Paul Leonard

A FULLY AUTOMATED ALGORITHM FOR THE DETERMINATION OF RESPIRATORY RATE FROM THE PHOTOPLETHYSMOGRAM

Objective. To determine if an automatic algorithm using wavelet analysis techniques can be used to reliably determine respiratory rate from the photoplethysmogram (PPG). Methods. Photoplethysmograms were obtained from 12 spontaneously breathing healthy adult volunteers. Three related wavelet transforms were automatically polled to obtain a measure of respiratory rate. This was compared with a secondary timing signal obtained by asking the volunteers to actuate a small push button switch, held in their right hand, in synchronisation with their respiration. In addition, individual breaths were resolved using the wavelet-method to identify the source of any discrepancies. Results. Volunteer respiratory rates varied from 6.56 to 18.89 breaths per minute. Through training of the algorithm it was possible to determine a respiratory rate for all 12 traces acquired during the study. The maximum error between the PPG derived rates and the manually determined rate was found to be 7.9%. Conclusion. Our technique allows the accurate measurement of respiratory rate from the photoplethysmogram, and leads the way for developing a simple non-invasive combined respiration and saturation monitor.

Regular in situ simulation training of paediatric Medical Emergency Team improves hospital response to deteriorating patients

AIM OF THE STUDY The introduction of a paediatric medical emergency team (pMET) was accompanied by integration of weekly in situ simulation team training into routine clinical practice. On a rotational basis, all key ward staff participated in team training, which focused on recognition of the deteriorating child, teamwork and early consultant review of patients with evolving critical illness. This study aimed to evaluate the impact of regular team training on the hospital response to deteriorating in-patients and subsequent patient outcome. METHODS Prospective cohort study of all deteriorating in-patients of a tertiary paediatric hospital requiring admission to paediatric intensive care (PICU) the year before, and after, the introduction of pMET and concurrent team training. RESULTS Deteriorating patients were: recognised more promptly (before/after pMET: median time 4/1.5 h, p<0.001), more often reviewed by consultants (45%/76%, p=0.004), more often transferred to high dependency care (18%/37%, p=0.021) and more rapidly escalated to intensive care (median time 10.5/5 h, p=0.024). These improved responses by ward staff extended beyond direct involvement of pMET. There was a trend towards fewer PICU admissions, reduced level of sickness at the time of PICU admission, reduced length of PICU stay and reduced PICU mortality. Introduction of pMET coincided with significantly reduced hospital mortality (p<0.001). CONCLUSIONS These results indicate that lessons learnt by ward staff during regular in situ team training led to significantly improved recognition and management of deteriorating in-patients with evolving critical illness. Integration of in situ simulation team training in clinical care has potential applications beyond paediatrics.

An Algorithm for the Detection of Individual Breaths from the Pulse Oximeter Waveform

Objectives. To determine if wavelet analysis techniques can be used to reliably identify individual breaths from the photoplethysmogram (PPG). Methods. Photoplethysmograms were obtained from 22 healthy adult volunteers timing their respiration rate in synchronisation with a metronome. A secondary timing signal was obtained by asking the volunteers to actuate a small push button switch, held in their right hand, in synchronisation with their respiration. Each PPG was analyzed using primary wavelet decomposition and two new, related, secondary decompositions to determine the accuracy of individual breath detection. Results. The optimal breath capture was obtained by manually polling the three techniques, allowing detection of 466 out of the 472 breaths studied; a detection rate of 98.7% with no false positive breaths detected. Conclusion. Our technique allows the accurate capture of individual breaths from the photoplethysmogram, and leads the way for developing a simple non-invasive combined respiration and saturation monitor.

An automated algorithm for determining respiratory rate by photoplethysmogram in children

Background: We have developed an automated algorithm to allow the measurement of respiratory rate directly from the photoplethysmogram (pulse oximeter waveform). Aim: To test the algorithms ability to determine respiratory rate in children. Methods: A convenience sample of patients attending a paediatric Accident and Emergency Department was monitored using a purpose‐built pulse oximeter and the photoplethysmogram (PPG) recorded. Respiration was also recorded by an observer activating a push‐button switch in synchronization with the childs breathing. The switch marker signals were processed to derive a manual respiratory rate that was compared with the wavelet‐based oximeter respiratory rate derived from the PPG signal. Results: Photoplethysmograms were obtained from 18 children aged 18 mo to 12 y, breathing spontaneously at rates of 17 to 27 breaths per minute. There was close correspondence between the wavelet‐based oximeter respiration rate and the manual respiratory rate, with the difference between them being less than one breath per minute in all children.

Wavelet analysis of pulse oximeter waveform permits identification of unwell children

Background: Children who are unwell often display signs of circulatory compromise. It has been observed that pronounced changes occur in the appearance of the photoplethysmogram (pulse oximeter tracing) in these children. The aim of the study was to discover if wavelet transforms can identify more subtle changes in the photoplethysmogram of children who are unwell. Methods: Photoplethysmograms were obtained from children attending a paediatric accident and emergency department with clinical features suggestive of significant bacterial illness or circulatory compromise. Photoplethysmograms were also obtained from a control group of well children. Wavelet transforms were applied to the traces in an attempt to separate the two groups. Results: 20 traces were obtained from unwell children and 12 from controls. Analysis of the entropy of the wavelet transform of the photoplethysmogram allows the differentiation of unwell children from controls (p = 0.00002). Conclusions: Wavelet transform of the photoplethysmogram offers the possibility of a rapid non-invasive method of screening children for significant illness.

Under representation of morbidity from paediatric bicycle accidents by official statistics—a need for data collection in the accident and emergency department

Objectives—To determine the accuracy of currently available data on bicycle related injuries in children. Setting—A paediatric accident and emergency (A&E) department which annually treats approximately 30 000 new patients under the age of 13 years. Methods—Data on all attendances with bicycle related injuries over a four week period were compared with that currently available from police road traffic accident data (Stats 19) and the International Classification of Diseases, 10th revision, hospital discharge coding. Results—Eighty six children attended the A&E department. Only two bicycle related injuries were identified from Stats 19, and 10 from hospital discharge data. Conclusion—Currently available official data do not give an accurate representation of the incidence of bicycle related injuries in children. If health promotion measures are to be assessed properly data collection needs to be improved.

Regular in-situ simulation training of paediatric Medical Emergency Team leads to sustained improvements in hospital response to deteriorating patients, improved outcomes in intensive care and financial savings

AIM OF THE STUDY The introduction of a paediatric Medical Emergency Team (pMET) was accompanied by weekly in-situ simulation team training. Key ward staff participated in team training, focusing on recognition of the deteriorating child, teamwork and early involvement of senior staff. Following an earlier study [1], this investigation aimed to evaluate the long-term impact of ongoing regular team training on hospital response to deteriorating ward patients, patient outcome and financial implications. METHODS Prospective cohort study of all deteriorating in-patients in a tertiary paediatric hospital requiring admission to paediatric intensive care (PICU) the year before, 1year after and 3 years after the introduction of pMET and team training. RESULTS Deteriorating patients were recognised more promptly (before/1year after/3years after pMET; median time 4/1.5/0.5h, p<0.001), more often reviewed by consultants (45%/76%/81%, p<0.001) and more rapidly escalated to PICU (median time 10.5/5/3.5h, p=0.02). There was a significant reduction in associated PICU admissions (56/51/32, p=0.02) and PICU bed days (527/336/193, p<0.001). The total annual cost of training (£74,250) was more than offset by savings from reduced PICU bed days (£801,600 per annum). Introduction of pMET coincided with significantly reduced hospital mortality (p<0.001). CONCLUSION These results indicate that lessons learnt by ward staff during team training led to sustained improvements in the hospital response to critically deteriorating in-patients, significantly improved patient outcomes and substantial savings. Integration of regular in-situ simulation training of medical emergency teams, including key ward staff, in routine clinical care has potential application in all acute specialties.

Recurrent respiratory papillomatosis presenting to an emergency department.

Recurrent respiratory papillomatosis is a rare but important cause of stridor in children presenting to the emergency department. Delayed diagnosis makes treatment more difficult and can lead to critical upper-airway obstruction. This case report illustrates the typical presenting features of the disease in a 3-year-old child.

C reactive protein, erythrocyte sedimentation rate, or both, in the diagnosis of atraumatic paediatric limb pain?

Objective To assess if measurement of either C reactive protein (CRP) or erythrocyte sedimentation rate (ESR) individually has an equivalent diagnostic value to measurement of both in identifying orthopaedic infection as the cause of paediatric atraumatic limb pain. Setting Emergency department of a paediatric teaching hospital. Study design Retrospective study of case notes for patients attending the emergency department with a complaint of atraumatic limb pain and in whom both ESR and CRP were measured at the time of presentation. Laboratory results at the time of presentation were recorded along with the final diagnosis. Receiver operating characteristic (ROC) curves were created using the data and the optimum cut-off values for each of ESR and CRP were derived using the point of best trade off between sensitivity and specificity. Likelihood ratios for ESR and CRP individually and in combination were calculated. Results 259 patients were included in the study, of whom 17 were considered to have an orthopaedic infection. ROC curves revealed the best results were obtained using cut-off values of CRP >7 and ESR >12. The combination of a CRP >7 and an ESR >12 gave the best positive likelihood ratio at 6.26 (likelihood ratio 5.34 (CRP >7) vs 2.57 (ESR >12)). For ruling out disease, the combination of CRP ≤7 and ESR ≤12 also outperformed either variable individually (negative likelihood ratio 0.09 (CRP ≤7 and ESR ≤12) vs 0.34 (CRP ≤7) vs 0.18 (ESR ≤12)). Conclusion Measurement of both CRP and ESR should be considered an important aid in the investigation of atraumatic limb pain.

Can paediatric emergency clinicians identify and manage clavicle fractures without radiographs in the emergency department? A prospective study

Background Paediatric clavicle fractures are commonly seen in the emergency department (ED), and the current standard of care is to obtain a radiograph for all suspected clavicle fractures. We are yet to determine whether radiographs add valuable information to clinicians’ assessment and therefore if they are necessary in the management of paediatric clavicle fractures. Objective To determine whether clinicians can manage paediatric clavicle fractures without radiographs, first by determining the accuracy of clinicians in identifying the presence of a clavicle fracture, and second by evaluating the level of agreement (kappa (κ)) between the ultimate management of children with suspected clavicle fractures and clinicians’ blinded prediction prior to the radiograph. Methods This prospective study enrolled patients presenting to a paediatric ED with a suspected clavicle fracture. Prior to requesting a radiograph, clinicians completed a standardised form, where they predicted the presence of a fracture and their ultimate management based on their clinical findings, and rated their confidence. Results Of the 50 patients aged 7.2±3.9 years included, 40 (80%) had a radiologically proven clavicle fracture, and clinicians were able to accurately identify them (sensitivity 93%, positive predictive value 88%). There were five (50%) patients without a radiological fracture that were treated with broad arm sling. Clinicians’ prediction of ultimate management had the highest agreement with the ultimate management of the patient on leaving the ED, compared with clinicians’ prediction of the presence of fracture and the final radiograph findings: κ of 0.88 (95% CI 0.64 to 1), 0.67 (95% CI 0.36 to 0.98) and 0.62 (95% CI 0.30 to 0.94), respectively. Thirty-six (72%) of the clinicians felt comfortable treating without radiographs, and this was dependent on their level of training. Conclusions Clinicians can identify the presence of a fracture and tend to be overconservative in their management. Despite negative radiological findings, some patients were treated as though they had a fracture, based on clinical judgement. This adds evidence that radiographs are not routinely required for uncomplicated paediatric clavicle fractures.