The clinical science behind Respiratory Rate as an Early Indicator of patient deterioration. The National Institute for Clinical Excellence (NICE) state that the respiratory rate (RR) is the most sensitive marker to indicate a deterioration in a patient’s clinical status (NICE 2007). Research studies repeatedly and consistently support such statements into early predictors of adverse clinical events such as cardiac arrest and deterioration requiring ITU admission (Fieselmann 1997, Hodgetts 2002, Goldhill 2005, Subbe 2003).
The importance of RR is increasingly recognized, as evidenced by its inclusion as a core element of Early Warning Systems (EWS) (Goldhill 2005, Subbe 2003), identification of the Systemic Inflammatory Response Syndrome (SIRS) (Bone 1992), and the assessment of acute asthma. Furthermore, inadequate clinical monitoring has been implicated as a principal factor in up to 31% of preventable deaths in English hospitals (Hogan 2013).
Alterations in RR can result from several causes. Perhaps most importantly, RR alteration is the fastest way a person’s physiology adapts to serum pH changes. Such changes can result from a wide range of severe conditions such as sepsis and ischaemia, altering cellular metabolism away from predominantly more sustainable oxidative phosphorylation to less and sometimes unsustainable anaerobic alternatives. Maintaining appropriate acid-base balance is integral to overall physiological homeostasis, as excessive dysregulation is incompatible with life. Another critical driver of RR is, in most patients, the hypoxic drive. It almost goes without saying that if a patient’s condition has changed, such that they cannot maintain sufficient oxygenation, it must be identified and acted upon at the earliest opportunity.
It would be inappropriate to suggest that RR’s value is only an early indicator of a deteriorating patient. RR has multiple other uses, including identifying psychological stress (Suess 1980), assessing responses to treatment, identifying transfusion reactions, monitoring fluctuations, and postoperative comparisons with baseline assessments (Dougherty 2008).
Therefore, identifying an altered or abnormal RR is key in assessing how a patient is, or is not, managing to respond to their condition. This, in turn, helps guide what interventions are required for optimising patient outcomes. Identifying this change is the first step in identifying the problem and, therefore, the solution. Rather than waiting for laboratory or imaging investigations, it should be appreciated that vital signs provide real-time information regarding the most fundamental aspects of physiological regulation and homeostasis. Calling them ‘vital signs’ is no understatement, and RR can be seen as primus inter pares, the first among equals.
The current procedures used to capture this vital sign or challenges with the same.
The most basic and frequently used method is an observational measurement by healthcare staff. This is the assessment method used for the vast majority of hospital patients, multiple times per day, throughout most acute care facilities in the world. Due to its importance, it has been the focus of much of my service evaluation work. This work has identified multiple challenges relating to this method of assessment. Our initial work determined that the clinical staff’s confidence in recorded RR assessments’ accuracy is low. The perception that recordings are often based on ‘guesstimates’ or other inaccurate assessment methods (Philip 2013). The main barrier to proper assessment was the perceived lack of time. Our further work has identified that the observational evaluation of respiratory rate methods can be highly inaccurate (Philip 2014). We specifically assessed the accuracy of doctor’s assessments using the techniques they stated they used, finding that both full minute assessments and shorter ‘spot’ assessments were highly inaccurate. Another limitation is that such evaluations are not continuous. If those assessments occur infrequently, then the delay in identifying a change will reflect that, so the delay in appropriate action occurs.
In more intensive care settings, continuous RR monitoring is achieved through methods such as capnography and pneumonography, and less frequently estimation methods using pulse oximeters and electrocardiograms. Challenges with such methodologies include relative invasiveness for patients, limitation of patient mobility, and inaccuracies due to ‘noise’ from movement.
Rapid Response Teams; How could continuous RR monitoring support teams to impact patient outcomes?
As previously stated, RR is the most sensitive marker of deterioration in a patient's clinical condition (NICE 2007); a useful predictor of adverse events (Fieselmann 1997, Hodgetts 2002, Goldhill 2005, Subbe 2003); and inadequate monitoring has been implicated in approximately a third of preventable deaths in English hospitals (Hogan 2013). For these reasons, it is an integral part of EWS. Accurate continuous RR monitoring, with preset alert criteria, could address the significant limitations of current RR monitoring, namely delays in identifying change due to non-continuous methods and multiple levels of escalation; and inaccuracy of current RR techniques.
Alerting Rapid Response Teams (RRTs) directly through portable devices would eliminate vital delays and facilitate prompt assessment, diagnosis, and appropriate care escalation. Secondly, they would facilitate the evaluation of response to treatment following an intervention. It is enabling staff to gain a clearer understanding of the next steps required to optimise patient outcomes. Thirdly, such methods are likely to provide far greater accuracy of RR assessment than commonly employed observational methods. This would improve the ability of RRTs to rely on the accuracy of the data and have confidence in making clinical decisions utilising this information.
It is not uncommon for RRTs to be caring for multiple patients on different wards throughout a hospital. Continuous monitoring facilitates RRTs to prioritise between patients appropriately. RRTs are repeatedly asked to make ‘perfect decisions using imperfect data.’ Continuous RR monitoring would improve the quality of the data used for decision-making and optimize patient outcomes.
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