Derek Burke

Respiration Rate Monitoring Methods: A Review

Respiration rate is an important indicator of a persons health, and thus it is monitored when performing clinical evaluations. There are different approaches for respiration monitoring, but generally they can be classed as contact or noncontact. For contact methods, the sensing device (or part of the instrument containing it) is attached to the subjects body. For noncontact approaches the monitoring is performed by an instrument that does not make any contact with the subject. In this article a review of respiration monitoring approaches (both contact and noncontact) is provided. Concerns related to the patients recording comfort, recording hygiene, and the accuracy of respiration rate monitoring have resulted in the development of a number of noncontact respiration monitoring approaches. A description of thermal imaging based and vision based noncontact respiration monitoring approaches we are currently developing is provided. Pediatr. Pulmonol. 2011; 46:523–529.

Weight estimation in paediatrics: a comparison of the APLS formula and the formula ‘Weight=3(age)+7’

Objectives To gather data on the ages and weights of children aged between 1 and 16 years in order to assess the validity of the current weight estimation formula ‘Weight(kg)=2(age+4)’ and the newly derived formula ‘Weight=3(age)+7’. Design Retrospective study using data collected from paediatric attendances at an emergency department (ED). Setting A large paediatric ED in a major UK city. Patients 93 827 children aged 1–16 years attending the ED between June 2003 and September 2008. Main outcome measures Percentage weight difference between the childs actual weight and the expected weight, the latter determined by ‘Weight(kg)=2(age+4)’ and by ‘Weight(kg)=3(age)+7’, in order to compare these two formulae. Results The weights of seriously ill children were recorded in only 20.5% of cases, necessitating a weight estimate in the remainder. The formula ‘Weight=2(age+4)’ underestimated childrens weights by a mean of 33.4% (95% CI 33.2% to 33.6%) over the age range 1–16 years whereas the formula ‘Weight=3(age)+7’ provided a mean underestimate of 6.9% (95% CI 6.8% to 7.1%). The formula ‘Weight=3(age)+7’ remains applicable from 1 to 13 years inclusive. Conclusions Weight estimation is of paramount importance in paediatric resuscitation. This study shows that the current estimation formula provides a significant underestimate of childrens weights. When used to calculate drug and fluid dosages, this may lead to the under-resuscitation of a critically ill child. The formula ‘Weight=3(age)+7’ can be used over a larger age range (from 1 year to puberty) and allows a safe and more accurate estimate of the weight of children today.

Tracking human face features in thermal images for respiration monitoring

A method has been developed to track a region related to respiration process in thermal images. The respiration region of interest (ROI) consisted of the skin area around the tip of the nose. The method was then used as part of a non-contact respiration rate monitoring that determined the skin temperature changes caused by respiration. The ROI was located by the first determining the relevant salient features of the human face physiology. These features were the warmest and coldest facial points. The tracking method was tested on thermal video images containing no head movements, small random and regular head movements. The method proved valuable for tracking the ROI in all these head movement types. It was also possible to use this tracking method to monitor respiration rate involving a number of head movement types. Currently, more investigations are underway to improve the tracking method so that it can track the ROI in cases larger head movements.

Things that go bump … bump … bump: an analysis of injuries from falling down stairs in children based at Sheffield Children's Hospital

Background Falls down stairs are a common presentation to the paediatric emergency department. The pattern of injury associated with this mechanism of injury has not been described for the UK population. A retrospective analysis of attendances to the Emergency Department of Sheffield Childrens Hospital was carried out. Results Overall 90% (216/239) of patients sustained one or more injuries; 69% (165/239) sustained minor head and facial injuries; 12% (29/239) sustained minor soft tissue injuries of other regions; 10% (23/239) had limb fractures, of which 60% (14/23) were of the upper limb (nine clavicle fractures, one supracondylar fracture of the elbow and four wrist fractures) and 40% (9/23) were of the lower limb (four femoral fractures and five tibial fractures). Two per cent (5/239) had skull fractures (all were in the group of children dropped while being carried on the stairs). Injuries to more than one body part occurred in only 3% (8/239) of cases. Discussion The results suggest that children who fall down the stairs are mainly toddlers and in general sustain only minor injuries, the commonest being a minor head injury. Severe truncal and extremity injuries or injuries involving multiple body regions should provoke further questioning looking for evidence of non-accidental injury. There is no correlation between the number of stairs fallen down and the likelihood or severity of injury. Conclusion Infants who fall down stairs with their carer or are dropped while being carried down stairs require an especially close evaluation.

How do clinical features help identify paediatric patients with fractures following blunt wrist trauma

Objective: Wrist injuries are a common presentation to the emergency department (ED). There are no validated decision rules to help clinicians evaluate paediatric wrist trauma. This study aimed to identify which clinical features are diagnostically useful in deciding the need for a wrist radiograph, and then to develop a clinical decision rule. Methods: This prospective cohort study was carried out in the ED of Sheffield Children’s Hospital. Eligible patients were recruited if presenting within 72 hours following blunt wrist trauma. A standardised data collection form was completed for all patients. The outcome measure was the presence or absence of a fracture. Univariate analysis was performed with the χ2 test. Associated variables (p<0.2) were entered into a multivariate model. Classification and regression tree (CART) analysis was used to derive the clinical decision rule. Results: In total, 227 patients were recruited and 106 children were diagnosed with fractures (47%). Of 10 clinical features analysed, six were found by univariate analysis to be associated with a fracture. CART analysis identified the presence of radial tenderness, focal swelling, or an abnormal supination/pronation as the best discriminatory features. Cross fold validation of this decision rule had a sensitivity of 99.1% (95% confidence interval 94.8% to 100%) and a specificity of 24.0% (17.2% to 32.3%). The radiography rate would be 87%. Conclusions: Radial tenderness, focal swelling, and abnormal supination/pronation are associated with wrist fractures in children. The clinical decision rule derived from these features had a high sensitivity, but low specificity, and would not substantially alter our current radiography rate. The potential for a clinical decision rule for paediatric wrist trauma appears limited.

Facial Tracking in Thermal Images for Real-Time Noncontact Respiration Rate Monitoring

A noncontact respiration rate monitor is developed. The method detected and tracked the face and then matched a pre-selected template in order to track a facial point of interest associated with respiration, located beneath the nostril. A region of interest (ROI) was then specified around the detected point of interest. Unwanted noise in the image was removed using image processing techniques. Feature extraction and signal processing techniques were applied to this ROI to compute the respiration feature and thereafter the respiration rate. It was shown that the method could detect and continuously track the subjects face by enclosing it in a rectangle. The method updated the location of the ROI and also determined respiration rate in a noncontact manner. The computation time for each frame was 40 ms, making it suitable for real-time respiration monitoring. Further work is in progress to enhance the algorithm to eliminate the need for pre-selection of a template.

Things that go beep: experience with an ED guideline for use of a handheld metal detector in the management of ingested non-hazardous metallic foreign bodies

Objectives: To review compliance with our emergency department (ED) guideline on the imaging of ingested non-hazardous metallic foreign bodies in children, investigate adverse outcomes, and make suggestions for improving the guideline. Methods: Retrospective analysis of patients presenting in a 3 year period to a paediatric ED with a history of possible metallic foreign body (MFB) ingestion, who were managed according to an ED guideline. Results: We identified 430 episodes of possible MFB ingestion, of which 422 were eligible for inclusion in the study. Compliance with the guideline was 77.8% with no significant adverse events. The exclusion of symptoms as a criterion for x ray results in a reduction in the x ray rate of 56% in the symptomatic group with no increase in adverse events. Conclusion: A handheld metal detector (HMD) can be safely and reliably used in lieu of plain radiography to investigate children with a history of MFB ingestion, irrespective of symptoms and without incurring any significant adverse events.

Dipstick urinalysis for the emergency department evaluation of urinary tract infections in infants aged less than 2 years.

Background The clinical diagnosis of urinary tract infection (UTI) in infants under the age of 2 years is challenging because of the nonspecific symptoms and signs in this age group. Prompt diagnosis and treatment is critical, and although dipstick testing allows rapid testing, there is some doubt about its use in infants. We sought to show the use of the dipstick test in identifying or excluding UTI in infants under the age of 2 years presenting to the emergency department with a febrile illness. Methods We conducted a retrospective diagnostic cohort study for over a 12-month period in a UK Paediatric Emergency Department, including all febrile children who had a urine dipstick and a quantitative culture as part of their diagnostic workup. The gold standard was the quantitative culture. Results Three hundred and twenty-one samples were eligible for inclusion. The mean age of the children included was 9.3 months. Sixty-three percent were female children. A test positive for nitrite, leucocyte esterase and blood gave a specificity of 97.12% [95% confidence interval (CI): 94.17–98.60] and a positive likelihood ratio of 15.13 (95% CI: 6.99–32.76). A test negative for nitrite, LE, blood and protein had a sensitivity of 97.44% (95% CI: 91.12–99.29) and a negative likelihood ratio of 0.10 (95% CI: 0.02–0.39). Conclusion In febrile infants who were below 2 years of age, dipstick urinalysis shows promising results in identifying or ruling out a UTI.

The safety of emergency medicine

The patient safety movement has been active for over a decade, but the issue of patient safety in emergency care and the emergency department (ED) has only recently been brought into the forefront. The ED environment has traditionally been considered unsafe, but there is little data to support this assertion. This paper reviews the literature on patient safety and highlights the challenges associated with using the current evidence base to inform practice due to the variability in methods of measuring safety. Studies looking at safety in the ED report low rates for adverse events ranging from 3.6 to 32.6 events per 1000 attendances. The wide variation in reported rates on adverse events reflects the significant differences in methods of reporting and classifying safety incidents and harm between departments; standardisation in the ED context is urgently required to allow comparisons to be made between departments and to quantify the impact of specific interventions. We outline the key factors in emergency care which may hinder the provision of safer care and consider solutions which have evolved or been proposed to identify and mitigate against harm. Interventions such as team training, telephone follow-up, ED pharmacist interventions and rounding, all show some evidence of improving safety in the ED. We further highlight the need for a collaborative whole system approach as almost half of safety incidents in the ED are attributable to external factors, particularly those related to information flow, crowding, demand and boarding.

Thermal image processing for real-time non-contact respiration rate monitoring

A real-time thermal imaging based, non-contact respiration rate monitoring method was developed. It measured the respiration related skin surface temperature changes under the tip of the nose. Facial tracking was required as head movements caused the face to appear in different locations in the recorded images over time. The algorithm detected the tip of the nose and then, a region just under it was selected. The pixel values in this region in successive images were processed to determine respiration rate. The segmentation method, used as part of the facial tracking, was evaluated on 55,000 thermal images recorded from 14 subjects with different extent of head movements. It separated the face from image background in all images. However, in 11.7% of the images, a section of the neck was also included, but this did not cause an error in determining respiration rate. The method was further evaluated on 15 adults, against two contact respiration rate monitoring methods that tracked thoracic and abdominal movements. The three methods gave close respiration rates in 12 subjects but in 3 subjects, where there were very large head movements, the respiration rates did not match.