Effect of skin tone on the accuracy of the estimation of arterial oxygen saturation by pulse oximetry: a systematic review.

BACKGROUND: Pulse oximetry-derived oxygen saturation (SpO2) is an estimate of true arterial oxygen saturation (SaO2). The aim of this review was to evaluate available evidence determining the effect of skin tone on the ability of pulse oximeters to accurately estimate SaO2. METHODS: Published literature was screened to identify clinical and non-clinical studies enrolling adults and children when SpO2 was compared with a paired co-oximetry SaO2 value. We searched literature databases from their inception to March 20, 2023. Risk of bias (RoB) was assessed using the QUADAS-2 tool. Certainty of assessment was evaluated using the GRADE tool. RESULTS: Forty-four studies were selected reporting on at least 222 644 participants (6121 of whom were children) and 733 722 paired SpO2-SaO2 measurements. Methodologies included laboratory studies, prospective clinical, and retrospective clinical studies. A high RoB was detected in 64% of studies and there was considerable heterogeneity in study design, data analysis, and reporting metrics. Only 11 (25%) studies measured skin tone in 2353 (1.1%) participants; the remainder reported participant ethnicity: 68 930 (31.0%) participants were of non-White ethnicity or had non-light skin tones. The majority of studies reported overestimation of SaO2 by pulse oximetry in participants with darker skin tones or from ethnicities assumed to have darker skin tones. Several studies reported no inaccuracy related to skin tone. Meta-analysis of the data was not possible. CONCLUSIONS: Pulse oximetry can overestimate true SaO2 in people with darker skin tones. The clinical relevance of this bias remains unclear, but its magnitude is likely to be greater when SaO2 is lower. SYSTEMATIC REVIEW PROTOCOL: International Prospective Register of Systematic Reviews (PROSPERO): CRD42023390723.

The Use of Metaraminol as a Vasopressor in Critically Unwell Patients: A Narrative Review and a Survey of UK Practice.

Background: Major international guidelines state that norepinephrine should be used as the first-line vasopressor to achieve adequate blood pressure in patients with hypotension or shock. However, recent observational studies report that in the United Kingdom and Australia, metaraminol is often used as second line medication for cardiovascular support. Aim of the study: The aim of this study was to carry out a systematic review of metaraminol use for management of shock in critically unwell patients and carry out a survey evaluating whether UK critical care units use metaraminol and under which circumstances. Methods: A systematic review literature search was conducted. A short telephone survey consisting of 6 questions regarding metaraminol use was conducted across 30 UK critical care units which included a mix of tertiary and district general intensive care units. Results: Twenty-six of thirty contacted centres responded to our survey. Metaraminol was used in 88% of them in various settings and circumstances (emergency department, theatres, medical emergencies on medical wards), with 67% reporting use of metaraminol infusions in the critical care setting. The systematic literature review revealed several case reports and only two studies conducted in the last 20 years investigating the effect of metaraminol as a stand-alone vasopressor. Both studies focused on different aspects of metaraminol use and the data was incomparable, hence we decided not to perform a meta-analysis. Conclusions: Metaraminol is widely used as a vasopressor inside and outside of the critical care setting in the UK despite limited evidence supporting its safety and efficacy for treating shock. Further service evaluation, observational studies and prospective randomised controlled trials are warranted to validate the role and safety profile of metaraminol in the treatment of the critically unwell patient.

Congestion in the tube: air trapping in a ventilated patient with COVID-19 secondary to mucinous valves.

A woman in her 50s was admitted to the intensive therapy unit with acute hypoxaemic respiratory failure secondary to COVID-19 pneumonitis. The patient was intubated on admission and worsening gas exchange necessitated multiple rounds of proning . She later improved, and her ventilation was switched to spontaneous mode. However, the patient started to develop air trapping with subsequent respiratory and cardiovascular compromise. Routine investigations showed no clear cause for her sudden deterioration and a suction catheter passed easily through the endotracheal tube. Bronchoscopy revealed mucinous/phlegmatic membranes had developed across the inner diameter of the endotracheal tube. This had created a one-way valve that allowed positive pressure ventilation through the tube into her lungs but only allowed a fraction of air to passively escape in expiration. This case report highlights a less commonly regarded complication associated with long-term intubation and lack of circuit humidification in the context of productive lung pathology.

Intensive care unit staffing during the periods of fluctuating bed occupancy: An alternative dynamic model.

OBJECTIVES: Staffing is the single biggest cost component in the critical care budgets. Due to the fluctuation in both bed occupancy and the level of care needs, nursing staff requirement can vary considerably from day to day. This makes the traditional 'fixed roster' staffing system inefficient, costly and potentially unsafe. In this study, we used the existing bed occupancy data to test the viability two 'dynamic' workforce management models. RESEARCH METHODOLOGY: Nursing requirement data were prospectively collected over one year at a thirty-two-bed critical care unit. Using mathematical models, we then tested the concept of two alternative workforce management models and compared the level of staffing, as well as the estimated cost per year. The first was an 'on-call' model, which was a two-tier roster with a standard staffing level and an additional on-call component; the second was a 'predictive' model, which estimated the staffing requirement based on the bed occupancy a few days prior. SETTING: Single centre study in a busy district general hospital with a 32-bed critical care unit. MAIN OUTCOME MEASURES: The number of days with safe staffing levels and the cost of the alternative workforce management models. RESULTS: Data were collected over 331 days. The on-call model was estimated to cost 16% less per year (£431,320, or 2,630 nurse-shift equivalent) compared to the fixed roster, while fulfilling the adequate staffing standards in 97% of the days. While the predictive model could also be used to improve the workforce efficiency, this was overall less efficient than the on-call model. CONCLUSION: The modelled data suggests that the implementation of an 'on-call' model in critical care nursing rostering could potentially improve coverage and appear to be cost effective.

'Should I Stay, or Should I Go?' Psychological Distress Predicts Career Change Ideation among Intensive Care Staff in Lithuania and the UK Amid COVID-19 Pandemic.

The COVID-19 pandemic had a significant effect on healthcare globally. Additional pressure created by coronavirus adversely affected the mental health and psychological well-being of healthcare workers, leading many to question their desire and willingness to continue working in healthcare. This study aimed to identify predictors for career change ideation among healthcare professionals in two countries; Lithuania and the United Kingdom amid the coronavirus pandemic. In total, 610 healthcare professionals from Lithuania and the UK (285 and 325, respectively) participated in a survey from May to August 2020. Psychological distress and psychological well-being were measured using the self-report scales "DASS-21" and "WHO-5". Almost half of the sample (49.2%), 59.6% and 40.0% in Lithuanian and the UK, respectively, exhibited career change ideation, the country effect was significant (AOR = 2.21, p < 0.001). Stronger ideation to leave healthcare was predicted by higher levels of depression (AOR = 1.10, p = 0.005), stress (AOR = 1.10, p = 0.007), anxiety surrounding inadequate personal protective equipment (AOR = 2.27, p = 0.009), and lower psychological well-being scores (AOR = 1.10, p = 0.007). We conclude that psychosocial support must be provided for healthcare professionals to prevent burnout and loss of staff amid the pandemic.

Cost-effectiveness of a national quality improvement programme to improve survival after emergency abdominal surgery: Learning from 15,856 patients.

BACKGROUND: Patients undergoing emergency abdominal surgery are exposed to a high risk of death. A quality improvement (QI) programme to improve the survival for these patients was evaluated in the Enhanced Peri-Operative Care for High-risk patients (EPOCH) trial. This study aims to assess its cost-effectiveness versus usual care from a UK health service perspective. METHODS: Data collected in a subsample of trial participants were employed to estimate costs and quality-adjusted life years (QALYs) for the QI programme and usual care within the 180-day trial period, with results also extrapolated to estimate lifetime costs and QALYs. Cost-effectiveness was estimated using incremental cost-effectiveness ratios (ICERs). The probability of being cost-effective was determined for different cost-effectiveness thresholds (£13,000 to £30,000 per QALY). Analyses were performed for lower-risk and higher-risk subgroups based on the number of surgical indications (single vs multiple). RESULTS: Within the trial period, QI was more costly (£467) but less effective (-0.002 QALYs). Over a lifetime, it was more costly (£1395) and more effective (0.018 QALYs), but did not appear to be cost-effective (ICER: £77,792 per QALY, higher than all cost-effectiveness thresholds; probability of being cost-effective: 28.7%-43.8% across the thresholds). For lower-risk patients, QI was more costly and less effective both within trial period and over a lifetime and it did not appear to be cost-effective. For higher-risk patients, it was more costly and more effective, and did not appear cost-effective within the trial period (ICER: £158,253 per QALY) but may be cost-effective over a lifetime (ICER: £14,293 per QALY). CONCLUSION: The QI programme does not appear cost-effective at standard cost-effectiveness thresholds. For patients with multiple surgical indications, this programme is potentially cost-effective over a lifetime, but this is highly uncertain.

Chronotropic incompetence and myocardial injury after noncardiac surgery: planned secondary analysis of a prospective observational international cohort study.

BACKGROUND: Physiological measures of heart failure are common in surgical patients, despite the absence of a diagnosis. Heart rate (HR) increases during exercise are frequently blunted in heart failure (termed chronotropic incompetence), which primarily reflects beta-adrenoreceptor dysfunction. We examined whether chronotropic incompetence was associated with myocardial injury after noncardiac surgery. METHODS: This was a predefined analysis of an international cohort study where participants aged ≥40 yr underwent symptom-limited cardiopulmonary exercise testing before noncardiac surgery. Chronotropic incompetence was defined as the ratio of increase in HR during exercise to age-predicted maximal increase in HR <0.6. The primary outcome was myocardial injury within 3 days after surgery, defined by high-sensitivity troponin assays >99th centile. Explanatory variables were biomarkers for heart failure (ventilatory efficiency slope [minute ventilation/carbon dioxide production] ≥34; peak oxygen consumption ≤14 ml kg-1 min-1; HR recovery ≤6 beats min-1 decrease 1 min post-exercise; preoperative N-terminal pro-B-type natriuretic peptide [NT pro-BNP] >300 pg ml-1). Myocardial injury was compared in the presence or absence of sympathetic (i.e. chronotropic incompetence) or parasympathetic (i.e. impaired HR recovery after exercise) thresholds indicative of dysfunction. Data are presented as odds ratios (ORs) (95% confidence intervals). RESULTS: Chronotropic incompetence occurred in 396/1325 (29.9%) participants; only 16/1325 (1.2%) had a heart failure diagnosis. Myocardial injury was sustained by 162/1325 (12.2%) patients. Raised preoperative NT pro-BNP was more common when chronotropic incompetence was <0.6 (OR: 1.57 [1.11-2.23]; P=0.011). Chronotropic incompetence was not significantly associated with myocardial injury (OR: 1.05 [0.74-1.50]; P=0.78), independent of rate-limiting therapy. HR recovery <12 beats min-1 decrease after exercise was associated with myocardial injury in the presence (OR: 1.62 [1.05-2.51]; P=0.03) or absence (OR: 1.60 [1.06-2.39]; P=0.02) of chronotropic incompetence. CONCLUSIONS: Chronotropic incompetence is common in surgical patients. In contrast to parasympathetic dysfunction which was associated with myocardial injury, preoperative chronotropic incompetence (suggestive of sympathetic dysfunction) was not associated with postoperative myocardial injury.