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Biomedical subjects

H L Snider

Publications and source records attributed to H L Snider.

At least 19 recordsLinked to original sources
PubMed1994

Understanding the metabolic response to critical illness: factors that cause patients to deviate from the expected pattern of hypermetabolism.

Resting energy expenditure is comprised by the sum of the metabolic needs of the peripheral tissues and individual organ systems, influenced by an interaction between thyroid hormone and the sympathetic nervous system. Multiple primary, secondary, and tertiary factors affect this sum to generate the total energy expenditure. Disease processes may increase energy expenditure through direct (stimulating the sympathetic nervous system, increasing oxygen delivery, raising body temperature, increasing motor activity) or indirect processes (uncoupling effect, inefficient metabolism, release of cytokine mediators). Not all patients demonstrate the classic hypermetabolic response. A number of factors involving treatment, weight, choice of predictive formula, timing of the metabolic study, nutritional support, and level of consciousness may contribute in a factitious manner to a hypometabolic response. In some patients, a true serial progressive pattern of inappropriate low metabolism may imply impending septic shock and identifies that patient at risk for organ failure and increased mortality. Serial indirect calorimetric studies may be needed in the intensive care setting to adequately establish patterns of response to critical illness.

Body Temperature↗
PubMed1993

Primary spontaneous pneumothorax. Therapeutic considerations.

Primary pneumothorax represents the single most frequent cause of admission of young adults to a hospital's thoracic service. However, the best management of these patients with rupture of subpleural blebs in the apical region remains controversial. In a retrospective analysis of 108 consecutive patients with spontaneous primary pneumothorax treated at a university hospital over a 5-year period, we were able to examine the risks and benefits of various treatment approaches. Interestingly, although male patients outnumbered female patients approximately 2:1, female patients were statistically more likely to undergo operative intervention.

Adolescent↗
PubMed1992

Immunonutrition and enteral hyperalimentation of critically ill patients.

Physicians need to be maximally aggressive in their use of total enteral nutrition (TEN) in the critically ill patient, due to its lower cost, better physiology, and lower complication rate when compared to parenteral therapy. Various components in TEN such as glutamine, arginine, RNA nucleotides, omega-3 fish oils, and fiber, may have important roles in immunonutrition by maintaining gut integrity, stimulating the immune system, and preventing bacterial translocation from the gut. For each patient, the physician must choose the optimal enteral formula for that particular disease or organ failure state to maximize nutrient substrate assimilation and tolerance. Total parenteral nutrition (TPN) should be used only when a true contraindication to enteral feedings exists or as adjunctive therapy when full nutritional requirements cannot be met by TEN alone.

Contraindications↗
PubMed1992

Use of indirect calorimetry in clinical nutrition.

The tremendous variability in resting energy expenditure makes efforts to predict caloric requirements difficult. Indirect calorimetry has provided a valuable tool in assessing energy expenditure, evaluating the way in which the body uses nutrient fuel, and designing nutritional regimens that best fit the clinical condition of the patient. The many indirect calorimetric instruments available vary in their application to clinical nutrition. The best metabolic studies are achieved by controlling the testing environment, accounting for the many clinical factors that may affect measurements, and eliminating potential sources for error. Although indirect calorimetry would seem to reduce the likelihood of complications from overfeeding, its greatest effect may be in cost savings by avoiding unnecessary nutritional support and in providing a means for clinical research.

Bias↗
PubMed1989

Autonomic influence on cardiovascular performance in diabetic subjects.

PURPOSE: Cardiomyopathy, coronary artery atherosclerosis, or autonomic neuropathy may affect the cardiovascular performance of the diabetic patient. To evaluate the role of parasympathetic nervous system activity on cardiovascular performance, 25 diabetic subjects who lacked symptoms, signs, or objective measurements of ischemia or cardiomyopathy were studied. PATIENTS AND METHODS: Diabetic subjects were classified according to their RR variation, an index of cardiac parasympathetic nervous system activity. Fourteen diabetic subjects had a normal RR variation of greater than 30 (D-NOR), and 11 diabetic patients had an abnormal RR variation of less than 20 (D-ABN). Fifteen age- and weight-matched, healthy, nondiabetic subjects (NOR) constituted the control group. All subjects had oxygen consumption, multigated acquisition determination of cardiac output, and work product measured before and during supine bicycle maximum exercise testing. RESULTS: There was no difference in the resting cardiac output among the groups. Resting work product, however, was greatest in the D-ABN group when compared with performance in the other two groups (D-ABN: 11,500 +/- 800; D-NOR: 9,000 +/- 600; NOR: 8,700 +/- 400; p less than 0.0025). This was due to an increase in both heart rate (p less than 0.025) and systolic blood pressure (p less than 0.015). In the diabetic subjects, there was an inverse relationship between the RR variation and resting work product (r = 0.47, n = 25, p less than 0.005). In response to exercise, the percent increase in cardiac output at matched percent maximum oxygen uptake was greatest in the NOR, D-NOR, and D-ABN groups, respectively (analysis of variance, p less than 0.01). In the diabetic subjects, there was a significant relationship between the RR variation and the maximum percent change in cardiac output (r = 0.41, n = 25, p less than 0.02). Compared with the NOR group, the maximum increase in work product was impaired in diabetic subjects (p less than 0.002) and not different between the D-NOR and D-ABN groups. CONCLUSIONS: The increase in resting work product and the poor cardiac output responses to exercise in the D-ABN group are due to a decrease in cardiac parasympathetic nervous system activity and can be suggested by an abnormal RR variation. This index of parasympathetic nervous system activity can help the physician identify that subset of diabetic patients that may need special consideration when exercise training is prescribed.

Adult↗
PubMed1989

Resting gas exchange in nonsmoking bituminous-coal miners with simple pneumoconiosis.

Gas exchange at rest under normoxic conditions was studied in 2,297 nonsmoking bituminous-coal miners with and without simple coal workers' pneumoconiosis (CWP). Measurements of arterial oxygen tension (Pao2) and arterial carbon dioxide tension (Paco2) from blood gas samples obtained at rest in the seated position were used to calculate the alveolar-arterial oxygen tension difference, (A-a)Do2, using the classic alveolar-air equation. We then recalculated the (A-a)Do2 using the age-predicted Pao2 for each miner. The difference between the actual and the predicted (A-a)Do2 was measured and the mean difference for each category of simple CWP was analyzed. We found no evidence that the resting gas exchange differs significantly from the age-predicted (A-a)Do2 in the nonsmoking bituminous-coal minor with simple CWP. Likewise, there is no significant change in (A-a)Do2 with change in the category of simple CWP.

Age Factors↗
PubMed1989

Pulmonary complications after tricyclic antidepressant overdose.

We studied 82 consecutive patients admitted to the ICU with predominant tricyclic antidepressant overdose (mean plasma tricyclic level, 1,025 ng/ml) to determine the nature and incidence of respiratory complications. The majority of patients (80.4 percent) had a decreased arterial to alveolar oxygen tension ratio (PaO2/PAO2) on initial emergency room arterial blood gas analysis (mean, 0.56). Mechanical ventilation was required in 76.8 percent of the patients for a mean duration of 46.2 h. Chest radiograph abnormalities developed during the first 48 h in 32/82 patients (39 percent). The group with radiographic abnormalities had higher mean drug levels than the group without (p less than 0.05). Of 82 patients, nine (11 percent) developed radiographic evidence of bilateral alveolar infiltrates suggestive of acute lung injury. This group had significantly higher mean drug levels than the groups with other types of radiographic abnormalities (p less than 0.001). Charcoal was recovered from the airway of 18/72 patients who received activated charcoal slurry by nasogastric tube in the emergency room after endotracheal intubation. The group who aspirated did not show statistically significant difference in the incidence of chest radiograph abnormalities, gas exchange, or survival compared with the group that did not aspirate.

Adult↗
PubMed1989

Cigarette smoking and federal black lung benefits in bituminous coal miners.

The records of 1000 consecutive coal miners applying for benefits under the Federal Coal Mine Health and Safety Act were examined to determine the contribution of age, dust accumulation, and cigarette smoking to the profile of the miner who satisfies the current pulmonary criteria for disability. Using the presence of pneumoconiosis on chest radiograph as the indication of significant coal dust accumulation, the miners were separated into Group A--those without pneumoconiosis (n = 316) and Group B--those with pneumoconiosis (n = 684). The federal spirometric criteria for disability identified 55/316 miners in Group A (14.5%) and 99/684 miners in Group B (17.4%) potentially eligible for an award (P = .27). The mean ages of miners in both groups did not differ significantly, nor was there difference in the mean ages of groups that did or did not meet the federal criteria. In both groups, those miners potentially eligible for a financial award smoked more cigarettes than did their counterparts (Group A, 31.0 v 18.5 pack-years, P less than .001; Group B, 31.3 v 23.6 pack-years, P less than .001). There was no difference in the smoking histories of the miners from either group who met the federal criteria. Our data indicate that, in the case of bituminous coal miners, the present federal legislation intended to identify and remunerate those who suffer lung impairment from chronic occupational exposure to coal dust is biased in favor of those who sustain additional damage to their ventilatory capacity by smoking cigarettes.

Coal↗
PubMed1987

Variability in the evaluation of the Federal black lung benefits claimant.

A critical review of the medical data accumulated on 100 consecutive miners referred for evaluation for disability under the Federal Coal Mine Health and Safety Act documented the generation of an excess of unreliable data at an unacceptable cost, even though the evaluations had been performed by physicians who regularly perform this service. Physician training appears to have an impact on the accuracy and reproducibility of historical inquiry regarding items that would identify other causes of activity-limiting dyspnea. Physicians with pulmonary training are statistically more likely to include the cigarette smoking history, as well as history for the presence or absence of exertional chest pain and paroxysmal nocturnal dyspnea. Spirometric pulmonary functions that are supervised and interpreted by physicians with pulmonary training are less likely to show wide variation between the forced expiratory volume in 1 sec, and the direct maximum voluntary ventilation. Regardless of the source, the direct MVV measurement does not contribute additional useful information about a claimant's pulmonary impairment. Arterial blood gas analysis does not add to the discriminatory value of spirometry and should be dropped from the routine claimant's evaluation. Electrocardiography identifies cardiovascular disease in a sufficient number of applicants to make this test worthwhile. The presence or absence of pneumonconiosis on chest radiograph does not vary significantly when interpreted by the examining physician regardless of pulmonary training.(ABSTRACT TRUNCATED AT 250 WORDS)

Coal Mining↗
PubMed1985

Primary pulmonary lymphoma. A clinical and immunohistochemical study of six cases.

Six patients with lymphomatous lesions primarily involving the pulmonary parenchyma were studied. In these patients, both the history and physical findings were vague and minimal. The laboratory findings also were nonspecific, although the findings of large multiple lesions in the lungs and pleural adhesion or effusion were more consistent with lymphoma. Histologic examination revealed lymphocytic infiltration of the pulmonary parenchyma in all six patients and presence of germinal or growth centers in some areas of the lesions in four. The hilar or mediastinal lymph nodes were not involved in five patients so examined. Immunocytochemical study of cytoplasmic immunoglobulin revealed monoclonal lymphocytic proliferation in five patients and negative staining in one patient. Clinical, histologic, or immunohistochemical studies alone may not be sufficient to detect all of the lymphomatous lesions. The combined use of all of these parameters is more advantageous for accurate diagnosis of these lesions. Treatment is surgical resection. Radiotherapy or chemotherapy are used when residual disease is present after surgery. Three patients died of disseminated lymphoma 96, 42, and 8 months after diagnosis, respectively, and three patients are still alive at 18, 24, and 4 months, respectively.

Aged↗
PubMed1981

Unusual manifestations of hypereosinophilia.

The hypereosinophilic syndrome is a heterogeneous group of clinical disorders comprising a spectrum of pathologic conditions. We have described a patient with chronic eosinophilia for eight years. His course of progressive organ dysfunction and tissue infiltration by eosinophils, with myelofibrosis, lytic bone lesions, hepatomegaly, and generalized adenopathy are most compatible with a chronic myeloproliferative syndrome.

Chronic Disease↗