This was a cross-sectional questionnaire survey assessing nursing staff knowledge of clinical PO device application. The survey was conducted on paper, remained anonymous and did not require the nursing participant’s personal identification, including name, date of birth, license number or any other personal health identifiers protected by Health Insurance Portability and Accountability Act (HIPAA). A copy of the survey was submitted for review to the institution’s IRB along with the study’s educational aim and for which exemption was granted. Furthermore, consent for research was obtained via a study statement on each questionnaire which indicated that completion implied consent for participation.

The study was conducted at an American academic tertiary referral hospital with Nursing Magnet status in September 2019. A total of 150 clinical nurses from the PACU and MRICU were surveyed, based on willingness to complete the survey. Both groups were given a brief verbal introduction to the study. Questionnaires were placed in an accessible area for nurses to take and complete at their discretion. A total of 51 questionnaires (32 MRICU and 19 PACU) were completed and submitted for data analysis within a time period of one week. The completed questionnaires were returned to a centralised location with the unit’s charge nurse and collected at the end of the week by members of the research team.

Questionnaire design: Numerous tools to assess nursing knowledge regarding PO have been previously described [10-12]. After this review, the questionnaire developed by Kiekkas P et al., was selected as the most comprehensive in its assessment of gas exchange, oxygen transport, ventilation, and practical limitations of PO [4]. In order to improve completion rates of questionnaires and suitability for data analysis, a true or false design was used for the 21-item questionnaire adapted from Kiekkas P et al., [4].

Three optional free-response questions were added at the end of the questionnaire. The first two assessed PO troubleshooting and the third offered opportunity for feedback. The three free-response questions were:

22: What are the things that you check or patient do when a PO alarm goes off?

23: Do you have any frustrations with working with and relying on PO?

24: Any other questions or comments?”

Statistical analysis was performed using R Core Team (2020) [13]. Categorical variables were analysed using Pearson Chi-square test and continuous variables underwent Student t-test. Post-hoc analysis was not required to be performed. Significance was set at p<0.05.

Fifty one questionnaires were completed (32 MRICU, 19 PACU) with a 34% response rate from 150 questionnaires distributed. Of the entire set of responses, the largest fraction (31.3%) was from nurses with 3-5 years of clinical experience. Among the MRICU cohort, the largest group (46.9%) had 2 years or less of clinical experience, while the largest group in the PACU nurses (47.4%) had greater than 10 years of clinical experience. Subgroup analysis by years of clinical experience for both cohorts has reported in [Table/Fig-1].

The mean TKS of the 21-item survey assessing clinical knowledge of PO application was 16.4±2.0 correct responses. The mean TKS for the MRICU and PACU cohorts has reported in [Table/Fig-2]. Of the 51 total participants, 50 (98.0%) had a score ≥11, and 37 (72.5%) had a score ≥16. A breakdown of how participants performed on each question is recorded in [Table/Fig-3]. TKS was comparable regardless of nursing staff location or practice, with 100% of MRICU and 94.7% of PACU nurses answering >50% of questions correctly. Fewer nurses achieved ≥90% correct scores (13.7%), with a breakdown of 15.7% in PACU nurses and 12.5% in MRICU nurses [Table/Fig-3].

Overall, nurses with 6-10 years of experience showed trends toward very high scores, with 37.5% answering at least 90% of the questions correctly [Table/Fig-4].

Years of clinical experience correlated with higher TKS in PACU nurses (72.1%, 77.3%, 79.8%; 3-5 years, 6-10 years, ≥10 years, respectively). Length of MRICU experience did not correlate with rising TKS, as most respondents scored 75-80% from 0-2 years of experience to ≥10 years [Table/Fig-5].

Of the 21 true/false questions that addressed knowledge of PO, three questions had an overall correct response rate of lower than 50% with no difference in performance based on nursing staff location or experience [Table/Fig-6]. Two questions with <50% correct scores addressed physiologic principles, while the remaining question addressed PO technique. Of the 51 participants, only 18 provided answers to the open-ended questions. In response to the question concerning what one should do when a PO alarm goes-off, the majority of participants (n=15) commented on checking to make sure the PO monitor is correctly placed, checking connections, and checking the monitor to look for appropriate waveforms. Nine respondents commented on making sure that the patient is not moving and that the PO sensor is not on the same arm as the blood pressure cuff. Eight respondents recommended a physical assessment of the patient. Regarding the question about “any frustrations with PO,” the majority of respondents (n=8) expressed the frustration that they believe most alarms are false [Table/Fig-7].

This study assessed the knowledge base of PACU and MRICU nurses from a single United States center and revealed several areas of significant strength along with opportunities for focused education and review.

Total knowledge scores: The study reported questionnaire results as TKS. The mean TKS of the population was higher than the mean TKS of those evaluated by Kiekkas P et al., and Seeley MC et al., (12.8 and 11.7, respectively). Given the differences in TKS among United States, Greek, and Australian nurses, a brief overview of nursing curricula in these countries was undertaken [4,5].

In the United States, students may start nursing coursework in a three to four-year undergraduate program. Alternatively, nursing coursework may be completed within a focused two-year program covering the basics of nursing for students who have already completed other undergraduate degrees. Upon the successful completion of nursing school, a US nursing candidate must pass the national National Council Licensure Exam (NCLEX) to become eligible to work as a Registered Nurse (RN). Upon starting a clinical position, the typical orientation for recent graduate nurses is variable and individualised to each healthcare system. This orientation typically consists of several weeks of sessions teaching basic skills such as BLS, ACLS, and CPR [14]. Most hospitals in the United States have a collegial environment where learning is ongoing and discussion between nurses, physicians, pharmacists, nutritionists and other healthcare members is encouraged to facilitate learning [14].

In Greece, nursing undergraduate degrees consist of eight semesters over four years, with the eighth semester being clinical practice [15]. There is no nationwide board exam upon completion of the nursing program. Similarly, Australian nursing students may start work following completion of a three-year program with no requirement of a nationwide board exam [16]. In contrast, nursing students in the United States are required to take a national board exam in order to practice as registered nurses. This may support the claim that nursing students trained in the United States undergo a more comprehensive education which is reflected in the relatively higher TKS of United States nurses. A national board exam such as the National Council Licensure Examination -Registered Nurse (NCLEX-RN) aims to cover a broad range of basic physiology, including respiratory information such as PO [17]. To prepare, nurses taking this exam are encouraged to have adequate knowledge about PO.

This difference in TKS between nursing staff in this study and those in Greece may be attributed to differences in nursing curriculum. Other study done by Nimbalkar S et al., which compared knowledge of medical residents and nursing staff also suggest that a difference in curricula affects PO application [6]. Briefly, medical residents undergo a longer schooling period than nurses with more frequent standardised examination. This supports the authors claim that improvement in PO application knowledge will require some type of formal education and that experience alone is inadequate.

Role of clinical experience: The correlation between years of clinical experience and TKS was further analysed. The importance of “practical knowledge” was previously shown in the career development of healthcare professionals [18]. This study defined total years of clinical experience by time spent caring for patients both in the inpatient and outpatient setting. This study found a small but not statistically significant difference in TKS based on years of clinical experience. In PACU nursing staff, TKS incrementally increased from 72.1% correct in those with 3-5 years of experience to 79.8% among those with 10 years or more clinical experience.

Role of healthcare setting: Across the literature, there exist conflicting views on how healthcare setting affects PO knowledge [6-8]. The current study found no significant difference between PO knowledge in ICU staff compared to non-ICU staff. On the other hand, a study has shown that clinical setting does make a difference with paediatricians scoring lower on a PO assessment compared to Level 3 ICU staff [8].

This study found that MRICU nurses had slightly higher but not statistically significant TKSs than PACU nurses (16.5 vs. 16.2, p=0.27). Kiekkas P et al., have similarly shown that nurses working in critical care environments such as the ICU had higher TKS scores than their counterparts in the Emergency or Anaesthesia Departments [4]. Curiously, a study done in Greece found that ICU nurses performed better on PO assessment relative to non-ICU nurses suggesting that perhaps the clinical experience in this region might be superior to other regions [8]. Further such studies should be conducted in various regions of the United States to get a more representative sample of healthcare setting on PO application.

ICU nurses may have a stronger grasp on cardiovascular and respiratory parameters by nature of caring for critically ill patients daily. Nurses in other clinical environments such as ward medicine, emergency departments may not frequently deal with the same types of patients [19]. This was the case in the aforementioned study where paediatricians scored lower on a PO assessment compared to Level 3 ICU staff. It seems healthcare setting might have also accounted for these differences as the training a general paediatrician receives does not revolve around critical care.

Graduates’ knowledge of gas exchange and PO: Regarding knowledge of gas exchange and cardiopulmonary physiology, this study’s results differed from the results of Kiekkas P et al., and Seeley MC et al., [4,5] Whereas these previous studies found significant gaps in fundamental principles required for the proper use and interpretation of PO, this study’s results did not demonstrate a significant knowledge gap.

For example, Seeley MC et al., found that 57% of their participants incorrectly thought that the relationship between SpO₂ and PaO₂ was linear (Questionnaire item # 9) [5]. This study found that only 21.6% of nurses incorrectly believed this statement. Kiekkas P et al., state that in their study the lowest percentages of correct responses (<50%) were found in five of eleven questions pertaining to physiologic principle required to understand PO [4]. This study demonstrates that the lowest percentages of correct responses (<50%) were found only in two of eleven questions pertaining to physiologic principles of PO (Question 3 and 16). Nurses in the United States undergo extensive education which has advantages in learning the basic physiologic principles and application of PO. Recent study have explored this concept, termed a “theory-practice gap,” and have consistently found that practical education is a critical supplement to theoretical classroom education [20].

Next, Seeley MC et., found that 71% of their total participants (and 83% of those with at least one postgraduate year) incorrectly thought PO was used for the rapid detection of tissue hypoxia (Questionnaire item # 3) [5]. Similarly, Kiekkas P et al., found that 71.5% of their participants incorrectly believed this. This study showed that 52.9% of participants incorrectly believed this statement [4]. While better than the other two studies, it is concerning that over half of this study’s cohort did not understand this concept. A pulse oximeter can indicate hypoxemia by estimating the SaO₂. Hypoxia, however, refers to decreased oxygen at the cellular level, which is not measured by PO. A nurse who is unaware of this limitation may fail to perform various physical assessments of inadequate tissue oxygenation status under conditions of normal SpO₂ [5].

Important deficits in the use of PO to assess perfusion in extremities were noted. Decreased arterial perfusion compromises the ability of PO to determine hypoxemia. This concept was well understood by participants in this study as well as participants in the Seeley MC et al., and Kiekkas P et al., studies [4,5]. A 100% of this study’s participants, 92.5% of Seeley MC et al., and 84.5% from Kiekkas P et al., understood that poor peripheral perfusion causes difficulty in obtaining accurate PO readings (Questionnaire item #11) [4,5]. A 90.2% of this study’s participants, 71% of Seeley MC et al., participants, and 69.1% of Kiekkas P et al., participants were able to expand on this concept by answering that vasoconstricted states create errors in peripheral PO sensors, encouraging centrally applied pulse oximeters probes to increase accuracy (Questions 6) [4,5]. However, participants from all studies, this current study included, failed to extrapolate this concept to the setting of cardiopulmonary resuscitation, a state where impaired cardiac functioning causes diminished perfusion, both centrally and peripherally. This error was committed by 45.1% of this study’s participants, 38% of Seeley MC et al., study, and 41% of Kiekkas P et al., correctly identified that PO is not recommended during cardiopulmonary resuscitation (Questionnaire item # 16) [4,5]. This again suggests a specific theoretical knowledge deficit that might be corrected at a pre-graduate level.

One of the main limitations to this study was the small sample size. Participation of nursing staff in this study was voluntary which increases the likelihood of a selection bias. Furthermore, responder fatigue may have skewed some results. To limit the risk of fatigue, the questionnaire was limited to a reasonable 21 items with a binary true/false format rather than multiple choice. Adding this additional choice may have prevented bias from a participant guessing the correct response.

Lastly, there existed no way of knowing if participants accessed any resources while taking the survey. This “open book” risk may have been a limitation of the reference study populations as well.

The effective use of PO in perioperative and critical care settings requires a strong grasp of physiologic and clinical knowledge. This study, conducted in the United States, indicates a higher fund of knowledge of nursing staff relative to other reference studies. In this study’s surveyed population, there was no significant difference in PO knowledge scores with regard to clinical setting or years of clinical experience. Some areas of opportunity were identified related to deficits in physiologic principles of PO. To address these areas, this study recommends frequent standardised assessments of clinical staff to ensure competency in physiologic and principles of clinical application. Improvement in postgraduate education curriculum and implementation of regular assessments will ensure up-to-date understanding of these clinical principles and ultimately lead to safer patient care.