Susannah Fleming

Normal ranges of heart rate and respiratory rate in children from birth to 18 years of age: a systematic review of observational studies.

BACKGROUND Although heart rate and respiratory rate in children are measured routinely in acute settings, current reference ranges are not based on evidence. We aimed to derive new centile charts for these vital signs and to compare these centiles with existing international ranges. METHODS We searched Medline, Embase, CINAHL, and reference lists for studies that reported heart rate or respiratory rate of healthy children between birth and 18 years of age. We used non-parametric kernel regression to create centile charts for heart rate and respiratory rate in relation to age. We compared existing reference ranges with those derived from our centile charts. FINDINGS We identified 69 studies with heart rate data for 143,346 children and respiratory rate data for 3881 children. Our centile charts show decline in respiratory rate from birth to early adolescence, with the steepest fall apparent in infants under 2 years of age; decreasing from a median of 44 breaths per min at birth to 26 breaths per min at 2 years. Heart rate shows a small peak at age 1 month. Median heart rate increases from 127 beats per min at birth to a maximum of 145 beats per min at about 1 month, before decreasing to 113 beats per min by 2 years of age. Comparison of our centile charts with existing published reference ranges for heart rate and respiratory rate show striking disagreement, with limits from published ranges frequently exceeding the 99th and 1st centiles, or crossing the median. INTERPRETATION Our evidence-based centile charts for children from birth to 18 years should help clinicians to update clinical and resuscitation guidelines. FUNDING National Institute for Health Research, Engineering and Physical Sciences Research Council.

Are treatments more effective than placebos? A systematic review and meta-analysis.

Background Placebos are widely used in clinical practice in spite of ethical restrictions. Whether such use is justified depends in part on the relative benefit of placebos compared to ‘active’ treatments. A direct test for differences between placebo and ‘active’ treatment effects has not been conducted. Objectives We aimed to test for differences between treatment and placebo effects within similar trial populations. Data Sources A Cochrane Review compared placebos with no treatment in three-armed trials (no treatment, placebo, and treatment). We added an analysis of treatment and placebo differences within the same trials. Synthesis Methods For continuous outcomes we compared mean differences between placebo and no treatment with mean differences between treatment and placebo. For binary outcomes we compared the risk ratio for treatment benefit (versus placebo) with the risk ratio for placebo benefit (versus no treatment). We conducted several preplanned subgroup analyses: objective versus subjective outcomes, conditions tested in three or more trials, and trials with varying degrees of bias. Results In trials with continuous outcomes (n = 115) we found no difference between treatment and placebo effects (MD = −0.29, 95% CI −0.62 to 0.05, P = 0.10). In trials with binary outcomes (n = 37) treatments were significantly more effective than placebos (RRR = 0.72, 95%CI = 0.61 to 0.86, P = 0.0003). Treatment and placebo effects were not different in 22 out of 28 predefined subgroup analyses. Of the six subgroups with differences treatments were more effective than placebos in five. However when all criteria for reducing bias were ruled out (continuous outcomes) placebos were more effective than treatments (MD = 1.59, 95% CI = 0.40 to 2.77, P = 0.009). Conclusions and Implications Placebos and treatments often have similar effect sizes. Placebos with comparatively powerful effects can benefit patients either alone or as part of a therapeutic regime, and trials involving such placebos must be adequately blinded.

Assessment of central haemomodynamics from a brachial cuff in a community setting

BackgroundLarge artery stiffening and wave reflections are independent predictors of adverse events. To date, their assessment has been limited to specialised techniques and settings. A new, more practical method allowing assessment of central blood pressure from waveforms recorded using a conventional automated oscillometric monitor has recently been validated in laboratory settings. However, the feasibility of this method in a community based setting has not been assessed.MethodsOne-off peripheral and central haemodynamic (systolic and diastolic blood pressure (BP) and pulse pressure) and wave reflection parameters (augmentation pressure (AP) and index, AIx) were obtained from 1,903 volunteers in an Austrian community setting using a transfer-function like method (ARCSolver algorithm) and from waveforms recorded with a regular oscillometric cuff. We assessed these parameters for known differences and associations according to gender and age deciles from <30 years to >80 years in the whole population and a subset with a systolic BP < 140 mmHg.ResultsWe obtained 1,793 measures of peripheral and central BP, PP and augmentation parameters. Age and gender associations with central haemodynamic and augmentation parameters reflected those previously established from reference standard non-invasive techniques under specialised settings. Findings were the same for patients with a systolic BP below 140 mmHg (i.e. normotensive). Lower values for AIx in the current study are possibly due to differences in sampling rates, detection frequency and/or averaging procedures and to lower numbers of volunteers in younger age groups.ConclusionA novel transfer-function like algorithm, using brachial cuff-based waveform recordings, provides robust and feasible estimates of central systolic pressure and augmentation in community-based settings.

Self-Screening and Non-Physician Screening for Hypertension in Communities: A Systematic Review

BACKGROUND Community-based self-screening may provide opportunities to increase detection of hypertension, and identify raised blood pressure (BP) in populations who do not access healthcare. This systematic review aimed to evaluate the effectiveness of non-physician screening and self-screening of BP in community settings. METHODS We searched the Cochrane Central Trials Register, Medline, Embase, CINAHL, and Science Citation Index & Conference Proceedings Citation Index—Science to November 2013 to identify studies reporting community-based self-screening or non-physician screening for hypertension in adults. Results were stratified by study site, screener, and the cut-off used to define high screening BP. RESULTS We included 73 studies, which described screening in 9 settings, with pharmacies (22%) and public areas/retail (15%) most commonly described. We found high levels of heterogeneity in all analyses, despite stratification. The highest proportions of eligible participants screened were achieved by mobile units (range 21%–88%) and pharmacies (range 40%–90%). Self-screeners had similar median rates of high BP detection (25%–35%) to participants in studies using other screeners. Few (16%) studies reported referral to primary care after screening. However, where participants were referred, a median of 44% (range 17%–100%) received a new hypertension diagnosis or antihypertensive medication. CONCLUSIONS Community-based non-physician or self-screening for raised BP can detect raised BP, which may lead to the identification of new cases of hypertension. However, current evidence is insufficient to recommend specific approaches or settings. Studies with good follow-up of patients to definitive diagnosis are needed.

Track and trigger in an emergency department: an observational evaluation study

Objective To evaluate the utilisation of paper-based track and trigger (T&T) charts in a UK emergency department (ED). Methods A single-centre prospective observational cohort study was conducted in the ED of a medium-sized teaching hospital. Charted vital-sign data were collected from adults attending the resuscitation room, majors or observation ward. These data were examined in parallel with clinical notes to identify ‘escalation’ events. For each set of vital signs, the authors calculated the T&T score retrospectively. Results Data from 472 patient episodes (2965 sets of vital signs) were examined. 85.8% of patients had at least one full set of observations (CEM standard) and 60.6% had at least one T&T score documented. However, only 34.5% of observation sets had a corresponding T&T score. 20.6% of T&T score totals (1024) were incorrect, potentially preventing a ‘trigger’ from being recognised. 204 patient episodes had at least one recorded escalation. Physiological escalations were associated with vital-sign scores that met the triggering thresholds (98/104), while patients who had non-physiological escalations or no escalations were more likely to have scores below the triggering thresholds (88/100). Only 26.9% of physiological escalations were associated with a documented T&T score above the triggering threshold. Retrospective completion of the charts increased that figure to 94.2%. Conclusion T&T in the ED is challenged by poor completion rates and numerical errors made during score calculation. However the potential for recognition of a deteriorating patient should not be ignored. The future work of the authors intends to evaluate an electronic system for automatically calculating T&T scores within the ED environment.

Validity and reliability of measurement of capillary refill time in children: a systematic review

Background Most guidelines recommend the use of capillary refill time (CRT) as part of the routine assessment of unwell children, but there is little consensus on the optimum method of measurement and cut-off time. Methods We searched Medline (from 1948), Embase (from 1980) and CINAHL (from 1991) to June 2014 to identify studies with information on the normal range of CRT in healthy children, the validity of CRT compared with reference standard measures of haemodynamic status, reliability and factors influencing measurement of CRT, such as body site, pressing time and temperature. Findings We included 21 studies on 1915 children. Four studies provided information on the relationship between CRT and measures of cardiovascular status, 13 provided data on the normal range of CRT, 7 provided data on reliability and 10 assessed the effect of various confounding factors. In children over 7 days of age, the upper limit of normal CRT is approximately 2 s when measured on a finger, and 4 s when measured on the chest or foot, irrespective of whether the child is feverish or not. Longer pressing times and ambient temperature outside 20°C–25°C are associated with longer CRT. Evidence suggests that the use of stopwatches reduces variability between observers. Interpretation We recommend use of the following standardised CRT method of measurement: press on the finger for 5 s using moderate pressure at an ambient temperature of 20°C–25°C. A capillary refill time of 3 s or more should be considered abnormal.

Non-invasive measurement of respiratory rate in children using the photoplethysmogram

Respiratory rate is recognised as a valuable predictor of the severity of illness in children, but it is not currently feasible to measure this automatically in a triage environment. Autoregressive modelling on data from the pulse oximeter photoplethysmogram has the potential to introduce automated breathing measurement into the realm of paediatric triage. Using autoregressive modelling, it is shown that respiratory rate can be extracted from the paediatric photoplethysmogram with a mean error of 3.4 breaths per minute.

Performance of pulse wave velocity measured using a brachial cuff in a community setting

BackgroundWe have previously reported that estimation of central blood pressure (BP) and augmentation using an automated oscillometric device are robust and feasible in a community setting. The same method has recently been validated for estimating aortic pulse wave velocity (aPWV) in laboratory settings, and its prognostic value has been confirmed in a prospective clinical trial. ObjectiveThe aim of this study was to assess the performance of aPWV estimates from an oscillometric device in a community-based setting. MethodsWe assessed estimates of aPWV for compatibility with data from reference noninvasive techniques. Estimates of aPWV were obtained in a community setting from a general population of 1903 volunteers (age range 14–99 years). Values of aPWV were analyzed according to sex and each age decile from less than 30 years to greater than 80 years and for a subset of patients with a peripheral systolic BP of less than 140 mmHg (n=1064). ResultsWe obtained valid measures of PWV from 1794 volunteers. Age (r=0.94, P<0.001) and BP category (r=0.63, P<0.001) were associated with aPWV, which was also statistically (P=0.002) but not clinically (<0.1 m/s) higher among female individuals after correction for quadratic age and mean BP. Known differences in and associations of aPWV with sex, age, and BP category mirrored those previously established from reference-standard noninvasive techniques in nonroutine clinical settings. ConclusionData presented here represent initial reference values for cuff-based estimates of aPWV, which can now be obtained in routine clinical practice (e.g. primary care).

The diagnostic value of capillary refill time for detecting serious illness in children: A systematic review and meta-analysis

Importance Capillary refill time (CRT) is widely recommended as part of the routine assessment of unwell children. Objective To determine the diagnostic value of capillary refill time for a range of serious outcomes in children. Methods We searched Medline, Embase and CINAHL from inception to June 2014. We included studies that measured both capillary refill time and a relevant clinical outcome such as mortality, dehydration, meningitis, or other serious illnesses in children aged up to 18 years of age. We screened 1,265 references, of which 24 papers were included in this review. Where sufficient studies were available, we conducted meta-analysis and constructed hierarchical summary ROC curves. Results Meta-analysis on the relationship between capillary refill time and mortality resulted in sensitivity of 34.6% (95% CI 23.9 to 47.1%), specificity 92.3% (88.6 to 94.8%), positive likelihood ratio 4.49 (3.06 to 6.57), and negative likelihood ratio 0.71 (0.60 to 0.84). Studies of children attending Emergency Departments with vomiting and diarrhea showed that capillary refill time had specificity of 89 to 94% for identifying 5% dehydration, but sensitivity ranged from 0 to 94%. This level of heterogeneity precluded formal meta-analysis of this outcome. Meta-analysis was not possible for other outcomes due to insufficient data, but we found consistently high specificity for a range of outcomes including meningitis, sepsis, admission to hospital, hypoxia, severity of illness and dengue. Conclusions Our results show that capillary refill time is a specific sign, indicating that it can be used as a “red-flag”: children with prolonged capillary refill time have a four-fold risk of dying compared to children with normal capillary refill time. The low sensitivity means that a normal capillary refill time should not reassure clinicians.

Respiratory rate estimation during triage of children in hospitals

Abstract Accurate assessment of a child’s health is critical for appropriate allocation of medical resources and timely delivery of healthcare in Emergency Departments. The accurate measurement of vital signs is a key step in the determination of the severity of illness and respiratory rate is currently the most difficult vital sign to measure accurately. Several previous studies have attempted to extract respiratory rate from photoplethysmogram (PPG) recordings. However, the majority have been conducted in controlled settings using PPG recordings from healthy subjects. In many studies, manual selection of clean sections of PPG recordings was undertaken before assessing the accuracy of the signal processing algorithms developed. Such selection procedures are not appropriate in clinical settings. A major limitation of AR modelling, previously applied to respiratory rate estimation, is an appropriate selection of model order. This study developed a novel algorithm that automatically estimates respiratory rate from a median spectrum constructed applying multiple AR models to processed PPG segments acquired with pulse oximetry using a finger probe. Good-quality sections were identified using a dynamic template-matching technique to assess PPG signal quality. The algorithm was validated on 205 children presenting to the Emergency Department at the John Radcliffe Hospital, Oxford, UK, with reference respiratory rates up to 50 breaths per minute estimated by paediatric nurses. At the time of writing, the authors are not aware of any other study that has validated respiratory rate estimation using data collected from over 200 children in hospitals during routine triage.