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Large pleural effusions are typically associated with dyspnea and potential respiratory compromise. Experimental evidence suggests that with large effusions, increased intrapleural pressure may be transmitted to the pericardial space, resulting in impaired cardiac filling and reduced stroke volume. We report two cases in which large pleural collections were complicated by hypotension. The effusions were due to an infected right hepatic hydrothorax (Case 1) and a left malignant effusion (Case 2). Echocardiography demonstrated right and left ventricular diastolic collapse, respectively, confirming a diagnosis of cardiac tamponade. Large volume thoracentesis resulted in immediate hemodynamic improvement as demonstrated by a reduction in right ventricular and atrial pressures (Case 1) and echocardiographic resolution of left ventricular diastolic collapse (Case 2). These cases establish that large pleural effusions can cause hemodynamically significant cardiac tamponade. In addition, they illustrate how the demonstration of cardiac compressive physiology can significantly alter the therapeutic approach to large pleural effusions.
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PMID:Clinical, echocardiographic, and hemodynamic evidence of cardiac tamponade caused by large pleural effusions. 788 90

We evaluated the effects of Escherichia coli endotoxin on the peripheral vascular hemodynamics and myocardial function of the newborn lamb to understand how gram-negative endotoxemia can lead to cardiovascular collapse in newborn infants. Fifteen lambs, 0-3 d old, were acutely instrumented with a micromanometer-tipped catheter and two pairs of ultrasonic crystals to measure left ventricular (LV) pressure and LV anterior-posterior and septal-free wall dimensions, a fluid-filled catheter for monitoring aortic pressure, and an electromagnetic flow probe to measure systemic blood flow. Cardiovascular performance was evaluated by measuring or deriving the following variables: mean arterial blood pressure (MABP), LV pressure, heart rate, stroke volume, systemic vascular resistance, LV dp/dt, end-diastolic area, arterial elastance, and end-systolic elastance (the slope of the end-systolic pressure-area relationship) as an index of contractility independent of loading conditions and heart rate. Once instrumented, nine lambs received endotoxin, 0.5 mg/kg i.v., and six animals, serving as controls, received a saline infusion. Of the endotoxin-treated lambs, five survived the duration of the study (120 min from the beginning of the endotoxin infusion), and four died by 90 min from the beginning of the endotoxin infusion. No significant changes in any of the cardiovascular variables occurred in the control group. A significant decrease in MABP was seen in all endotoxin-treated animals by 45 min after the beginning of the endotoxin infusion. MABP decreased by 52% from baseline in the survivors and 38% in the nonsurvivors. In the survivors, the MABP stabilized with saline boluses, whereas in the nonsurvivors MABP continued to decrease until death.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Escherichia coli endotoxin depresses left ventricular contractility in neonatal lambs. 813 1

The high prevalence of obstructive sleep apnea (OSA) has only recently been appreciated, in part because the symptoms and signs of chronic sleep disruption are often overlooked in spite of their debilitating consequences. They typically develop insidiously during a period of years. We now know that the lives of millions of people each year are significantly impaired by the sequelae of OSA. Many of these patients go unrecognized, with tremendous medical and economic consequences for individual patients and for society. Evidence indicates that chronic, heavy snoring may be associated with increased long-term cardiovascular and neurophysiologic morbidity. Therefore considerable interest lies in the study of the epidemiology and the natural history of these related disorders. The fundamental problem in OSA is the periodic collapse of the pharyngeal airway during sleep. The pathophysiology of this phenomenon is reviewed in some detail. During apneas caused by obstruction, airflow is impeded by the collapsed pharynx in spite of continued effort to breathe. This causes progressive asphyxia, which increasingly stimulates breathing efforts against the collapsed airway, typically until the person is awakened. Hypopneas predominate in some patients and are caused by partial pharyngeal collapse. The clinical sequelae of OSA relate to the cumulative effects of exposure to periodic asphyxia and to sleep fragmentation caused by apneas and hypopneas. Some patients with frequent, brief apneas and hypopneas and normal underlying cardiopulmonary function may have considerable sleep disruption without much exposure to nocturnal hypoxia. Patients with sleep apnea often have excessive daytime sleepiness. As the disorder progresses, sleepiness becomes increasingly irresistible and dangerous, and patients develop cognitive dysfunction, inability to concentrate, memory and judgment impairment, irritability, and depression. These problems may lead to family and social problems and job loss. Cardiac and vascular morbidity in OSA may include systemic hypertension, cardiac arrhythmias, pulmonary hypertension, cor pulmonale, left ventricular dysfunction, stroke, and sudden death. The challenge for the clinician is to routinely consider the diagnosis and to incorporate several basic questions in the historical review of systems regarding daytime or inappropriate sleepiness. The diagnosis of OSA is made with polysomnography, and the decision to treat is based on an overall assessment of the severity of sleep-disordered breathing, sleep fragmentation, and associated clinical sequelae. The therapeutic options for the management of OSA are reviewed. Recognition and appropriate treatment of OSA and related disorders will often significantly enhance the patient's quality of life, overall health, productivity, and safety on the highways.
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PMID:Obstructive sleep apnea. 814 53

Obstructive sleep apnea affects millions of individuals. It usually is due to pharyngeal collapse during sleep, resulting in daytime somnolence. This can have grave consequences on everyday life and in the long term can lead to pulmonary and systemic hypertension, myocardial disease, and stroke. Non-structural obstructive sleep apnea can be relieved by tracheostomy and continuous positive airway pressure, two methods that bypass the overly compliant pharyngeal musculature during inspiration. It may well be desirable to exchange a dynamic and more physiologic approach to obstructive sleep apnea for these purely static solutions. This approach should restore disturbed cyclical stiffening of the upper airway by electronically stimulating the appropriate muscles, timed by information originating during the inspiratory effort. The open-loop systems proposed here are based upon principles pioneered by us for the rehabilitation of the paralyzed larynx that are now well within practical reach of current technologies.
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PMID:The potential for neurostimulation in obstructive sleep apnea. 818 85

In eight recreational runners (seven men and one woman, aged 16 to 50 years) participating in a 16 kilometer run, disturbances in thermoregulation were diagnosed. Six experienced sudden collapse without any prodromal signs, two were exhausted and had muscle spasms. Heat exhaustion was diagnosed in four runners, exertion-related hyperthermia in three and exertion-related heat stroke in one. As a complication the latter patient developed rhabdomyolysis with low grade intravascular coagulation and acute renal insufficiency. The most important therapy consists of cooling the patient, the most important preventive measures are wearing light clothing and drinking regularly during the run.
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PMID:[Exertion-related disorders in body temperature regulation in 8 participants in the Dam-to-Dam run 1993]. 819 77

We studied the results for seventeen patients (eighteen feet) who had had a triple arthrodesis at an average age of sixty-six years (range, fifty-two to eighty years). There were twelve women and five men. The procedures had been performed to correct deformities of the hindfoot and midfoot caused by an untreated rupture of the posterior tibial tendon in ten patients; by rheumatoid arthritis in three patients (four feet); and by neuropathic arthropathy (associated with diabetes mellitus), trauma, old poliomyelitis, and a stroke in one patient each. The average duration of follow-up was forty-two months (range, twenty-seven to 156 months). At the most recent follow-up examination, three patients had a non-union (one, of the talonavicular joint and two, of the calcaneocuboid joint), six patients (seven feet) had progressive degenerative joint disease involving the ankle, seven had progressive degenerative changes in the mobile joints of the feet, two had had an infection but both infections had healed, and one had had postoperative collapse of the foot because of premature, unauthorized weight-bearing. In one patient, a staple across the subtalar joint had been removed because of pain caused by impingement of the staple on the tip of the fibula. Over-all, fourteen of the seventeen patients were satisfied with the result of the operation. All seventeen had less pain postoperatively, but eleven still had some discomfort.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Triple arthrodesis in older adults. Results after long-term follow-up. 844 13

Age-related changes, for example reduced elasticity and earlier airways collapse, predispose the elderly to respiratory infection. Other factors such as a lifetime of smoking, the use of hypnotics, or the development of stroke also predispose. Pneumonia becomes increasingly common with advancing age, and both morbidity and mortality increase with associated disease burden. Diagnosis of pneumonia may be more difficult in the aged because of physiological changes. However, careful physical examination with accurate, regular recording of body temperature will usually reveal the characteristic features of pneumonia, which should be confirmed by chest radiograph. In the frail elderly, the onset of impaired function, such as confusion, immobility, falling or incontinence, should raise suspicion of infection. Pneumonia is classified as community-acquired, nursing home-acquired or nosocomial, which helps in the empirical choice of antibiotics. Streptococcus pneumoniae is the most common organism in the community, then Haemophilus influenzae and Branhamella catarrhalis. Gram-negative organisms like Klebsiella and Escherichia coli are more common in nosocomial infections. Nursing home patients with pneumonia tend to be more frail than those in the community. Treatment is directed at eradication of the organism with the appropriate antibiotic, maintaining hydration and oxygenation, as well as managing impaired mobility, faecal loading, urinary incontinence and confusion. Influenza vaccination is strongly recommended for the frail elderly. Tuberculosis remains an important diagnosis in the frail elderly and should always be considered, especially in patients with respiratory infection who fail to respond to conventional therapy.
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PMID:Treatment recommendations for respiratory tract infections associated with aging. 845 84

Although rare, exertional collapse and sudden death are the most serious potential complications of sickle cell trait. Studies suggest that this condition may occur in susceptible persons when poor physical conditioning, dehydration, heat stress or hypoxic states precipitate sickling of the abnormal erythrocytes. Sickling leads to endothelial damage, which can cause vasoconstriction, disseminated intravascular coagulation and local tissue damage. Cardiac effects include acute ischemia and arrhythmias. Muscle damage results in acute compartment syndromes and release of myoglobin into the circulation. Acute renal failure is possible. Diagnosis is based on a high index of suspicion, and characteristic presentation and laboratory findings, including myoglobinuria, hyperkalemia, hypocalcemia, hyperphosphatemia and elevated creatine kinase levels. The differential diagnosis includes pulmonary embolism, acute cardiac events, anaphylaxis and heat stroke. Management is based on stabilization, rehydration, and the treatment and prevention of complications.
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PMID:Exertional collapse and sudden death associated with sickle cell trait. 904 99

Rewarming from accidental hypothermia is associated with fatal circulatory derangements. To investigate potential pathophysiological mechanisms involved, we examined heart function and metabolism in a rat model rewarmed after 4 h at 15-13 degrees C. Hypothermia resulted in a significant reduction of left ventricular (LV) systolic pressure, cardiac output, and heart rate, whereas stroke volume increased. The maximum rate of LV pressure rise decreased to 191 +/- 28 mmHg/s from a control value of 9,060 +/- 500 mmHg/s. Myocardial tissue content of ATP, ADP, and glycogen was significantly reduced, whereas lactate content remained unchanged. After rewarming, heart rate returned to control value, whereas LV systolic pressure, cardiac output, and stroke volume all remained significantly depressed. The posthypothermic maximum rate of LV pressure rise was 5,966 +/- 1.643 mmHg/s. The posthypothermic myocardial lactate content was significantly increased (to 13.3 +/- 3.2 nmol/mg from control value of 5.7 +/- 1.9 nmol/mg), and ATP and glycogen remained significantly lowered. Creatine phosphate or energy charge did not change significantly during the experiment. The finding of deteriorated myocardial mechanical function and a shift in energy metabolism shows that the heart could be an important target during hypothermia and rewarming in vivo, thus contributing to the development of a posthypothermic circulatory collapse.
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PMID:Experimental hypothermia and rewarming: changes in mechanical function and metabolism of rat hearts. 884 17

Acute decompensating cardiomyopathy induced by cyclophosphamide is usually irreversible. To investigate the clinical course and the outcome of therapy, 13 patients (1.7%) with grade III acute cardiomyopathy and hypotension who were treated with ablative transplant regimens between January 1980 and September 1995 were analyzed. Eight of nine patients died of acute fatal restrictive cardiomyopathy with unresponsive hypotension (ARCH), whereas three of four patients who survived the initial episode died of subacute congestive heart failure (SCHF). Acute fatal restrictive cardiomyopathy was characterized with extreme sensitivity to volume overload, myocardial edema and a rapidly fatal course. It was associated with progressive, unresponsive hypotension, reduced left ventricular stroke work index (LVSWI: 29.29 +/- 9.74 g-m/beat/m2) and markedly reduced systemic and pulmonary vascular resistance indices (SVRI: 429.72 +/- 168.84, PVRI: 58.63 +/- 45.08 dyne.sec/cm5.m2). Subacute CHF was identified by myocardial edema, dilated chambers and biventricular pump failure represented by decreases in fractional shortening (FS: 19.5 +/- 4.9%). Of 10 patients who received conventional therapy, nine died and one sustained chronic CHF. One of three patients with ARCH on antioxidant therapy of ascorbic acid and theophylline survived the episode. The data suggests peripheral vascular collapse may also be responsible for fatal ARCH.
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PMID:Fatal cyclophosphamide cardiomyopathy: its clinical course and treatment. 887 20


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