Pulse oximetry knowledge and its effects on clinical ...

Pulse oximetry knowledge and its effects on clinical practice Thomas Paul Walters

Abstract

Aim: to explore literature pertaining to registered nurses’ and/or doctors’ knowledge in relation to the pulse oximetry in clinical practice. Background: pulse oximeters provide non-invasive readings of both pulse rate and peripheral oxygen saturation, leading to quick identification of potential/actual problems. Because of this, clinicians, like nurses, may become too dependent on it, neglecting other aspects of the holistic assessment process. Methods: a literature search was carried out between 1980 and 2006, with much of the data skewed towards 1994–2006. As the central focus was to be on pulse oximetry knowledge of nurses and/or doctors, articles included had to contain a central theme addressing this. Other criteria for inclusion were links between pulse oximetry and knowledge in clinical practice, nurses and/or doctors as participants in studies addressing this, as well as the clinical competency in relation to the device. Conclusion: improving knowledge may not necessarily be the answer in improving clinical competency. Future research will need to be carried out to measure the connection between knowledge and competency and to use that as a basis for education and training. Key words: Competency methodology

T Thomas Paul Walters is Staff Nurse, Intensive Care Unit, St Thomas’ Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London Accepted for publication: October 2007

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Education

Pulse oximetry

Research

he introduction of pulse oximetry to general health care has provided a huge advantage to clinical practice (Davidson and Hosie, 1993). In contrast to cooximeters that use arterial blood samples for analysis (Tallon, 1996), the pulse oximeter provides continuous noninvasive readings for both pulse rate and peripheral oxygen saturation (Woodrow, 1999). This ability to provide real-time measurements leads to problems and trends being identified early, positively affecting health outcomes (Carroll, 1997; Allen, 2004). Furthermore, the technology requires no calibration, nor sensor heating (Harrahill, 1991), is inexpensive, small, and portable (Woodrow, 1999). In addition, Severinghaus and Astrup (1986) claim it to be the most important advance reached in the monitoring of patients during anaesthesia, recovery and critical care. Although Place (2000) believes the technology to be a valuable contributor to nurses’ assessment skills, he does not believe it to be a replacement for it. Place further asserts that the pulse oximeter’s convenience and explicit advantages may lead to health staff ’s inevitable dependence on it. Jevon

and Ewens (2000) back this, claiming that it is simply an aid to observation and holistic care, and not a substitute. Harrahill (1991) goes further in arguing peripheral oxygen saturation (SpO2) to be only one aspect of the assessment process. Perhaps it is simply knowledge and understanding of the uses and limitations of this technology, that can prevent its over-reliance? Jensen et al (1998) concurs, claiming that the technology can only be considered valuable if combined with an insight to its operations and limitations. This article explores literature pertaining to healthcare professionals’, in particular registered nurses’ (RNs), level of knowledge in relation to the comprehension and use of the pulse oximeter. The main concepts to be included in the review will be issues of knowledge, clinical competency and pulse oximeter limitations in practice. An amalgamation of the literatures’ understanding of research designs, methods and general focus will be appraised. Research questions, possible gaps and potential opportunities for further study will be subsequently examined.

Literature review methods A literature review was conducted on CINAHL, MEDLINE, British Nursing Index, Blackwell-Synergy and BioMed Central, covering years 1980–2005, with much of the literature found to be skewed towards 1994–2006. The following search terms were used: pulse oximetry, pulse oximeter, knowledge, knowledge of, knowledge about, understanding, understanding of, training, education, peripheral oxygen saturation, arterial oxygen saturation, oxygen saturation, oxygen therapy, oxygen treatment, cooximeters, co-oximetry, hypoxia, and hypoxaemia.The search was restricted to articles that were available from the electronic databases used, with 40% from the United States (US), 27% from the United Kingdom (UK), 20% from Australia, 7% from New Zealand and 7% from Turkey. Of all the authors, 53% were RNs, while 47% were medical doctors. Two informative articles, one letter with mini-research study, one audit study, one clinical audit, and ten research articles encompassing both qualitative and quantitative studies were selected for review (Table 1). As the focus for this literature review was to be on healthcare professional’s knowledge of pulse oximetry, articles to be included had to contain a central theme addressing such. Key aspects for inclusion included ties between pulse oximetry and knowledge in clinical practice, registered nurses and/or doctors as participants in studies pertaining to education/ knowledge, as well as articles on nursing and/or medical clinical competency in relation to the device.

British Journal of Nursing, 2007, Vol 16, No 21

CLINICAL COMPETENCY Literature review Reviewing the literature of pulse oximetry resulted in a number of key components being made apparent, from knowledgebased issues to aspects of clinical practice, each pertaining to the use of the pulse oximeter by nurses and/or doctors.

Knowledge Harper (2004) detailed a study in the US to determine the knowledge of post-anaesthetic care unit RNs regarding the principles and use of the pulse oximeter. Using a 20-item truefalse questionnaire Harper found that 89% believed that the normal minimum SpO2 reading for an adult was 93%, where in fact it is 95% (Carroll, 1997); 42% of the sample actually thought that SpO2 denoted ventilation, when in reality a pulse oximeter can only measure oxygenation (Gilboy and McGaffigan, 1989). Furthermore, 21% even believed SpO2 readings to be similar to arterial blood gas (ABG) results. In fact, pulse oximeters simply provide an estimation of arterial oxygen saturation, in contrast to actual aspirated arterial blood samples used for in vitro analysis in ABGs (Tallon, 1996; Grap, 2002). What made these results worrying was the fact that they were collated from RNs working in a acute recovery unit; a unit dealing with post-anaesthetic patients, where airway and breathing form central priorities in overall patient management, and where knowledge of the pulse oximeter could arguably mean the difference between life and death. Harper’s (2004) conclusion concurred with similar studies by Stoneham et al (1994), Kruger and Longden, (1997) and Howell (2002) – that there is a deficit in pulse oximetry knowledge in both hospital nurses and doctors.

Competency and knowledge In an audit study, Howell (2002) found that deficits in the knowledge of both nurses and doctors, in particular what they believed the device recorded and why, were evident. Sixty per cent of the RN sample understood what the device measured, yet only 57% of RNs and 60% of doctors knew how it worked. The study concluded by asking participants to annotate on probable actions that they would normally have taken during certain clinical scenarios, involving the use of the device. These same clinical scenarios were found to have been replicated from a similar paper by Stoneham et al (1994), both finding significant patterns of incorrect actions being selected by their sample (Table 1). Even the medical staff in each of the studies’ samples proved no greater level of knowledge than the RNs, which again could be attributed to the sample’s lack of knowledge of the device. Harper’s (2004) study supports this finding through Pearson’s correlation, a positive link between education/experience and pulse oximeter knowledge test scores. By comparing the results of the clinical scenarios from both UK studies (Stoneham et al, 1994; Howell, 2002), a mean average knowledge improvement increase of 22% from 1994 to 2002 can be found (Table 2), fuelling the debate of whether pulse oximeter knowledge in RNs is improving. Furthermore, a similar study conducted in New Zealand by Davies et al (2003), who had the same research design as Stoneham et al (1994), achieved improvements in results from both the clinical scenario and the device knowledge questions. Despite


the results from Davies et al’s (2003) study being nowhere near as improved as Howell’s (2002), Davies et al (2003) concluded that their sample of RNs and doctors had a good understanding of the pulse oximeter device, with the majority of their sample knowing what it is (90%), what it measures (93%) and how it works (72%). This is a stark improvement to what was found by Stoneham et al (1994) with the results of 93%, 80% and 7%, respectively. Yet, if Davies et al (2003) had found that the majority of their sample of RNs had a good understanding of the pulse oximeter, then why had they scored so poorly in the clinical scenario questions? From this, it is reasonable to conclude that these findings disprove Harper’s (2004) statement of pulse oximetry competency being important in the positive outcomes of patients. Davies et al’s (2003) findings further suggest that good knowledge of pulse oximetry does not automatically equate to good clinical judgement/competence. One of the first studies to evaluate hospital staff ’s knowledge of the pulse oximeter was carried out by Rodriguez et al (1994).The study comprised a survey design aimed at assessing paediatric house officers’ (HO) knowledge of the device, and their capacity to decipher results generated by such technology. A 16-item multiple-choice questionnaire was used, which was first tested on six experienced pulmonologists/intensivists to ensure validity and clarity of the questions being used. This was then subsequently piloted on 34 paediatric HOs, and later administered to a further 100 paediatric HOs of varying postgraduate experience (n=134). The results of the study concluded that, in many cases, their sample of paediatric HOs had inadequate understanding of the pulse oximeter, with 43% not knowing what the device measured. Additionally, the study claimed that poor knowledge of the technology may actually add to patient morbidity, supporting Harper’s (2004) findings, implying a link between knowledge and patient health outcomes. In Australia, a similar study was carried out by Teoh et al (2003) using the exact same questionnaire as was developed and piloted by Rodriguez et al (1994). Much like the latter mentioned study, Teoh et al (2003) used paediatric medical doctors that consisted of an achieved sample of 47 junior medical officers (JMOs) and 74 senior medical officers (SMOs), from a drawn sample of 47 and 137, giving a response rate of 100% and 54%, respectively. Teoh et al’s (2003) conclusion reflected that of Rodriguez et al’s (1994), indicating that their sample of paediatric doctors had inadequate knowledge and comprehension concerning the clinical use, application and limitations of the pulse oximeter. Despite this, 85% of the former study’s sample knew what the device measured, in comparison to 43% from the latter. Yet, results for staff ’s understanding of the oxyhaemoglobin dissociation curve remained poor, with only 19% of Teoh et al’s (2003) sample and 17% of Rodriguez et al’s (1994) sample fully understanding its implications to both the machine and the patient’s clinical picture. This could quite possibly suggest that Teoh et al’s (2003) findings are further strengthening the assumption that good pulse oximeter knowledge is not necessarily equating to good clinical competence, supporting Davies et al’s (2003) findings and invalidating Harper’s (2004) and Rodriguez et al’s (1994) statement.

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European Journal of Anaesthesiology (Turkey)

British Journal of Nursing (UK)

Bilgin et al (2000) Correspondence/ Quantitative and qualitative study

Howell (2002) Quantitative study under audit

12 untrained nurses, 30 trained nurses and 8 doctors

12 resident doctors and 44 nurses (intensive care unit)

33 doctors, 164 nurses (83% registered, 8% enrolled and 9% student nurses)

New Zealand Medical 29 nurses and 34 doctors Journal (New Zealand)

Davies et al (2003) Quantitative study

177 patient case notes were used (in 5 acute medical wards)

Clinical Effectiveness in Nursing (Australia)

Simon and Clark (2002) Clinical audit

American Journal of Critical Care (US)

331 nurses, 82 physicians and 29 respiratory thrapists

Anaesthesia and Intensive Care (Australia)

Kruger and Longden (1997) Quantitative study

30 nurses and 30 preregistration house (PRHOs) officers and senior house officers (SHOs)

Attin et al (2002) Quantitative study

The Lancet (United Kingdom)

Stoneham et al (1994) Qualitative and quantitative study

134 paediatric house officers (HOs)

108 PRHOs and 77 SHOs

Pediatrics (United States)

Rodriguez et al (1994) Quantitative study

Sample

Smith and Poplett (2002) Postgraduate Quantitative study Medical Journal (UK)

Source

Author/literature type

Table 1. Summary of literature studies in this review

Both medical and nursing staff had a good understanding of the technology.

Use of pulse oximetry was performed with very little documentation of interpreted results, showing that majority of readings were done as stand alone observations. Data did not show evidence that the oximeter was being used as a trend measure for oxygen titration.

The educational programme lead to an increase in the pulse oximetry knowledge of doctors, nurses and respiratory therapists

Suggests medical graduates lack knowledge in pulse oximetry, rendering them poorly prepared to identify/treat critically ill patients. That they may not have been taught at university, which could have a potential to negatively affect patient outcomes.

Found a striking deficit in nurses’ and doctors’ knowledge behind what a pulse oximeter records and why it records it

The quantity of incorrect answers was due to poor knowledge

Lack of knowledge of pulse oximetry were found among nurses and doctors, which included the inability to know correct SpO2 ranges, recognize potential errors, and comprehend the oxyhaemoglobin dissociation

Nurses and junior doctors were not appropriately trained in pulse oximetry use, had little knowledge of the technology’s principles, and made mistakes in SpO2 interpretations

Paediatric HOs’ knowledge of pulse oximetry were found to be variable and may contribute to patient morbidity

Conclusion

Staff training may raise the clinical value of pulse oximetry

A more rationale approach to using pulse oximeters in medical wards is recommended.

Future plans and research must be focused on pulse oximetry use and its underlying costs. Furthermore, application has to made on better ways to reach physicians. Maintained education and research into pulse oximetry will aid in the technology’s integration into patient’s care.

Recommends introducing training on the use of pulse oximetry technology

It is recommended that improved pulse oximeter training be carried out prior to the technology’s utilization on patients. That all new staff be targetted and constant updates be organized for all existing staff

Focus should be made on teaching the principles of pulse oximetry, with frequent updates for new staff

The pulse oximeter must be accompanied by suffucient education for staff to be able to interpret results and act accordingly to those findings

It is essential that nurses and doctors are trained in the use of pulse oximeters

More emphasis be placed on education with regard to the principles/applications of pulse oximetry and oxyhaemoglobin dissociation curve

Recommendation


Not applicable Not applicable Orthopaedic Nursing (US) Miller (1992) (Informative article)

Not applicable

Not applicable British Journal Not applicable of Anaesthetic and Recovery Nursing (United Kingdom) Prowse (2000) (Informative article)

Not applicable

Dimensions of Critical 551 nurses (critical care) Care Nursing (US) Giuliano and Liu (2006) Quantitative study

Nurses in the sample had sufficient knowledge Future research should concentrate on clinical to provide monitoring and had a higher degree application and patient outcomes related of knowledge than that which has been reported to the use of SpO2 monitoring in previous research. Most of the sample had knowledge of the type of SpO2 device they had in their unit, as well as the major clinical conditions for their usage.

Competency in the use of pulse oximetry would ensure a positive clinical outcome. Nurse educators would need to implement research-based education sessions on pulse oximetry to staff, as part of their continual professional education. Nurses demonstrated a knowledge deficit in pulse oximetry Journal for Nurses in Staff Development (US) Harper (2004) Quantitative study

19 nurses (post-anaesthesia care unit)

There is a need for improving education on the correct use of pulse oximeters, as well as on interpreting data results 15 doctors, 42 nurses, and 9 respiratory practitioners Pediatric Nursing (United States) Popovich et al (2004) Quantitative study

Although the majority of participants thought that they were well trained and knowledgeable on the pulse oximetry, they lacked consistent knowledge in interpreting the data and making correct alterations in plans of care

More emphasis must be directed to teaching, with frequent updates thereafter There is insufficient knowledge/understanding among doctors concerning the principles and clinical uses of the pulse oximeter 74 senior medical officers officers (SMO) and 47 junior medical (JMO) participated (tertiary refferal hospital) Journal of Paediatrics and Child Health (Australia) Teoh et al (2003) Quantitative study

Conclusion Sample Source

Giuliano and Liu (2006) conducted a survey design study to measure the pulse oximeter knowledge-base of RNs at a nurse teaching conference in Atlanta, Georgia. Not only was this study one of the few that was centred on critical care nurses’ knowledge of the pulse oximeter device, but it is currently one of the largest with an achieved sample of 551.The sample had a mean age of 44 years, a mean of 15 years critical care experience, and were from a variety of hospitals in the US, from university teaching and community hospitals, to rural and military hospitals. The survey involved several demographic questions and a 5-point Likert scale questionnaire to test subjects knowledge of the pulse oximeter. Like Davies et al (2003), Teoh et al (2003) and Popovich et al (2004), this most recent US study had found their RN sample to have good knowledge in using the pulse oximeter. With Stoneham et al (1994) and Howell’s (2002) studies showing a knowledge improvement of 22% in the UK (1994–2002), and Rodriguez et al (1994) and Teoh et al (2003) with 42% in the US (1994–2003), it appears that pulse oximeter knowledge is improving. Furthermore, a study by Attin et al (2002) even went as far as not only measuring current pulse oximeter knowledge but to see if education would improve it. The education implemented was in the form of travelling posters, newsletters, staff meetings and conferences for doctors. With a sample of 331 RNs and 82 doctors the study found improvements in

Author/literature type

Improvements in knowledge

Table 1. Summary of literature studies encompassed within this review (continued)

A study by Popovich et al (2004) found similar findings from their paediatric doctors’ sample, discovering that although 100% understood what the device measured, only 47% knew about the oxyhaemoglobin dissociation curve. Moreover, through a number of clinical scenario questions devised to test clinical response and course of action, they found unacceptably high rates of poor answers, backing both Teoh et al (2003) and Davies et al’s (2003) findings that good pulse oximeter knowledge does not correlate to sound clinical judgement. Brent (1999) and Newell (1996), however, would claim Popovich et al’s (2004) sample of doctors (n=15) to be too small for solid evidence to be corroborated. Nonetheless, Popovich et al (2004) also had an achieved sample of 42 paediatric RNs, where it was found that they had achieved better results than the doctors in the clinical scenario questions, with a correct answer percentage range of 14–52%, in contrast to 7–47% from the latter. They too recognized what the pulse oximeter measured (76%), yet only 5% understood the oxyhaemoglobin dissociation curve, more or less conforming to results made from their sample of paediatric doctors.

Recommendation

CLINICAL COMPETENCY

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knowledge, with an overall increase of 16% in RN test scores before and after. This could indirectly rationalize the increase in general pulse oximeter knowledge found in UK and US studies, suggesting possible applications of education that may have slowly been increasing or evolving. Studies by Davies et al (2003),Teoh et al (2003) and Popovich et al (2004) showed that their sample of doctors/RNs had good knowledge of the pulse oximeter, yet were found to have achieved poorly on either clinical scenario questions or oxyhaemoglobin dissociation curve questions, supporting a theory that pulse oximeter knowledge does not necessarily equate to clinical competency. However, how would one define someone with good knowledge of such a device? Attin et al (2002), Howell (2002), Teoh et al (2003) and Giuliano and Liu (2006) clearly show increases in knowledge over time, which may suggest that education methods are improving, particularly in the US and UK. But it is not simply a question of knowing what the device measures, how it measures it, and the ability to identify normal/abnormal results. It is understanding the pulse oximeter in relation to the patient’s clinical picture, as well as the numerous factors that would affect its readings (Rodriguez et al, 1994; Popovich et al, 2004).

Evidence within practice In a study by Simon and Clark (2002), a prospective case note audit was carried out on a random 3-month period at five pre-selected acute medical wards, at a hospital in Australia. The aim was to review clinical practice with regard to SpO2 measurements and the physiological data essential for accurate pulse oximeter reading interpretations. They had found that after reviewing a total of 177 patient casenotes, 254 pulse oximeter readings were taken, of which 25% had SpO2 readings of below the normal limit of 95% (Carroll, 1997). ABGs were taken on an average of 9 days before the latest SpO2 readings, 53% of them indicating abnormal pH, with significant body temperature changes between ABG and SpO2 readings. Only one patient had peripheral perfusion checked, with 42% of nursing care plans involving the pulse oximeter, and 67% of all written nursing reports detailing either no evidence the device was ever used, or attempts at interpretation. The audit study concluded that both RNs/doctors were misinterpreting pulse oximeter readings, consequently affecting their ability to deliver competent clinical care. Unfortunately, Simon and Clark (2002) were not able to directly measure the knowledge base of the RNs/doctors involved in the

Table 2. Registered nurse results from the clinical scenario questions used by all three studies Clinical scenarios

Stoneham et al (1994) (30 nurses) (United Kingdom)

Howell (2002) (30 nurses) (United Kingdom)

Total increase 1994–2002* (contrasting results of Stoneham et al and Howell)

Elderly patient with pneumonia has an SpO2 reading of 75% on room air, rising to 85% on oxygen (O2) at 6 litres/min.

No evidence that any respondents mentioned to the patient to be seriously hypoxic, even with oxygen, and that further investigations such as ABG analysis needed to be carried out. 33% gave their only action as increasing the inspired O2 concentration.

30% identified ABGs should be checked, and a further 12% suggested further investigations would be needed

30%

Fairly fit patient has just returned from theatre following a laparotomy. O2 at 4 litres/min is given via face mask, raising SpO2 to 85%.

93% identified respiratory depression as the problem and suggested giving naloxone. None of them mentioned checking vital signs nor conscious levels.

20% identified conscious levels should be checked and that the patient’s vital signs closely monitored

20%

Patient with tension pneumothorax 17% correctly stated that they would and central cyanosis is admitted ignore the readings and treat the patient to the emergency assessment unit. on the basis of clinical signs The pulse oximeter displays an SpO2 of 100%.

40% identified that the equipment may be faulty and should be checked or replaced. (No mention whether these 40% would have based subsequent treatment on clinical signs!)

23%

What happens to the pulse oximetry reading immediately after a cardiac arrest?

7% correctly stated that the device would require a pulse to operate, and without one (i.e. during a cardiac arrest) the alarm would immediately sound. The others all thought saturations would fall either suddenly or gradually.

14% indicated that the machine would alarm once the pulse was lost, with the majority claiming that saturations would simply decrease

7%

What happens to the pulse oximetry reading during a respiratory arrest?

63% of nurses correctly predicated that SpO2 would fall until cardiac arrest occurred secondary to hypoxia

70% identified a decrease in saturations

7%

*Percentage increase of correct answers from Stoneham et al to Howell from 1994 to 2002. ABG = Arterial blood gas.

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CLINICAL COMPETENCY development of the case reports. Despite that, indirect evidence was gathered through the collation of legal documentation of clinical actions made, providing a recorded insight into clinical competence through the use of the pulse oximeter. It would be difficult to prove that the results of the audit study were caused by knowledge insufficiencies rather than perhaps stressful working conditions, lack of staff, lack of experience, limited time for documentation, varying educational background, not to mention individual hospital policies with regard to clinical management/care. Notwithstanding this, Simon and Clark (2002) published a paper that provided a good insight into aspects of pulse oximeter practice, arguably backing assertions made by Rodriguez et al (1994), Prowse (2000) and Popovich et al (2004), that knowledge simply makes up but one aspect of the competent use of the pulse oximeter. In an informative article, Miller (1992) asserted the importance of critical thinking in relation to knowledge of the pulse oximeter and the theories surrounding its use. Miller argued that the user must have an ability to interpret the results, to have an awareness of the patient’s total clinical picture, and to make sure that readings are accurate and reliable, supporting the notion that knowledge does not automatically equate to competency. Miller’s (1992) article provided a good insight not just on the pulse oximeter and its underlying physiological theories, but she was also able to outline the clinical considerations and descriptions of actions to take when using the device. Yet, it is important to note that the article used hypoxaemia in general terms, unlike studies by Stoneham et al (1994); Howell (2002), Davies et al (2003) and Popovich et al (2004); all of which covered a much wider angle with regard to the physiological problems that a pulse oximeter can be used to identify and help treat.

Limitations of the pulse oximetry Before any clinician can use SpO2 readings to determine their clinical decision, the RN/doctor would need to know not just the whole clinical picture of the patient involved and the technical aspects of the machine, but they would need to be certain that the readings were accurate (Miller, 1992). Most of the literature selected for this review contained at least some evidence of the importance of an awareness of pulse oximeter limitations, particularly when accuracy, reliability and subsequent clinical outcomes are at stake. A chart was used to provide a clear picture of the number of limitation factors each piece of literature contained (Table 3). All but one of all literature in this review explicitly stated at least three factors that would have had an effect on pulse oximeter accuracy.The three most popularly stated factors were perfusion (93%), movement (73%) and pulsatile flow (67%), with only Prowse (2000) stating that elevated plasma lipid concentrations would affect SpO2 readings (7%), and Giuliano and Liu (2006) stating that one time SpO2 measurements would highly be inaccurate and unreliable (7%). The studies included in this review had the shared aim of measuring the knowledge base of RNs and/or doctors in relation to the use of the pulse oximeter. However, it was found that none of the studies had fully stated all factors that could affect SpO2 accuracy. It was even found that some studies even contained small discrepancies in relation to the


minimum SpO2 accuracy reading – Bilgin et al (2000) assert the lower limit of reliability to be 85%, whereas Miller (1992) proclaims it to be 80%. Prowse (2000) and Teoh et al (2003), on the other hand, argue that SpO2 readings are least accurate when below 70%. Severinghaus and Honda (1987) and Carroll (1997) would back this, asserting that pulse oximeter readings are at their most reliable when between 70–100%.Though this may appear to contradict Bilgin et al (2000) and Miller’s (1992) assertions, it should be noted that only 27% of all literature selected for this review had taken the time to state the lowest SpO2 reliability reading. Miller (1992) acknowledged the significance of anaemia in rendering SpO2 readings inaccurate, with Spyr and Preach (1990) backing this, arguing that pulse oximeter reliability can only be trusted when haemoglobin levels are 5 g per litre (of blood) and above. However, studies by Stoneham et al (1994), Davies et al (2003) and Popovich et al (2004) clearly state that such a factor would not lead to significant changes to SpO2 readings. They had further asserted that skin pigmentation and jaundice do not affect pulse oximeter accuracy. Yet, Howell (2002) had maintained jaundice (7%) to be a significant factor to consider, with Kruger and Longden (1997) and Simon and Clark (2002) arguing that significant skin pigmentation (20%) could also affect SpO2 readings. Nevertheless, 93% of all literature selected in this review had addressed at least three factor limitations, with most factors found in Kruger and Longden (1997), Howell (2002) and Simon and Clark (2002), each with 62% of all the factors found within the review (Table 3). Although Attin et al (2002) had included actual questions on pulse oximeter limitations from their study, they had failed to inform the reader of the actual answers. Furthermore, on close inspection of their results section, they had mentioned that their sample lacked knowledge with regard to effects of darkly pigmented patients and probe positioning, to which no acknowledgement was made, again to actual answers. Any trained user of the pulse oximeter who is versed in both its clinical application and limitations would be highly necessary, effectively rendering the tool invaluable (Miller, 1992, Davies et al, 2003). Yet, knowledge of the limitations would not be enough to guarantee sound clinical management and care. Prowse (2000) wrote a paper to summarize the knowledge required for the use of the pulse oximeter in nursing practice. She went on to discuss how bioscience knowledge positively affects patient health outcomes, using the device as a prime example for her argument. Although Prowse’s (2000) paper was not an actual study used to measure knowledge, her article is highly detailed with regard to the clinical relevance of the pulse oximeter, and its underpinning theory behind its use in relation to health care. Most of the references included in the article were for her discussion on the theories of teaching and education, with only seven (out of forty-two) references used to support her detailed discussion of the pulse oximeter. It is, however, important to note that at the time of publishing the author was a highly ranked university lecturer, adding profound credibility to her ideas/arguments. In conclusion, Prowse (2000) argued the importance of considering clinical practice in establishing the level of bioscience

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6 (46%)

3 (23%)

10

67%

Prowse (2000)

Miller (1992)

Total score (out of 15 articles)

14

Percentage total

93%

9

9

9

53%

8

9

33%

5

9

73%

11

9

9

4 (31%)

Giuliano and Liu (2006)

9

4 (31%)

Harper (2004)

9

Popovich 5 (38%) et al (2004)

9

9

3 (23%)

Teoh et al (2003) 9

9

9

9

Davies et al 6 (46%) (2003)

9

9

9

9

9

9

9

Simon and 8 (62%) Clark (2002)

0*

Attin et al (2002)

9

6 (46%)

Smith and Poplett (2002)

9

9

9

8 (62%)

Howell (2002)

9

9

9

5 (38%)

Bilgin et al (2000)

9

9

9

8 (62%)

Kruger and Longden (1997)

9

9

9

9

Stoneham 6 (46%) et al (1994)

Motion artefact 9

Haemoglobin (i.e. anaemia, elevated Hb levels in COPD)

9

Light factors (ambient Peripheral light and perfusion probe (factors that sensor affect this) light)

Rodriguez 4 (31%) et al (1994)

Literature author (year)

Pulsatile flow (factors that affect this)

13%

2

9

9

Intravenous dyes

13%

2

9

9

Jaundice and bilirubin

53%

8

9

9

9

9

9

9

9

9

False positive (i.e. severe hypercapnia showing 100% SpO2, carbon monoxide)

60%

9

9

9

9

9

9

9

9

9

9

Dirty probe, dirty probe site and/or nail polish

13%

2

9

9

9

Clinician’s desensitization of pulse oximetry alarms

7%

1

9

9

Exact/single direct measurements will not be accurate

20%

3

9

9

9

7%

1

9

Elevated plasma lipids Skin (i.e. from pigmentation TPN)

*The chart below will only mark stated factors that affect SpO2 readings only if the literature had specifically addressed it as such. Please also note that all highlighted numbers are the amount of factors found within each piece of literature, with their percentage equivalent in brackets.

Table 3. Main factors that may limit pulse oximetry results, as mentioned within the selected literature

CLINICAL COMPETENCY knowledge underpinning nurses’ skills. Prowse further outlined that knowing the theory of the pulse oximeter without the application of clinical relevance and first-hand experience will not improve clinical outcomes, supporting Davies et al (2003), Teoh et al (2003) and Popovich et al (2004).

Methodological issues Research is vital for establishing and extending knowledge in effective practice (Russell and Wilson, 1992) and is what 67% of papers in this review used. However, where research establishes the right things to do, audits ensure these right things are in fact done (Bull, 1993), with 13% of the studies having conducted such. However, where research findings can be generalized, audit results apply only to participating local populations (Smith, 1992); yet, they raise questions that can then be further investigated through research (Balogh, 1996), as what studies by Howell (2002) and Simon and Clark (2002) had done, promoting positive changes to practice (Harvey, 1991).

Questionnaires All 13 studies selected for this literature review used questionnaires, with 23% encompassing interviews falling within quantitative and qualitative fields. Morse (1991) would view this as maximizing the strengths and minimizing the weaknesses of each approach, and is backed by Polit and Hungler (1999), asserting such an approach would amplify results procured. However, with every strength comes limitations, one of which pertains to the questionnaire tool itself. Though this tool is relatively cheap and is able to reach large numbers of people, as demonstrated in studies by Attin et al (2002) and Giuliano and Liu (2006), questionnaire research can never be completely objective. The RNs and doctors that had participated may simply have been motivated by interest, boredom, or even pressure to take part (Boynton, 2004). Studies by Davies et al (2003), Teoh et al (2003) and Popovich et al (2004) had clearly stated that some of their samples refused to participate on account of fear of deficiencies in knowledge. Kruger and Longden (1997) on the other hand had avoided clinical scenario questions in their study, believing it to be too threatening, potentially lowering response rates. Even the 31% of studies that had used multiple-choice questionnaires may have easily produced answers that could heighten intended outcomes (Burns and Grove, 2001).

Sample Sample size was another issue to consider, with Stoneham et al (1994), Howell (2002) and Davies et al (2003) each using a 30 RN sample, and Harper (2004) managing 19 nurses. Polit and Hungler (1991) assert that small sample sizes create greater variation, thus the greater the difference between the sample and the population to which it is being sampled from. It could be argued that small samples, like the four studies mentioned, have an increased likelihood of being different to the population to which it is suppose to represent (Newell 1996), rendering results unrepresentative of the whole, and thus invalid. With regard to sample strategy Rodriguez et al (1994), like all research studies in this review, used a non-probability sampling technique to generate their sample, in the form of convenience sampling where participants were selected on


the basis of accessibility (Beyea and Nicoll, 1997). Though this method may save on time and costs for the researchers, because of its non-random method of selection, Blackdrop (1996) would assert this technique to be ungeneralizable to the focused population. Nevertheless, Beyea and Nicoll (1997) would counter this by asserting that a random sample is not always appropriate in every study. In fact, the majority of the literature in this review required participants with attributes that conformed to their research focus, this being pulse oximeter knowledge of doctors and/or RNs.

Validity Overall, 38% of studies in this review had stated to have conducted a pilot study. One study (Popovich et al, 2004) tested their tool on eight intensive care unit RNs, resulting in no recommendations made to change neither wording nor format of the tool. Nevertheless, by having their developed tool tested prior to the actual study meant that content validity was able to be measured and acted upon, thus ensuring that items within the questionnaire adequately covered the subject area, in this case being pulse oximetry (Gibbon, 1995; Watson, 1995). In comparison, Rodriguez et al’s (1994) method of testing was more meticulous with their developed questionnaire tested on six experienced pulmonologists/intensivists and subsequently piloted to a further 34 paediatric HOs. Eby (1993) would assert that by using experts in the fields pertaining to the subject of the questionnaire you effectively validate the tool. Yet, even if content validity, in the form of piloting a research tool, was carried out it is unlikely that all problems relating to validity can be identified (Gibbon, 1998). One such problem can be found in Attin et al (2002), Teoh et al (2003) and Popovich et al’s (2004) studies, where they used doctors and RNs in their drawn sample. Parahoo (1997) maintains that one of the key validity questions one would need to ask centres on whether all respondents can interpret, understand, and respond to the questionnaire in the same way. Obviously medical and nursing training, and the cultures and backgrounds that exist within these two professions, could present a serious question mark to the questionnaires own validity.

Conclusion Choosing knowledge as the first theme for this review enabled an introduction to its importance in health care and an arguable link to the second theme of clinical competency, both of which are said to be important in the utilization of the pulse oximeter. Sixty-two per cent of studies in this review had deduced that a lack of knowledge pertaining to the device was evident and was indeed affecting clinical ability. Outlining evidence found within practice as another theme allowed for a possible bridge to connect nurses’ knowledge to competency, as was found by Simon and Clarke (2002). They had identified legally written evidence that RNs/doctors were misinterpreting pulse oximeter readings, consequently affecting their ability to deliver competent clinical care. Though many studies suggest a lack of knowledge, there had been numerous papers finding clear improvements over time, particularly in the UK and the US. Furthermore, Attin et al’s (2002) study found that simple education in the form of posters and staff meetings had actually increased the knowledge

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Figure 1. Main recommendations provided by all 13 studies included in literature review.

80 70

Per cent

60 50 40 30 20 10 0

Teaching/ Education

Improved research

Improved rationale

among their sample and may account for such knowledge improvements over time. In all, 77% of the literature reviewed had recommended further education be carried out to improve knowledge (Figure 1). Improving knowledge, however, may not necessarily be the answer, as proven by Davies et al (2003), Teoh et al (2003) and Popovich et al (2004), claiming that poor competency does not necessarily pertain to sound knowledge. Perhaps it is not simply measuring current knowledge, improvements in knowledge, or measuring competency that is the answer. Conducting research into the connection between knowledge and competency and to use that as a basis for education and training may be what is called for in the future. Knowledge may or may not connect with competency but it is competency that is important in patient treatment, care and clinical outcome. Examining this within the realms of the pulse oximeter provides a flavour of how knowledge can be integral with competency, and how competency can be so BJN vital to clinical treatment and care.

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KEY POINTS There is evidence suggesting knowledge deficiencies in the use of pulse oximeters by both registered nurses (RNs) and medical doctors. Knowledge of the pulse oximeter may not correlate to clinical competency. Both clinical experience and clinical theory, coupled with sound pulse oximetry knowledge may be significant in the improvement of clinical outcomes Recommendations by literature suggest that further education be carried out to improve pulse oximetry knowledge among both RNs and doctors. Evidence arguably points to an improvement in RN pulse oximetry knowledge over time.
