The frustrating problem of smoke inhalation injury.
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Animals↗
Biomedical subjects
C M Ryan
Publications and source records attributed to C M Ryan.
The psychometric and cardiac effects of pseudoephedrine in the hyperbaric environment.
STUDY OBJECTIVES: To examine the psychometric and cardiac effects of pseudoephedrine at 1 and 3 atmospheres (atm) of pressure (0 and 66 feet of sea water, respectively), and to make recommendations about the agent's safety in the diving environment. DESIGN: Double-blind, placebo-controlled, crossover study. SETTING: Monoplace hyperbaric chamber of a university hospital. SUBJECTS: Thirty active divers (mean age 38 yrs). INTERVENTION: A bank of seven tests was used to assess cognitive function during four different simulated dive combinations: placebo-1 atm, placebo3 atm, pseudoephedrine-1 atm, and pseudoephedrine-3 atm. MEASUREMENTS AND MAIN RESULTS: Heart rate and cardiac rhythm were recorded during all dives. Repeated-measures analysis of variance was used to analyze the effects of pseudoephedrine, depth, and drug-depth interaction. No significant, independent effects of pseudoephedrine were seen on any of the seven psychometric test scores (p>0.05), although the drug tended to increase anxiety scores (p=0.092). Depth resulted in a significant increase in anxiety scores (p=0.021) and a significant decrease in verbal fluency test scores (p=0.041); it had no significant effects on the other five psychometric tests (p>0.05). Pseudoephedrine caused a significant increase (p=0.036) in mean heart rate, and depth caused a significant decrease (p=0.013). Neither pseudoephedrine nor depth affected cardiac rhythm. CONCLUSION: Pseudoephedrine does not cause significant alterations in psychometric performance at 3 atm of pressure that might increase the risk of diving. Depth causes significant adverse effects on anxiety levels and semantic memory at 3 atm. Pseudoephedrine and depth have significant but opposite effects on heart rate; although, these effects are unlikely to be clinically significant during diving. It is unlikely that pseudoephedrine adds significant risk to the diver.
Adult↗
The psychometric and cardiac effects of dimenhydrinate in the hyperbaric environment.
STUDY OBJECTIVES: To examine the psychometric and cardiac effects of dimenhydrinate at 1 and 3 atmospheres (atm) of pressure (0 and 66 feet of sea water, respectively), and to make recommendations about the drug's safety in the diving environment. DESIGN: Double-blind, placebo-controlled, crossover study SETTING: Monoplace hyperbaric chamber of a university hospital. SUBJECTS: Thirty active divers (mean age 38 yrs). INTERVENTIONS: A bank of seven tests was used to assess cognitive function during four different dive combinations: placebo-1 atm, placebo-3 atm, dimenhydrinate-1 atm, and dimenhydrinate-3 atm. MEASUREMENTS AND MAIN RESULTS: Heart rate and cardiac rhythm were recorded during all dives. Repeated-measures multivariate analysis of variance was used to analyze the effects of dimenhydrinate, depth, and drug-depth interaction. Dimenhydrinate resulted in a significant decrease in scores of mental flexibility (trail-making, part B, p<0.05) but had no effect on scores in the six other psychometric tests (p>0.05). It had no effect on mean heart rate (p>0.05), although frequent unifocal ventricular ectopic beats occurred in two subjects after ingestion of the drug. Depth resulted in a significant decrease in verbal memory test scores (p=0.001) and mean heart rate (p<0.001). CONCLUSION: Dimenhydrinate adversely affects mental flexibility. This effect, when added to the adverse effect of depth on memory, may contribute to the dangers of diving.
Aged↗
Circumscribed cognitive dysfunction in middle-aged adults with type 2 diabetes.
OBJECTIVE: To examine the extent to which type 2 diabetes is associated with poorer performance on measures of learning, memory, psychomotor speed, and problem-solving in middle-aged adults. RESEARCH DESIGN AND METHODS: This cross-sectional study evaluated 50 adults (age range 34-65 years, mean 50.8) with type 2 diabetes and 50 demographically similar community control subjects without diabetes. Each subject received a thorough physical examination and a detailed neuropsychological assessment. Factor analysis was used to assign specific tests to 1 of 4 cognitive domains (learning, memory for stories, problem-solving, and psychomotor speed). Hierarchical regression analysis was used to identify demographic and biomedical variables associated with cognitive dysfunction. RESULTS: Learning, memory, and problem-solving skills were unaffected by type 2 diabetes. In contrast, psychomotor slowing was predicted by a diagnosis of diabetes (r2 change = 0.075, P < 0.002) with additional variance in psychomotor efficiency explained independently by HbA1 (r2 = 0.064, P < 0.003) and vibratory threshold (r2 = 0.112, P < 0.0001). The magnitude of psychomotor slowing on specific tests ranged from 12% (Digit Vigilance) to 23% (Grooved Pegboard). CONCLUSIONS: Middle-aged adults with type 2 diabetes manifest psychomotor slowing that is associated with poorer metabolic control, whereas learning, memory, and problem-solving skills appear to be largely intact. The development of psychomotor slowing may be a manifestation of a "central neuropathy" induced by chronic hyperglycemia.
Adult↗
Adherence in chronic disease.
Nonadherence to treatment regimen is a prevalent problem of patients with chronic disorders. Approximately half of the patients with a chronic disease have problems following their prescribed regimen to the extent that they are unable to obtain optimum clinical benefit. This chapter reviews the state of knowledge regarding adherence to chronic disease regimens across the life span and demonstrates that the extent and nature of the adherence problems are similar across diseases, across regimens, and across age groups. Adherence to the commonly prescribed regimens is addressed, including pharmacological therapies, therapeutic diets, and therapeutic exercise. Randomized, controlled studies focusing on various educational, behavioral, cognitive, and affective interventions to improve adherence are included. Based on this review, further work is needed to better understand and improve adherence. New strategies for analysis and measurement will support these needed advances in the field of adherence.
Adolescent↗
The perception of safe driving ability during hypoglycemia in patients with type 1 diabetes mellitus.
PURPOSE: Insulin-induced hypoglycemia and its sequelae of cognitive impairment may place patients with type 1 diabetes at risk when driving and when making decisions about driving. Little is known about the factors that influence judgments of safe driving ability during hypoglycemia in these patients. PATIENTS AND METHODS: Thirty men and 30 women with uncomplicated type 1 diabetes (age [mean +/- SD] 33 +/- 9 years, duration 9 +/- 3 years, hemoglobin A1c level 8.7% +/- 1.0%) underwent a stepped hypoglycemic insulin clamp. Serum glucose levels were reduced from 120 mg/dL to 80, 70, 60, 50, and then 40 mg/dL during 190 minutes. At each glucose plateau, patients completed a symptom questionnaire and neuropsychological test, estimated their glucose level, and reported whether they could drive safely. RESULTS: The proportion of patients judging that they could drive safely decreased as serum glucose levels decreased from 70% at 120 mg/dL to 22% at 40 mg/dL. Men and middle-aged patients were more likely to consider it safe to drive during hypoglycemia than women and those under 25 years of age. Those who were symptomatic and those who recognized hypoglycemia were less likely to report safe driving ability during hypoglycemia. Most patients who were cognitively impaired appeared to recognize this and reported that they could not drive safely at a serum glucose level of 40 mg/dL. CONCLUSIONS: Adults with type 1 diabetes need educational reinforcement of safe driving habits, particularly to check glucose levels before driving. Glucose levels less than 70 mg/dL should be treated before driving. This information is as important for middle-aged, experienced drivers as it is for younger, inexperienced drivers.
Adult↗
Intensive diabetes therapy in childhood: is it achievable? Is it desirable? Is it safe?
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Child↗
Hypoglycemia in children with type 1 diabetes mellitus. Risk factors, cognitive function, and management.
This article examines the relationship between hypoglycemia and brain function in children with type 1 diabetes. Hypoglycemic episodes occurring in the first 5 years of life may permanently disrupt cognitive function in a subset of children with diabetes, and a single acute episode of hypoglycemia may produce a transient reduction in mental efficiency, alter the electroencephalogram, and increase regional cerebral blood flow. Because iatrogenic development of hypoglycemic unawareness and autonomic failure are the most likely mediators of moderately severe hypoglycemia, medical management efforts should be directed at the prevention of frequently recurring, mild hypoglycemia.
Adolescent↗
Acute hand burns in children: management and long-term outcome based on a 10-year experience with 698 injured hands.
OBJECTIVE: To document long-term results associated with an coordinated plan of care for acutely burned hands in children. SUMMARY AND BACKGROUND DATA: Optimal hand function is a crucial component of a high-quality survival after burn injury. This can be achieved only with a coordinated approach to the injuries. Long-term outcomes associated with such a plan of care have not been previously reported. METHODS: Over a 10-year period, 495 children with 698 acutely burned hands were managed at a regional pediatric burn facility; 219 children with 395 injured hands were followed in the authors' outpatient clinic for at least 1 year and an average of >5 years. The authors' approach to the acutely burned hand emphasizes ranging and splinting throughout the hospital stay, prompt sheet autograft wound closure as soon as practical, and the selective use of axial pin fixation and flaps. Long-term follow-up, hand therapy, and reconstructive surgery are emphasized. RESULTS: Normal functional results were seen in 97% of second-degree and 85% of third-degree injuries; in children with burns involving underlying tendon and bone, 70% could perform activities of daily living and 20% had normal function. Reconstructive hand surgery was required in 4.4% of second-degree burns, 32% of third-degree burns, and 65% of those with injuries involving underlying bone and tendon. CONCLUSIONS: When managed in a coordinated long-term program, the large majority of children with serious hand burns can be expected to have excellent functional results.
Adolescent↗
Neuropsychological study of frontal lobe function in psychotropic-naive children with obsessive-compulsive disorder.
OBJECTIVE: The authors' goal was to evaluate cognition in children with obsessive-compulsive disorder (OCD) early in their illness. METHOD: They administered neuropsychological tests to 21 pediatric patients with OCD and 21 healthy children matched for age, sex, socioeconomic status, and intelligence. The children with OCD were not depressed, and none had ever received psychotropic medication. The neuropsychological tests were used to assess the relationship between psychiatric symptoms and cognitive function. RESULTS: The children with OCD performed as well as the healthy children on the neuropsychological tests. Psychiatric symptoms and cognitive performance were not related. CONCLUSIONS: Nondepressed children with recently diagnosed OCD who had never received psychotropic medication demonstrated no cognitive impairment according to their performance on neuropsychological tests. The authors conclude that OCD symptoms may not interfere with cognitive abilities early in the illness.
Age of Onset↗
Substance use disorders and the risk of HIV infection in gay men.
OBJECTIVE: Previous studies have suggested that high rates of recent alcohol or drug use are associated with increased risk for HIV infection in gay men. To examine whether this relationship is mediated by substance use per se or by more enduring patterns of problematic substance use, lifetime DSM-III-R alcohol and other drug dependence disorders were ascertained and used to predict self-reported serostatus. METHOD: Gay men (N = 187) who had been tested for HIV and knew their serostatus (31 are HIV+) completed demographic, drug use and sexual practices questionnaires. Formal DSM-III-R psychiatric diagnoses were made on the basis of an individual interview, using the Structured Clinical Interview for DSM-III-R. RESULTS: Subjects had lifetime rates of alcohol dependence and drug dependence disorders that were two to three times higher than the general population, and 58% of the subjects who met criteria for alcohol dependence also met criteria for other substance dependence. Logistic regression analysis indicated that serostatus was best predicted by presence of both alcohol and drug dependence, and by race. When analyses were repeated in seronegative men, using unprotected anal sex as the outcome and recent substance use as predictors, no relationship between alcohol and behavior was found. CONCLUSIONS: Data do not support the view that alcohol use alone increases the risk of HIV infection in gay men. Finding that risk for HIV is highest in men with histories of both alcohol and drug problems suggests that the link between HIV infection and substance use may be mediated by "third variables" that may include personality characteristics and situational factors.
Adult↗
Memory and metabolic control in children.
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Cognition Disorders↗
Objective estimates of the probability of death from burn injuries.
BACKGROUND: Over the past 20 years, there has been remarkable improvement in the chances of survival of patients treated in burn centers. A simple, accurate system for objectively estimating the probability of death would be useful in counseling patients and making medical decisions. METHODS: We conducted a retrospective review of all 1665 patients with acute burn injuries admitted from 1990 to 1994 to Massachusetts General Hospital and the Shriners Burns Institute in Boston. Using logistic-regression analysis, we developed probability estimates for the prediction of mortality based on a minimal set of well-defined variables. The resulting mortality formula was used to determine whether changes in mortality have occurred since 1984, and it was tested prospectively on all 530 patients with acute burn injuries admitted in 1995 or 1996. RESULTS: Of the 1665 patients (mean [+/-SD] age, 21+/-20 years; mean burn size, 14+/-20 percent of body-surface area), 1598 (96 percent) lived to discharge. The mean length of stay was 21+/-29 days. Three risk factors for death were identified: age greater than 60 years, more than 40 percent of body-surface area burned, and inhalation injury. The mortality formula we developed predicts 0.3 percent, 3 percent, 33 percent, or approximately 90 percent mortality, depending on whether zero, one, two, or three risk factors are present. The results of the prospective test of the formula were similar. A large increase in the proportion of patients who chose not to be resuscitated complicated comparisons of mortality over time. CONCLUSIONS: The probability of mortality after burns is low and can be predicted soon after injury on the basis of simple, objective clinical criteria.
Adolescent↗
A rabbit model for metabolic studies after burn injury.
BACKGROUND: A rabbit burn model was developed and characterized, which will allow conduct of repeated, noninvasive and more sophisticated in vivo metabolic studies to explore the pathophysiology of burn injury, owing to its larger blood volume and tissue mass than the rat. MATERIALS AND METHODS: A 20% body surface, full thickness burn was applied to the backs of six anesthetized rabbits by immersion into a boiling-water bath for 10 s, followed by resuscitation with saline. Resting energy expenditure (REE) was measured daily in pre- and postburn periods. Whole body protein kinetics were evaluated using L-[1(-13)C]leucine tracer, on the preburn and the third postburn day. Fasting plasma glucose was also measured. RESULTS: A significant elevation of REE began on the second postburn day and reached 34 +/- 8% above the preburn level (P < 0.05, paired t test) on the third postburn day. The fasting plasma leucine flux and oxidation were significantly elevated from their preburn levels (both P < 0.05), indicating an accelerated proteolysis and a more negative body protein balance (P < 0.05); however, the rate of whole body protein synthesis did not differ significantly pre- and postburn injury. Fasting plasma glucose also increased (P < 0.001). on the third postburn day. The burn scar remained intact during the study, without any sign of infection. CONCLUSIONS: The metabolic changes observed in this animal model can be attributed to burn injury per se and they mimic those for flow phase in burn patients. This rabbit burn model should be suitable for exploring mechanistic aspects of the burn-induced changes in metabolism and nutrient balance.
Animals↗
Death in the burn unit: sterile multiple organ failure.
It has been our impression over the years that the most common cause of death in our burn patients is multiple organ failure, despite the clinical absence of uncontrolled infection at the time of death. A six year review of all deaths in our unit confirmed this impression, revealing that multiorgan failure is indeed the most common cause of death (48 patients, 67 per cent), followed rather distantly by early withdrawal of support (15 patients, 21 per cent), resuscitation failure (4 patients, 6 per cent) and isolated pulmonary failure (4 patients, 6 per cent). Finally, we found that our patients dying of multiorgan failure, although often having had multiple small infections during their course, were indeed clinically uninfected at the time of death. These findings are consistent with the supposition that uncontrolled systemic inflammation, initially triggered by tissue injury and isolated infection, persists despite control of these infections and leads to multiple organ failure and death.
Adolescent↗
Cerebral blood flow in hypertensive patients: an initial report of reduced and compensatory blood flow responses during performance of two cognitive tasks.
We asked whether the altered cerebral vasculature associated with essential hypertension might dampen or redirect the regional cerebral blood flow (rCBF) response to cognitive work. Relative rCBF was assessed with [(15)O]water positron emission tomography during a working memory task, a memory span task, and two perceptual control tasks. Unmedicated hypertensive patients and control subjects differed in rCBF response during both memory tasks. Hypertensives showed relatively diminished rCBF responses in right hemisphere areas combined with compensatory activation of homologous areas in the left cerebral cortex. Essential hypertension appears to selectively influence the circulatory reserve of portions of cerebral cortex and secondarily induce recruitment of other cortical areas to process certain tasks.
Aged↗
Evaluating the effects of treatment for medical disorders: has the value of neuropsychological assessment been fully realized?
Cognitive functioning can be affected by medical disorders and by the regimens used to treat them. To evaluate the cognitive risks and benefits of specific medical treatments, an increasing number of medical clinical trials have included a formal neuropsychological evaluation. This selective review has three goals: (a) to survey the range of assessment techniques used with different patient populations (e.g., those with diabetes, chronic obstructive pulmonary disease [COPD], hypertension, HIV, or cardiac disease) and treatment regimens (e.g., medical management, pharmacotherapy, surgery), (b) to demonstrate how cognitive outcome measures can contribute to an understanding of the value of certain treatments, and (c) to identify critical conceptual and methodological problems. The utility of this approach is incontrovertible-most large-scale medical trials have found either no adverse cognitive side effects or improved cognitive functioning following treatment. Nevertheless, before cognitive measures are routinely included in medical clinical trials, investigators will have to resolve problems that include the measurement of behavior change over time and the identification of clinically significant impairment.
Journal Article↗
Inhaled nitric oxide in burn patients with respiratory failure.
BACKGROUND: Inhaled nitric oxide (NO) has the potential to improve ventilation/perfusion matching and decrease pulmonary artery pressure in patients with profound respiratory failure. METHODS: Eight patients, average age of 35 years (range, 2.5-77 years) and burn size 49% (range, 19-80%), with inhalation injury and respiratory failure failing conventional management (average Pao2/FiO2 ratio (PFR) 85) were given inhaled NO at 20 ppm. RESULTS: An immediate mean increase in PFR of 10% and a decrease in pulmonary artery mean pressure of 7.8% was noted. At 24 hours, the average improvement in PFR was 28% and that in pulmonary artery mean pressure was 7.7%. Although not reaching statistical significance, these changes were more pronounced in those patients who went on to survive. There was no hypotension attributed to NO administration, and maximum methemoglobin levels averaged 0.9%. CONCLUSIONS: Inhaled NO can be safely administered to selected burn patients with severe respiratory failure who are perceived to be failing conventional support. Although current data are not adequate to support its general use, an immediate and sustained improvement in PFR and pulmonary artery mean pressure may correlate with eventual recovery of pulmonary function. Continued evaluation in controlled settings seems warranted and is in progress.
Administration, Inhalation↗