Latest News - Part 32
Comparison of Cardiac Pacing Modes in Patients With Chronic Obstructive Pulmonary Disease – Results
All patients with COPD had sinus node dysfunction, including four with chronotropic incompetence. All had AV nodal disease, three 3° AV block, four 1° AV block, and one 2° AV block. Three of these patients had documented retrograde conduction and a history of pacemaker syndrome in the WI mode. However, only one of these patients demonstrated a symptomatic pacemaker syndrome, that is, retrograde conduction and a drop in blood pressure during testing in this study. In patients with normal lung function, all had sinus node disease, including seven with chronotropic incompetence, four had AV nodal disease, one had 3° AV block, and three had 1° AV block. Two patients had demonstrated retrograde conduction in the WWVIR mode during testing in this study, though they did not have a simultaneous fall in blood pressure. Both of these patients had a documented history of pacemaker syndrome in the WI mode. An additional three patients in this group had a documented history of pacemaker syndrome in the WI mode, but this was not observed during testing in this study (Table 1). No cardiac arrhythmias occurred during exercise, and there were no adverse pacemaker interactions with underlying rhythms. asthma inhalers
Comparison of Cardiac Pacing Modes in Patients With Chronic Obstructive Pulmonary Disease – Methods
Spirometry was used to evaluate baseline lung function for each patient. This was performed prior to exercise, with the patient standing. Patients were required to perform three reproducible forced expiratory and inspiratory maneuvers. All patients were then evaluated with paired exercise testing using the Chronotropic Assessment Exercise Protocol Pulmonary gas exchange, exercise duration, heart rate, and rhythm were measured during exercise.
Although there may be some variability in exercise results with serial testing when several exercise tests are done on the same day or on different days, attempts were made to minimize any inadvertent bias by random selection of the pacing modes and strict adherence to the study protocol. A minimum of 2 h was allowed between each exercise study. Cardiac output was obtained at rest and immediately after maximum exercise using echo-Doppler techniques. Stroke volume was determined from the flow velocity integral recorded with the Doppler sample volume positioned in the left ventricular outflow tract. Cardiac output determination by echo-Doppler technique has been shown to be reliable in measuring qualitative changes. buy claritin online
Comparison of Cardiac Pacing Modes in Patients With Chronic Obstructive Pulmonary Disease – Patient Population
Limitations in exercise tolerance are a common manifestation of patients with chronic lung disease. Compromised pulmonary mechanics limit the ability of the lungs to respond to increasing oxygen demands. This leaves these patients dependent on other mechanisms to deliver available oxygen to the tissues to support the metabolic demands of exercise. Optimizing cardiac output is, therefore, important to provide maximum oxygen delivery. This is no less important for patients with moderate to severe lung disease who develop symptomatic bradycardia and require implantation of a cardiac pacemaker. This study was designed to compare the relative efficacy in optimizing cardiac performance and exercise capacity of two different cardiac pacing modes. The relatively complex dual chamber adaptive rate pacing (DDDR) was compared with the significantly simpler ventricular adaptive-rate pacing (WIR) in patients with lung disease who require pacemaker implantation for symptomatic bradycardia. buy flovent inhaler
The Third Epidemic—Multidrug-Resistant Tuberculosis: Discussion
During the past decade, the incidences of HIV infection and ТВ have ascended to epidemic proportions in several major US cities. At Bellevue Hospital Center in Manhattan, the incidence of MDR-TB has increased sevenfold in 1991 as compared with any of the previous 20 years. buy antibiotics online
Several case series have been reported by the Centers for Disease Control in which M tuberculosis isolates were resistant to first-line anti-ТВ medications. In a cooperative Centers for Disease Control-New York City Department of Health study, 466 cultures positive for M tuberculosis were tested for drug susceptibilities from laboratories throughout the city collected during April 1991. Thirty-three percent had resistance to one or more anti-ТВ drugs and almost 20 percent had resistance to both isoniazid plus rifampin. Patients who were currently or previously treated with anti-ТВ drugs were more likely to have resistant organisms than those who had not been previously treated. Of isolates obtained from Bellevue for this cooperative study, 13 of 50 (26 percent) were resistant to both isoniazid plus rifampin, suggesting that our reported rates may actually be underestimates. Chawla and colleagues found an overall resistance rate of 30.9 percent to one or more drugs at Kings County Hospital in Brooklyn. More than half (56.6 percent) of those resistant were resistant to more than one drug. They found a combined pattern of isoniazid-plus-rifampin resistance in 30.2 percent of cases. Our results showed an overall resistance rate of 33 percent, and also that patients were most commonly resistant to isoniazid (25 percent) followed by rifampin (20 percent). Our patient population showed a similar distribution with an isoniazid-rifampin resistance of 16 percent and an isoniazid-rifampin-streptomycin-ethambutol resistance of 13 percent. These figures are especially disturbing, since the case fatality rate for MDR-TB exceeds 50 percent, and approaches 90 percent among HIV-positive individuals.
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The Third Epidemic—Multidrug-Resistant Tuberculosis: Results
We analyzed the drug susceptibilities of 4,681 cases of ТВ from 1971 to 1991 at Bellevue Hospital Center, finding a dramatic increase in MDR-TB (isoniazid plus rifampin) in 1991 (Fig 1). There was an increase from a baseline of 2.5 to 16 percent combined isoniazid plus rifampin resistance in 1991. Among the 224 positive initial isolates collected over the first 6 months of 1991, the following drug resistances were found: 25 percent isoniazid, 20 percent rifampin, 17 percent streptomycin, and 14 percent ethambutol. Of these cases, 16 percent were isoniazid-plus-rifampin-resis-tant, and 13 percent were resistant to isoniazid, rifampin, streptomycin, and ethambutol. review
To define the clinical characteristics of this epidemic, we evaluated 100 consecutive DR-ТВ patients on the Chest Service and compared them to 54 randomly selected DS-TB patients over a 10-month period. Demographic data were similar in the DR-TB and DS-TB groups (Table 1). The patients we studied had a mean age of 40 years with 75 percent of the patients less than 44 years old. Ninety percent of the patients were male, and 85 percent were Hispanic or black. All of the patients admitted were unemployed, and approximately 65 percent were homeless.
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The Third Epidemic—Multidrug-Resistant Tuberculosis: Methods
The reported incidence of tuberculosis (ТВ) declined for decades in the United States reaching a nadir of 22,255 cases in 1984, but then leveled off and began to rise. During the period from 1985 to 1991, approximately 39,000 excess cases occurred over and above the expected number. This alarming reversal of the downward trend in incidence of ТВ is primarily attributed to AIDS and secondly, worsening urban economic and social conditions. An economic downturn has led to an increase in homelessness, and budget reductions or even elimination of public health programs involved with ТВ control have exacerbated the problem. In addition to the above factors, changes in immigration patterns have led to an influx of immigrants from countries with endemic ТВ (ie, Mexico, Haiti, Vietnam, China).
Several cities within the United States have been hit especially hard by this increase in the incidence of ТВ. In New York City, case rates have been rising since 1979 with 3,673 new cases in 1991 and a case rate of 50.2/100,000 population. This incidence of new cases represents a 143 percent increase over the incidence in 1980. According to the New York City Department of Health, the case rate is the highest in two decades and is five times the national rate. In fact, in 1991, New York City alone accounted for 14 percent of the nation’s 26,283 reported cases of ТВ. canadian neighbor pharmacy
The Lack of Effect of Routine Magnesium Administration on Respiratory Function in Mechanically Ventilated Patients: Finally
The role of worsening diaphragmatic weakness as an acute cause of failure to wean from mechanical ventilation is not well defined. Several reviews have concluded that inspiratory muscle weakness may predispose to acute respiratory failure or complicate weaning from mechanical ventilation. The corollary of this would be that treatment aimed at improving respiratory muscle strength should help to hasten weaning from mechanical ventilation. We did not specifically test whether magnesium infusion would shorten the time to successful weaning but rather tested whether magnesium infusion improved respiratory muscle performance. We did, however, find that those patients who increased VC most following magnesium infusion (ie, change in VC greater than 0) tended to be more rapidly weaned from mechanical ventilation (5 ±2 days) compared with those patients who did not demonstrate an increase in VC (9 ±8 days). This, however, may merely reflect the tautology that patients wean when they improve.