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Biomedical subjects

R D White

Publications and source records attributed to R D White.

At least 19 recordsLinked to original sources

Ventricular fibrillation, automatic external defibrillators, and the United States Food and Drug Administration: confrontation without comprehension.

More people die in the United States each day of potentially reversible VF than of any other cause of death, reversible or not. Early defibrillation is the definitive treatment. Automated external defibrillation is a proven technology now confirmed to have saved thousands of lives. As with all medical devices and technology, perfection is not possible. Some problems, such as those represented by the two cases discussed in this article, are inevitable and acceptable and give little cause for alarm. One would not stop penicillin from being manufactured and distributed because of a sudden, unexpected allergic reaction in one patient (error of commission) or an unexpected resistant organism in another (error of omission). The FDA must understand that AEDs, even if they are imperfect, are not anywhere near as dangerous as no defibrillator at all. AEDs have finally allowed many EMS systems to achieve early defibrillation. Discontinuing use of AEDs or closing AED manufacturers could mean a significant number of lives lost unnecessarily. Therefore EMS agencies planning to implement early-defibrillation programs should continue with such plans. Why the agents of an important federal regulatory agency have singled out this technology for an intense review puzzles many observers in the medical-device field. Two meetings have been hosted by officials of the FDA to discuss the continuing concern the FDA officials have expressed over automated defibrillation technology. These meetings included representatives from the AHA, the American College of Cardiology, ACEP, defibrillator manufacturers, and other interested organizations. The FDA leadership has repeatedly focused on data acquired through the FDA Medical Device Reporting systems. Congress requires the FDA to investigate reports of problems with "critical medical devices." Because the indication for the use of a defibrillator is cardiac arrest, there will inevitably be a high association between defibrillator use and patient deaths. FDA personnel may view such reports of device problems in association with patient deaths as evidence that an intrinsically flawed technology has reached the marketplace without rigorous testing and evaluation. From the clinician's perspective, however, these reports represent a small numerator over a huge denominator of daily, lifesaving clinical use. The non-FDA participants at the two meetings have stated that the FDA complaints appear to be random and reveal a lack of understanding of AED technology.(ABSTRACT TRUNCATED AT 400 WORDS)

Algorithms

Prognostic value of end-tidal carbon dioxide pressures during out-of-hospital cardiac arrest.

STUDY OBJECTIVE: To assess the prognostic value of initial end-tidal CO2 pressures (PETCO2) during CPR in patients with out-of-hospital cardiac arrest (OHCA). DESIGN: A prospective observational study using a convenience sample. SETTING: Primary service area of an advanced life support (ALS) ambulance service, including a city with a population of 70,745 and the surrounding area, with a population of 30,000. PARTICIPANTS: Adults with nontraumatic OHCA. INTERVENTIONS: Quantitative monitoring of PETCO2 during CPR after endotracheal intubation using an infrared capnograph. RESULTS: PETCO2 after 1 and 2 minutes and the maximum PETCO2 during CPR were compared between the group in which restoration of spontaneous circulation (ROSC) was achieved and the group in which it was not. PETCO2 was measured during CPR in 27 patients. After 1 minute, PETCO2 was higher in patients who had on-scene ROSC than in patients without ROSC (23.0 +/- 7.4 versus 13.2 +/- 14.7 mm Hg, P = .0002). After 2 minutes, PETCO2 was higher in patients with ROSC (26.8 +/- 10.8 versus 15.4 +/- 5.7 mm Hg, P = .0019). The maximum PETCO2 during CPR was also higher in the ROSC group (30.8 +/- 9.5 versus 22.7 +/- 8.8 mm Hg, P = .0154). Thirteen of 27 patients presented in ventricular fibrillation (VF). The 1-minute (24.3 +/- 6.8 versus 12.0 +/- 4.2 mm Hg, P = .0022), 2-minute (28.2 +/- 11.4 versus 12.4 +/- 4.3 mm Hg, P = .0088), and maximum (33.0 +/- 10.2 versus 20.6 +/- 11.1 mm Hg, P = .0316) PETCO2 values during CPR were all significantly higher in patients in VF with ROSC. CONCLUSION: In this observation study of 27 patients, initial PETCO2 during CPR with automated ventilation was prognostic for ROSC in patients with OHCA. Patients with ROSC have higher PETCO2 values after 1 and 2 minutes than do patients without ROSC.

Carbon Dioxide

Temporomandibular joint considerations in orthognathic surgery.

The relationship between the temporomandibular joint and developmental jaw deformities is both undeniable as well as controversial as to its magnitude or importance. This article addresses the importance of a complete temporomandibular joint and orthognathic diagnostic work-up prior to the choice of either temporomandibular joint or orthognathic surgery. The surgical procedure is determined by the internal derangement that is present as well as its response to non-surgical care. The intraoperative techniques for handling the bony fragments, seating the condyle and rigid fixation techniques are also of utmost importance and are discussed for each of the orthognathic procedures. The postoperative physiotherapy is also discussed both for the temporomandibular joint patient as well as the orthognathic patient.

Humans

Fixation method useful for cytologic examination and DNA flow cytometry of exfoliated bladder cells.

Single-institution studies have shown that DNA flow cytometry is superior to routine cytologic evaluation of following patients for bladder cancer recurrence. For 15 urine and 15 bladder washing specimens, we evaluated a fixative employing methanol plus acetic acid (MA), freshly mixed 20:1 (vol/vol). Routine cytologic evaluation following Papanicolaou staining, and DNA flow cytometry were performed. Paired aliquots from the same washings and urines were processed as fresh spray-fixed samples and MA-fixed samples. The majority of the MA-fixed specimens showed good nuclear preservation when assessed for chromatin texture, presence of distinct nuclear envelope, and clarity of nucleolus, while only a minority of the fresh urine and washing samples showed these features. Cytoplasmic degeneration was seen only in fresh specimens. The presence of aneuploidy and the percentage of hyperdiploid cells could be reliably determined in the MA-fixed samples. This fixation protocol is recommended for the transport of urine and bladder washing specimens to centralized laboratories for both cytologic and flow cytometric evaluation.

Acetates

Cardiac tumors: diagnosis and management.

The first step towards the diagnosis of cardiac neoplasia is made when the clinician considers the diagnosis. While the classically described signs and symptoms of left-atrial myxomas are noteworthy, the vast majority of patients present with symptomatology that is less specific--either of a constitutional nature, or related to right- or left-sided congestion. Likewise, the physical examination may rarely disclose classic auscultatory signs, but is more likely to confirm the presence of the right- or left-sided congestion inferred from history. Peripheral, embolic, or vasculitis lesions should raise suspicion of the diagnosis. Nevertheless, the majority of patients will be diagnosed by the unexpected detection of a tumor at the time of echocardiography. Transthoracic echocardiography remains the procedure of choice in screening for cardiac neoplasia. It has excellent sensitivity for intracavitary and endocardial lesions. Myocardial lesions are also well imaged. Pericardial lesions, with or without extension into contiguous structures, are poorly visualized and, here, magnetic resonance imaging is unquestionably the superior investigative approach. Further, a limited degree of tissue characterization is possible with the latter technology. Transesophageal echocardiography is ideally suited for the examination of suspected tumors involving the atria, interatrial septum, superior vena cava, atrioventricular valves and, to a lesser extent, the ventricles. These three imaging modalities clearly complement one another and the choice of application will depend upon factors including the patient's transthoracic echogenicity, the availability of magnetic resonance imaging or transesophageal echocardiography, cost, and the physical status of the patient.

Angiocardiography

The hemodynamics of vacuum constriction erections: assessment by color Doppler ultrasound.

Duplex ultrasound with pulsed Doppler and color flow sonography were used to image the penis and conduct blood flow velocity studies in 5 patients. Cavernous body cross sectional area, cavernous artery diameters and peak systolic velocities were measured in the flaccid shaft, after transient exposure to negative pressure in a vacuum constriction device, and with a vacuum constriction device band applied to the tumescent shaft. We found that exposure to vacuum transiently increased central cavernous arterial blood flow velocities compared to baseline values in all patients. After a trial of a vacuum constriction device and application of the constricting band cavernous body cross sectional areas doubled. Despite increased cavernous arterial diameters in 4 of 5 patients and increased blood flow in all patients after vacuum-induced tumescence alone, we could not visualize arterial inflow in the penile shaft once the constricting band was in place. Color Doppler ultrasound can detect cavernous artery systolic flow as low as 2 to 9 cm. per second. Our data suggest that the erectile state maintained distal to the vacuum constriction device band is low flow and relatively ischemic.

Aged

Out-of-hospital pleomorphic ventricular tachycardia and resuscitation: association with acute myocardial ischemia and infarction.

Pleomorphic ventricular tachycardia is characterized by QRS complexes with repeated variation in polarity, amplitude, and regularity. When associated with prolongation of the QT interval, the term torsades de pointes is used to describe the arrhythmia. It usually is seen clinically in association with class IA antiarrhythmic drugs such as quinidine and procainamide, bradycardia, hypokalemia, and, much less often, other drugs and electrolyte disorders as well as a result of congenital and neurogenic causes. It also may accompany acute myocardial infarction or ischemia. We describe four patients in whom pleomorphic ventricular tachycardia was observed as the presenting rhythm or during the course of resuscitation in out-of-hospital cardiac arrest. In all four patients, acute myocardial ischemia appeared to be the provocative mechanism. Therapeutic implications include an awareness of the unusual behavior of this arrhythmia, especially its propensity to terminate spontaneously. Such awareness may prevent the delivery of unnecessary defibrillatory shocks.

Acute Disease

Prehospital recognition of multifocal atrial tachycardia: association with acute myocardial infarction.

Patients with chronic obstructive pulmonary disease and acute decompensation commonly present with an irregularly irregular supraventricular tachycardia that is, in fact, multifocal atrial tachycardia, but frequently misdiagnosed as atrial fibrillation. To heighten awareness of this arrhythmia, its clinical and electrocardiographic presentations, and its potential therapeutic implications, two patients are reported who presented with multifocal atrial tachycardia during prehospital care. In these two patients the clinical substrate was not chronic obstructive pulmonary disease but instead acute myocardial infarction. By means of a high index of clinical suspicion and close scrutiny of an electrocardiogram, a diagnosis of multifocal atrial tachycardia can be established during prehospital management, and potentially ineffective therapeutic interventions can be avoided, both during prehospital care and in the emergency department.

Aged

Protective effects of a novel perfluorochemical emulsion in photodynamic therapy.

The effects of pre-injection of mice with a novel perfluorodecalin-based emulsion on the responses to photodynamic therapy (PDT) using the photosensitizer, metatetra (hydroxyphenyl) porphyrin (m-THPP), have been studied. Injection of emulsion after m-THPP and before illumination (activating wavelength 648 nm) protected skin against PDT-induced inflammatory effects, as reflected by decreases (P less than 0.05) in vascular permeability and oedema formation. However, there was no protection against epidermal cell loss. In contrast, injection of emulsion before sensitizer had no corresponding effect. A fall in mean dermal temperature of up to 6 degrees C occurred in mice injected with emulsion 1-2.5 h before illumination suggesting a decrease in skin blood flow which would reduce oedema formation. Possible mechanism(s) for this apparent protective effect are discussed.

Animals

Single-lung transplantation with atrial septal defect repair for Eisenmenger's syndrome.

Heart-lung transplantation has been used successfully for patients with pulmonary vascular disease but its application has been very limited due to the scarcity of donors. We report a patient with Eisenmenger's syndrome who underwent right single-lung transplantation with closure of atrial septal defect; postoperative convalescence was uneventful. Serial magnetic resonance imaging examinations demonstrate improved right heart function.

Adult

Anatomic validation of electrocardiographic estimation of the size of acute or healed myocardial infarcts.

Seventeen new criteria added to the simplified version of the Selvester QRS scoring system to comprise the complete version were evaluated to determine their value in estimating the size of single infarcts. These non-Q-wave criteria might be particularly useful regarding posterolateral infarcts in the distribution of the left circumflex artery. The study population was made up of 21 anterior, 30 inferior and 20 posterolateral single myocardial infarction (MI) patients with no evidences of bundle branch or fascicular blocks, ventricular hypertrophy or previous MI on their final stable electrocardiogram. The complete system's maximum 32 points is capable of indicating MI in 96% of the left ventricle and it estimated a mean electrocardiographic MI size that better approximated the anatomic size compared with the simplified version in all MI locations. The correlation between anatomic and electrocardiographic MI size using the complete system was better and statistically significant for the posterolateral MI group (simplified r = 0.55, p less than 0.01 vs complete r = 0.70, p less than 0.0006). Criteria such as Q and S amplitude less than or equal to 0.3 mV in V1 and less than or equal to 0.4 mV in V2 were particularly helpful. This study documents the improved ability provided by the 17 additional non-Q-wave criteria which have been added in the complete version of this scoring system regarding the sizing of infarcts in the region of the left ventricle supplied by the left circumflex artery.

Electrocardiography

Perfluorochemicals and photodynamic therapy in mice.

The effects of pre-treatment with a novel PFC emulsion on PDT-induced tumor necrosis have been studied in mice. Injection of emulsion either 2.5 hr or 24 hr before PDT did not affect the depth of tumour necrosis. However, pre-treatment with the emulsion appeared to protect skin against photodynamic damage although the mechanism(s) and active principle(s) involved were not identified. These results suggest that there may be specific advantages in using emulsified PFCs in conjunction with PDT which may be independent of changes in tumour oxygenation.

Animals

Induction of maternal toxicity in the rat by dermal application of retinoic acid and its effect on fetal outcome.

Time-mated Sprague-Dawley rats were administered all-trans-retinoic acid (RA) dermally on gestational days 11 through 14 at three dosage levels (25, 100, and 250 mg/kg body weight). Dams administered ethylenethiourea (ETU) dermally on gestational days 11 to 12 or RA orally on day 12 were used to indicate the strain's sensitivity to teratogenesis. The chemicals were dissolved in dimethylsulfoxide (DMSO) for dermal application or suspended in corn oil for treatment by gavage. The maternal weight gain, pup weight, number of resorptions and number of fetuses with gross malformations, and skeletal/organ-level anomalies were determined. Beginning with day 15, dams dermally treated with RA exhibited dermal lesions at the site of application, most dams showed vaginal bleeding by day 16, and approximately 20% did not survive to day 19. Relative to the DMSO control group, maternal weight gain in the dermal RA groups was decreased by approximately 50% at the lowest dose, with essentially no weight gain at the intermediate- and high-dose levels. The decrease in average fetal weight at the two higher doses was significant, whereas the resorption and malformation frequencies were not significantly increased by dermal treatment with RA. Without significantly affecting fetal weight or resorption frequency, dermal application of ETU significantly increased the frequency of skeletal anomalies, primarily tail defects. Oral administration of RA did not increase the malformation frequency nor produce significant maternal or fetotoxic effects. In summary, treatment of pregnant Sprague-Dawley rats by dermal application of RA dissolved in DMSO resulted in significant toxicity to the dam.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced