Giles N. Cattermole

Background Brain abscess has a high mortality, with nonspecific signs and symptoms, and diagnosis requires advanced imaging. Point-of-care ultrasound is widely used in emergency departments (EDs), but transcranial ultrasound (TCUS) is often limited by the difficulty of obtaining acoustic windows through bone. Case Presentation A 33-year-old male patient presented to the ED with 6 days of progressive headache and no other symptoms. Initially discharged, he reattended 2 days later with worsening headache, vomiting, and restlessness. Computed tomography demonstrated a left temporal lesion with mass effect, confirmed as an abscess on magnetic resonance imaging. TCUS performed in the ED identified this as a hypoechoic lesion with hyperechoic walls. The patient underwent neurosurgery and made a good recovery. Conclusion TCUS does not accurately diagnose brain abscess, but might be a useful triage tool to help expedite definitive imaging and surgery, and could be especially beneficial in low- and middle-income settings.

Background and Objective Accurate drug dosing in obese patients requires an estimation of ideal body weight (IBW) or lean body weight (LBW) for dosing hydrophilic medications. Erroneous weight estimates during the management of adults requiring weight-based treatment may contribute to poor outcomes. Existing methods of IBW and LBW estimation or measurement are very difficult to use during emergency care. A new point-of-care model would be useful to provide rapid estimates of IBW and LBW for this purpose. Methods A model was derived based on the PAWPER XL-MAC tape, a pediatric weight estimation system which uses recumbent length and mid-arm circumference to estimate IBW and LBW. The new adult model was used to generate IBW and LBW estimations for a derivation sample (n = 33155) and a validation sample (n = 5926) from National Health and Nutrition Examination Survey (NHANES) datasets. The model was developed in two steps, with calibration at each step, before being validated on an unused dataset. The outcome measure was to achieve >95% of IBW and LBW estimations within 20% of recognized reference standards (P20 > 95%) and >70% of estimations within 10% of these standards (P10 > 70%). Results The new model achieved a P20 of 100% and a P10 of 99.9% for IBW and a P20 of 98.3% and a P10 of 78.3% for LBW. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths, and in all habitus types, except for the severely obese female subgroup. Conclusions The modified PAWPER XL-MAC model proved to be an accurate method of IBW and LBW estimation. It could, therefore, have an important role in facilitating emergency drug dose calculations in obese adult patients.

Objective Accurate drug dosing in obese patients requires an estimation of ideal body weight (IBW) or lean body weight (LBW) for dosing hydrophilic medications. Erroneous weight estimates during the management of critically ill adults may contribute to poor outcomes. Existing methods of IBW and LBW estimation or measurement are very difficult to use during emergency care. A new point-of-care model is needed to provide rapid estimates of IBW and LBW for this purpose. Methods A model was derived based on the PAWPER XL-MAC tape, a paediatric weight estimation system, which uses recumbent length and mid-arm circumference to estimate IBW and LBW. The model was used to generate weight estimations in a derivation sample (n=33155) and a validation sample (n=5926) from National Health and Nutrition Examination Survey (NHANES) datasets. The outcome measure was to achieve >95% of IBW and LBW estimations within 20% of recognised reference standards (P20>95%) and >70% of estimations within 10% of these standards (P10>70%). Main Results The new model achieved a P20 of 100% and a P10 of 99.9% for IBW and a P20 of 98.3% and a P10 of 78.3% for LBW. This accuracy was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus-types, except for the morbidly obese female subgroup. Conclusions The modified PAWPER XL-MAC model proved to be an accurate method of IBW and LBW estimation. It could, therefore, have an important role in facilitating emergency drug dose calculations in acutely or critically ill obese adult patients. Why is this topic important?Errors in weight estimation, or the use of an inappropriate weight scalar, can translate into medication errors and potential patient harm. The ability to easily estimate TBW, IBW and LBW would enhance patient safety and make correct drug dosing more accessible during the provision of emergency and critical care. What does this study attempt to show?This study describes the derivation and validation of a point of care model to provide estimates of IBW and LBW for the purposes of weight based dosing. The model is an adult version of a well-studied paediatric weight estimation system. What are the key findings?The model was able to provide accurate estimations of IBW and LBW in a wide range of patient-types. It was the first study to have evaluated such a system. It established that this system would be useful to test in clinical trials. How is patient care impacted?The PAWPER XL-MAC system could provide quick and easy estimations of IBW and LBW which can be used in obese patients for appropriate drug dose calculations. This would improve the accuracy of dosing with a potential reduction in medication errors and patient harm.

Background Erroneous weight estimation during the management of emergency presentations in adults may contribute to patient harm and poor outcomes. Patients can often not be weighed during emergencies and a weight estimation is required to facilitate weight-based therapies. Many existing methods of weight estimation are either unacceptably inaccurate or very difficult to use during the provision of emergency care. Methods The weight estimation system developed in this study was based on and modified from the PAWPER XL-MAC method, a paediatric weight estimation system that uses recumbent length and mid-arm circumference (MAC) to predict total body weight. This model was validated in the 2015 – 2018 National Health and Nutrition Examination Survey (NHANES) datasets. The primary outcome measure was to achieve >95% of estimations within 20% of measured weight (P20>95%). Results The modified PAWPER XL-MAC model achieved a P20 of 96.0% and a P10 of 71.3% in the validation dataset (N=11520). This accuracy (P20>95%) was maintained in both sexes, all ages, all ethnic groups, all lengths and in all habitus-types, except for the subgroup of severely obese individuals. Conclusions The modified PAWPER XL-MAC model proved to be a very accurate method of weight estimation. It is more accurate than most other published reports of existing methods of weight estimation, except for patients’ own estimations. It therefore could have a role in facilitating emergency drug dose calculations, if prospective studies bear out the accuracy found in this study.