Biomedical subjects
Publications and source records attributed to T J Meyer.
Insomnia is common, but the causes are so diverse that careful evaluation is needed to ensure selection of effective treatment. Duration is the most important guide to intervention. Therapies include behavior modification, exercise, and medication. Drugs for patients who require long-term therapy should be selected to minimize side effects. Long-acting drugs should be used with caution in the elderly.
A diagnosis of severe obstructive sleep apnea was made after a 52-year-old hypertensive man developed a large intracranial hemorrhage. Therapeutic noninvasive positive pressure ventilation (NPPV) for obstructive sleep apnea and hypoventilation was complicated by transient unilateral orbital herniation. As best as can be determined, this represents a new, potentially deleterious side effect of NPPV.
Air leaking through the mouth has been reported in kyphoscoliotic patients receiving nasal ventilation via volume-limited ventilators. This study accessed the frequency of occurrence and effect on sleep quality of air leaking through the mouth during nocturnal nasal ventilation in patients with chest wall and neuromuscular disease using pressure-limited ventilation. Overnight and daytime polysomnography was performed in six stable experienced users of nocturnal nasal noninvasive positive-pressure ventilation (NPPV) who had chronic respiratory failure due to neuromuscular disease or chest wall deformity. All patients used the BiPAP S/T-D ventilatory support system (Respironics, Inc., Murrysville, PA). Measures included sleep scoring, leak quantitation, diaphragm and submental electromyograms (EMGs), and tidal and leak volumes. All patients had air leaking through the mouth for the majority of sleep. Sleep quality was diminished because of poor sleep efficiency and reduced percentages of slow-wave and rapid eye movement (REM) sleep. Air leaking through the mouth was associated with frequent arousals during stages 1 and 2 and REM sleep that contributed to sleep fragmentation, but arousals were infrequent during slow-wave sleep. Despite prevalent leaking, oxygenation was well maintained in all but one patient. Patients used a-combination of passive and active mechanisms to control air leaking. Although nasal ventilation improves nocturnal hypoventilation and symptoms in patients with restrictive thoracic disorders, air leaking through the mouth is very common during use. The leaking is associated with frequent arousals during lighter stages of sleep that interfere with progression to deeper stages, compromising sleep quality. Portable pressure-limited ventilators compensate for leaks, maintaining ventilation and oxygenation, but further studies are needed to determine which interfaces and ventilator techniques best control air leaking and optimize sleep quality.
Supervised, hospital-based exercise rehabilitation programs are effective for improving functional status for patients with claudication due to peripheral arterial occlusive disease. However, it has been suggested that unsupervised, home-based exercise programs, which have been relatively little evaluated, would be equally efficacious as compared with hospital-based programs. The authors tested the hypothesis that a hospital-based exercise rehabilitation program would improve treadmill exercise performance more than a home-based program. Of 20 consecutively enrolled patients with claudication, 10 were randomly placed into a supervised, hospital-based program and 10 into an unsupervised, home-based program for a three-month period. Exercise performance was evaluated by treadmill testing using a graded protocol. In addition, functional status was evaluated by the Walking Impairment Questionnaire (WIQ) and the Medical Outcomes Study SF-20 questionnaire (MOS). Patients in the hospital-based program were treated with treadmill walking three times a week for one hour/visit. Patients in the home-based program were instructed to walk at least three times a week and were contacted weekly to provide encouragement and to record compliance with the program. Patients in the hospital-based group improved peak walking time by 137%, pain-free walking time by 150%, and peak oxygen consumption by 19% (all P < 0.05). Patients reported an improved walking distance and speed according to WIQ data (both P < 0.05). In addition, the MOS physical functioning score in the hospital-based group improved by 20 percentage points (P < 0.05). In contrast, patients in the home-based program did not improve exercise performance measured on the treadmill. Improvement in the ability to walk on the treadmill was greater in the hospital-based than the home-based program (P < 0.05). The ability to walk distances was the only questionnaire measure that improved in persons who received the home-based program (P < 0.05). Preliminary results suggest that a supervised, hospital-based program is more effective for improving treadmill exercise performance than an unsupervised, home-based program.
BACKGROUND: Managed care advocates suggest that primary care gatekeepers may improve patient care and reduce costs. Training internal medicine residents in these gatekeeping functions has not been emphasized in most internal medicine programs. OBJECTIVE: To determine if residents could perform gatekeeper functions and if patient costs and satisfaction would be favorable. METHODS: Patients (n = 254) followed up by residents (n = 26) in continuity clinics at the Denver Veterans Affairs Medical Center in Denver, Colo, were divided into 2 groups. A control group of 128 was followed up by residents with no restrictions on appointments made for them. An intervention group of 126 patients were followed up by residents who had to approve all referrals made for their patients. A research nurse assisted with the approvals when the residents were rotating through other institutions. Utilization of resources, satisfaction with care, and health status were monitored over a 1-year period. RESULTS: A minor reduction of resource utilization was found in the intervention group, particularly in medication use. Significantly more visits were made to primary care providers in the intervention group (3.01 vs 2.59; P = .03). Patient satisfaction and health status were similar in both groups with a trend toward better satisfaction in the intervention group in some areas. CONCLUSIONS: Our study showed that residents can function as gatekeepers of highly complex patients and that satisfaction with care and utilization of resources does not suffer. Drug utilization and costs may be less when a gatekeeper exists.
A general method is described for constructing a helical oligoproline assembly having a spatially ordered array of functional sites protruding from a proline-II helix. Three different redox-active carboxylic acids were coupled to the side chain of cis-4-amino-L-proline. These redox modules were incorporated through solid-phase peptide synthesis into a 13-residue helical oligoproline assembly bearing in linear array a phenothiazine electron donor, a tris(bipyridine)ruthenium(II) chromophore, and an anthraquinone electron acceptor. Upon transient 460-nm irradiation in acetonitrile, this peptide triad formed with 53% efficiency an excited state containing a phenothiazine radical cation and an anthraquinone radical anion. This light-induced redox-separated state had a lifetime of 175 ns and stored 1.65 eV of energy.
This randomized, controlled clinical trial evaluated the effect of a postdischarge clinic on housestaff education and patient utilization of hospital services. Medicine housestaff were randomized either to attend a clinic once a week in which they saw all eligible patients they had recently discharged from the hospital, or to continue with usual discharge practices. We enrolled 751 patients, 312 on intervention teams and 439 on control teams. Intervention housestaff did not feel that the clinic took too much time and felt that they better knew how patients did after discharge. Fewer intervention patients had emergency room visits (28.0% to 20.8%, p = .03) in the 30 days after discharge. Length of stay, readmission rates, and mortality were similar for the two groups. We conclude that a postdischarge clinic can improve resident education and reduce postdischarge emergency room utilization.
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Our laboratory previously reported continuously monitored peak sound levels in several areas at Rhode Island Hospital. The number of sound peaks greater than 80 A-weighted decibels (dBA) was found to be high in the intensive and intermediate respiratory care unit (IRCU) areas, even at night. Environmental noise of this magnitude is potentially sleep-disruptive. Therefore, we hypothesized that nocturnal peak sound levels of > or = 80 dBA would be associated with an increase in EEG arousals from sleep in patients in the IRCU. Six patients underwent sleep monitoring while environmental peak sound levels were continuously recorded. Each 8-hour period (2200 to 0600 hours) was broken down into 30-minute segments. If there were 10 minutes or more of wakefulness in a segment, that segment was dropped from further analysis. Of the remaining 61 segments, there was a very strong correlation (r = 0.57, p = 0.0001) between the number of sound peaks of > or = 80 dBA and arousals from sleep. These 61 periods were then classified as quiet, moderately loud, and very loud based on the number of sound peaks (< or = 5, 6-15, and > 15, respectively). Analysis of variance revealed a significant difference between the number of arousals (p = 0.001) in quiet periods and that in very loud periods. We conclude that environmental noise may be an important cause of sleep disruption in the IRCU.
The marine bioluminescent dinoflagellate Gonyaulax polyedra is capable of producing various indoleamines. The first enzyme in their formation, tryptophan hydroxylase, exhibits a high-amplitude circadian rhythm with a maximum during photophase. Hydroxyindole-O-methyltransferase shows a biphasic pattern with a major maximum during scotophase. 5-Methoxylated indoleamines, such as melatonin and 5-methoxytryptamine, peak at the beginning and in the second half of scotophase, respectively. A drop in temperature from 20 to 15 degrees C leads to dramatic increases of melatonin, up to more than 50 ng/mg protein. This effect may explain why a lower temperature sensitizes this organism to photoperiodic, indoleamine-mediated induction of asexual cysts. Melatonin can be catabolized either enzymatically or non-enzymatically. The non-enzymatic pathway involves free radicals, e.g., photooxidant cation radicals, and leads to the formation of N1-acetyl-N2- formyl-5-methoxykynuramine. Enzymatic catabolism comprises deacetylation to 5-methoxytryptamine and formation of 5-methoxytryptophol. 5-Methoxytryptamine represents a key substance acting as a stimulator of bioluminescence and a mediator of the encystment response. It opens proton channels in the membrane of an intracellular acidic vacuole system which is loaded by the action of a V-type ATPase, as shown by experiments using bafilomycin A1.
There recently has been increasing interest at substance abuse treatment centers in smoking cessation treatment. Because a history of depression has been shown in other populations to complicate cessation efforts, the relationship between depression and nicotine dependence was tested in 726 methadone patients. Elevated odds of nicotine dependence given depression were found with three of four depression measures. Additional research is recommended to determine whether smoking cessation treatment will be more successful for methadone patients with a history of depression if it also addresses depression.
Meta-analytic methods were used to synthesize the results of published randomized, controlled-outcome studies of psychosocial interventions with adult cancer patients. Forty-five studies reporting 62 treatment-control comparisons were identified. Samples were predominantly White, female, and from the United States. Beneficial effect size ds were .24 for emotional adjustment measures, .19 for functional adjustment measures, .26 for measures of treatment- and disease-related symptoms, and .28 for compound and global measures. The effect size of .17 found for medical measures was not statistically significant for the few reporting studies. Effect sizes for treatment-control comparisons did not significantly differ among several categories of treatment: behavioral interventions, nonbehavioral counseling and therapy, informational and educational methods, organized social support provided by other patients, and other nonhospice interventions.
Parasomnias are generally described as disorders of arousal that arise out of stage 3 and 4 nonrapid eye movement (NREM) sleep without identifiable cause. We present a case of a 35-year-old man who during nasal continuous positive airway pressure (nCPAP) treatment for severe obstructive sleep apnea experienced an intense night terror triggered by a residual obstructive apnea during rebound deep sleep. The role of rebound deep sleep was thought to be essential in creating a state of sleep with a high arousal threshold hypothesized to be important for the occurrence of parasomnias. This case supports the clinical wisdom that identifiable sources of arousal can trigger parasomnias.
Melatonin is widely abundant in many eukaryotic taxa, including various animal phyla, angiosperms, and unicells. In the bioluminescent dinoflagellate Gonyaulax polyedra, melatonin is produced in concentrations sometimes exceeding those found in the pineal gland, exhibits a circadian rhythm with a pronounced nocturnal maximum, and mimics the short-day response of asexual encystment. Even more efficient as a cyst inducer is 5-methoxyptryptamine (5MT), which is also periodically formed in Gonyaulax. In this unicell, the photoperiodic signal-transduction pathway presumably involves melatonin formation, its deacetylation to 5MT, 5MT-dependent transfer of protons from an acidic vacuole, and cytoplasmic acidification. According to this concept, we observe that cyst formation can be induced by various monoamine oxidase inhibitors and protonophores, that 5MT dramatically stimulates H(+)-dependent bioluminescence and leads to a decrease of cytoplasmic pH, as shown by measurements of dicyanohydroquinone fluorescence. Cellular components from Gonyaulax catalyze the photooxidation of melatonin. Its property of being easily destroyed by light in the presence of cellular catalysts may have been the reason that many organisms have developed mechanisms utilizing this indoleamine as a mediator of darkness. Photooxidative reactions of melatonin, as studied with crude Gonyaulax extracts and, more in detail, with protoporphyrin IX as a catalyst, lead to the formation of N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) as one of the main products. Photochemical mechanisms involve interactions with a photooxidant cation radical leading to the formation of a melatonyl cation radical, which subsequently combines with a superoxide anion.(ABSTRACT TRUNCATED AT 250 WORDS)
Administration of nasal continuous positive airway pressure (NCPAP) is the treatment of choice for most patients with obstructive sleep apnea. Many patients experience side effects with NCPAP use, and the compliance rate is reported to vary between 46-89%. The ramp is a device found on many NCPAP machines that resets the pressure to 3 cm H2O and then slowly increases the pressure to the prescribed pressure over a period of up to 45 min. The ramp allows patients time to fall asleep before the higher and likely more uncomfortable prescribed pressure is administered. We present a case in which a patient's repeated remote-controlled activation of this ramping feature severely limited effective therapy even when the NCPAP mask was properly in place, the machine was on, and the patient was breathing nasally.
Recent studies suggest that noninvasive positive pressure ventilation (NPPV) administered by nasal or oronasal mask avoids the need for endotracheal intubation, rapidly improves vital signs, gas exchange, and sense of dyspnea, and may reduce mortality in selected patients with acute respiratory failure, but few controlled trials have been done. The present study used a randomized prospective design to evaluate the possible benefits of NPPV plus standard therapy versus standard therapy alone in patients with acute respiratory failure. Patients to receive NPPV were comfortably fitted with a standard nasal mask connected to a BiPAP ventilatory assist device (Respironics, Inc., Murrysville, PA) in the patient flow-triggered/time-triggered (S/T) mode, and standard therapy consisted of all other treatments deemed necessary by the primary physician, including endotracheal intubation. The need for intubation was reduced from 73% in the standard therapy group (11 of 15 patients) to 31% in the NPPV group (5 of 16 patients, p < 0.05). Among chronic obstructive pulmonary disease (COPD) patients, the reduction was even more striking, with 8 of 12 (67%) control patients requiring intubation compared with 1 of 11 (9%) NPPV patients (p < 0.05). Heart and respiratory rates were significantly lower in the NPPV group than in control patients within 1 h, and PaO2 was significantly improved in the NPPV group for the first 6 h. Dyspnea scores and maximal inspiratory pressures were better in the NPPV than in control patients at 6 h, and nurses and therapists spent similar amounts of time at the bedside for both groups.(ABSTRACT TRUNCATED AT 250 WORDS)
PURPOSE: To review the clinical use of noninvasive positive pressure ventilation, including its efficacy with acute and chronic forms of respiratory failure, its mechanism of action, and its implementation. DATA SOURCES: Studies were identified through a MEDLINE search using the key words respiratory failure and mechanical ventilation and through a manual review of reference lists of published articles. STUDY SELECTION: All original studies relating to the use of noninvasive positive pressure ventilation in respiratory failure were included. Because of the paucity of controlled trials, cohort studies were not excluded. DATA EXTRACTION: Study design, numbers and diagnoses of patients, ventilator modes, and success and complication rates were extracted and compiled. RESULTS: For acute respiratory failure, studies report improved gas exchange and avoidance of intubation in 60% to 80% of patients with chronic obstructive pulmonary disease, restrictive thoracic disease, congestive heart failure, pneumonia, or postoperative extubation failure. However, the patients were highly selected, and relatively few studies have been published, only one of which was a randomized controlled trial. For chronic respiratory failure due to restrictive thoracic disease, all studies report improved gas exchange and symptoms of hypoventilation after prolonged nocturnal use, although no study was controlled. Some cohort studies of patients with severe chronic obstructive pulmonary disease yielded favorable results, but longer-term, randomized, controlled studies showed minimal, if any, benefit. CONCLUSION: Noninvasive positive pressure ventilation is effective in the treatment of chronic respiratory failure due to restrictive thoracic diseases. The routine use of such treatment for chronic respiratory failure due to chronic obstructive pulmonary disease and for acute respiratory failure needs to be studied in randomized controlled trials in better-defined patient subsets.
Sleep deprivation and fragmentation occurring in the hospital setting may have a negative impact on the respiratory system by decreasing respiratory muscle function and ventilatory response to CO2. Sleep deprivation in a patient with respiratory failure may, therefore, impair recovery and weaning from mechanical ventilation. We postulate that light, sound, and interruption levels in a weaning unit are major factors resulting in sleep disorders and possibly circadian rhythm disruption. As an initial test of this hypothesis, we sampled interruption levels and continuously monitored light and sound levels for a minimum of seven consecutive days in a medical ICU, a multiple bed respiratory care unit (RCU) room, a single-bed RCU room, and a private room. Light levels in all areas maintained a day-night rhythm, with peak levels dependent on window orientation and shading. Peak sound levels were extremely high in all areas representing values significantly higher than those recommended by the Environmental Protection Agency as acceptable for a hospital environment. The number of sound peaks greater than 80 decibels, which may result in sleep arousals, was especially high in the intensive and respiratory care areas, but did show a day-night rhythm in all settings. Patient interruptions tended to be erratic, leaving little time for condensed sleep. We conclude that the potential for environmentally induced sleep disruption is high in all areas, but especially high in the intensive and respiratory care areas where the negative consequences may be the most severe.