can support a practitioner to identify altered respiratory physiology that will aid recognition of a deteriorating patient. Recognising trends using NEWS 2 should help reduce significant deterioration of patients if acted upon judiciously.
LEARNING OUTCOMES
CPD reflective questions
The discussion in this article has focused on the importance of respiratory rate monitoring. Consider the following reflective points in relation to your knowledge and area of practice: