Ischemic ST-Segment Depression Maximal in V1-V4 (Versus V5-V6) of Any Amplitude Is Specific for Occlusion Myocardial Infarction (Versus Nonocclusive Ischemia)

Background Occlusion myocardial infarctions (OMIs) of the posterolateral walls are commonly missed by ST-segment-elevation myocardial infarction (STEMI) criteria, with >50% of patients with circumflex occlusion not receiving emergent reperfusion and experiencing increased mortality. ST-segment depression maximal in leads V1-V4 (STDmaxV1-4) has been suggested as an indicator of posterior OMI. Methods and Results We retrospectively reviewed a high-risk population with acute coronary syndrome. OMI was defined from prior studies as a culprit lesion with TIMI (Thrombolysis in Myocardial Infarction) 0 to 2 flow or TIMI 3 flow plus peak troponin T >1.0 ng/mL or troponin I >10 ng/mL. STEMI was defined by the Fourth Universal Definition of Myocardial Infarction. ECGs were interpreted blinded to outcomes. Among 808 patients, there were 265 OMIs, 108 (41%) meeting STEMI criteria. A total of 118 (15%) patients had "suspected ischemic" STDmaxV1-4, of whom 106 (90%) had an acute culprit lesion, 99 (84%) had OMI, and 95 (81%) underwent percutaneous coronary intervention. Suspected ischemic STDmaxV1-4 had 97% specificity and 37% sensitivity for OMI. Of the 99 OMIs detected by STDmaxV1-4, 34% had <1 mm ST-segment depression, and only 47 (47%) had accompanying STEMI criteria, of which 17 (36%) were identified a median 1.00 hour earlier by STDmaxV1-4 than STEMI criteria. Despite similar infarct size, TIMI flow, and coronary interventions, patients with STEMI(-) OMI and STDmaxV1-4 were less likely than STEMI(+) patients to undergo catheterization within 90 minutes (46% versus 68%; P=0.028). Conclusions Among patients with high-risk acute coronary syndrome, the specificity of ischemic STDmaxV1-4 was 97% for OMI and 96% for OMI requiring emergent percutaneous coronary intervention. STEMI criteria missed half of OMIs detected by STDmaxV1-4. Ischemic STDmaxV1-V4 in acute coronary syndrome should be considered OMI until proven otherwise.

Accuracy of OMI ECG findings versus STEMI criteria for diagnosis of acute coronary occlusion myocardial infarction

OBJECTIVE

In the STEMI paradigm of Acute Myocardial Infarction (AMI), many NSTEMI patients have unrecognized acute coronary occlusion MI (OMI), may not receive emergent reperfusion, and have higher mortality than NSTEMI patients without occlusion. We have proposed a new OMI vs. Non-Occlusion MI (NOMI) paradigm shift. We sought to compare the diagnostic accuracy of OMI ECG findings vs. formal STEMI criteria for the diagnosis of OMI. We hypothesized that blinded interpretation for predefined OMI ECG findings would be more accurate than STEMI criteria for the diagnosis of OMI.

METHODS

We performed a retrospective case-control study of patients with suspected acute coronary syndrome. The primary definition of OMI was either 1) acute TIMI 0-2 flow culprit or 2) TIMI 3 flow culprit with peak troponin T ≥ 1.0 ng/mL or I ≥ 10.0 ng/mL.

RESULTS

808 patients were included, of whom 49% had AMI (33% OMI; 16% NOMI). Sensitivity, specificity, and accuracy of STEMI criteria vs Interpreter 1 using OMI ECG findings among 808 patients were 41% vs 86%, 94% vs 91%, and 77% vs 89%, and for Interpreter 2 among 250 patients were 36% vs 80%, 91% vs 92%, and 76% vs 89%. STEMI(-) OMI patients had similar infarct size and mortality as STEMI(+) OMI patients, but greater delays to angiography.

CONCLUSIONS

Blinded interpretation using predefined OMI ECG findings was superior to STEMI criteria for the ECG diagnosis of Occlusion MI. These data support further investigation into the OMI vs. NOMI paradigm and suggest that STEMI(-) OMI patients could be identified rapidly and noninvasively for emergent reperfusion using more accurate ECG interpretation.

Relationship between body temperature and heart rate in adults and children: A local and national study

BACKGROUND

A patient's vital signs are all inextricably interrelated, and together provide critical information regarding hemodynamic and physiological status. Yet, the precise relationship between body temperature (T) and heart rate (HR) in adults remains a fundamental gap in our knowledge.

METHODS

We performed a retrospective secondary analysis of (1) electronic medical records from a large academic center (annual ED census of 110,000) and (2) the National Hospital Ambulatory Medical Care Survey (NHAMCS), a large CDC-sponsored weighted sample of U.S. EDs and our own large tertiary care ED, extracting demographic and clinical data including vital signs.

RESULTS

We included 8715 local ED visits and approximately 123.3 million estimated national adult ED visits. Mean T was 36.9 °C, and 5.2% of patients had a T over 38 °C. Mean (SD) HR was 93.3 bpm, 28% had a HR over 100 bpm. Males had significantly lower HR than females (coefficient -1.6, 95%CI -2.4 to -0.8), while age was negatively associated with HR (coefficient -0.08, 95%CI -0.10 to -0.06). For national data, an increase of 1 °C in T corresponded to an increase in HR of 7.2 bpm (95%CI 6.2 to 8.3). After adjusting for age and gender, a 1 °C increase in T corresponded to a mean (95%CI) 10.4 (9.5-11.4) and 6.9 (5.9-7.8) increase in HR locally and nationally, respectively.

CONCLUSIONS

Among adult ED patients nationally, for every increase in T of 1 °C, the HR increases by approximately 7 bpm.

Association between burn characteristics and pain severity

INTRODUCTION

Traditionally, full thickness burns have been thought to be painless due to destruction of underlying nerves. We explored the association between patient and burn characteristics and pain severity in burn patients and determined whether full thickness burns were less likely to be painful than more superficial burns.

METHODS

We performed a structured review of medical records of patients presenting to a burn center between 2010 and 2013. Data abstracted included baseline patient and burn characteristics. The primary end point was pain severity on patient arrival to the emergency department using a verbal numeric score of 0 to 10. Univariate and multivariate analyses were used to explore the association between patient and burn characteristics and pain severity.

RESULTS

There were 507 patients. Mean (SD) age was 29.9 (23.6); 38% were ages younger than 18, and 68% were males. The median (interquartile ranges) pain score was 5 (2-8). Of all patients, 7% had isolated full thickness burns. Median (interquartile ranges) pain scores in isolated full thickness burns were slightly lower than in more superficial burns: 4 (1-8) vs 6 (2-8), respectively, P = .09. Twenty-five percent of patients with isolated full thickness burns had pain scores of 0 compared with 18% of all others (P = .28). There was no correlation between total body surface area and pain severity, however, pain scores increased with the number of burns (P = .007).

CONCLUSIONS

Pain severity is slightly less with full thickness burns; however, most patients have pain. The presence of pain should not be used to exclude full thickness burns.

The effects of rat mesenchymal stem cells on injury progression in a rat model

OBJECTIVES

Burns are common injuries that can result in significant scarring, leading to poor function and disfigurement. Unlike mechanical injuries, burns often progress both in depth and in size over the first few days after injury, possibly due to inflammation and oxidative stress. A major gap in the field of burns is the lack of an effective therapy that reduces burn injury progression. Because stem cells have been shown to improve healing in several injury models, the authors hypothesized that species-specific mesenchymal stem cells (MSCs) would reduce injury progression in a rat comb-burn model.

METHODS

Using a brass comb preheated to 100°C, the authors created four rectangular burns, separated by three unburned interspaces on both sides of the backs of male Sprague-Dawley rats. The interspaces represented the ischemic zones surrounding the central necrotic core. In an attempt to reduce burn injury progression, 20 rats were randomized to tail vein injections of 1 mL of rat-specific MSCs, 10(6) cells/mL (n = 10), or normal saline (n = 10), 60 minutes after injury.

RESULTS

While the authors were unable to identify any quantum dot (Q-dot)-labeled MSCs in the injured skin, at 7 days the mean percentage of the unburned interspaces that became necrotic in the MSC group was significantly less than in the control group (80% vs. 100%, p < 0.0001).

CONCLUSIONS

Intravenous injection of rat MSCs reduced burn injury progression in a rat comb-burn model.

Histologic effects of laser-assisted topical anesthesia in a porcine model

OBJECTIVES

A handheld laser device that removes the stratum corneum, the major barrier to transdermal absorption, has recently been approved to assist with topical anesthesia before painful procedures such as intravenous cannulation. The authors assessed the cutaneous histomorphologic effects of the laser device and the ability of the laser-treated skin to resist infection in a porcine model.

METHODS

This was a blinded, randomized animal experiment using isoflurane-anesthetized young domestic pigs. The ventral surface of the animals was irradiated multiple times with a lightweight, portable erbium yttrium-aluminum-garnet unit or a sham laser. One third of the wounds were inoculated with a Staphylococcus aureus suspension. The treated areas were then covered with a dry dressing, and full-thickness biopsy specimens of the treated areas were obtained immediately after treatment and at three, seven, ten, and 14 days for blinded histopathologic evaluation using hematoxylin and eosin staining and electron microscopy. Quantitative bacterial counts were obtained at three days in wounds exposed to bacteria. Main outcomes were quantitative bacterial counts, presence of cellular necrosis, epidermal integrity, and dermal scarring. Data analysis was conducted with descriptive statistics.

RESULTS

Laser irradiation resulted in immediate disruption of the cornified layer of the skin and necrosis of the stratum spinosum in all treated areas. There were also focal areas of vacuolar alteration of the basal one third of the epidermis. There was no evidence of any damage to the basement membrane or the underlying dermis. At three days, the epidermis had healed and there was evidence of epidermal hyperplasia and hyperkeratosis that was completely resolved by 14 days. There were no infections and no scarring. Sham laser had no histomorphologic effects on the skin. There was no bacterial growth from all sham laser-treated wounds challenged with bacteria. Three of 20 (15%; 95% confidence interval = 0% to 31%) laser-irradiated wounds that were challenged with bacteria grew between 280,000 and 1,600,000 colony-forming units/g.

CONCLUSIONS

Laser irradiation results in ablation of the stratum corneum and a superficial burn to the epidermis that heals by three to 14 days without any scarring or infection in pigs. Challenging laser-irradiated cutaneous wounds with a large bacterial inoculum resulted in bacterial growth in a minority of wounds.

Evaluation of a new liquid occlusive dressing for excisional wounds

We evaluated a novel octylcyanoacrylate-based liquid occlusive dressing for partial-thickness wounds. One hundred and fifteen standardized wounds were created with an electric dermatome set at a depth of 600 micro on the flanks of three pigs and randomly treated with liquid occlusive dressing, a hydrocolloid dressing, or gauze. In one pig, wounds were swabbed with Staphylococcus aureus. Biopsies were taken after 4, 5, 6, and 21 days. Hemostasis was obtained in all wounds treated with the liquid occlusive. The percent reepithelialization of wounds treated with the liquid occlusive and hydrocolloid dressings were significantly greater at days 4 and 5 than control wounds (78% and 82% vs. 40%, p < 0.001 and 99% and 100% vs. 72%, p < 0.001, respectively). None of the liquid occlusive-treated wounds challenged with bacteria became infected. Foreign body reactions were least common in wounds treated with the liquid occlusive (p < 0.001). Scar depth was less for liquid occlusive- and hydrocolloid-treated wounds than controls (285 micro and 303 micro vs. 490 micro, p < 0.001). We conclude that excisional wounds treated with the liquid occlusive dressing reepithelialize as quickly as hydrocolloid-treated wounds. The liquid occlusive dressing is an effective microbial barrier and hemostatic agent resulting in fewer foreign body reactions than hydrocolloid-treated wounds or controls.