Fast Estimation of Møller-Plesset Correlation Energies Based on Atomic Contributions.

Dynamic correlation plays an important role in the accurate calculation of chemical compounds such as the description of equilibrium structures in chemical systems. A model for the fast estimation of dynamic correlation energy is introduced in this work. This model is based on the idea of decomposition of the contribution of dynamic correlation energy calculated by nth order Møller-Plesset perturbation (MPn) theory with respect to atomic regions. Multiple levels of theory, including MP2, MP2.5, and MP4, are used as the reference, and the corresponding correlation energy densities are calculated. The proposed model is concise, fast, and promising for practical use, such as the prediction of reaction energies. It can also work as a baseline model or pretrained model for follow-up studies of machine learning.

Paroxysmal supraventricular tachycardia: outcome after ED care.

The objective of this study was to investigate the outcome and rate of symptomatic recurrence of paroxysmal supraventricular tachycardia (PSVT) in an emergency department (ED) patient population, after ED management and disposition. A retrospective descriptive review of ED records and state death registry was performed. The study took place at a University hospital ED with 60,000 annual patient volume. The subjects were all patients presenting to the ED in PSVT from January 1993 to December 1996. One hundred eleven patients met entry criteria. The mean age was 53 years, 49% were men, and 51% were women. EMS was used by 47 (42%) patients. Ten of these patients who used the EMS system had an unstable event in the prehospital setting. Eleven patients had unstable events once in the ED. ED therapy given (with number of successes in parentheses) included: Adenosine 48 (41), vagal maneuvers 44 (22), calcium channel blockers 22 (14), beta-blockers 10 (4), and electrical cardioversion 5 (1). Twenty-six patients (23%) spontaneously converted to normal sinus rhythm (NSR). Seventy-nine (71%) patients were discharged from the ED. Mean age for this group was 49 years, and the mean ED stay for this group was 3.8 hours. Three patients (4%) in this group had a recurrence of their SVT after discharge. These patients all had recurrence within 24 hours, and none had an unstable event associated with their recurrence. Thirty-two (29%) patients were admitted to the hospital, with 3 (9%) going to a monitored floor, and 29 (91%) going to an intensive care unit. Mean age for this group was 65 years. Twenty-one of these 32 admitted patients (65%) required continued in-hospital therapy once admitted for their arrhythmia. Six of the 32 admitted patients (19%) had recurrent PSVT in the hospital, with 1 episode of instability. Recurrence of PSVT was more likely to occur among those admitted (P <.05), in older patients (P<.01), and in those with a history of cardiovascular disease (P <.01). No deaths were recorded in either group. Most patients with PSVT can be safely discharged from the ED after short-term observation if therapy produces prompt conversion to NSR. PSVT recurrence is relatively uncommon and usually occurs within 24 hours of ED presentation. PSVT recurrence occurs more often in the elderly and in those with established cardiac disease.

Indications for computed tomography in patients with minor head injury.

BACKGROUND: Computed tomography (CT) is widely used as a screening test in patients with minor head injury, although the results are often normal. We performed a study to develop and validate a set of clinical criteria that could be used to identify patients with minor head injury who do not need to undergo CT. METHODS: In the first phase of the study, we recorded clinical findings in 520 consecutive patients with minor head injury who had a normal score on the Glasgow Coma Scale and normal findings on a brief neurologic examination; the patients then underwent CT. Using recursive partitioning, we derived a set of criteria to identify all patients who had abnormalities on CT scanning. In the second phase, the sensitivity and specificity of the criteria for predicting a positive scan were evaluated in a group of 909 patients. RESULTS: Of the 520 patients in the first phase, 36 (6.9 percent) had positive scans. All patients with positive CT scans had one or more of seven findings: headache, vomiting, an age over 60 years, drug or alcohol intoxication, deficits in short-term memory, physical evidence of trauma above the clavicles, and seizure. Among the 909 patients in the second phase, 57 (6.3 percent) had positive scans. In this group of patients, the sensitivity of the seven findings combined was 100 percent (95 percent confidence interval, 95 to 100 percent). All patients with positive CT scans had at least one of the findings. CONCLUSIONS: For the evaluation of patients with minor head injury, the use of CT can be safely limited to those who have certain clinical findings.

Hypoglycemia presenting as acute respiratory failure in an infant.

Hypoglycemia, a common metabolic abnormality seen in the pediatric population, is most often easily diagnosed and rapidly treated with satisfactory outcome. If not recognized and treated in prompt fashion, however, hypoglycemia may cause irreversible central nervous system injury or expose the patient to unnecessary procedures; it rarely results in death. The classic emergency department (ED) presentation of hypoglycemia, the diabetes mellitus patient using hypoglycemic therapy, is frequently encountered and adequately managed with excellent outcome. Alternatively, the patient may present to the ED in a fashion suggestive of a situation other than hypoglycemia. For example, the patient with an altered sensorium following a traumatic event, with a focal neurologic finding, or with bradycardia--all situations in which hypoglycemia is the causative issue--may not be immediately recognized as such a metabolic problem. This report presents a case of a 9-month-old boy who presented with acute respiratory failure and mental status change; the initial ED impression was one of pneumonia with sepsis. Further evaluation uncovered the actual reason for the mental status change and respiratory insufficiency: hypoglycemia was noted on laboratory analysis; no clinical evidence of pneumonia was found after thorough ED evaluation and a prolonged hospital stay. His mental status improved and his respiratory insufficiency resolved after glucose therapy. No other explanation for the respiratory failure was found during the hospital admission. It is imperative that the emergency physician consider hypoglycemia in all patients with any degree of mental status abnormality, even when the findings seem to be explained initially by other etiologies.

Psoas abscess with sepsis mimicking traumatic hemorrhagic shock after a fall.

Abscess of the psoas muscle is infrequently encountered. An infectious emergency of this type usually presents in a nonspecific manner and thus poses a significant diagnostic challenge to the emergency physician. Diagnosis and specific treatment are often delayed, which can lead to increased mortality. This case report presents a patient with altered mental status and hypotension after a fall, who was initially managed as a trauma victim. Emergency department evaluation initially focused on a traumatic etiology of the above abnormalities. Subsequent assessment determined that the patient's condition was due to an underlying psoas abscess with sepsis. Appropriate anatomy, clinical presentation, and management are discussed in hopes of increasing physician awareness of this uncommon infectious condition.

Multiphasic anaphylaxis: report of a case with prehospital and emergency department considerations.

Anaphylaxis, a multisystem allergic reaction, represents a true medical emergency. Anaphylaxis is characterized by a combination of the following symptoms: urticaria, angioedema, distributive shock, and respiratory failure. Most often, the patient is rapidly treated with prompt resolution of the anaphylaxis in either the out-of-hospital or emergency department (ED) setting. Infrequently, recurrent or multiphasic anaphylaxis is encountered, involving a reappearance of allergic phenomena after complete resolution of the original reaction. Recurrence may involve nuisance-level issues such as urticaria; alternatively, multiphasic reactions may be characterized by cardiovascular collapse or respiratory compromise. Initially aggressive pharmacological therapy followed by prolonged observation in either the ED or the in-hospital setting is strongly recommended to monitor for potential recurrence.

Multiphasic anaphylaxis: an uncommon event in the emergency department.

OBJECTIVE: To determine the rate of clinically significant recurrence of symptoms in patients treated for anaphylaxis in the ED. METHODS: Retrospective chart review of out-of-hospital, ED, and hospital records over 4.5-year period (July 1991 to December 1995) at a university hospital ED with an annual patient volume of 60,000. Subjects were ED anaphylaxis patients with > or = 2 of the following 3 organ systems involved: cutaneous, respiratory, and cardiovascular. The major outcome criterion was recurrence of symptoms after ED release. Recurrences were sought at the primary treatment hospital and at surrounding hospitals (radius of 75 miles from the primary institution) within a 7-day period from the initial visit. Review of the state death registry also was made to verify the absence of out-of-hospital deaths. RESULTS: The medical records of 1,261 allergic reaction patients were reviewed, with 67 (5.3%) cases of anaphylaxis identified. Symptoms and signs in patients during the ED phase included: dyspnea, 42 (63%); pruritus, 38 (57%); emesis, 27 (41%); throat/chest tightness, 25 (37%); orthostatic complaints, 12 (18%); urticaria, 47 (70%); circulatory shock, 32 (48%); upper airway angioedema, 7 (33%); stridor, 11 (16%); and bronchospasm, 20 (30%). Of the 67 patients, 93% had immediate resolution and remained asymptomatic for a mean time of 4.2 hours in the ED. Protracted reaction occurred in 5 cases (3 using beta-adrenergic blocking agents). For 19 (28%) patients admitted to hospital, the mean hospital length of stay was 63 hours. Only 2 (3%) recurrent cases were identified, both manifested solely by urticaria. CONCLUSION: Recurrent anaphylactic reactions were rare, occurring in 3% of cases and without life threat in this patient population. Selective outpatient management of patients with severe anaphylactic reactions that promptly respond to therapy with complete, rapid resolution may be reasonable. Further study of this medical emergency is required to develop criteria to guide the choice of an outpatient disposition.

Acute hypoglycemia masquerading as head trauma: a report of four cases.

Hypoglycemia, a commonly encountered metabolic emergency, is most often easily diagnosed and rapidly treated with satisfactory patient outcome. If not recognized and treated promptly, hypoglycemia may cause irreversible central nervous system injury; it rarely results in death. The classic presentation of hypoglycemia, a patient with diabetes mellitus on medical therapy (Insulin or oral hypoglycemic agents) who presents with an altered sensorium, is frequently seen in the emergency department (ED). Less often, patients with this metabolic emergency present to the ED in a manner suggestive of a situation other than hypoglycemia. Patients may present with seizure activity or focal neurological deficits, leading the physician to treat a primary neurological syndrome and not immediately recognize the primary cause of the problem. Alternatively, patients with hypoglycemia will present to the ED with an altered mental status after a traumatic event. The physician may again assume that the alteration in consciousness has resulted from a head injury and not a metabolic disorder. Four cases are presented in which the medical history of the event (i.e., trauma) suggested head injury as an explanation of the presentation when, in fact, hypoglycemia was responsible for the altered sensorium. The diagnosis of hypoglycemia is easily made with the performance of a bedside screening test which can be subsequently confirmed by laboratory blood analysis. It is imperative that emergency physicians consider hypoglycemia in all patients with any mental status abnormality, focal neurological deficit, or seizure activity, even when the findings seem to be explained initially by other etiologies.