Evaluation of patients with chest pain and nondiagnostic ECG using thallium-201 myocardial planar imaging and technetium-99m first-pass radionuclide angiography in the emergency department.

STUDY OBJECTIVE: The purpose of this study was to determine if thallium-201 myocardial planar imaging and technetium-99m first-pass radionuclide angiography, performed in the emergency department, could predict which patients with acute chest pain and nondiagnostic ECGs were more likely to have an acute myocardial infarction (AMI). DESIGN: Retrospective analysis. SETTING: Urban, county ED. TYPE OF PARTICIPANTS: Convenience sample of 47 patients with acute chest pain suggestive of myocardial ischemia and nondiagnostic ECG. INTERVENTIONS: Thallium-201 myocardial imaging and technetium-99m first-pass radionuclide angiography in the ED. MEASUREMENTS AND MAIN RESULTS: Four patients had an AMI (ie, CK-MB greater than or equal to 6% total CK). The combined scans had a sensitivity of 75%, (95% confidence interval [Cl], 19-99%), a specificity of 42% (95% CI, 27-58%), an accuracy of 45% (95% CI, 19-99%), a positive predictive value of 11% (95% CI, 2-29%), and a negative predictive value of 95% (95% CI, 75-100%) in predicting AMI. CONCLUSION: Thallium-201 myocardial planar imaging and technetium-99m first-pass radionuclide angiography performed in the ED do not appear to be useful in determining which patients with acute chest pain and nondiagnostic ECG are likely to have an AMI.

Assessment of suicide potential by nonpsychiatrists using the SAD PERSONS score.

We were unable to validate the predictive ability of a previously described mneumonic (SAD PERSONS score, SPS) for determining the need for hospitalization of patients who have expressed suicidal ideation or behavior. After reviewing published studies on the subject, we arrived at a modification of this scale (MSPS). The MSPS obtained by nonpsychiatric and psychiatric house staff was compared and correlated with patient disposition for 100 consecutive adult patients presenting to the Harbor-UCLA Medical Center emergency department for the assessment of suicidal behavior. We were unable to correlate the MSPS with patient disposition. However, four criteria were found to correlate with the need for hospitalization (P less than .001). After weighting the MSPS, giving two points for each of these four criteria, and one point for each of the other six, we found that a score of greater than or equal to 6 had a sensitivity of 94% and a specificity of 71% in identifying need for hospitalization. A score of less than or equal to 5 had a negative predictive value for hospitalization of 95%. When two nonsuicidal patients, admitted for situational reasons only, were eliminated, a score of greater than or equal to 6 had a 100% sensitivity and a score of less than or equal to 5 had a 100% negative predictive value in identifying patients requiring hospitalization. Subsequent use of the weighted MSPS for an additional 82 patients confirmed these results. Follow-up of 97.5% (116/119) of all patients discharged from the emergency department at 6 to 12 months found no mortalities. Using a weighted MSPS, nonpsychiatrists can quickly and easily obtain the objective information necessary to make an initial assessment of suicidality.(ABSTRACT TRUNCATED AT 250 WORDS)

Appendicitis: evaluation by Tc-99m leukocyte scan.

Diagnosing appendicitis may be difficult. We report the use of a new technetium-99m-albumin colloid white blood cell (TAC-WBC) scan in the evaluation of appendicitis. In a synthesis requiring 75 minutes, autologous neutrophils and macrophages from 40 mL of whole blood were labelled with technetium-99m-albumin colloid and administered to 100 patients with possible appendicitis. The entire process, from labelling the cells to completion of the scan took a maximum of 5 1/4 hours. Two patients had second scans on separate hospitalizations. Twenty-six patients had appendicitis; 12 had perforations, five of whom had an abscess. Eighty-five scans were read as either positive or negative for appendiceal pathology with a sensitivity of 89%, a specificity of 92%, and an accuracy of 92% in diagnosing appendicitis. Seventeen scans were indeterminant; eight of these patients had appendicitis. The value of the TAC-WBC scan in the evaluation of appendicitis lies in its ability to be used emergently, its high negative predictive value for men and women (NPV = 97%), and its high positive predictive value for men (PPV = 93%). At present, the scan does not appear to be reliable in diagnosing appendicitis in women (PPV = 43%). It is most useful in those patients in whom diagnosis is uncertain, and should not be used in patients with clear-cut appendicitis in whom its use will delay definitive surgical care.

Esophageal electrocardiography in acute cardiac care. Efficacy and diagnostic value of a new technique.

Esophageal electrocardiography can detect atrial electrical activity during tachyarrhythmias when P waves are not evident by surface electrocardiography. However, patient discomfort, the difficulty of accurately interpreting cardiac signals against a background of electrical noise, and the complexity of use have limited widespread application. In this study, esophageal electrocardiography was used in 48 acutely ill patients with a new "pill electrode" system, consisting of a bipolar electrode pair (3 by 20 mm) attached to 0.5 mm diameter Teflon wires contained in a standard gelatin capsule. The capsule with enclosed electrodes was voluntarily swallowed, and the recording electrodes were positioned posterior to the left atrium. A preamplifier system with a low-frequency filter and a standard three-channel electrocardiographic recorder were used. Esophageal "pill" electrocardiographic recordings were made in 48 of 50 eligible study patients (96 percent) with tachyarrhythmias and absent or equivocal atrial activity on surface electrocardiography. In these patients, a high-quality esophageal electrocardiographic recording was obtained within one to 10 minutes with minimal patient discomfort. In 25 of 48 study patients (52 percent), the original diagnosis, based on the surface electrocardiographic recording, was incorrect after review of the esophageal recording. Results of esophageal recording altered management in 19 of 48 (40 percent) patients. This new and simple technique facilitates diagnosis and management of perplexing tachyarrhythmias in acutely ill patients by physicians with minimal training in the technique.

Varicella pneumonia in adults: a spectrum of disease.

Varicella (Chicken pox) is a contagious disease common in childhood but uncommon in adulthood. Pneumonia, however, is a relatively common complication of the disease in adults. Recognition of the potential for this complication in adult patients with varicella is essential for the emergency physician. Three cases of varicella pneumonia in adults are presented, representing the spectrum of disease. The first patient was a 58-year-old man without respiratory complaints who was managed successfully as an outpatient. The second patient was a 24-year-old woman who progressed from mild to marked respiratory distress over several hours, and was treated successfully with high-flow oxygen alone. The third patient was a pregnant 23-year-old woman who presented without respiratory symptoms but rapidly developed adult respiratory distress syndrome, resulting in death. Clinical assessment, patient management, and indications for hospitalization are discussed.

Electrocardiographic criteria for tricyclic antidepressant cardiotoxicity.

To determine if electrocardiographic findings characterize tricyclic antidepressant (TCA) overdose and cardiotoxicity, 25 patients suspected of taking an overdose of TCA were studied. Toxicologic assays for a TCA were positive in 11 patients (+TCA, n = 11). Toxicologic study results for a TCA were negative in 14 patients (-TCA, control subjects). Patients with positive TCA results (+TCA) had a significantly greater heart rate (117 +/- 23 vs 100 +/- 22 beats/min, p less than 0.05), QRS duration (103 +/- 15 vs 87 +/- 10 ms, p less than 0.005) and corrected QT interval (449 +/- 38 vs 418 +/- 36 ms, p less than 0.05) than control patients (-TCA) on admission. Patients with positive TCA results also had a more rightward terminal 40-ms frontal plane QRS vector (195 +/- 51 degrees vs 54 +/- 64 degrees, p less than 0.001) than control patients. This observation has not been previously reported. A terminal QRS vector of 130 degrees to 270 degrees accurately discriminated between -TCA and +TCA patients (positive and negative predictive value = 1.00). Counterclockwise rotation (normalization) of the terminal frontal plane QRS vector was noted in +TCA patients during hospitalization. All +TCA patients had a sinus tachycardia, a corrected QT interval 418 ms or longer, and a terminal QRS vector between 130 degrees and 270 degrees. Using these values as selection criteria, a computer-aided search of 15,064 electrocardiograms (ECGs) recorded in our emergency department was performed. The likelihood of encountering such an electrocardiographic pattern in this population was 1.0%.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial contusion diagnosed by first-pass radionuclide angiography.

Myocardial contusion, (traumatic myocardial dysfunction) is a relatively common complication of blunt trauma. The diagnosis is often elusive. Studies using clinical and laboratory parameters often fail to detect patients with significant myocardial injury. No constellation of clinical signs, electrocardiographic findings, or cardiac enzymes has been sensitive or specific enough to evaluate such patients accurately. Recently, radionuclide angiography was found to be a sensitive indicator of myocardial dysfunction. The authors studied ten patients with blunt thoracic or multisystem trauma who had myocardial dysfunction documented by first-pass radionuclide angiography. Follow-up study within five weeks demonstrated normalization or improvement in ejection fraction and wall motion abnormalities in all patients. Radionuclide angiography is cost effective, can be performed in the emergency department, and can assist in the management of patients with blunt thoracic or multisystem trauma.

Use of naloxone during cardiac arrest and CPR: potential adjunct for postcountershock electrical-mechanical dissociation.

Naloxone has been shown to increase arterial pressure in hemorrhagic and septic shock. To determine if naloxone has salutary effects during cardiac arrest with conventional closed-chest cardiopulmonary resuscitation (CPR), ten dogs were studied during 20 minutes of ventricular fibrillation (VF) and CPR and during a 30-minute postcountershock period. Central aortic (Ao) and right atrial (RA) systolic and end-diastolic (EDP) pressures, instantaneous Ao-RA pressure difference (coronary perfusion pressure), and electromagnetic Ao flow were measured. Ao and RA samples were analyzed during a control period and at five-minute intervals during CPR for PO2, PCO2, and pH. During VF, a piston-cylinder device was used to perform anteroposterior sternal depressions and positive pressure ventilations (100% O2) at standard rates and ratios. After 15 minutes of CPR, animals were randomized and given either naloxone (5 mg/kg) or epinephrine (1 mg). Defibrillation was attempted five minutes later using 1 J/kg and then, if necessary, 2, 4, 8, 12, and 16 J/kg until VF was terminated or the maximum energy dose was reached. If VF persisted or if countershock resulted in asystole or a nonperfusing rhythm (electrical-mechanical dissociation [EMD]), the alternate drug (naloxone or epinephrine) was then given. Measured systolic pressures, coronary perfusion pressures, aortic flow, and blood gases were not significantly different during the control period or at five, ten, and 15 minutes of VF and CPR between animal groups prior to drug administration. When compared to hemodynamic values measured at 15 minutes, naloxone had no significant effect on pressures or aortic flow measured five minutes after administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessing severity of adult asthma and need for hospitalization.

Exacerbations of asthma requiring emergency treatment are common but, fortunately, asthma is rarely life threatening. In the course of treating acute asthmatics, however, the question of whether to admit the patient often is raised. With the current costs of hospitalization and morbidity associated with the disease, it is advantageous to be able to separate accurately those who require in-hospital treatment from those who can be treated as outpatients. The choice to hospitalize the asthmatic patient must be based on objective findings, including spirometry alone, spirometry plus history and physical signs, or index scoring (Figure). The best method awaits elucidation by prospective study. The most objective indicator of asthma severity is the indirect measurement of airways obstruction by spirometry, either by FEV1.0 or PEFR. FEV1.0 and PEFR yield comparable results. Simple, inexpensive devices for these measurements are available. An FEV1.0 less than 0.8 to 1.0 L (less than 25% predicted in women and men ages 25 to 65 years) or a PEFR less than 100 L/min (less than 20% predicted in women and men ages 25 to 65 years) accurately indicates a severe asthma exacerbation. The percentage predicted is utilized in those individuals who lack average stature. An increase in FEV1.0 to greater than 1.6 to 2.1 L (greater than 60% predicted) or a PEFR improvement to greater than 300 L/min (greater than 60% predicted) after therapy negates the need for hospitalization. In order to gain such improvement the patient may require approximately four to six hours of outpatient treatment. Some will treat patients for longer periods. Evidence of worsening obstruction or impending respiratory failure during this period mandates admission.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory-related activity of upper airway muscles in anesthetized rabbit.

The electromyographic activity of the glossal, suprahyoid, infrahyoid, and pharyngeal muscles was examined during spontaneous respiration in rabbits anesthetized with ketamine hydrochloride. This activity was then correlated with phases of the respiratory cycle. Our findings indicate that the overwhelming majority of the muscles comprising these groups show activity that increased during inspiration and returns to the background level during expiration and the end-expiratory pause. The exceptions are the inferior pharyngeal constrictor muscle, which demonstrates increased activity during expiration and the end-expiratory pause, and the stylohyoid major and digastric muscles, whose activity was not modulated with respiration. In general, the results obtained under ketamine anesthesia are in agreement with the studies on a more limited number of muscles in humans during sleep or in animal studies utilizing light anesthesia. Furthermore, the use of ketamine avoids the central suppressant effects produced by barbituate anesthesia. It has been argued that the upper airway muscles are rhythmically active during respiration to maintain the patency of the upper airway. Both the number of muscles that are rhythmically active and their strict correlation with specific phases of the respiratory cycle suggest that the forces exerted on the upper airway are complex and that peak tension is generated during inspiration. Further studies are required to evaluate the effects of ketamine anesthesia on these upper airway muscles before this rabbit model can be utilized to examine respiratory disorders of the upper airway.

Hemodynamic effects of pneumatic external counterpressure in canine hemorrhagic shock.

To assess the effects of external counterpressure in a hypovolemic canine model, mean right atrial pressure (RA), left ventricle end-diastolic pressure (LVEDP), mean aortic pressure (Ao), and cardiac output (CO) (indicator dilution technique or electromagnetic ascending aortic flow) were measured in eight closed-chest mongrel dogs following phlebotomy to an Ao of 50 to 60 mm Hg. Inferior vena cava (IVC) flow was measured electromagnetically with a cannulating probe in four animals. The antishock garment was inflated to pressures of 40, 60, 80, and 100 mm Hg. An extended shock "control" period preceded inflation to minimize the effect of reflex circulatory responses to acute blood loss. IVC flow (2 +/- 1 mL/min/kg) during and immediately following antishock garment inflation was not significantly different from control (3 +/- 1 mL/min/kg) regardless of inflation pressure. Ao, RA, and LVEDP measured 30 seconds and 15 minutes after garment inflation were increased, but CO was not significantly different from control values at each inflation pressure. Garment inflation significantly increased peripheral vascular resistance (PVR) at all inflation pressures, and there was a significant correlation (r = .53; P less than .001) between the change in Ao and PVR. These results indicate that the change in arterial pressure produced by external counterpressure is the result of an increase in PVR and not the result of an autotransfusion and subsequent increased left heart outflow in the canine shock model.

The double-strand-break repair model for recombination.

Gene conversion is the nonreciprocal transfer of information from one DNA duplex to another; in meiosis, it is frequently associated with crossing-over. We review the genetic properties of meiotic recombination and previous models of conversion and crossing-over. In these models, recombination is initiated by single-strand nicks, and heteroduplex DNA is generated. Gene conversion is explained by the repair of mismatches present in heteroduplex DNA. We propose a new mechanism for meiotic recombination, in which events are initiated by double-strand breaks that are enlarged to double-strand gaps. Gene conversion can then occur by the repair of a double-strand gap, and postmeiotic segregation can result from heteroduplex DNA formed at the boundaries of the gap-repair region. The repair of double-strand gaps is an efficient process in yeast, and is known to be associated with crossing-over. The genetic implications of the double-strand-break repair model are explored.

One-step gene disruption in yeast.

The one-step gene disruption techniques described here are versatile in that a disruption can be made simply by the appropriate cloning experiment. The resultant chromosomal insertion is nonreverting and contains a genetically linked marker. Detailed knowledge of the restriction map of a fragment is not necessary. It is even possible to "probe" a fragment that is unmapped for genetic functions by constructing a series of insertions and testing each one for its phenotype.

Genetic applications of yeast transformation with linear and gapped plasmids.

Techniques for high frequency yeast transformation have been described. A double-strand break introduced by restriction enzyme cleavage can be used to direct a plasmid to integrate into a particular chromosomal locus. Plasmids containing a double-strand gap can be used in a straightforward method for the isolation and mapping of chromosomal alleles. These techniques extend the genetic applications of yeast transformation.