The global elements of vital signs' assessment: a guide for clinical practice

Vital signs' assessment is a key component of safe, high-quality care and a fundamental nursing priority. Trends in vital sign data provide early warning of impending sepsis and respiratory failure, and can independently predict mortality (Churpek et al, 2014; Nielsen et al, 2015). Furthermore, vital signs' data is important for medical emergency teams and early warning scores to function effectively, but only if there is adherence to vital sign monitoring protocols (Hands et al, 2013).

Despite their clinical importance, research has consistently found that vital signs' assessment is often inaccurate, incomplete or falsified (Ludikhuize et al, 2012; Philip et al, 2013; Cooper et al, 2014). The reasons for this are not clear, but nurses' knowledge, skills and clinical judgement, culture, tradition and ritual, along with laziness and workload have been identified as contributing factors (Hogan, 2006; Yeung et al, 2012; Philip et al, 2013; Burchill et al, 2015; Cardona-Morrell et al, 2016). It has therefore been recommended that nurses need ongoing education to improve their attitudes towards vital sign monitoring (Mok et al, 2015).

To help emphasise the importance of vital signs' assessment, Global Elements of Vital Signs' Assessment are proposed. The Elements reflect key principles underpinning vital signs' assessment and are grounded in national and international guidelines and the current literature. The Elements aim to address the enduring neglect of vital signs' assessment and are a guideline for clinical practice. The Table of Elements (Figure 1) can be printed for students and clinicians to use as a visual prompt. The Elements can also be used for audit, benchmarking and teaching.

Figure 1. The Global Elements of Vital Signs' Assessment

Respiratory rate

Changes in respiratory function are increasingly recognised as the most sensitive indicator of clinical deterioration (Cahill et al, 2011). Respiratory rate is an early and extremely good indicator of conditions such as hypoxia, hypercapnia and acidosis (Rolfe, 2019). Respiratory rate is also often the first vital sign to be affected if there is a change in the patient's cardiac or neurological state (Liddle, 2013). The global elements of respiratory rate assessment are (Figure 1: dark blue cells):

• Sensitive marker (Sm): Respiratory rate is the most Sensitive marker of acute illness (Cahill et al, 2011). A respiratory rate of 21–24 breaths per minute is an early clinical sign of deterioration (Wheatley, 2018). A decrease in respiratory rate is also indicative of deterioration (Rolfe, 2019)
• First sign (Fs): Respiratory rate is often the First sign affected if there is an acute change in the patient's condition (Kelly, 2018). Alteration in the respiratory rate can occur up to 24 hours before other signs of clinical deterioration (Malgaard et al, 2016)
• Powerful predictor (Pp): Respiratory rate is a Powerful predictor of disease severity and of a poor outcome (Kellett, 2017; Bunkenborg et al, 2019).
• Illness marker (Im): A high or increasing respiratory rate is an Illness marker and a warning that the patient may deteriorate suddenly (Resuscitation Council UK (RCUK), 2021)
• Minor changes (Mc): Minor changes in respiratory rate (3–5 breaths/minute) can be an early sign of deterioration (Dougherty et al, 2015; Kelly, 2018)
• Never falsify (Nf): Respiratory rate should Never be falsified or not assessed simply because ‘the patient looks fine’ or the oxygen saturations are normal
• Assess independently (Ai): Respiratory rate should be Assessed independently of oxygen saturation (SpO₂), as respiratory rate measurements correlate poorly with SpO₂ measurements (Kellett and Sebat, 2017)
• Count manually (Cm): The respiratory rate must be Counted manually rather than guessed or estimated (ACT Government Health, 2011)
• One minute (Om): The ideal length of time to measure respiratory rate is One minute, without the patient's awareness that they are being assessed (Hill et al, 2018)
• Other characteristics (Oc): When assessing the respiratory rate, Other characteristics such as respiratory depth, use of accessory muscles, pattern and signs of distress should also be assessed (Rolfe, 2019).

Oxygen saturation

A pulse oximeter measures peripheral arterial oxygen saturation (SpO₂), reflecting the percentage of haemoglobin that is bound with oxygen (Williams, 2018). SpO₂ readings should be interpreted within clinical context—and appropriate clinical judgement rather than complete reliance on oximetry readings should provide the basis for effective patient management (Pretto et al, 2014). The global elements of oxygen saturation assessment are (Figure 1: light blue cells):

• Clinical context (Cc): Interpret SpO₂ readings within Clinical context (Pretto et al, 2014)
• Not ventilation (Nv): SpO₂ does Not reflect the adequacy of ventilation (Pretto et al, 2014)
• Pulsatile flow (Pf): A pulse oximeter requires adequate Pulsatile blood flow to be accurate. Without a pulse signal, any SpO₂ readings are meaningless (World Health Organization (WHO), 2011)
• Probe site (Ps): The Probe site may affect the reliability of SpO2 readings (Fernandez et al, 2007). Depending on the patient's clinical condition, some probe sites are more reliable than others (Chan et al, 2013)
• Random checks (Rc): Although Random SpO₂checks have clinical benefit, they cannot be used to accurately estimate PaO₂, particularly because the response time of oximeter probes varies (Pretto et al, 2014; Jubran, 2015)
• Allow time (At): Allow time for the oximeter to detect the pulse and calculate the oxygen saturation (WHO, 2011). The response time of oximeter probes varies (Jubran, 2015)
• Impaired delivery (Id): SpO₂ does not necessarily reflect tissue oxygen delivery (Pretto et al, 2014). SpO₂ readings may actually be normal, despite Impaired O₂delivery. Oxygen delivery to the tissues cannot be solely determined by using a pulse oximeter because an oximeter does not evaluate the haemoglobin concentration or cardiac output (Casey, 2011)
• Waveform (Wf): If the Waveform displayed on the oximeter is attenuated or inconsistent, the SpO₂ reading is unreliable (Chan et al, 2013)
• Unreliable readings (Ur): Many factors may cause Unreliable or misleading SpO₂readings such as poor perfusion, venous pulsations, excessive movement, fingernail polish, and severe anaemia (Chan et al, 2013)
• No surrogate (Ns): SpO₂ is Not a surrogate marker or replacement for respiratory rate assessment (Rolfe, 2019). It is possible, for example, for the SpO₂ to be normal but for the respiratory rate to be increased due to hypercapnia (Parkes, 2011)
• Not attach (Na): Do Not attach the probe to an area that is oedematous, has compromised skin integrity, to fingers or toes that are hypothermic, or where the patient has peripheral vascular disease (ACT Government Health, 2011)
• Re-evaluate (Ev): After manually palpating the patient's pulse, compare it with the pulse rate calculated by the pulse oximeter. If a difference exists, re-Evaluate the probe placement (ACT Government Health, 2011)
• Remain normal (Rn): During early stages of deterioration, the SpO₂ may Remain in the normal range due to an increase in respiratory rate to compensate for inadequate O₂ delivery (Kellett and Sebat, 2017; Dix, 2018).

Pulse

Although heart rate is calculated by a pulse oximeter, manual pulse assessment provides an opportunity to touch the patient and thus assess numerous characteristics related to cardiac output. These include heart rate, rhythm, amplitude or strength, equality and regularity (Elliott and Coventry, 2012). The global elements of pulse assessment are (Figure 1: orange cells):

• Alteration (Al): Alteration in the pulse rate along with respiratory rate is often the first sign of deterioration (Tollefson and Hillman, 2019)
• Assess manually (Am): Pulse rate should be Assessed manually; reliance on automated machines should be avoided where possible (ACT Government Health, 2011)
• Thirty sixty (Ts): If the pulse is regular, count for Thirty seconds and multiply by two; if the pulse is irregular, count for sixty seconds (ACT Government Health, 2011)
• Ignore monitor (Im): Ignore any monitor's heart rate reading until you have assessed the pulse manually; doing so will help validate your findings. Manual palpation also allows for assessment of pulse amplitude and volume—information that monitors are not designed to evaluate (Dougherty et al, 2015)
• Characteristics (Ch): When palpating the pulse, assess all Characteristics such as rate, rhythm, quality and regularity (RCUK, 2021)
• Normal range (Nr): Know the Normal range for an adult patient and ideally the patient's normal range (Liddle, 2013). Using established normal ranges can help quantify abnormal findings (Chester and Rudolph, 2011).

Blood pressure

Blood pressure is one of the most inaccurately measured vital signs, despite being an indicator of oxygen delivery (Pickering et al, 2005). Automated blood pressure monitors, for example, might be used to save time, but their use increases the risk of measurement error (Elliott and Coventry, 2012). Even if blood pressure is measured manually, there is still the risk of an inaccurate reading due to human error (Coogan et al, 2015). The global elements of blood pressure assessment are (Figure 1: red cells):

• Use cautiously (Uc): Use automated blood pressure monitors cautiously. Manual auscultatory blood pressure assessment is the gold standard (Liu et al, 2015; Shahbabu et al, 2016). If there is doubt about a blood pressure reading obtained from an automated monitor, it should be verified by auscultatory assessment (Dougherty et al, 2015)
• Carefully verify (Cv): Automated blood pressure machines provide less reliable readings than those taken manually (Mirdamadi and Etebari, 2017). Once systolic blood pressure falls below 100 mmHg, detection by automated monitors is unreliable. All low blood pressure readings should be Carefully verified (Kellett and Sebat, 2017)
• Second reading (Sr): If the automated blood pressure reading is outside the patient's usual range, a manual Second reading should be obtained (ACT Government Health, 2011)
• Normal (No): Even in shock the blood pressure may be Normal because compensatory mechanisms increase peripheral resistance in response to reduced cardiac output (RCUK, 2021)
• Late sign (Ls): A change in a blood pressure reading is a Late sign of clinical deterioration as compensatory mechanisms fail (Tollefson and Hillman, 2019)
• Never assume (Na): An abnormal blood pressure should Not be assumed to be the patient's normal; it should be assessed in relation to previous readings, the patient's clinical condition and other assessments (Dougherty et al, 2015)
• Contraindications (Ci): Assess the patient for Contraindications to cuff placement, eg arteriovenous (AV) fistula, lymphoedema, intravenous (IV) therapy (ACT Government Health, 2011). If these are present, the other limb should be used.

Temperature

Core body temperature is a valuable vital sign in the seriously ill patient (Smith et al, 2005). Nurses should use their judgement about whether the recorded temperature is within an acceptable range for the patient's condition and if more frequent temperature measurement is needed (Grainger, 2013). The global elements of temperature assessment are (Figure 1: green cells):

• Temperature differs (Td): Normal body Temperature differs between anatomical sites (Elliott and Coventry, 2012). Awareness of this is important when interpreting readings
• Favourable conditions (Fc): Check for Favourable conditions of the site to perform accurate temperature monitoring, eg for the oral site, no recent consumption of hot or cold beverages (ACT Government Health, 2011)
• Repeat (Re): If the temperature reading is abnormally high or low, Repeat the reading with another thermometer (ACT Government Health, 2011)
• Individual variability (Iv): As body temperature varies with age, gender and site of measurement, it should be assessed in relation to Individual variability, ie a baseline value (Sund-Levander and Grodzinsky, 2013)
• Three temperatures (Tt): Clinically, there are Three temperatures: core body temperature, how the patient says they feel, and how the patient feels to touch. These are not always the same and awareness of these might make interpretation of conflicting assessment findings easier (Elliott and Coventry, 2012)
• Accuracy (Ac): Numerous factors affect the Accuracy of temperature measurements such as the device and technique (Jevon, 2020)
• Hypothermia (Ho): Research has found only modest increases in mortality associated with temperatures above 38°C; a low temperature though was found to be much more ominous (Bleyer et al, 2011; Kellett and Kim, 2012; Kellett, 2017). The clinical importance of a low temperature (Hypothermia) should not be ignored.

Consciousness and cognition

Many factors, both primary and secondary, can affect a patient's level of consciousness or cognition. Accurate assessment of consciousness is therefore paramount for the early diagnosis and management of deterioration, as changes in conscious level are associated with poor outcomes (Rylance et al, 2009; Vink et al, 2018). The global elements of consciousness and cognition assessment are (Figure 1: lilac cells):

• Routinely assess (Ra): Because many factors may affect consciousness or cognition, these should be Routinely assessed in all patients (National Institute for Health and Care Excellence (NICE), 2007). The established vital signs (eg temperature, pulse, blood pressure, respiratory rate) fail to provide insight into a patient's cognitive function and mental status (Chester and Rudolph, 2011)
• Validated scale (Vs): Use a Validated scale or tool to quantify the assessment, eg the Glasgow Coma Scale, Alert Verbal Pain Unresponsive (RCUK, 2021). Terms such as semiconscious or stuporous should be avoided because they are subjective (Dougherty et al, 2015)
• Predictor (Pr): A decrease in the Glasgow Coma Scale score Predicts an adverse event. A drop of two or more predicts a major adverse event (Massey et al, 2015)
• Subtle changes (Sc): changes to consciousness or cognition are often Subtle. Mild alteration of mental status is therefore often not noticed, even though this might reflect early deterioration (Kellett, 2017)
• Perform frequently (Pf): In patients with an acute or rapidly changing status, assessment of consciousness should be Performed more frequently, ie every 15–60 minutes (Tollefson and Hillman, 2019)
• Delayed signs (Ds): Vital sign changes are a Delayed sign of neurological deterioration (Tollefson and Hillman, 2019).

Critical elements (CE)

Underpinning all vital signs' assessments are the following critical elements (Figure 1: yellow cells):

• Compare (Co): Never trust the monitor. Compare manual assessments of the patient with the anticipated result and the monitor
• Anticipate (An): Anticipate the vital sign measurement before you assess it. Doing so will help validate the data obtained
• Patient's baseline (Pb): Know the Patient's baseline where possible, because changes from an individual reference point may indicate important warning signs and thus require additional evaluation (Chester and Rudolph, 2011; Liddle, 2013)
• Previous readings (Pr): Ignore the Previous vital signs readings (until you have assessed the signs yourself)
• Don't copy (Dc): Do not copy the last vital sign readings. Although a patient's vital signs might remain stable, each assessment must be an objective measurement of physiological function, ie measured not surmised (Chester and Rudolph, 2011)
• No blanks (Nb): Leave No blanks on the chart. Assess and document all vital signs (McGhee et al, 2016). The ability of a chart to identify deterioration depends on the reliability and completeness of the observations (Clinical Excellence Commission, 2021)
• Increase frequency (If): Increase frequency of vital sign assessments if abnormal vital signs are observed (NICE, 2007). If the patient is acutely ill, for example, vital signs may need to be assessed every 15 minutes (Alexis, 2010)
• Eight hourly (Eh): In the absence of a documented monitoring plan, patients should have a completed set of vital signs assessed at least 3 times per day at Eight-hourly intervals (Clinical Excellence Commission, 2021). Eight-hourly measurement results in earlier detection of physiological abnormalities and clinical deterioration (Ludikhuize et al, 2014; Kellett and Sebat, 2017)
• Trends (Tr): Vital signs are constantly changing, so they are better expressed and interpreted by their Trends rather than just their precise value at any point in time (Kellett, 2017). Vital sign trends significantly improve the accuracy of detecting clinical deterioration compared to the current vital sign values alone (Churpek et al, 2016)
• Clinical judgement (Cj): Clinical judgement, rather than complete reliance on vital signs' readings, should be the basis for effective patient management (Pretto et al, 2014)
• Calling criteria (Cc): Know the Calling criteria for emergency medical assistance (DeVita et al, 2010).
• No delegation (Nd): Vital signs' assessment should Not be delegated to less qualified or experienced nursing staff. The recognition of and response to acute physiological deterioration requires appropriately qualified, skilled and experienced staff (Australian Commission on Safety and Quality in Health Care (ACSQHC,) 2017). Recognising patients whose condition is acutely deteriorating is essential for safe and high-quality care (ACSQHC, 2017)
• Full set (Fs): A Full set of vital signs should be assessed prior to and on transfer of care from one ward to another, from emergency departments, high dependency or intensive care units to general wards, and from one facility to another (ACT Government Health, 2018). When vital signs' assessment is incomplete, physiological instability is often missed (Clifton et al, 2015)
• Document interpret (Di): Accurate Documentation and interpretation of accurately measured vital signs helps improve patient outcomes (Rolfe, 2019)
• Analyse collectively (Ac): Vital signs should not be assessed in isolation but Analysed collectively in conjunction with other signs and the patient's ongoing health condition (Tollefson and Hillman, 2019).

Summary

Vital signs serve as a universal communication tool for patient status and severity of illness and are a critical component of early warning scores and medical emergency teams (Chester and Rudolph, 2011). When acting on abnormal vital signs, any clinical intervention needs to be implemented in a timely manner to prevent, where possible, any further deterioration in the patient's condition (Grainger, 2013). For this to happen, nurses must understand the clinical importance of vital signs' monitoring, but research suggests that this is not always the case (Cardona-Morrell et al, 2016; Burchill et al, 2015).

The proposed Global Elements guide can be used as a benchmarking tool when auditing vital sign assessment patterns or when performing a root cause analysis to determine specific areas of neglect of vital signs' assessment. For example, one coroner's case involved a 46-year-old woman who was admitted to a ward following an endoscopic procedure to correct complications of previous surgeries (Patient Safety Surveillance Unit, 2014). During the second postoperative night, her heart rate, blood pressure and respiratory rate were elevated and oxygen saturation low. No concern was expressed about these signs. She remained unwell with persistently elevated heart rate, temperature and respiratory rate, and hypoxia requiring supplemental oxygen. Routine observations continued 4-to 6-hourly. Although these vital signs constantly met the emergency medical call criteria, no call was made and the frequency of observations was not increased. The patient continued to deteriorate requiring further surgery and later died from surgical complications (Patient Safety Surveillance Unit, 2014).

Using the Global Elements as a guide, numerous deficits can be seen in this patient's vital sign assessments. The clinical importance of the patient's elevated respiratory rate is reflected in the respiratory rate Elements sensitive marker (Sm), First sign (Fs), powerful predictor (Pp), illness marker (Im) and minor changes (Mc). These Elements highlight the critical nature of the patient's initial respiratory rate elevation and emphasise that action should have been taken at that point. An increased frequency of respiratory rate assessment should have been evident on her vital signs' chart. Similarly, the low oxygen saturation in the clinical context (Cc) of an elevated respiratory rate and heart rate should have triggered urgent clinical action. The alteration (Al) in heart rate also reflected the initial deterioration in her condition and a deviation from normal range (Nr). An increased frequency of pulse rate assessment should also have been evident on the vital signs' chart (If) in response to the heart rate elevation.

Finally, the abnormal vital signs should have triggered staff to increase the frequency (If) of vital sign assessments, and familiarity with the emergency calling criteria (Cc) should also have promoted action. The staff continued to assess vital signs 4-to 6-hourly, suggesting they did not understand the importance of vital signs' assessments nor recognise the patient's deterioration. The application of the Global Elements highlights the care deficits in this case.

The current limited research on vital signs' assessment means that clinicians have little guidance for establishing a policy for evidence-based practice (McGhee et al, 2016). It is hoped that the global elements proposed here are one small advance towards enhancing nurses' understanding of the critical importance of vital signs' assessments.

KEY POINTS

• Vital signs' assessment is a key component of safe, high-quality care
• Abnormal vital signs are associated with poor clinical outcomes
• Research shows that vital signs' assessment is often neglected in clinical practice
• To help emphasise the importance of vital signs' assessment, Global Elements of vital signs' assessment are proposed
• The proposed framework of Global Elements reflects the key principles underpinning vital signs' assessment

CPD reflective questions

• What is the purpose of assessing patients' vital signs?
• Why is vital signs' assessment often neglected by nurses?
• How can vital signs' data be used to influence clinical management?