Masseter Deoxygenation in Adults at Risk for Temporomandibular Disorders

Patients with muscular temporomandibular disorder (TMD) present with abnormal oxygenation of the jaw muscles. Nonetheless, the deoxygenation pattern of jaw muscles of healthy subjects with frequent wake-time tooth-clenching episodes, who are at greater risk for TMD, has never been investigated. This case-control study compared the deoxygenation of the masseter during standardized tasks between TMD-free individuals with frequent self-reports of wake-time clenching and those with infrequent self-reports. University students ( N = 255) filled out the Oral Behavior Checklist. Fourteen females with high versus low scores-high parafunctional (HP) group ( n = 7, ≥80th percentile of score distribution) versus low parafunctional (LP) group ( n = 7, ≤20th percentile)-completed 2 sessions during which they clenched at their maximum voluntary contraction (MVC) for 2 min and at 10% to 20% MVC for 20 min. Tissue oxygen saturation (StO₂) and changes in oxygenated hemoglobin, deoxygenated hemoglobin, and total hemoglobin of the masseter were measured via near-infrared spectroscopy and analyzed with a generalized mixed effect model. A significant interaction effect (task × study group) was found on all outcome measures, indicating that the deoxygenation pattern of the HP group differed from the LP group (all P < 0.001). MVC of the masseter induced an almost 5-times-greater reduction of StO₂ in the HP group as compared with the LP group ( P = 0.023). However, the relative increase in StO₂ at rest after the MVC was similar between groups ( P > 0.05). At the end of the prolonged MVC task (10% to 20%), the blood flow (change in total hemoglobin) was almost 6 times higher in the LP group as compared with baseline. On the contrary, it increased minimally in the HP group (all P < 0.001). Healthy individuals at risk for TMD have abnormalities in masseter deoxygenation. Future prospective studies are needed to test whether this contributes to the onset of muscular TMD.

Reliability and validity of the Brief Pain Inventory in individuals with chronic obstructive pulmonary disease

BACKGROUND

Pain is prevalent in chronic obstructive pulmonary disease (COPD) and the Brief Pain Inventory (BPI) appears to be a feasible questionnaire to assess this symptom. However, the reliability and validity of the BPI have not been determined in individuals with COPD. This study aimed to determine the internal consistency, test-retest reliability and validity (construct, convergent, divergent and discriminant) of the BPI in individuals with COPD.

METHODS

In order to examine the test-retest reliability, individuals with COPD were recruited from pulmonary rehabilitation programmes to complete the BPI twice 1 week apart. In order to investigate validity, de-identified data was retrieved from two previous studies, including forced expiratory volume in 1-s, age, sex and data from four questionnaires: the BPI, short-form McGill Pain Questionnaire (SF-MPQ), 36-Item Short Form Survey (SF-36) and Community Health Activities Model Program for Seniors (CHAMPS) questionnaire.

RESULTS

In total, 123 participants were included in the analyses (eligible data were retrieved from 86 participants and additional 37 participants were recruited). The BPI demonstrated excellent internal consistency and test-retest reliability. It also showed convergent validity with the SF-MPQ and divergent validity with the SF-36. The factor analysis yielded two factors of the BPI, which demonstrated that the two domains of the BPI measure the intended constructs. The BPI can also discriminate pain levels among COPD patients with varied levels of quality of life (SF-36) and physical activity (CHAMPS).

CONCLUSION

The BPI is a reliable and valid pain questionnaire that can be used to evaluate pain in COPD.

SIGNIFICANCE

This study formally established the reliability and validity of the BPI in individuals with COPD, which have not been determined in this patient group. The results of this study provide strong evidence that assessment results from this pain questionnaire are reliable and valid.

The reliability of short-term measurement of heart rate variability during spontaneous breathing in people with chronic obstructive pulmonary disease

BACKGROUND

Reduced heart rate variability (HRV), a marker of autonomic system dysfunction, has been reported in patients with chronic obstructive pulmonary disease (COPD). Yet, limited data exists on the reliability of HRV measurement in this population. Here we investigated the reliability of short-term HRV measurement performed during spontaneous breathing in patients with COPD.

METHODS

Thirteen individuals (8 males) with moderate-to-severe COPD (FEV₁ 46±16% predicted; FEV₁/FVC 49±13) underwent standard time and frequency domain HRV measurements derived from 5-minute electrocardiograms collected on two separate days using a SphygmoCor device. Absolute and relative reliability was assessed by a number of coefficients including within-subject random variation, systematic change in the mean, and retest correlations.

RESULTS

Within-subject coefficients of variation (CV) ranged from 4.3% to 193.4%. The intraclass correlation coefficients (ICCs) ranged from 0.72 to 0.93 for parameters related to overall HRV, and from 0.57 to 0.59 for those related to parasympathetic tone in both time and frequency domains. Mean heart rate was the only parameter that showed excellent absolute and relative reliability (CV=4.3%, ICC=0.93).

CONCLUSION

The HRV measurements showed overall moderate-to-substantial reliability during spontaneous breathing in COPD population. Our findings support the use of HRV parameters for diagnosis and cardiac risk assessment, but only mean heart rate can be used reliably for monitoring changes in autonomic status following rehabilitation intervention in this population.

A survey of physiotherapists' experience using outcome measures in total hip and knee arthroplasty

PURPOSE

To identify physiotherapists' familiarity with and experience using outcome measures (OMs) along the care continuum for patients undergoing total joint arthroplasty (TJA) of the hip and knee. Views on future use and barriers were also captured.

METHODS

A stratified random sample of physiotherapists in one Canadian province completed a questionnaire about 19 standardized and clinically feasible OMs. Analyses included descriptive statistics and chi-square and McNemar tests to compare use of OMs for clinical decision making and program evaluation.

RESULTS

Of 694 physiotherapists surveyed, 298 (43%) responded. Of these, 172 (58%) treated TJA clients and completed the full questionnaire. A majority worked in public practice settings and >1 care phase (e.g., pre-op, acute, rehab). All physiotherapists reported using ≥1 OM and having greater experience using performance-based measures than patient-reported OMs. OMs were used more often for clinical decision making than for program evaluation. Dissatisfaction with available tools was evident from respondents' comments. Several barriers to using OMs were identified in varied clinical settings and care phases.

CONCLUSIONS

While physiotherapists use a variety of OMs along the TJA continuum, there remain challenges to routine use across clinical settings, care phases, and patient sub-groups.

Postural Control Is Impaired in People with COPD: An Observational Study

PURPOSE

We investigated deficits in postural control and fall risk in people with chronic obstructive pulmonary disease (COPD).

METHOD

Twenty people with moderate to severe COPD (mean age 72.3 years, standard deviation [SD] 6.7 years) with a mean forced expiratory volume in 1 second (FEV(1)) of 46.7% (SD 13%) and 20 people (mean age 68.2 years, SD 8.1) who served as a comparison group were tested for postural control using the Sensory Organization Test (SOT). A score of zero in any trial of the SOT was registered as a fall. On the basis of the SOT results, participants were categorized as frequent fallers (two or more falls) or as fallers (one fall). To explore the potential influence of muscle weakness on postural control, knee extensors concentric muscle torque was assessed with an isokinetic dynamometer. Physical activity level was assessed with the Physical Activity Scale for the Elderly.

RESULTS

People with COPD showed a 10.8% lower score on the SOT (p=0.016) and experienced more falls (40) than the comparison group (12). The proportion of frequent fallers and fallers during the SOT was greater (p=0.021) in the COPD group (four of 10) than in the comparison group (two of seven). People with COPD showed deficits in knee extensors muscle strength (p=0.01) and a modest trend toward reduced physical activity level. However, neither of these factors explained the deficits in postural control observed in the COPD group.

CONCLUSIONS

People with COPD show deficits in postural control and increased risk of falls as measured by the SOT. The deficits in postural control appear to be independent of muscle weakness and level of physical activity. Postural control interventions and fall risk strategies in the pulmonary rehabilitation of COPD are recommended.

Falls in people with chronic obstructive pulmonary disease: an observational cohort study

STUDY OBJECTIVE

To investigate incidence, risk factors and impact of falls on health related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD).

DESIGN

Observational cohort study.

METHODS

Patients completed these questionnaires at baseline and at 6-months: Medical Outcomes Study Short Form 36 (SF-36), Chronic Respiratory Questionnaire (CRQ), Activities Balance Confidence (ABC) Scale and a form to record demographic data, medications, co-morbidities, oxygen use, acute exacerbations, fall history and assistive device use. Physical activity was measured with the Physical Activity Scale for the Elderly (PASE) only at baseline. Fall incidence was monitored through monthly fall diaries. Patients were categorized as non-fallers (0 falls) or fallers (≥ 1 falls).

RESULTS

Data from 101 patients with a forced expiratory volume in 1 s of 46.4 ± 21.6% predicted were analyzed. Thirty-two patients (31.7%) reported at least one fall during the 6-months. Fall incidence rate was 0.1 (95% CI: 0.06-0.14) falls per person-month. Fallers tended to be older (p = 0.04), female (p = 0.04) and oxygen dependent (p = 0.02), have a history of previous falls (p < 0.001), more co-morbidities (p = 0.007) and take more medications (p = 0.001). Previous falls (OR = 7.36; 95% CI: 2.39-22.69) and diagnosis of coronary heart disease (OR = 7.07; 95% CI: 2.14-23.36) were the most important predictors of falls. The Dyspnea Domain of the CRQ declined significantly more (p = 0.02) in the fallers group at 6-months.

CONCLUSIONS

Patients with COPD have a high susceptibility to falls, which is associated with a worsening of dyspnea perception as related to HRQoL. Fall prevention programs in COPD are recommended.

The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis

The aim of this systematic review was to determine if eccentric exercise is superior to concentric exercise in stimulating gains in muscle strength and mass. Meta-analyses were performed for comparisons between eccentric and concentric training as means to improve muscle strength and mass. In order to determine the importance of different parameters of training, subgroup analyses of intensity of exercise, velocity of movement and mode of contraction were also performed. Twenty randomised controlled trials studies met the inclusion criteria. Meta-analyses showed that when eccentric exercise was performed at higher intensities compared with concentric training, total strength and eccentric strength increased more significantly. However, compared with concentric training, strength gains after eccentric training appeared more specific in terms of velocity and mode of contraction. Eccentric training performed at high intensities was shown to be more effective in promoting increases in muscle mass measured as muscle girth. In addition, eccentric training also showed a trend towards increased muscle cross-sectional area measured with magnetic resonance imaging or computerised tomography. Subgroup analyses suggest that the superiority of eccentric training to increase muscle strength and mass appears to be related to the higher loads developed during eccentric contractions. The specialised neural pattern of eccentric actions possibly explains the high specificity of strength gains after eccentric training. Further research is required to investigate the underlying mechanisms of this specificity and its functional significance in terms of transferability of strength gains to more complex human movements.

Increased injury and intramuscular collagen of the diaphragm in COPD: autopsy observations

Evidence for diaphragm injury in people with chronic obstructive pulmonary disease (COPD) has been reported, although the extent of injury and collagen accumulation post mortem have not previously been examined. In addition, it is not known whether the amount of injury and collagen are different in key regions of the diaphragm. The cross-sectional area of collagen and the percentage of abnormal myofibres in the post mortem diaphragm and psoas major were determined by computer-assisted image analysis of stained cross-sections of the diaphragm for collagen with picrosirius red and with haematoxylin and eosin for morphology. In the midcostal diaphragm of six subjects with COPD and six subjects with no significant respiratory disease, the COPD diaphragm displayed a greater cross-sectional area of collagen and percentage of abnormal myofibres (collagen: 24.2+/-1.0 versus 18.6+/-1.1%; injury: 28.4+/-7.2 versus 12.0+/-1.3%). In 18 patients with various respiratory conditions, the midcostal diaphragm displayed more collagen and abnormal myofibres than the crural diaphragm, while both costal and crural diaphragms displaying more collagen and abnormal myofibres than psoas major. This study reveals extensive injury and collagen accumulation in the chronic obstructive pulmonary diseased diaphragm, and reveals a regional pattern of injury and intramuscular collagen which may correspond to variations in diaphragm loading.

Granulocytosis and increased adhesion molecules after resistive loading of the diaphragm

Upregulation of endothelial cell adhesion molecules, followed by an influx of granulocytes and macrophages, can contribute to exertion-induced skeletal muscle injury. The purpose of this study was to quantify circulating leukocyte subsets, diaphragm injury and infiltrating leukocyte subsets, and surface expression of vascular cell adhesion molecule (VCAM)-1 and intracellular adhesion molecule (ICAM)-1 in the diaphragm after inspiratory resistive loading (IRL). Eight New Zealand white rabbits underwent 1.5 h of IRL and seven control rabbits underwent a sham procedure. Blood samples, taken at baseline and 2, 6, 12, 24, 48 and 72 h after the onset of IRL or sham, showed that band cell counts had increased at 6 h post-IRL. Point counting of haematoxylin and eosin-stained cross-sections, sampled at 72 h post-IRL, showed greater injury in diaphragms from IRL rabbits compared with controls. Immunohistochemical processing showed increased expression of ICAM-1 and VCAM-1, and higher granulocyte and macrophage counts in IRL diaphragms than control diaphragms. Macrophages were the predominant inflammatory cells. Increased intracellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression, and infiltration of granulocytes and macrophages may contribute to inspiratory resistive loading-induced diaphragm injury.

Free radical scavengers and diaphragm injury following inspiratory resistive loading

Three groups of NZW rabbits were studied to examine the role of free radical scavengers in preventing diaphragm injury produced by inspiratory resistive load (IRL): control, IRL, and scavenger groups. An IRL (Pao: 45-55 cm H2O) was applied to the IRL and the scavenger groups on Day 1. Free radical scavengers (polyethylene glycol superoxide dismutase, N-acetylcysteine, and mannitol) were given (intravenously) to the scavenger group both before and after the IRL. All rabbits were killed on Day 3 to collect diaphragms. Point counting H&E-stained diaphragm x-sections indicated that abnormal diaphragm muscle in the IRL group was significantly greater than control (p < 0.01). However, it was significantly lower in the scavenger group than the IRL group (p < 0.05) and it did not differ from control. In vitro diaphragm physiological studies found that the twitch tension (p < 0.05) and maximal tension (p < 0.01) in the IRL group were significantly lower than control. The maximal tensions (p < 0.05) in the scavenger group were lower than control. After the fatigue protocol, diaphragmatic contractility in the scavenger group was similar to control and was better maintained compared with the IRL group. We conclude that free radical scavengers can prevent the development of diaphragm injury as evidenced by histology but the protection of diaphragm function is limited.

Respiratory muscle injury: evidence to date and potential mechanisms

Respiratory muscle dysfunction associated with ventilatory loading may be partially attributed to respiratory muscle injury. Exertion-induced muscle injury can be defined as structural alterations of the muscle, however, a better understanding of the biochemical, morphologic, and functional correlates of injured respiratory muscles will facilitate discrimination of how injury, fatigue, and weakness contribute to respiratory muscle dysfunction. In addition to the increased loads associated with lung disease, many factors such as poor arterial blood gases, immobilization, sepsis, decreased nutrition, and corticosteroids may increase susceptibility to exertion-induced respiratory muscle injury. Respiratory muscle injury in humans is not well-described, however, more extensive evidence has been shown in animal models of increased ventilatory loading. Potential mechanisms of respiratory muscle injury are mechanical stress, metabolic stress, and inflammation. In order to optimize therapeutic interventions, a better understanding of these mechanisms and the patients that are most susceptible to respiratory muscle injury needs to be determined.

Diaphragm injury in individuals with airflow obstruction

The purpose of this study was to describe the nature of diaphragm injury, to quantify the injury and number of macrophages at the light microscopic level, and to determine their association with airflow obstruction in humans. Partial-thickness diaphragm biopsies were obtained from 21 subjects going for thoracotomy surgery (FEV(1): 74 +/- 34% predicted; range: 16 to 122% predicted). Cross sections cut from frozen diaphragm were processed with H&E or processed for immunohistochemistry using the monoclonal antibody Ber-MAC3 (DAKO Corp., Carpinteria, CA) to label macrophages. Area fractions (A(A)) or the proportions of the cross- sectional area were determined by point counting all viable fields of H&E-stained diaphragm cross sections. A(A) were 66.2 +/- 9.0% for normal muscle, 17.6 +/- 7.2% for abnormal muscle, and 16.3 +/- 4.2% for connective tissue. Percent predicted FEV(1) was inversely related to the A(A) of abnormal muscle (r = -0.53, p < 0.01) and directly related to the A(A) of normal muscle (r = 0.37, p < 0.05). The number of macrophages was not related to % predicted FEV(1) (mean +/- SD: 0.41 +/- 0.18/fiber; 52 +/- 19/mm(2)). We conclude that increasing severity of airflow obstruction is associated with an increased A(A) of abnormal diaphragm and a decreased A(A) of normal diaphragm.

Time course of diaphragm injury and calpain activity during resistive loading

The purpose of this study was to determine the time course of arterial blood gas (ABG) deterioration, increased calpain activity, and diaphragm injury during 4 d of resistive loading. Adult Sprague- Dawley rats were divided into control (C) animals and groups that were tracheally banded (TB) for 1 d (TB1), 2 d (TB2), 3 d (TB3), and 4 d (TB4). In TB rats, the carotid artery was cannulated and the trachea was banded during anesthesia. TB groups (TB1, TB2, TB3, and TB4) had a 67% smaller internal cross-sectional area of the trachea than did C animals. ABG samples from awake rats showed a decreased arterial oxygen tension (Pa(O(2))) and a respiratory acidosis in the TB1, TB2, and TB3 groups. Calpain activity was higher in the diaphragm of TB than of C rats; calpainlike activities in soluble fractions of diaphragm tissue were greater in all TB groups than in C rats, whereas those in bound fractions were greater in the TB2 and TB3 groups. Point counting of hematoxylin and eosin-stained cross-sections showed that the area fraction (A(A)) of normal diaphragm was lower and the A(A) of abnormal muscle and connective tissue was higher in TB3 than in C rats. Increased resistive loading induced by tracheal banding was associated with hypercapnic ventilatory failure, increased calpain activity, and diaphragm injury. Ventilatory failure in response to resistive loading may be due to diaphragm injury and/or to decreased minute ventilation.

Quality of life after pulmonary rehabilitation: assessing change using quantitative and qualitative methods

BACKGROUND AND PURPOSE

The purpose of this study was to use quantitative and qualitative research methods to evaluate quality-of-life (QOL) changes in patients with chronic obstructive pulmonary disease after pulmonary rehabilitation.

SUBJECTS

Twenty-nine individuals with COPD (18 women and 11 men), with a mean age of 69 years (SD=8.6, range=53-92), participated.

METHODS

Subjects were assessed before and after a 5-week control phase and after a 5-week rehabilitation phase using the Chronic Respiratory Questionnaire (CRQ), the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36), and spirometry. Our qualitative research was based on a subsample of 7 subjects who were interviewed after pulmonary rehabilitation.

RESULTS

Pulmonary rehabilitation improved QOL, as demonstrated by increases of 22% and 14% in the physical function categories of the CRQ and the SF-36, respectively, and by an increase of 10% in the CRQ's emotional function category. The qualitative data indicated how pulmonary rehabilitation influenced QOL.

CONCLUSION AND DISCUSSION

The use of both quantitative and qualitative methods illustrated the nature of improvement in QOL after pulmonary rehabilitation. Improved physical function, less dyspnea, and a heightened sense of control over the subjects' COPD resulted in increased confidence and improved emotional well-being.

Different effects of strenuous eccentric exercise on the accumulation of neutrophils in muscle in women and men

The purpose of this study was to evaluate the sex differences in delayed onset muscle soreness (DOMS), torque, and accumulation of technetium-99m (Tc-99m) neutrophils in eccentric-exercised muscle. A group of 10 female and 12 male subjects took part in this study. The subjects completed a pre-test using the descriptor differential scale (DDS) to describe DOMS, and tests of concentric and eccentric torque of the right quadriceps. A volume of 100 ml of blood was taken by venipuncture for neutrophil labelling in the early morning of the exercise day. The Tc-99m neutrophils were re-infused intravenously before the eccentric exercise. The exercise stimulus consisted of 300 eccentric repetitions of the right quadriceps muscles. Radionuclide images of both quadriceps muscles (lateral views) were taken at 2 and 4 h. The DDS, and concentric and eccentric torques of the quadriceps were subsequently evaluated at 0 h, 2, 4, 20 and 24 h post-exercise. The presence of Tc-99m neutrophils was greater in the exercised leg than the non-exercised leg at 2 and 4 h post-exercise (P </= 0.013) and greater in the exercised leg of the women compared to the men at 2 h (P = 0.03). The DOMS had increased post-exercise (P < 0.001) and torque had decreased post-exercise (P </= 0.002) but the patterns were different between the sexes. We concluded that the sex influences the presence of Tc-99m neutrophils in the exercised muscle following eccentric exercise. In addition, different patterns of DOMS and torque were observed between the sexes after eccentric exercise, and require further investigation.

Chronic resistive loading induces diaphragm injury and ventilatory failure in the hamster

The purpose of this study was to examine the effects of tracheal banding for 30 days on arterial blood gases, and diaphragm structure and function. Hamsters were tracheal banded (TB) or underwent a sham procedure (C) (n = 16 and 18, respectively). After 30 days, arterial blood gases from awake TB hamsters showed hypoxemia and a respiratory acidosis. Histochemical analysis of diaphragm cross-sections showed a five-fold greater area fraction of abnormal muscle; a greater variation in fiber size; and a 3% higher proportion of type 1 fibers in TB than C hamsters. In vitro physiologic studies of costal strips from TB hamsters showed lower stress (45-70% over 10-100 Hz) than C values. Maximal esophageal pressure during occlusion was 45% higher and normalized diaphragm mass was 10% higher in TB hamsters than C hamsters. We conclude that the lower stress in vitro was attributable, at least in part, to diaphragm injury. Hypercapnea was present in spite of the higher diaphragm mass and maximal esophageal pressures in banded hamsters.

Delayed diaphragm injury and diaphragm force production

The present study was designed to examine the effect of delayed diaphragm injury produced by inspiratory resistive loading (IRL) on diaphragm force production. On Day 1, three groups of anesthetized and intubated NZW rabbits (n = 7 in each group) were subjected to moderate IRL (Pao approximately 30 cm H2O), high IRL (Pao approximately 45 cm H2O), or no load for 1.5 h. On Day 3, the baseline twitch transdiaphragmatic pressure (Pdi) and Pdi at 10 to 80 Hz were measured during bilateral phrenic stimulation and these measurements were repeated after another IRL (high level) in all three groups. Diaphragm injury was assessed by the point-counting technique. Marked diaphragm injury was observed in the high-IRL group (p < 0.01), but no significant diaphragm injury was observed in the moderate-IRL or control groups. The baseline twitch Pdi was maintained in both IRL groups, whereas the baseline Pdi-frequency values in the high-IRL group were significantly reduced at most frequencies (p < 0.05). The decreases in twitch and Pdi at different frequencies were more pronounced after the IRL on Day 3 in the high-IRL group compared with controls. Moderate IRL did not decrease diaphragm force either before or after the high IRL on Day 3. We conclude that the diaphragm injury induced by high IRL has a significant impact on diaphragm force production and the attendant force loss produced by IRL is dependent on the intensity of inspiratory loading.

Respiratory muscle injury in animal models and humans

Respiratory muscle injury may result from excessive loading due to a decrease in respiratory muscle strength, an increase in the work of breathing, or an increase in the rate of ventilation. Other conditions such as hypoxemia, hypercapnia, aging, decreased nutrition, and immobilization may potentiate respiratory muscle injury. Respiratory muscle injury has been shown in animal models using direct muscle or phrenic nerve stimulation, acute inspiratory resistive loading, tracheal banding, corticosteroids, phrenic nerve section, and the mdx mouse. Although numerous examples of diaphragm injury have been shown in animal models, evidence in humans is sparse. Potential mechanisms which may contribute to respiratory muscle injury include high levels of intracellular calcium-activated degradative enzymes, non-uniformity of stresses and strains, plasma membrane disruptions, and activation of the inflammatory process.

Fatigue of the knee extensor muscles following eccentric exercise

The purposes of this study were to determine the time course of muscle fatigue in the knee extensor muscles following an eccentric exercise protocol, and to determine if the position of the subjects during assessment affected the measurement of muscle fatigue. Twenty-four female subjects were assigned to three groups. All subjects completed baseline measure (pre-exercise test) of a power spectrum analysis of the vastus medialis, rectus femoris and vastus lateralis muscles. Following an exercise protocol of 300 eccentric repetitions of the knee extensors, power spectrum analysis was repeated at two, four, 20, 24, 48 and 72 hours for group one, at 0 hour (immediately following the exercise) and two hours for group two, and at 0 hour for group three. Groups one and two were tested in sitting, while group three was tested supine. The slope of the median frequency of the vastus lateralis muscle changed significantly over time (p < 0.001) for group one, but there were no significant changes in the slope of the median frequency of the vastus medialis muscle, while the rectus femoris muscle showed an increase in the slope of the median frequency when the subjects were in the sitting position. Further testing, in supine (group three), indicated that the position of the hip joint influenced the power spectrum analysis of the rectus femoris muscle but not the vasti muscles. In addition, fatigue occurred immediately post-exercise with recovery within 24 hours.

Load dependence of secondary diaphragm inflammation and injury after acute inspiratory loading

Chronic or prolonged low-intensity loading of the inspiratory muscles has recently been shown to produce diaphragm injury. The present study was designed to examine whether an acute episode of inspiratory resistive loading (IRL) could produce secondary diaphragm inflammation and injury. On Day 1, three groups of anesthetized and intubated New Zealand White rabbits were subjected to moderate IRL (Pao of approximately 30 cm H2O), high IRL (Pao of approximately 45 cm H2O), or no load for 1.5 h. On Day 3, costal and crural diaphragms, parasternals, and gastrocnemius muscles were taken to assess injury by point counting. Normal muscle, abnormal and inflamed muscle, and connective tissue on hematoxylin and eosin-stained cross-sections were expressed as percentage of the total points for that cross-section. For the costal diaphragm, both the abnormal muscle (7.3 +/- 0.6% versus 1.1 +/- 0.2%; p < 0.001) and connective tissue (8.0 +/- 0.6% versus 5.7 +/- 0.2%; p < 0.01) in the high IRL group were higher than control, whereas in the moderate IRL group they were not significantly different from control. Total calpain-like activity was increased in the moderate IRL group but not in the high IRL group. Injury was observed in the parasternal muscles but to a lesser extent. No injury was observed in the gastrocnemius muscle. We conclude that secondary diaphragm injury occurs after acute IRL but only when the IRL exceeds the fatigue threshold.

Regional and fiber-type percentages and sizes in the hamster diaphragm after swim training

BACKGROUND AND PURPOSE

The purpose of this study was to determine the effect of a swimming endurance training program on changes in percentages and sizes of fiber types in different regions of the hamster diaphragm.

METHODS

Adult male golden Syrian hamsters were randomly assigned to a control group (n = 9) or a swimming group (n = 10). Hamsters in the swimming group swam for 80 minutes per session, 5 days per week, for 13 weeks. Fiber-type percentages and sizes were determined for the costal region and for the abdominal and thoracic surfaces of the crural region of the diaphragm from cross sections processed for myofibrillar adenosine triphosphatase.

RESULTS

Muscle fibers in the thoracic surface of the crural region were smaller in the swimming group than in the control group. Fiber-type percentages in the diaphragm, however, were not different between groups.

CONCLUSION AND DISCUSSION

Swim training may have improved the endurance of the thoracic/crural region by decreasing cross-sectional area and thus decreasing the distance for oxygen to diffuse to the internal regions of the muscle fibers.

Influence of referring physicians on interventions by a pediatric and neonatal critical care transport team

The objective of this study was to determine the influence of: a) pediatrician versus nonpediatrician referrals on a transport team's therapeutic interventions and b) referring physician's year of graduation on interventions performed by the transport team. From November 1987 through December 1989 we prospectively compared the therapeutic interventions performed by the critical care transport team on newborns and pediatric patients with the referring physician's specialty and year of graduation. The transport team (critical care physician [PL3 or greater], registered respiratory therapist, critical care nurse), recorded all therapeutic interventions, including both procedural and pharmacologic, for 213 newborn and 149 consecutive pediatric transports. Referring physicians were categorized as pediatricians and nonpediatricians. Data were analyzed by analysis of variance, chi2, or linear regression. All patients were admitted to either the pediatric or the neonatal intensive care unit, and over 80% of both age groups received assisted ventilation. Newborns referred by nonpediatricians required significantly more procedural interventions (2.64 vs 1.91, P = 0.016) than those referred by pediatricians. The opposite relationship was observed among pediatric patients in that children referred by pediatricians received more frequent intervention (P = 0.008) than those referred by nonpediatricians. There was a significant inverse relationship between the referring physicians year of medical school graduation and the number of therapeutic interventions (total interventions = 6.17 - 0.040 x graduation year, P = 0.01) and procedural interventions (procedural interventions = 3.54 - 0.024 x graduation year, P = 0.01). We found that the referring physicians' medical training affected the number of interventions their patients received. Similarly, patients were likely to receive more interventions if the referral physicians training was not recent. These data have educational implications and support the concepts of continuing medical education, recertification, and maintenance of skills among physicians providing care to critically ill newborns and pediatric patients.

Presence of WBC, decreased strength, and delayed soreness in muscle after eccentric exercise

The purposes of this study were to assess the presence of 99mTc-labeled white blood cells (WBC) in exercised muscle compared with nonexercised muscle over time and to determine the time course of delayed onset muscle soreness (DOMS) and eccentric torque in 10 female subjects. A pretest was followed by 300 eccentric repetitions of the right quadriceps. DOMS and eccentric torque were measured at 2, 4, 20, 24, 48, and 72 h postexercise. Eccentric torque was also tested at 0 h. Radionuclide images of both quadriceps were taken at 2, 4, 20, and 24 h postexercise. The presence of 99mTc-WBC in the exercised muscle was significantly greater (P < 0.001) than in the nonexercised muscle. Eccentric torque declined at 0 and 24 h postexercise. DOMS peaked at 24 h postexercise. The presence of 99mTc-WBC in the exercised muscle in the first 24 h suggests that acute inflammation occurs as a result of exercise-induced muscle injury. The bimodal pattern of eccentric torque supports the hypothesis that more than one mechanism is involved.

Pediatric and neonatal critical care transport: a comparison of therapeutic interventions

OBJECTIVE

To compare the therapeutic interventions provided to newborn and pediatric patients by a dedicated combined neonatal pediatric critical care transport team.

METHOD

From November 1987 through December 1989 we prospectively compared the number of therapeutic interventions performed by the critical care transport team on newborns and pediatric patients. The transport team (critical care physician [PL3 or greater], pediatric respiratory therapist, critical care nurse), recorded all therapeutic interventions, including both procedural and pharmacologic, for 213 newborn and 149 pediatric consecutive transports. Data were analyzed by analysis of variance or chi 2 statistic.

RESULTS

All patients were admitted to either the pediatric or the neonatal intensive care unit, and over 80% of both age groups received assisted ventilation. Newborns commonly suffered from respiratory diseases (159/213), while pediatric patients suffered from respiratory (52/149), central nervous system (28/149), and traumatic conditions (37/149). Airway maintenance procedural interventions (intubation, ventilation) were the commonest in both groups, although more frequent in neonates. Neonates received antibiotics and morphine (P < 0.05) while pediatric patients received anticonvulsants and respiratory drugs (P < 0.05) more frequently. Newborns received significantly more interventions than pediatric patients (average 3.56 vs 2.93, P < 0.05). Newborns also received significantly more procedural interventions (2.06 vs 1.36, P = < 0.05) including intubation (34.7% vs 15.4%, P < 0.05) and the initiation of mechanical ventilation (38% vs 22%, P < 0.05).

CONCLUSION

Overall, newborns received more interventions, including intubation, and ventilation from the transport team than did pediatric patients. Our data suggest that combined pediatric neonatal transport teams should be prepared to intervene in a wide range of conditions from preterm respiratory distress to the multiply traumatized adolescent.

Considerations when testing and training the respiratory muscles

The purpose of this review is to describe the muscles of respiration, mechanisms that lead to their dysfunction, and unique features of the respiratory muscles that should be considered when designing testing and training protocols for patients with respiratory compromise. The diaphragm's unique shape is an important determinant of its function. Respiratory pathophysiology combined with systemic abnormalities may result in inspiratory muscle weakness, fatigue, and injury. The specificity of training principle, as it applies to respiratory muscle training in patients with respiratory compromise, will be described. Precautions related to this type of training will also be outlined. In conclusion, a better understanding of the mechanisms contributing to inspiratory muscle dysfunction will assist physical therapists in designing the most appropriate training programs. This article, along with the other articles in this focus on respiratory muscle training, will provide therapists with scientifically based guidelines for rehabilitation of patients with impaired respiratory muscle function.

Respiratory muscle training for patients with chronic obstructive pulmonary disease

The purpose of this article is to describe respiratory muscle training techniques and the effectiveness of this training in patients with chronic obstructive pulmonary disease (COPD). The respiratory muscles can be strengthened, but the benefit of stronger respiratory muscles in patients with COPD is not clear. Maximal sustained voluntary ventilation, inspiratory resistive breathing, and threshold loading are the three most commonly used techniques for improving the endurance of the inspiratory muscles in patients with COPD. Recent studies using inspiratory resistive breathing with targeted devices or threshold trainers have shown more consistent increases in inspiratory muscle function and exercise tolerance than studies using other techniques. Endurance exercise involving the extremities improves inspiratory muscle endurance in younger individuals with cystic fibrosis but not in older persons with COPD. Recommendations are outlined regarding the techniques to use for respiratory muscle training and which patient populations may benefit from these techniques.

Characteristics of diaphragm muscle fibre types in hibernating squirrels

Muscle samples from the diaphragms of 7 full-awake (FA), 10 winter-awake (WA), and 8 hibernating (H) squirrels (Spermophilus lateralis) were quick frozen, sectioned and processed for NADH-TR reaction end-product and myofibrillar-ATPase. Both WA and H squirrels showed small increases in diaphragm weight, reductions in body weight, and hence, significant increases in the diaphragm weight to body weight ratio compared to FA squirrels. They also showed increases in muscle fibre type cross-sectional areas and in the oxidative capacity of type 2b fibres as well as a reduction in capillary density. Furthermore, there also was an increase in the proportion of type 2b fibres in the diaphragm of the H squirrels. Thus, despite the dramatically reduced ventilation associated with hibernation, H squirrels exhibited (1) hypertrophy of the diaphragm which may represent an adaptive response that enables them to work against a stiffer chest wall, and (2) an increased oxidative capacity which enables them to fuel this with fat.

Pulmonary mechanics of hibernating squirrels (Spermophilus lateralis)

In this study we examined the effects of hibernation on several aspects of pulmonary mechanics in golden mantled ground squirrels. Measurements were made on anesthetized animals that were active in late fall (FA, n = 7), maintained at 23 degrees C and normal photoperiod in mid-winter (WA, n = 0) and hibernating at 5 degrees C in mid-winter (H, n = 8). Compared with FA animals, WA animals showed an increase in inspiratory reserve volume (IRV) and in inspiratory, vital and total lung capacities (IC, VC, and TLC). Hibernating animals exhibited further increases in IRV, IC, VC and TLC, an elevated residual volume, and virtual elimination of the expiratory reserve volume. There was also a decrease in specific lung compliance and a sharp knee in the lower portion of the quasi-static volume-pressure curve. There was a significant increase in the elastic work required to ventilate the hibernating animals compared with FA animals. The data suggest that, despite an increase in compliance at TLC, there is decreased compliance at low volumes, gas trapping at functional residual capacity, and an increase in the work required to breathe in hibernating animals.

Delayed muscle soreness. The inflammatory response to muscle injury and its clinical implications

Delayed onset muscle soreness (DOMS) is a sensation of discomfort that occurs 1 to 2 days after exercise. The soreness has been reported to be most evident at the muscle/tendon junction initially, and then spreading throughout the muscle. The muscle activity which causes the most soreness and injury to the muscle is eccentric activity. The injury to the muscle has been well described but the mechanism underlying the injury is not fully understood. Some recent studies have focused on the role of the cytoskeleton and its contribution to the sarcomere injury. Although little has been confirmed regarding the mechanisms involved in the production of delayed muscle soreness, it has been suggested that the soreness may occur as a result of mechanical factors or it may be biochemical in nature. To date, there appears to be no relationship between the development of soreness and the loss of muscle strength, in that the timing of the two events is different. Loss of muscle force has been observed immediately after the exercise. However, by collecting data at more frequent intervals a second loss of force has been reported in mice 1 to 3 days post-exercise. Future studies with humans may find this second loss of force to be related to DOMS. The role of inflammation during exercise-induced muscle injury has not been clearly defined. It is possible that the inflammatory response may be responsible for initiating, amplifying, and/or resolving skeletal muscle injury. Evidence from the literature of the involvement of cytokines, complement, neutrophils, monocytes and macrophages in the acute phase response are presented in this review. Clinically, DOMS is a common but self-limiting condition that usually requires no treatment. Most exercise enthusiasts are familiar with its symptoms. However, where a muscle has been immobilised or debilitated, it is not known how that muscle will respond to exercise, especially eccentric activity.

Regional and fibre type glycogen utilization patterns in the hamster diaphragm following swimming

The purpose of this study was to determine the regional and myofibrillar ATPase (M-ATPase) fibre type glycogen utilization patterns in response to increased ventilation induced by pre-exhaustive (Pre-Exh) and exhaustive (Exh) durations of swimming. Twenty-eight hamsters were studied: six controls (Con), 11 Pre-Exh (swam 82 min), 11 Exh (swam to exhaustion). We examined the optical density of PAS-stained fibres from the different regions of the diaphragm as a measure of glycogen remaining after the exercise or control period. The optical densities of PAS-stained fibres in most M-ATPase fibre types and diaphragmatic regions for the Pre-Exh and Exh groups was less than those in the Con hamsters except for the optical densities of all the M-ATPase fibre types in the sternal region. The optical densities of PAS-stained fibres in different regions and M-ATPase fibre types did not differ in the Exh and Pre-Exh groups. This data indicates that significant glycogen utilization occurred in all three M-ATPase fibre types in the costal, and both the thoracic and abdominal surface of the crural diaphragm in hamsters following pre-exhaustive and exhaustive durations of swimming. Glycogen utilization was greater in type 1 fibres of the thoracic surface of the crural region than in the type 1 fibres of the sternal region of the Pre-Exh group. Further, significant utilization of glycogen did not occur in any of the three M-ATPase fibre types of the sternal region of the diaphragm following prolonged durations of swimming. It would appear that glycogen is an important substrate in the hamster diaphragm during swimming.(ABSTRACT TRUNCATED AT 250 WORDS)

Diaphragm injury and myofibrillar structure induced by resistive loading

The purpose of this study was to determine whether ventilatory failure is associated with muscle fiber damage and myofibrillar protein alterations. Ventilatory failure was induced by tightening a polyvinyl band around the trachea of hamsters (TB; n = 14) for 6 days, which resulted in severe respiratory acidosis (PCO2: 97.9 +/- 29.6 vs. 51.6 +/- 19.6 Torr; pH: 7.16 vs. 7.35), hypoxemia (PO2: 42.8 +/- 16.8 vs. 65.9 +/- 25.8 Torr), and increased pulmonary resistance (1.89 +/- 1.61 vs. 0.29 +/- 0.27 cmH2O.ml-1 x min; P < 0.05). The point-counting technique of hematoxylin- and eosin-stained cross sections showed a higher area fraction of abnormal muscle and inflammatory cells in the costal [0.133 +/- (SE) 0.33 vs. 0.040 +/- 0.010] and crural regions (0.069 +/- 0.020 vs. 0.012 +/- 0.003) of the diaphragm in TB hamsters than in control hamsters. Electron micrographs revealed sarcomeric disruption and Z band streaming in the diaphragm of TB hamsters. Myofibrillar changes of the diaphragm associated with ventilatory failure were quantitative (i.e., a lower yield of purified myofibrils) but not qualitative (similar sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profiles); however, sulfhydryl group reactivities were reduced (P < 0.05). Proteolysis of purified myofibrils from the diaphragm digested with calpain showed faster degradation rates for tropomyosin and alpha-actinin but not for all proteins for the TB animals. Ventilatory failure induced by resistive loading was associated with diaphragm injury; some of this injury was linked to changes in myofibrillar complexes, specifically their susceptibility to calpain-mediated degradation.

Preampullary congenital duodenal obstruction in a father and son

This is the report of an infant seen on June 25, 1960 with preampullary total duodenal obstruction caused by a combined annular pancreas and duodenal stenosis above the ampulla. A gastroduodenostomy was performed. In December 1989, he fathered a 1,700-g boy with preampullary duodenal atresia. A duodeno-duodenostomy was performed successfully by the same pediatric surgeon. Second-generation duodenal obstruction is rare; to our knowledge, there are no other cases.

Circadian rhythm of glycogen in the hamster diaphragm

The purpose of this study was to determine the diurnal fluctuation of glycogen stores for the whole hemidiaphragm and within a specific myofibrillar ATPase (M-ATPase) fibre type and diaphragmatic region. Fifty-six golden Syrian hamsters were randomly divided into six groups according to the time of sampling biopsies from the diaphragm: 03:00, 07:00, 11:00, 15:00, 19:00, and 23:00. The right hemidiaphragm was quick frozen and biochemically assayed for glycogen levels. Biopsies from the left hemidiaphragm of the same animal were cut from the anterior costal and crural regions, and stained with periodic acid--Schiff (PAS) and for M-ATPase. Optical density measures of PAS-stained fibres were determined to quantitate glycogen in different M-ATPase fibre types and diaphragmatic regions. Biochemical assay of the entire hemidiaphragm showed slightly greater glycogen content of biopsies taken at 11:00 and 15:00 than at 03:00, 19:00, and 23:00 (range of differences: 6.4-10.0%). However, glycogen levels within a specific M-ATPase fibre type and diaphragm region were not different in biopsies sampled at different times. Because the hamster has a small diurnal variation of glycogen in the diaphragm, which is similar to the small diurnal variation of glycogen in human skeletal muscle, this species may be a good animal model for metabolic studies of the diaphragm that could be affected by diurnal glycogen variability.

Lumbar epidural anaesthesia for inguinal hernia repair in low birth weight infants

In view of the complications of general, spinal, and caudal anaesthesia for inguinal hernia repair in high-risk neonates, an evaluation of lumbar epidural anaesthesia (LEA) was undertaken to assess its technical feasibility, effectiveness and incidence of complications. In 18 consecutive cases, gestational age 26 +/- 2.6 wk, birth weight 877 +/- 310 g, 16 (89%) had bronchopulmonary dysplasia and 12 (67%) were oxygen-dependent at the time of surgery. Using a standard loss of resistance technique and a 4.0 cm 20 G epidural needle, the epidural space was positively identified on the first attempt in 16 (89%), and on the second attempt in 2 patients (11%). Reflux of 0.9% saline used to identify the epidural space was blood tinged in two cases. Epidural analgesia was achieved in all cases with bupivacaine 0.25% with and without 1:200,000 epinephrine, 0.75 ml.kg-1 for the first two cases, and subsequently 1.0 ml.kg-1. In 15 patients (83%), good operating conditions were achieved with epidural analgesia alone. Inhalational anaesthesia supplementation was necessary in three cases (17%). In the first two patients, the level of analgesia (T8) was insufficient to control the response to traction on the hernial sac. In one infant, analgesic to T4, whose surgery was inadvertently delayed for four hours, inhalation anaesthesia was needed to control restlessness rather than pain. Ten infants were analgesic to T2, four to T4, two to T6 and two to T8. Intraoperative periodic breathing was seen in seven infants (39%), four with oxyhaemoglobin desaturation to 75%, and two to 85%. All responded to increased FIO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Fiber type and regional differences in oxidative capacity and glycogen content in the hamster diaphragm

The purpose of this study was to define variability of the oxidative capacity and glycogen content between different fiber types and regions of the hamster diaphragm. Using histochemical and microphotometric techniques, the oxidative capacity (identified by nicotinamide-adenine dinucleotide tetrazolium reductase reaction end product) and glycogen levels (identified by the periodic acid-Schiff stain test) were examined in three myofibrillar ATPase (M-ATPase) fiber types and four diaphragmatic regions: sternal, anterior costal, thoracic surface of the crural (thor/crur), and abdominal surface of the crural (abd/crur). Most regional differences were found between the crus and the rest of the diaphragm. There were no differences in the oxidative capacity between diaphragmatic regions in the types 1 and 2a fibers, but the type 2b fibers in the thor/crur region had the greatest oxidative capacity and the 2b fiber in the sternal region had the lowest oxidative capacity. There were differences in glycogen content between diaphragmatic regions for all of the three M-ATPase fiber types. Variability in oxidative capacity between fiber types was demonstrated in all regions except the thor/crur region. Variation in glycogen content between fiber types was only demonstrated in the two surfaces of the crus. The type 2b fiber demonstrated the most differences from types 1 and 2a fibers in oxidative capacity and glycogen content in the different diaphragmatic regions, whereas the types 1 and 2a fibers demonstrated few differences from each other in these features across the different diaphragmatic regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventilatory failure induced by tracheal banding in the hamster

Previous animal models of hypercapnic ventilatory failure are limited in that the resistive load has only been applied acutely and often in anesthetized animals. We therefore developed a chronic animal model of hypercapnic ventilatory failure by increasing airway resistance via tracheal banding over several days. To test the efficacy of this model, we compared arterial blood gases, pulmonary function, and internal area of the trachea 6 days after the banding or sham procedure in 20 hamsters. Six days later, banded animals had an increased airway resistance as indicated by a 66% reduction in internal cross-sectional area of the trachea and a 6.5-fold increase in pulmonary resistance compared with control hamsters. The increased airway resistance resulted in a severe respiratory acidosis and hypoxemia in the awake banded hamsters. Banded hamsters were also hyperinflated. This animal model will be useful for investigating the various mechanisms that contribute to hypercapnic ventilatory failure and interventions that may promote recovery.

A digital technique for stimulus artifact reduction

A method of recovering compound muscle action potentials which are overwhelm by a stimulus artifact is presented. In the specific example reported, such action potentials were recorded from the hamster diaphragm using an apposing platinum electrode for both stimulation and recording. To recover the artifact-free action potential, a combination of digital data acquisition and simple signal processing was employed. The recording of a stimulus artifact from a sub-threshold stimulus was used to subtract the artifact component from subsequent recordings and thus faithfully reveal the action potentials. The technique should find application in other preparations.

Respiratory muscle fiber morphometry. Correlation with pulmonary function and nutrition

To examine the relationship between nutrition, pulmonary function, respiratory muscle strength, and respiratory muscle morphometry, we compared physiologic data and muscle morphometry obtained from internal intercostal, external intercostal, and latissimus dorsi muscle biopsies in 68 patients who were having a thoracotomy. We stained the biopsies for myosin ATPase and measured the proportions and diameters of the type 1 and type 2 fibers. There were more qualitative changes in the external intercostal muscles than in the other two, and some of these changes related to the incidence of malignancy. There were more type 1 fibers in the external intercostal (64 +/- 10 percent) and internal intercostal muscles (59 +/- 12 percent) than in the latissimus dorsi (44 +/- 13 percent) (p less than 0.005). The mean diameter of the type 2 fibers in the external intercostal muscles was less (44 mu +/- 7 mu) than the diameter in the latissimus dorsi (51 mu +/- 9 mu) and the internal intercostal muscles (52 mu +/- 8 mu) (p less than 0.01). The diameters of both fiber types were greater in men than in women. There was no significant relationship between measures of pulmonary function or respiratory muscle strength and muscle fiber proportions and diameters. There were significant correlations between the percentage of ideal body weight and type 1 and type 2 fiber diameters. We conclude that sex and nutrition influence respiratory muscle morphometry.

Diaphragmatic plate electrode stimulation of the hamster diaphragm

We developed a new technique of diaphragmatic stimulation by apposing plate electrodes directly against the diaphragm (DPS) in adult Golden Syrian hamsters. The electrophysiological and the mechanical responses to DPS were compared with those with phrenic nerve stimulation. In four animals, evaluation of the electromyogram before and after curare demonstrated that plate electrode stimulation occurred via the phrenic nerve filaments. In four animals, similar transdiaphragmatic pressure was produced at maximal current with DPS and phrenic nerve stimulation. Using DPS increasing current beyond a certain level resulted in recruitment of muscles besides the diaphragm. In six animals, an external abdominal pressure of 15 cmH2O produced maximal transdiaphragmatic pressure, suggesting that the diaphragm was contracting near optimal position with this external abdominal pressure. In another four animals the twitch and pressure-frequency characteristics with the use of DPS were found to be reproducible over a 2-h period. We conclude that DPS is an effective method of diaphragmatic stimulation and should prove to be a valuable technique to study the diaphragm in long-term studies of small rodents.

An effective combination of anaesthetics for 6-h experimentation in the golden Syrian hamster

The anaesthetics described for use in hamsters to date are suitable for the performance of short-term experimentation. However, an anaesthetic regimen was required which would provide a stable preparation for 6 h and hence, a suitable combination was developed. In the first set of experiments, the effect of anaesthetics (chloralose, urethane, and pentobarbital) were examined alone and in combination on arterial blood measurements. In the second set of experiments the effect of the combination of anaesthetics on arterial blood measurements and minute ventilation was examined for up to 6 h. Chloralose, urethane and pentobarbital when used alone in the hamster were considered inadequate for our needs. Chloralose did not produce adequate surgical anaesthesia whereas urethane and pentobarbital resulted in marked respiratory depression. Urethane also produced a trend towards metabolic acidosis. In contrast, the combination of agents resulted in surgical anaesthesia and the arterial blood measurements were adequate. Further, the use of the combination of anaesthetics in hamsters resulted in a stable preparation where arterial blood measurements and minute ventilation were maintained in a good range for up to 6 h. The combination of chloralose, urethane and sodium pentobarbital in hamsters should prove useful in long-term non-recovery experimentation which requires early surgical intervention, minimal respiratory depression and an even depth of anaesthesia.

Proportions and sizes of muscle fiber types in the hamster diaphragm

This study demonstrated that there was interanimal and interregional variability of proportions and sizes of the muscle fiber types in the hamster diaphragm. Muscle fiber type proportions and sizes were determined for each side (right, left), surface (abdominal, thoracic), and region (sternal, anterior costal, posterior costal, crural) in six hamsters. There was marked regional and surface-to-surface variability and some interanimal variability in proportions and sizes of fiber type within the hamster diaphragm. The sternal and costal regions were relatively homogeneous. However, there were differences in both proportions and sizes of fiber types between the thoracic surface of the crural region and the abdominal surface of the crural region. These two surfaces of the crural region differed from the rest of the diaphragm. For muscle fiber type proportions, type 2a fibers demonstrated the most interanimal variability. Muscle fiber size varied little between animals.

Respiratory muscle training

The application of skeletal muscle training principles to the respiratory muscles is a relatively new field. Strength and endurance training of the respiratory muscles can be achieved in normal humans and in patients with neuromuscular and chronic obstructive pulmonary diseases. Careful monitoring is required throughout a training program to ensure that the respiratory muscles are, in fact, being trained. This is a promising area, although further research is necessary to determine the indications for respiratory muscle training. Furthermore, it is still necessary to determine the optimal mode of training.

Cigarette smoke inhalation patterns and bronchial reactivity

The manner in which a cigarette is smoked varies considerably between individuals and may be an important determinant of the altered bronchial reactivity observed in cigarette smokers. Twenty smokers were examined to determine the relationship between cigarette smoke inhalation patterns and bronchial reactivity. Inhalation patterns were measured non-invasively with a respiratory inductive plethysmograph and these were related to the provocative concentration of histamine that caused a 20% fall in FEV1 (PC20) and to the cough threshold for inhaled citric acid. Histamine PC20 values were inversely correlated with depth and rate of inhalation. Cough threshold was inversely correlated with greater cigarette consumption and with depth of inhalation.

A case of single pleural cavity with esophageal atresia and tracheoesophageal fistula

This is a report of a premature infant presenting with an esophageal atresia. At surgery it was realized that there was no posterior mediastinum and a single pleural cavity only. Other serious congenital anomalies were present. She died rather suddenly upon cessation of her prostaglandin E 1 at 34 days of life.

Neonatal renal candidiasis: sonographic diagnosis

With improved survival of very-low-birth-weight infants, the incidence of neonatal renal candidiasis is increasing. The clinical and sonographic features of four premature infants with renal candidiasis are presented. Both parenchymal and intrapelvic renal lesions, with or without hydronephrosis, were detected. Abdominal sonography is a useful noninvasive technique for the diagnosis and follow-up management of renal candidiasis. Early diagnosis allows prompt intervention with antifungal therapy and should increase survival.