Digital electrical impedance analysis for single bacterium sensing and antimicrobial susceptibility testing.

Single-molecule and single-cell analysis techniques have opened new opportunities for characterizing and analyzing heterogeneity within biological samples. These detection methods are often referred to as digital assays because the biological sample is partitioned into many small compartments and each compartment contains a discrete number of targets (e.g. cells). Using digital assays, researchers can precisely detect and quantify individual targets, and this capability has made digital techniques the basis for many modern bioanalytical tools (including digital PCR, single cell RNA sequencing, and digital ELISA). However, digital assays are dominated by optical analysis systems that typically utilize microscopy to analyze partitioned samples. The utility of digital assays may be dramatically enhanced by implementing cost-efficient and portable electrical detection capabilities. Herein, we describe a digital electrical impedance sensing platform that enables direct multiplexed measurement of single cell bacterial cells. We outline our solutions to the challenge of multiplexing impedance sensing across many culture compartments and demonstrate the potential for rapidly differentiating antimicrobial resistant versus susceptible strains of bacteria.

Posterior Circulation Ischemic Stroke.

Approximately 20-25% of all acute strokes occur in the posterior circulation. These strokes can be rather difficult to diagnose because they present in such diverse ways, and can easily be mistaken for more benign entities. A fastidious history, physical exam, high clinical suspicion, and appropriate use of imaging are essential for the emergency physician to properly diagnose and treat these patients. Expert stroke neurologist consultation should be utilized liberally.

Breaking bad (news) death-telling in the emergency department.

Many physicians struggle with death-telling in sudden death. Families can be negatively impacted by suboptimal death-telling. Appropriate preparation and education can make death notification less stressful for the physician and may help decrease the development of pathologic grief in the surviving family members that can occur when death is unexpected. Although still controversial, there is a growing body of evidence that family witnessed resuscitation may be beneficial to the grieving process and desired by the public. A previously healthy 21-year-old male comes toyour community emergency department (ED) for a cough that started 4 days ago. He denies fever, shortness of breath, and chest pain. He does admit to a remote history of drug abuse. He states he is feeling "OK" and is only here because his family insisted he come because they were worried he might have pneumonia. His vital signs are normal and he appears well; therefore, he is triaged to the waiting room. About 30 minutes lates the patient complains of shortness of breath and he is brought back to an exam room. The patient is now hypotensive, tachycardic, and pulse oximetry is noted to be 87% on room air. A chest x-ray reveals severe pulmonary edema and an EKG shows ST segment elevation in multiple leads. The patient is taken to the cardiac catheterization lab by the interventional cardiologist, who makes the diagnosis of a ruptured aortic valve due to damage from endocarditis. The patient is returned to the ED to await emergent transfer to a tertiary facility; however, the patient rapidly decompensates and a Code Blue is called. Despite the absence of return of spontaneous circulation, resuscitation efforts are prolonged while the ED social worker attempts to contact the patient's family to come to the ED. Finally, the resuscitation is terminated and the patient is pronounced dead. Several hours later the patient's elderly mother arrives and asks you: "What's going on with Mikey?"

Nonconcordance between Clinical and Head CT Findings: The Specter of Overdiagnosis.

Background. It is unclear whether history and physical examination findings can predict abnormalities on head computed tomography (CT) believed to indicate increased risk of lumbar-puncture- (LP-) induced brain herniation. The objectives of this study were to (1) identify head CT findings felt to be associated with increased risk of brain herniation and (2) to assess the ability of history and physical examination to predict those findings. Methods. Using a modified Delphi survey technique, an expert panel defined CT abnormalities felt to predict increased risk of LP-induced brain herniation. Presence of such findings on CT was compared with history and physical examination (H&P) variables in 47 patients. Results. No H&P variable predicted "high-risk" CT; combining H&P variables to improve sensitivity led to extremely low specificity and still failed to identify all patients with high-risk CT. Conclusions. "High-risk" CT is not uncommon in patients with clinical characteristics known to predict an absence of actual risk from LP, and thus it may not be clinically relevant. "Overdiagnosis" will be increasingly problematic as technological advances identify increasingly subtle deviations from "normal."

Clinically suspected coagulopathy in blunt head trauma.

Patients with moderate to severe head injury and abnormal coagulation studies have a significantly higher risk of brain injury. The objective of this study was to determine the association of clinical suspicion of coagulopathy and intracranial injury (ICI) among patients sustaining blunt head trauma, including minor injuries. As part of the NEXUS II blunt head injury study, enrolled patients were prospectively evaluated for ICI and suspicion of coagulopathy. We examined the relationship between suspicion of coagulopathy and the presence of any clinically significant or "therapeutically inconsequential" ICI based on head computed tomography (CT) scan results. The NEXUS II study enrolled 13,728 patients, including 493 with suspicion of coagulopathy. Significant ICI was present in 46 (9.3%; 95% confidence interval [CI] 6.9-12.2) patients with suspected coagulopathy, and in 460 of 9863 (4.7%; 95% CI 4.3-5.1) patients without such suspicion. "Therapeutically inconsequential" findings were found on head CT scan in 74 patients, and 7 of these had suspected coagulopathy. Interventions including intubation, intracranial pressure monitoring, or craniotomy were performed in 5 of these 7 (71%; 95% CI 29-96) individuals, compared with only 3 of 67 (4%; 95% CI 1-12) patients without suspicion of coagulopathy. Initial clinical suspicion of coagulopathy, independent of laboratory confirmation, is associated with a greater prevalence of significant ICI injury after blunt head trauma; it also substantially increases the risk of morbidity despite the presence of an apparent "therapeutically inconsequential" injury. CT scanning of the head should be performed initially based on clinical suspicion of coagulopathy.

Nontraumatic headaches in the Emergency Department: a systematic approach to diagnosis and controversies in two "big ticket" entities.

Headache is a very common presenting complaint in the Emergency Department (ED). While the vast majority of these have benign or self-limited etiologies, there are several life or organ threatening causes that must be excluded. This paper describes a systematic approach to the history and physical examination in these patients. Evidence-based recommendations for which patients should receive imaging in the ED are reviewed. Current diagnostic approaches and controversies in meningitis and subarachnoid hemorrhage are discussed.

Interrater reliability of criteria used in assessing blunt head injury patients for intracranial injuries.

OBJECTIVE: To determine the interrater reliability of potential predictor variables that may be used to construct a clinical decision rule for emergency computed tomography of the head in blunt head injury victims. METHODS: As a substudy of the NEXUS II study of blunt head trauma, physicians from 21 different emergency departments performed paired evaluations of patients undergoing computed tomography of the head after blunt head injury. Each physician independently determined, for each subject, the presence or absence of each of 19 separate clinical characteristics. The physicians were either residents or attending physicians in the participating emergency departments. Paired responses on a sample of 3,951 patients were compared for raw level of agreement and for interrater concordance using the kappa statistic. If the lower margin of the 95% confidence interval for raw agreement was at least 85% and was equal to or greater than 0.50 for kappa, this was predetermined to represent substantial interrater agreement. RESULTS: There was substantial interobserver agreement by both measures for 17 of the 19 candidate variables in patients with blunt head trauma. Interobserver agreement was substantial for all candidate variables except presence of seizure (kappa = 0.57 [95% CI = 0.47 to 0.67]; raw agreement = 96.5%) and abnormal cerebellar function (kappa = 0.54 [95% CI = 0.41 to 0.67]; raw agreement = 96.5%). CONCLUSIONS: The clinicians in our study had a substantial level of agreement regarding most clinical criteria assessed in this large sample of patients with blunt head injury.