Effect of routine emergency department triage pulse oximetry screening on medical management

Clinical Outcomes Associated With Overestimation of Oxygen Saturation by Pulse Oximetry in Patients Hospitalized With COVID-19

Importance

Many pulse oximeters have been shown to overestimate oxygen saturation in persons of color, and this phenomenon has potential clinical implications. The relationship between overestimation of oxygen saturation with timing of COVID-19 medication delivery and clinical outcomes remains unknown.

Objective

To investigate the association between overestimation of oxygen saturation by pulse oximetry and delay in administration of COVID-19 therapy, hospital length of stay, risk of hospital readmission, and in-hospital mortality.

Design, Setting, and Participants

This cohort study included patients hospitalized for COVID-19 at 186 acute care facilities in the US with at least 1 functional arterial oxygen saturation (SaO2) measurement between March 2020 and October 2021. A subset of patients were admitted after July 1, 2020, without immediate need for COVID-19 therapy based on pulse oximeter saturation (SpO2 levels of 94% or higher without supplemental oxygen).

Exposures

Self-reported race and ethnicity, difference between concurrent SaO2 and pulse oximeter saturation (SpO2) within 10 minutes, and initially unrecognized need for COVID-19 therapy (first SaO2 reading below 94% despite SpO2 levels of 94% or above).

Main Outcome and Measures

The association of race and ethnicity with degree of pulse oximeter measurement error (SpO2 - SaO2) and odds of unrecognized need for COVID-19 therapy were determined using linear mixed-effects models. Associations of initially unrecognized need for treatment with time to receipt of therapy (remdesivir or dexamethasone), in-hospital mortality, 30-day hospital readmission, and length of stay were evaluated using mixed-effects models. All models accounted for demographics, clinical characteristics, and hospital site. Effect modification by race and ethnicity was evaluated using interaction terms.

Results

Among 24 504 patients with concurrent SpO2 and SaO2 measurements (mean [SD] age, 63.9 [15.8] years; 10 263 female [41.9%]; 3922 Black [16.0%], 7895 Hispanic [32.2%], 2554 Asian, Native American or Alaskan Native, Hawaiian or Pacific Islander, or another race or ethnicity [10.4%], and 10 133 White [41.4%]), pulse oximetry overestimated SaO2 for Black (adjusted mean difference, 0.93 [95% CI, 0.74-1.12] percentage points), Hispanic (0.49 [95% CI, 0.34-0.63] percentage points), and other (0.53 [95% CI, 0.35-0.72] percentage points) patients compared with White patients. In a subset of 8635 patients with a concurrent SpO2 - SaO2 pair without immediate need for COVID-19 therapy, Black patients were significantly more likely to have pulse oximetry values that masked an indication for COVID-19 therapy compared with White patients (adjusted odds ratio [aOR], 1.65; 95% CI, 1.33-2.03). Patients with an unrecognized need for COVID-19 therapy were 10% less likely to receive COVID-19 therapy (adjusted hazard ratio, 0.90; 95% CI, 0.83-0.97) and higher odds of readmission (aOR, 2.41; 95% CI, 1.39-4.18) regardless of race (P for interaction = .45 and P = .14, respectively). There was no association of unrecognized need for COVID-19 therapy with in-hospital mortality (aOR, 0.84; 95% CI, 0.71-1.01) or length of stay (mean difference, -1.4 days; 95% CI, -3.1 to 0.2 days).

Conclusions and Relevance

In this cohort study, overestimation of oxygen saturation by pulse oximetry led to delayed delivery of COVID-19 therapy and higher probability of readmission regardless of race. Black patients were more likely to have unrecognized need for therapy with potential implications for population-level health disparities.

Descriptive characteristics of continuous oximetry measurement in moderate to severe covid-19 patients

Non-invasive oxygen saturation (SpO2) is a central vital sign used to shape the management of COVID-19 patients. Yet, there have been no report quantitatively describing SpO2 dynamics and patterns in COVID-19 patients using continuous SpO2 recordings. We performed a retrospective observational analysis of the clinical information and 27 K hours of continuous SpO2 high-resolution (1 Hz) recordings of 367 critical and non-critical COVID-19 patients hospitalised at the Rambam Health Care Campus, Haifa, Israel. An absolute SpO2 threshold of 93% most efficiently discriminated between critical and non-critical patients, regardless of oxygen support. Oximetry-derived digital biomarker (OBMs) computed per 1 h monitoring window showed significant differences between groups, notably the cumulative time below 93% SpO2 (CT93). Patients with CT93 above 60% during the first hour of monitoring, were more likely to require oxygen support. Mechanical ventilation exhibited a strong effect on SpO2 dynamics by significantly reducing the frequency and depth of desaturations. OBMs related to periodicity and hypoxic burden were markedly affected, up to several hours before the initiation of the mechanical ventilation. In summary, OBMs, traditionally used in the field of sleep medicine research, are informative for continuous assessment of disease severity and response to respiratory support of hospitalised COVID-19 patients. In conclusion, OBMs may improve risk stratification and therapy management of critical care patients with respiratory impairment.

Two simple replacements for the Triage Early Warning Score to facilitate the South African Triage Scale in low resource settings

BACKGROUND

The South African Triage Scale (SATS) requires the calculation of the Triage Early Warning Score (TEWS), which takes time and is prone to error.

AIM

to derive and validate triage scores from a clinical database collected in a low-resource hospital in sub-Saharan Africa over four years and compare them with the ability of TEWS to triage patients.

METHODS

A retrospective observational study carried out in Kitovu Hospital, Masaka, Uganda as part of an ongoing quality improvement project. Data collected on 4482 patients was divided into two equal cohorts: one for the derivation of scores by logistic regression and the other for their validation.

RESULTS

Two scores identified the largest number of patients with the lowest in-hospital mortality. A score based on oxygen saturation, mental status and mobility had a c statistic for discrimination of 0.83 (95% CI 0.079-0.87) in the derivation, and 0.81 (95% CI 0.77-0.86) in the validation cohort. Another score based on respiratory rate, mental status and mobility had a c statistic of 0.82 (95% CI 0.078-0.87) in the derivation, and 0.81 (95% CI 0.77-0.86) in the validation cohort. The oxygen saturation-based score of zero points identified 51% of patients in the derivation cohort who had in-hospital mortality rate of 0.5%, and 49% of patients in the validation cohort who had in-hospital mortality of 1.0%. A respiratory rate-based score of zero points identified 45% in the derivation cohort who had in-hospital mortality rate of 0.5%, and 44% of patients in the validation cohort who had in-hospital mortality of 0.8%. Both scores had comparable performance to TEWS.

CONCLUSION

Two easy to calculate scores have comparable performance to TEWS and, therefore, could replace it to facilitate the adoption of SATS in low-resource settings.

Pre-hospital predictors of an adverse outcome among patients with dyspnoea as the main symptom assessed by pre-hospital emergency nurses - a retrospective observational study

Background

Dyspnoea is one of the most common reasons for patients contacting emergency medical services (EMS). Pre-hospital Emergency Nurses (PENs) are independently responsible for advanced care and to meet these patients individual needs. Patients with dyspnoea constitute a complex group, with multiple different final diagnoses and with a high risk of death. This study aimed to describe on-scene factors associated with an increased risk of a time-sensitive final diagnosis and the risk of death.

Methods

A retrospective observational study including patients aged ≥16 years, presenting mainly with dyspnoea was conducted. Patients were identified thorough an EMS database, and were assessed by PENs in the south-western part of Sweden during January to December 2017. Of 7260 missions (9% of all primary missions), 6354 were included. Among those, 4587 patients were randomly selected in conjunction with adjusting for unique patients with single occasions. Data were manually collected through both EMS- and hospital records and final diagnoses were determined through the final diagnoses verified in hospital records. Analysis was performed using multiple logistic regression and multiple imputations.

Results

Among all unique patients with dyspnoea as the main symptom, 13% had a time-sensitive final diagnosis. The three most frequent final time-sensitive diagnoses were cardiac diseases (4.1% of all diagnoses), infectious/inflammatory diseases (2.6%), and vascular diseases (2.4%). A history of hypertension, renal disease, symptoms of pain, abnormal respiratory rate, impaired consciousness, a pathologic ECG and a short delay until call for EMS were associated with an increased risk of a time-sensitive final diagnosis. Among patients with time-sensitive diagnoses, approximately 27% died within 30 days. Increasing age, a history of renal disease, cancer, low systolic blood pressures, impaired consciousness and abnormal body temperature were associated with an increased risk of death.

Conclusions

Among patients with dyspnoea as the main symptom, age, previous medical history, deviating vital signs, ECG pattern, symptoms of pain, and a short delay until call for EMS are important factors to consider in the prehospital assessment of the combined risk of either having a time-sensitive diagnosis or death.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12873-020-00384-1.

Update in Pediatric Hospital Medicine

Pediatric Hospital Medicine has significantly developed as a field over the past two decades. With the goal of improving care for hospitalized children, much of the research in this field has focused on reducing unnecessary interventions, optimizing necessary treatments, and reducing variability for common inpatient conditions. While this is far from an exhaustive chapter on the vast diversity and advances in this field, it focuses on the updates for some of the top diagnoses in hospital medicine and the major trends in the field. Updated management of acute viral bronchiolitis, urinary tract infections, neonatal infections, brief resolved unexplained events (formerly, apparent life-threatening events), and osteomyelitis are highlighted with emphasis on major management changes. In addition, and distinct to pediatric hospital medicine, the topics of overuse and high value care are discussed as they have gained momentum in influencing the way hospitalists think and practice.

CLARIPED: a new tool for risk classification in pediatric emergencies

Objective:

To present a new pediatric risk classification tool, CLARIPED, and describe its development steps.

Methods:

Development steps: (i) first round of discussion among experts, first prototype; (ii) pre-test of reliability, 36 hypothetical cases; (iii) second round of discussion to perform adjustments; (iv) team training; (v) pre-test with patients in real time; (vi) third round of discussion to perform new adjustments; (vii) final pre-test of validity (20% of medical treatments in five days).

Results:

CLARIPED features five urgency categories: Red (Emergency), Orange (very urgent), Yellow (urgent), Green (little urgent) and Blue (not urgent). The first classification step includes the measurement of four vital signs (VIPE score); the second step consists in the urgency discrimination assessment. Each step results in assigning a color, selecting the most urgent one for the final classification. Each color corresponds to a maximum waiting time for medical care and referral to the most appropriate physical area for the patient's clinical condition. The interobserver agreement was substantial (kappa=0.79) and the final pre-test, with 82 medical treatments, showed good correlation between the proportion of patients in each urgency category and the number of used resources (p<0.001).

Conclusions:

CLARIPED is an objective and easy-to-use tool for simple risk classification, of which pre-tests suggest good reliability and validity. Larger-scale studies on its validity and reliability in different health contexts are ongoing and can contribute to the implementation of a nationwide pediatric risk classification system.

CLARIPED: a new tool for risk classification in pediatric emergencies

OBJECTIVE

To present a new pediatric risk classification tool, CLARIPED, and describe its development steps.

METHODS

Development steps: (i) first round of discussion among experts, first prototype; (ii) pre-test of reliability, 36 hypothetical cases; (iii) second round of discussion to perform adjustments; (iv) team training; (v) pre-test with patients in real time; (vi) third round of discussion to perform new adjustments; (vii) final pre-test of validity (20% of medical treatments in five days).

RESULTS

CLARIPED features five urgency categories: Red (Emergency), Orange (very urgent), Yellow (urgent), Green (little urgent) and Blue (not urgent). The first classification step includes the measurement of four vital signs (Vipe score); the second step consists in the urgency discrimination assessment. Each step results in assigning a color, selecting the most urgent one for the final classification. Each color corresponds to a maximum waiting time for medical care and referral to the most appropriate physical area for the patient's clinical condition. The interobserver agreement was substantial (kappa=0.79) and the final pre-test, with 82 medical treatments, showed good correlation between the proportion of patients in each urgency category and the number of used resources (p<0.001).

CONCLUSIONS

CLARIPED is an objective and easy-to-use tool for simple risk classification, of which pre-tests suggest good reliability and validity. Larger-scale studies on its validity and reliability in different health contexts are ongoing and can contribute to the implementation of a nationwide pediatric risk classification system.

Pulse Oxygen Saturation Values in a Healthy School-Aged Population

OBJECTIVES

The purpose of this study was to determine the normal values of oxygen saturation in a healthy school-aged pediatric population.

METHODS

This study enrolled students in grades K-8 at an elementary and middle school in Los Angeles. Although all students were invited to participate, only pulse oximetry results among healthy students were included. Healthy students were defined as not having asthma, bronchitis, a recent cold or pneumonia within the past week, any chronic lung disease, or any heart condition.

RESULTS

Two hundred forty-eight students participated in the study, and 246 students met the inclusion criteria. Pulse oxygen saturation values ranged from 97% to 100% with a mean of 98.7% (95% confidence interval [CI], 98.6%-99.8%) and median of 99%. The distribution of measured pulse oximetry values were 97%: 16 (95% CI, 6.5%), 98%: 45 (95% CI, 18.3%), 99%: 184 (95% CI, 74.8%), and 100%: 1 (95% CI, 0.4%).

CONCLUSIONS

Although the conventional wisdom is that pulse oximetry values 95% or greater are normal, these data suggest that the normal oxygen saturation range should be between 97% and 100%. Values of 95% and 96% should increase clinical suspicion of underlying disease.

The Use of Pulse Oximetry to Determine Hypoxemia in Acute Exacerbations of COPD

BACKGROUND

There is little evidence that the guideline-recommended oxygen saturation of 92% is the best cut-off point for detecting hypoxemia in COPD exacerbations.

OBJECTIVE

To detect and validate pulse oximetry oxygen saturation cut-off values likely to detect hypoxemia in patients with aeCOPD, to explore the correlation between oxygen saturation measured by pulse oximetry and hypoxemia or hypercapnic respiratory failure.

METHODOLOGY

Cross-sectional study nested in the IRYSS-COPD study with 2,181 episodes of aeCOPD recruited between 2008 and 2010 in 16 hospitals belonging to the Spanish Public Health System. Data collected include determination of oxygen saturation by pulse oximetry upon arrival in the emergency department (ED), first arterial blood gasometry values, sociodemographic information, background medical history and clinical variables upon ED arrival. Logistic regression models were performed using as the dependent variables hypoxemia (PaO2 < 60 mmHg) and hypercapnic respiratory failure (PaO2 < 60 mmHg and PaCO2 > 45). Optimal cut-off points were calculated.

RESULTS

The correlation coefficient between oxygen saturation and pO2 measured by arterial blood gasometry was 0.89. The area under the curve (AUC) for the hypoxemia model was 0.97 (0.96-0.98) and the optimal cut-off point for hypoxemia was an oxygen saturation of 90%. The AUC for hypercapnic respiratory failure was 0.90 (0.87-0.92) and the optimal cut-off point was an oxygen saturation of 88%.

CONCLUSIONS

Our results support current recommendations for ordering blood gasometry based on pulse oximetry oxygen saturation cut-offs for hypoxemia. We also provide easy to use formulae to calculate pO2 from oxygen saturation measured by pulse oximetry.

Pulse oximetry in discharge decision-making: a survey of emergency physicians

OBJECTIVES

Our primary objective was to describe the pulse oximetry discharge thresholds used by general and pediatric emergency physicians for well-appearing children with bronchiolitis and pneumonia, and to assess the related practice variability.

METHODS

This mail-in survey was conducted in August and September 2001 and included the 281 active members of the Pediatric Emergency Medicine Section of the American College of Emergency Physicians. The survey consisted of 2 case scenarios of previously healthy, well-appearing children: a 2-year-old with pneumonia and a 10-month-old with bronchiolitis. Respondents were asked about their years of experience, teaching load, percentage of children in their practice, whether they currently have a written departmental guideline at their institution, and the lowest pulse oximetry reading that they would accept and still discharge the patient directly home.

RESULTS

One hundred and eighty-two (65%) physicians answered the survey and met the inclusion criteria. The respondents' median oximetry value and interquartile range (IQR) for the pneumonia and bronchiolitis cases were 93% (92%-94%) and 94% (92%-94%) respectively. With the exception of the 3 physicians practising >1000 metres above sea level, the responses by subgroups were similar.

CONCLUSIONS

There does not yet exist a safe, clinically validated pulse oximetry discharge threshold. Emergency physicians from this study sample have a modest degree of practice variability in a self-reported pulse oximetry discharge threshold. Emergency physicians may use this data to compare their own practice with that reported by this group.

The Cost-Benefit of Pulse-Oximeter Use in the Prehospital Environment

Introduction:

Pulse-oximetry has proven clinical value in Emergency Departments and Intensive Care Units. In the prehospital environment, oxygen is given routinely in many situations. It was hypothesized that the use of pulse oximeters in the prehospital setting would provide a measurable cost-benefit by reducing the amount of oxygen used.

Methods:

This was a prospective study conducted at 12 ambulance stations (average transport times >20 minutes). Standard care protocols and paramedic assessments were used to determine which patients received oxygen and the initial flow rate used. Pulse-oximetry measurements (oxygen-saturation measured by pulse oximetry) were then taken. If oxygen-saturation measured by pulse oximetry fell below 92% or rose above 96% (except in patients with chest pain), oxygen (O2) flow rates were adjusted. Costs of oxygen use were calculated: volume that would have been used based on initial flow rate; and volume actually used based on actual flow rates and transport time.

Methods:

A total of 1,907 patients were recruited. Oximetry and complete data were obtained on 1,787 (94%). Of these, 1,329 (74%) received O2 by standard protocol: 389 (27.5%) had the O2 flow decreased; 52 had it discontinued. Eighty-seven patients (6%) not requiring O2 standard protocol were hypoxemic (oxygen-saturation measured by pulse oximetry < 92%) by oximetry, and 71 patients (5%) receiving oxygen required flow rate increases. Overall, O2 consumption was reduced by 26% resulting in a cost-savings of $0.20 / patient. Prehospital pulse-oximetry allows unncessary or excessive oxygen therapy to be avoided in up to 55% of patients transported by ambulance and can help to identify suboptimally oxygenated patients (11%).

Conclusion:

Rationalizing the O2 administration using pulse-oximetry reduced O2 consumption. Other health care savings likely would result from a reduced incidence of suboptimal oxygenation. Oxygen cost-saving justifies oximeter purchase for each ambulance annually where patient volume exceeds 1,750, less frequently for lower call volumes, or in those services where the mean transport time is less than the 23 minute average noted in this study.

Pulse oximetry in pediatric practice

The introduction of pulse oximetry in clinical practice has allowed for simple, noninvasive, and reasonably accurate estimation of arterial oxygen saturation. Pulse oximetry is routinely used in the emergency department, the pediatric ward, and in pediatric intensive and perioperative care. However, clinically relevant principles and inherent limitations of the method are not always well understood by health care professionals caring for children. The calculation of the percentage of arterial oxyhemoglobin is based on the distinct characteristics of light absorption in the red and infrared spectra by oxygenated versus deoxygenated hemoglobin and takes advantage of the variation in light absorption caused by the pulsatility of arterial blood. Computation of oxygen saturation is achieved with the use of calibration algorithms. Safe use of pulse oximetry requires knowledge of its limitations, which include motion artifacts, poor perfusion at the site of measurement, irregular rhythms, ambient light or electromagnetic interference, skin pigmentation, nail polish, calibration assumptions, probe positioning, time lag in detecting hypoxic events, venous pulsation, intravenous dyes, and presence of abnormal hemoglobin molecules. In this review we describe the physiologic principles and limitations of pulse oximetry, discuss normal values, and highlight its importance in common pediatric diseases, in which the principle mechanism of hypoxemia is ventilation/perfusion mismatch (eg, asthma exacerbation, acute bronchiolitis, pneumonia) versus hypoventilation (eg, laryngotracheitis, vocal cord dysfunction, foreign-body aspiration in the larynx or trachea). Additional technologic advancements in pulse oximetry and its incorporation into evidence-based clinical algorithms will improve the efficiency of the method in daily pediatric practice.

Brazilian guidelines for community-acquired pneumonia in immunocompetent adults - 2009

Community-acquired pneumonia continues to be the acute infectious disease that has the greatest medical and social impact regarding morbidity and treatment costs. Children and the elderly are more susceptible to severe complications, thereby justifying the fact that the prevention measures adopted have focused on these age brackets. Despite the advances in the knowledge of etiology and physiopathology, as well as the improvement in preliminary clinical and therapeutic methods, various questions merit further investigation. This is due to the clinical, social, demographical and structural diversity, which cannot be fully predicted. Consequently, guidelines are published in order to compile the most recent knowledge in a systematic way and to promote the rational use of that knowledge in medical practice. Therefore, guidelines are not a rigid set of rules that must be followed, but first and foremost a tool to be used in a critical way, bearing in mind the variability of biological and human responses within their individual and social contexts. This document represents the conclusion of a detailed discussion among the members of the Scientific Board and Respiratory Infection Committee of the Brazilian Thoracic Association. The objective of the work group was to present relevant topics in order to update the previous guidelines. We attempted to avoid the repetition of consensual concepts. The principal objective of creating this document was to present a compilation of the recent advances published in the literature and, consequently, to contribute to improving the quality of the medical care provided to immunocompetent adult patients with community-acquired pneumonia.

Pulse oximetry in emergency medicine

Although the recognition of hypoxemia is greatly enhanced through the proper and informed use of the pulse oximeter, the device can never be relied on to take the place of the clinician at the bedside who makes sure that the data provided matches the clinical picture with which he or she is presented.

Pulse oximetry in general practice: how would a pulse oximeter influence patient management?

The pulse oximeter is a vital piece of equipment in secondary care for the non-invasive monitoring of oxygen saturation. With the increasing affordability of the oximeter and recognition of its clinical applications, there is an increasing interest in its role in primary care. The decision was made that a systematic review was not feasible due to the lack of data concerning the influence of pulse oximetry on patient management and on the extent of oximetry use in the general practice setting. In this article, a selection of studies is presented looking into its clinical use and limitations. The role and potential of the oximeter as a screening tool and aid in the assessment of hypoxia in a variety of clinical situations in primary care is discussed.

Diagnosis and management of pneumonia in the emergency department

Pneumonia is a condition that is often treated by emergency physicians. This article reviews the diagnosis and management of pneumonia in the emergency department and highlights dilemmas in diagnostic testing, use of blood and sputum cultures, hospital admission decisions, infection control, quality measures for pneumonia care, and empiric antimicrobial therapy.

Pulse oximetry

PURPOSE OF REVIEW

Pulse oximetry is now a ubiquitous and essential tool of modern medicine, and while it is a relatively recent invention, the technology has rapidly matured since the first commercially available oximeters were introduced in the 1970s. This review seeks to provide an overview of the basic physical operation of the probe and discuss its limitations, sources of error and some current advances in the use of multi-wavelength probes.

RECENT FINDINGS

New multi-wavelength oximeters and plethysmographic waveform analysis may expand the information that we can collect and use non-invasively. This includes distinguishing between haemoglobinopathies, monitoring volume status and volume loss, and potentially monitoring cardiac output non-invasively.

SUMMARY

The pulse oximeter, like any basic tool, must be used properly. There is considerable misunderstanding and lack of education among junior clinicians as to the use and interpretation of pulse oximeters. The introduction of the pulse oximeter has demonstrated a cost saving, although the cost-benefit of new multi-wavelength probes remains unproven.

Clinical predictors of the severity of bronchiolitis

INTRODUCTION

Bronchiolitis is the most common serious, acute viral infection in infants. Besides the diagnostic and treatment challenges, the appropriate time and the need of hospitalization remain unanswered. We wonder whether clinical predictors such as age less than 6 months, respiratory frequency more than 45 breaths per minute and oxygen saturation less than 95% could be of any help in assessing the severity of the disease and the need for admission.

MATERIALS AND METHODS

A prospective study was held in the emergency department from November 2000 to January 2002, in which each patient with positive nasopharyngeal respiratory syncytial virus was included. Other inclusion criteria were full-term birth, clinical signs of respiratory diseases, age between 2 weeks up to 24 months and no underlying illnesses such as bronchopulmonary dysplasia and chronic heart or lung diseases. The sensitivity, specificity and relative risk (RR) were calculated by statistical analyses.

RESULTS

During the study period, 378 patients were included, 117 of whom were hospitalized (31%). Age less than 6 months (sensitivity 62%, specificity 72% and RR 2.68 ), respiratory frequency more than 45 breaths per minute (sensitivity 68%, specificity 82% and RR 4.57) and oxygen saturation less than 95% (sensitivity 68%, specificity 87% and RR 4.67) predicted the severity of the pulmonary disease and the need for admission. The cumulative analysis of the three parameters showed a specificity of 91% and a sensitivity of 86%, with a relative risk of 4.54 among those admitted into the hospital. Respiratory frequency more than 45 breaths per minute (sensitivity 76%, specificity 82% and RR 2.85) and oxygen saturation less than 95% (sensitivity 84%, specificity 86% and RR 2.65) were more significant than age less than 6 months (sensitivity 60%, specificity 70% and RR 3.70) in predicting the admission into the paediatric intensive care unit.

CONCLUSION

Oxygen saturation less than 95%, respiratory frequency more than 45 breaths per minute and age less than 6 months in respiratory-distressed infants are important parameters to predict the need for admission and emphasize the severity of bronchiolitis.

Decrease in emergency department length of stay as a result of triage pulse oximetry

OBJECTIVES

Many emergency departments do not perform pulse oximetry in triage, in spite of its potential for altering management decisions. We attempted to quantify the decrease in patient throughput time in a pediatric emergency department following the introduction of triage pulse oximetry.

METHODS

One hundred fifty-nine bronchiolitis patients from 2004 served as the preintervention group, and were evaluated against 89 severity-matched postintervention bronchiolitis patients from 2005. Their mean lengths of ED stay were compared by a t test.

RESULTS

The preintervention group had a mean length of stay of 4 hours and 59 minutes, and the postintervention group had a mean length of stay of 4 hours and 9 minutes, which was significantly different (P = 0.03). The sensitivity of respiratory distress on the triage exam for predicting hypoxia was fair (74%).

CONCLUSIONS

Institution of triage pulse oximetry significantly decreases ED throughput times. Clinical exam alone is not a replacement for measurement of oxygen saturation.

Impact of impedance cardiography on diagnosis and therapy of emergent dyspnea: the ED-IMPACT trial

BACKGROUND

Dyspnea is one of the most common emergency department (ED) symptoms, but early diagnosis and treatment are challenging because of multiple potential causes. Impedance cardiography (ICG) is a noninvasive method to measure hemodynamics that may assist in early ED decision making.

OBJECTIVES

To determine the rate of change in working diagnosis and initial treatment plan by adding ICG data during the course of ED clinical evaluation of elder patients presenting with dyspnea.

METHODS

The authors studied a convenience sample of dyspneic patients 65 years and older who were presenting to the EDs of two urban academic centers. The attending emergency physician was initially blinded to the ICG data, which was collected by research staff not involved in patient care. At initial ED presentation, after history and physical but before central lab or radiograph data were returned, the attending ED physician completed a case report form documenting diagnosis and treatment plan. The physician then was shown the ICG data and the same information was again recorded. Pre- and post-ICG differences were analyzed.

RESULTS

Eighty-nine patients were enrolled, with a mean age of 74.8 +/- 7.0 years; 52 (58%) were African American, 42 (47%) were male. Congestive heart failure and chronic obstructive pulmonary disease were the most common final diagnoses, occurring in 43 (48%), and 20 (22%), respectively. ICG data changed the working diagnosis in 12 (13%; 95% CI = 7% to 22%) and medications administered in 35 (39%; 95% CI = 29% to 50%).

CONCLUSIONS

Impedance cardiography data result in significant changes in ED physician diagnosis and therapeutic plan during the evaluation of dyspneic patients 65 years and older.

Comparison of the Emergency Severity Index (ESI) and the Taiwan Triage System in Predicting Resource Utilization

BACKGROUND/PURPOSE

The importance of accurate triage in Taiwan is becoming more apparent with the increasing number of emergency department (ED) patients, and resources for the National Health Insurance becoming constrained. This study compared the ability of the Taiwan triage system (TTS) and the standardized 5-level Emergency Severity Index (ESI) triage system to predict ED resource utilization.

METHODS

Patients arriving at the ED were triaged by both TTS and by using a two-page checklist of ESI criteria during the 3-month study period. The ESI triage level was calculated independently to avoid bias. Disease category (trauma vs. nontrauma), length of stay (LOS) and hospitalization data were evaluated.

RESULTS

A total of 3172 patients with both ESI and TWN evaluation were included. The distributions of ESI ratings within TTS level 1 were: ESI 1, 21.1%; ESI 2, 68.1%; ESI 3, 7.4%; ESI 4, 3.4%; ESI 5, 0%. For TTS level 3, they were: ESI 1, 0.1%; ESI 2, 26.2%; ESI 3, 39.5%; ESI 4, 27.5%; ESI 5, 6.8%. Hospitalization rates were 74.5%, 40.9% and 22.2% in TTS levels 1, 2 and 3, respectively; and were 96.2%, 47.0%, 30.9%, 6.7%and 6.6% in ESI levels 1, 2, 3, 4 and 5, respectively. TTS triaged more trauma patients as life-threatening/emergent condition than nontrauma patients (68.8% vs. 48.4%, p < 0.001). Triage by ESI, however, showed no significant difference in the percentage of trauma and nontrauma patients with highly acute conditions (44.2% vs. 46.6%, p = 0.230). Patients with ESI level 4 or 5 have significantly shorter ED LOS than those with ESI level 3.

CONCLUSION

ESI produces more accurate discriminating patient acuity, ED LOS and hospitalization rate than TTS. Adopting a standardized 5-level triage tool might improve resource utilization planning of ED practice.

Transthoracic electrical bioimpedance: a means of filling the void?

OBJECTIVES

To examine the published evidence regarding the use of transthoracic electric bioimpedance (TEB) for the non-invasive monitoring of cardiac output in the ED.

METHOD

Databases of the medical literature, relevant textbooks and the Internet were searched for articles regarding TEB. Criteria for inclusion were drawn up prior to examination of the articles and included adherence to guidelines for comparing methods of clinical measurement.

RESULTS

Results are discussed under the following headings: technological capability, diagnostic accuracy, limitations, range of possible uses, therapeutic impact, impact on health care providers, patient outcome and future directions.

CONCLUSION

TEB is a technique for the non-invasive monitoring of cardiac output whose ease of use, continuous data acquisition and versatility suggest it may have a role to play in the care of patients in our EDs.

Vital signs

BACKGROUND

Vital signs traditionally consist of blood pressure, temperature, pulse rate and respiratory rate, and are an important component of monitoring the patient's progress during hospitalisation. An initial search of the literature indicated that there was a vast volume of published information relating to this topic; however, there had been no previous attempt to systematically review this literature. This review was therefore initiated to identify, appraise and summarise the best available evidence relating to the measurement of vital signs in hospital patients.

OBJECTIVES

The objectives of this review were to present the best available information related to the monitoring of patient vital signs with regard to their purpose, limitations, optimal frequency of measurements, and what measures should constitute vital signs. The review also sought to identify additional issues of importance related to the individual parameters of temperature measurement, blood pressure assessment, pulse rate measurement and respiratory rate measurement.

REVIEW METHODS

This review considered all studies that related to the objectives and included neonatal, paediatric and/or adult hospital patients. The outcome measures of interest were those related to the accuracy of, required frequency of or the need for vital signs. The review also considered any study addressing some aspect of vital signs measurement to ensure all issues of importance were identified. The search sought to find both published and unpublished studies. Databases searched included CINAHL, Medline, Current Contents, Cochrane Library, Embase and Dissertation Abstracts. The references of all identified studies were examined for additional references. All studies were checked for methodological quality, and data was extracted using a data extraction tool.

RESULTS

Although a variety of measures may be useful additions to the traditional four vital sign parameters, only pulse oximetry and smoking status have been shown to change patient care and outcomes. There are suggestions that vital sign monitoring has become a routine procedure, but little useful information was identified in regard to the optimal frequency of vital sign measurement. It was noted that many of the important issues related to vital sign measurement have not been investigated through research.There is currently only limited research related to respiratory rate as a vital sign; however, its value as an indicator of serious illness has not been reliably established. There is only limited research relating to pulse rate measurements. Although routinely used for all hospital patients, the ability to detect serious physiological changes by assessment of pulse rate has not been rigorously evaluated. Many factors were identified that could potentially influence the accuracy of blood pressure measurement. Auscultation is accurate for the measurement of systolic blood pressure using phase I Korotkoff sound as the reference point, and for diastolic pressure if phase V Korotkoff sounds are used. Cuff size can influence accuracy, in that using a cuff that is too narrow will likely overestimate blood pressure and a cuff that is too wide will underestimate the pressure. Research suggests that blood pressure should be measured on the upper arm, while the arm is resting at approximate heart level. Studies have shown that healthcare workers often measure blood pressure in an incorrect and inaccurate way, and this is of some concern. However, a small number of studies suggest that education programs can be effective in improving blood pressure measurement techniques. The largest volume of research identified during this review related to the measurement of temperature. For accurate measurement of oral temperatures the thermometer should be positioned in either the left or right posterior sublingual pocket and remain in the mouth for 6-7 min. Although oxygen therapy and different types of breathing patterns will not influence accuracy of oral temperature measurements, hot or cold liquids will. For the measurement of tympanic temperatures, an ear tug should be used to help straighten the external auditory canal and so ensure measurement accuracy. The presence of impacted cerumen will likely result in inaccurate measurements. The only potential harm as a result of measuring vital signs was associated with glass mercury thermometers, in terms of rectal perforation, the risk of mercury poisoning was not clearly established.

CONCLUSIONS

Although there has been considerable research undertaken on many specific aspects of vital sign measurement, there is an urgent need for further primary research into the more general issues such as what parameters should be measured, the optimal frequency of measurements and the role of new technology in patient monitoring.

Evaluation and initial management of the patient in respiratory distress

Evaluation of the patient in acute respiratory distress poses a complex problem to the emergency physician. Because of the heterogeneity of the population of patients presenting in acute respiratory distress, there is a paucity of evidence-based medicine recommendations. Practice habit dictates most of our diagnostic and therapeutic approach. It is of paramount importance to understand the limitations of history, physical examination, and diagnostic screening studies in evaluating and treating patients with respiratory distress. The emergency physician should become aware of the benefits of NPPV in the management of respiratory failure. Essential to the management of these patients is the ability to anticipate difficulty in airway management and the formulation of alternative airway strategies.

Bronchiolitis management preferences and the influence of pulse oximetry and respiratory rate on the decision to admit

OBJECTIVE

High incidence, rising admission rates, and relatively ineffective therapies make the management of bronchiolitis controversial. Since 1980, the rate of hospitalization for children with bronchiolitis has increased by nearly 250%, whereas mortality rates for the disease have remained constant. It has been speculated that the increasing use of pulse oximetry has lowered the threshold for admission and may have contributed to the rise in bronchiolitis-related admissions. The objective of this study was to describe pediatric emergency medicine physicians' management preferences regarding infants with moderately severe bronchiolitis and to assess the influence of specific differences in oxygen saturation as measured by pulse oximetry (SpO2) and respiratory rate (RR) on the decision to admit.

METHODS

Physicians who are members of the American Academy of Pediatrics Section of Emergency Medicine and living in the United States were randomized into 4 groups and mailed a survey that contained 1 of 4 vignettes. Vignettes were identical except for given SpO2 values (94% or 92%) and RR (50/min or 65/min). Subjects were asked to answer questions regarding laboratory tests, treatment options, and the decision to admit for the patient in their vignette.

RESULTS

We received completed surveys from 519 (64%) of the 812 physicians contacted. Most respondents recommended use of bronchodilators (96%), nasal suction (82%), and supplemental oxygen (57%). Few respondents recommended decongestants (9%), steroids (8%), or antibiotics (2%). When asked to rank therapies, respondents gave nasal suction 182 number 1 votes; bronchodilators received 164. The decision to admit varied with SpO2 and RR. Forty-three percent of respondents who received a vignette featuring SpO2 of 94% and a RR of 50/min recommended admission for the infant in their vignette. Fifty-eight percent recommended admission when the vignette SpO2 was 94% and RR was 65/min (chi2 = 5.021). Respondents who received a vignette with SpO2 of 92% were nearly twice as likely to recommend admission: 83% recommended admission when vignette RR was 50/min, and 85% recommended admission when vignette RR was 65/min (chi2 = 0.126).

CONCLUSIONS

When treating infants with moderately severe bronchiolitis, pediatricians who work in emergency departments frequently use bronchodilators and nasal suction, 2 practices for which supporting data are either conflicting (bronchodilators) or nonexistent (nasal suction). In addition, their decisions to admit differ markedly on the basis of only a 2% difference in SpO2. It is possible that increased reliance on pulse oximetry has contributed to the increase in bronchiolitis hospitalization rates seen during the past 2 decades.

The use of pulse oximetry to exclude pneumonia in children

The objective of this study was to determine whether pulse oximetry alone or in conjunction with the clinical examination is predictive of pneumonia in children who present to the emergency department with respiratory complaints. A retrospective comparison of children with radiographic pneumonia with children with respiratory complaints and negative chest radiography was used. The study took place in an emergency department of a large academic, tertiary care hospital. All children less than 24 months of age who presented with a respiratory complaint and underwent chest radiography during a 1-year period were included. Charts of children with radiographic pneumonia were compared with charts of children without pneumonia, retrospectively. Data abstracted onto data collection forms included: pulse oximetry measurement, vital signs, general appearance, lung examination, and final radiology interpretation of chest radiographs. Pneumonia was defined as a chest radiograph showing any opacity consistent with pneumonia as read by a board-prepared or -certified radiologist. A total of 803 children qualified for the study. Radiograph interpretations were available for 762, and 10.5% were found to have radiographic pneumonia. The median pulse oximetry reading of children with radiographic pneumonia was 97% (interquartile range 95th-98th percentile) compared with 98% (interquartile range 96th-99th percentile) in the control group. Forty-five percent (35 of 78) of the children with radiographic pneumonia showed oxygen saturations of 98% or higher with greater than 10% (8 of 78) displaying oxygen saturations of 100%. By using logistic regression, pulse oximetry was not found to be a statistically significant predictive variable for radiographic pneumonia. Pulse oximetry could not be used to rule out the presence of radiographic pneumonia in children less than 2 years of age who presented with respiratory complaints.

Vital signs in hospital patients: a systematic review

OBJECTIVES

This review was initiated to identify the best available evidence on vital sign measurements in hospital patients.

METHOD

Inclusion Criteria--Studies that evaluated some aspect of vital signs. Search--Covered all major databases and the references of identified studies. Data Analysis--Because of the nature of identified studies, data were summarised using narrative rather than statistical methods.

RESULTS

A total of 737 papers of which 69 met the inclusion criteria.

CONCLUSION

This review has highlighted a need for further investigation of issues related to the role, nature and optimal practice of monitoring patient vital signs.

Noninvasive monitoring of oxygen and carbon dioxide

Pulse oximetry and capnography are widely used in clinical practice. They provide quick and noninvasive methods to estimate arterial oxygen saturation and carbon dioxide tension in different situations including emergency departments, intensive care units, and during procedures. This article reviews the principles of surgery, accuracy, limitations, and clinical applications of these instruments.

Management of fever without source in infants and children

Twenty percent of febrile children have fever without an apparent source of infection after history and physical examination. Of these, a small proportion may have an occult bacterial infection, including bacteremia, urinary tract infection (UTI), occult pneumonia, or, rarely, early bacterial meningitis. Febrile infants and young children have, by tradition, been arbitrarily assigned to different management strategies by age group: neonates (birth to 28 days), young infants (29 to 90 days), and older infants and young children (3 to 36 months). Infants younger than 3 months are often managed by using low-risk criteria, such as the Rochester Criteria or Philadelphia Criteria. The purpose of these criteria is to reduce the number of infants hospitalized unnecessarily and to identify infants who may be managed as outpatients by using clinical and laboratory criteria. In children with fever without source (FWS), occult UTIs occur in 3% to 4% of boys younger than 1 year and 8% to 9% of girls younger than 2 years of age. Most UTIs in boys occur in those who are uncircumcised. Occult pneumococcal bacteremia occurs in approximately 3% of children younger than 3 years with FWS with a temperature of 39.0 degrees C (102.2 degrees F) or greater and in approximately 10% of children with FWS with a temperature of 39.5 degrees C (103.1 degrees F) or greater and a WBC count of 15, 000/mm(3) or greater. The risk of a child with occult pneumococcal bacteremia later having meningitis is approximately 3%. The new conjugate pneumococcal vaccine (7 serogroups) has an efficacy of 90% for reducing invasive infections of Streptococcus pneumoniae. The widespread use of this vaccine will make the use of WBC counts and blood cultures and empiric antibiotic treatment of children with FWS who have received this vaccine obsolete.

Does the Manchester triage system detect the critically ill?

BACKGROUND

The Manchester triage system (MTS) is now widely used in UK accident and emergency (A&E) departments. No clinical outcome studies have yet been published to validate the system. Safety of triage systems is related to the ability to detect the critically ill, which has to be balanced with resource implications of overtriage.

OBJECTIVES

To determine whether the MTS can reliably detect those subsequently needing admission to critical care areas.

METHODS

Analysis of emergency admissions to critical care areas and comparison with original A&E triage code by a nurse using the MTS at time of presentation. Retrospective coding of all cases according to the MTS by experts and case analysis to determine whether any non-urgent coding was due to the system or to incorrect coding.

RESULTS

Sixty one (67%) of the patients admitted to a critical care area were given triage category 1 or 2 (that is, to be seen within 10 minutes of arrival). Eighteen cases given lower priority were due to incorrect coding by the triage nurse. Six cases were correctly coded by the MTS, of which five deteriorated after arrival in the A&E department. Only one case was critically ill on arrival and yet was coded as able to wait for up to one hour.

CONCLUSIONS

The MTS is a sensitive tool for detecting those who subsequently need critical care and are ill on arrival in the A&E department. It did fail to detect some whom deteriorated after arrival in A&E. Most errors were due to training problems rather than the system of triage. Analysis of critically ill patients allows easy audit of sensitivity of the MTS but cannot be used to calculate specificity.

Pulse oximetry: principles and limitations

The pulse oximeter has become an essential tool in the modern practice of emergency medicine. However, despite the reliance placed on the information this monitor offers, the underlying principles and associated limitations of pulse oximetry are poorly understood by medical practitioners. This article reviews the principles of pulse oximetry, with an eye toward recognizing the limitations of this tool. Among these are performance limitations in the settings of carboxyhemoglobinemia, methemoglobinemia, motion artifact, hypotension, vasoconstriction, and anemia. The accuracy of pulse oximetry is discussed in light of these factors, with further discussion of applications for pulse oximetry in emergency medicine, including both oximetric and plethysmographic operation. The pulse oximeter is an invaluable instrument for emergency medicine practice, but as with any test the data it offers must be critically appraised for proper interpretation and utilization.

Pulse oximetry

Pulse oximetry is one of the most commonly employed monitoring modalities in the critical care setting. This review describes the latest technological advances in the field of pulse oximetry. Accuracy of pulse oximeters and their limitations are critically examined. Finally, the existing data regarding the clinical applications and cost-effectiveness of pulse oximeters are discussed.

Pulse oximetry in severe carbon monoxide poisoning

STUDY OBJECTIVES

To evaluate the accuracy and quantitate the error of pulse oximetry measurements of arterial oxygenation in patients with severe carbon monoxide (CO) poisoning.

DESIGN

Retrospective review of patient clinical records.

SETTING

Regional referral center for hyperbaric oxygen therapy.

PATIENTS

Thirty patients referred for treatment of acute severe CO poisoning who demonstrated carboxyhemoglobin (COHb) levels >25%, with simultaneous determinations of arterial hemoglobin oxygen saturation by pulse oximetry (SpO2) and arterial blood gas (ABG) techniques.

MEASUREMENTS AND RESULTS

COHb levels and measurements of arterial oxygenation from pulse oximetry, ABG analysis, and laboratory CO oximetry were compared. SpO2 did not correlate with COHb levels. SpO2 consistently overestimated the fractional arterial oxygen saturation. The difference between arterial hemoglobin oxygen saturation (SaO2) calculated from ABG analysis and SpO2 increased with increasing COHb level.

CONCLUSIONS

Presently available pulse oximeters overestimate arterial oxygenation in patients with severe CO poisoning. An elevated COHb level falsely elevates the SaO2 measurements from pulse oximetry, usually by an amount less than the COHb level, confirming a prior observation in an animal model. Accurate assessment of arterial oxygen content in patients with CO poisoning can currently be performed only by analysis of arterial blood with a laboratory CO-oximetry.

Effect of routine pulse oximetry measurements on ED triage classification

Pulse oximetry is commonly used to rapidly determine oxygen saturation and is incorporated in emergency triage as a screening for potential cardiopulmonary complications. This study examined the effect of routine pulse oximetry measurements on emergency department (ED) triage classification. Using a portable pulse oximeter, oxygen saturation of 1,235 adults presenting to a university-based, urban ED was obtained and each patient was assigned a classification of severity based on a standard 1-to-4 scale before and after the measurement. According to data obtained, a small but statistically significant group (2.8%) benefitted from the routine use of pulse oximetry in an emergency triage system and only 40% of these patients required admission or extended care. Although this group is small in number, the potential consequences of missing a hypoxic condition could be devastating for the individual patient. Since pulse oximetry is presently an inexpensive technology, it would seem to be a worthwhile screening tool for emergency triage.

Monitoring during mechanical ventilation

Approximately half of the patients admitted to an ICU are admitted for the purposes of monitoring rather than interventional therapy. In the last decade, significant technologic advances have enhanced monitoring capacities, and the understanding of the pathophysiology of respiratory failure has improved pari passu, allowing clinicians to employ monitors in a more intelligent manner. This article deals with new developments in arterial blood gas monitoring, pulse oximetry, capnometry, and monitoring of neuromuscular function and pulmonary mechanics, emphasizing issues most relevant to mechanical ventilation.