Surface Electromyographic Activity of the Submental Muscles During Swallow and Expiratory Pressure Threshold Training Tasks

The use of expiratory muscle strength trainers improves parameters related to pulmonary function, speech, and cough in both healthy and patient populations. Recently, it has been speculated that expiratory strength training may alter the force generation of muscles used during the swallow process. Specifically, the use of the trainer may result in increased activation of the submental muscle complex. Support for this hypothesis was tested by examining the timing and amplitude of submental muscle activity obtained using surface EMG. These muscles are known to be important for normal swallow function. Twenty participants (10 males, 10 females; mean age = 29 years) were recruited to participate in a one-session study. Participants were asked to perform two swallows (saliva swallow and water swallow) and develop an expiratory pressure set at 25% and 75% of their maximum expiratory pressure (MEP) using an expiratory muscle strength trainer. These tasks allowed comparison of muscle activity during both the swallow and expiratory tasks completed with the trainer. Results indicated that the patterns of activation in the submental muscle group while training on the expiratory device had longer duration of activation with higher amplitude of EMG activity when compared with the swallowing condition. These findings indicate that expiratory muscle strength training (EMST) increases motor unit recruitment of the submental muscle complex. Discussion centers on the potential benefit of EMST as a treatment modality for dysphagia characterized by decreased amplitude of hyoid movement during swallowing. This study was completed at the Oral Motor-Human Performance Laboratory of the Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, Florida     

High-Resolution Manometry of Pharyngeal Swallow Pressure Events Associated with Effortful Swallow and the Mendelsohn Maneuver

Effortful swallow and the Mendelsohn maneuver are two common strategies to improve disordered swallowing. We used high-resolution manometry (HRM) to quantify the effects of these maneuvers on pressure and timing characteristics. Fourteen normal subjects swallowed multiple, 5-ml water boluses using three techniques: normal swallow, effortful swallow, and the Mendelsohn maneuver. Maximum pressure, rate, duration, area integral, and line integral were determined for the velopharynx and tongue base. Minimum pressure, duration of pressure-related change, duration of nadir pressure, maximum preopening and postclosure pressure, area integral, and line integral were recorded for the upper esophageal sphincter (UES). Area and line integrals of the velopharyngeal pressure curve significantly increased with the Mendelsohn maneuver; the line integral increased with the effortful swallow. Preopening UES pressure decreased significantly for the Mendelsohn, while postclosure pressure tended to increase insignificantly for both maneuvers. UES area and line integrals as well as nadir UES pressure duration increased with both maneuvers. Maneuver-dependent changes were observed primarily at the velopharynx and UES. These regions are critical to safe swallowing, as the velopharynx provides positive pressure at the bolus tail while the UES allows a bolus to enter the esophagus without risk of regurgitation. Integrals were more responsive than maximum pressure or duration and should be investigated further.     

Training Effects of the Effortful Swallow Under Three Exercise Conditions

The effortful swallow achieves overload through high effort. It was predicted that both immediate effects on biomechanics and long-term neuromuscular adaptations would be facilitated by maximal overload during this exercise. This study examined how high-effort sips from small-diameter straws influenced linguapalatal swallow pressures. Additionally, training effects of effortful swallows preceded by high-effort sips were compared to two other exercise conditions: effortful swallows preceded by maximum effort lingual elevation and effortful swallows performed in isolation. Training outcomes included linguapalatal pressures produced during effortful and noneffortful swallows, and maximum isometric pressure (MIP) produced during tongue elevation and interlabial compression. Forty healthy adults participated in the experiment. Lingual–palatal swallowing pressure during non effortful and effortful swallows and MIPs were measured prior to and after 4 weeks of training. Prior to training, anterior linguapalatal pressures were significantly higher during effortful compared to noneffortful swallows. Anterior linguapalatal pressures did not significantly differ during swallows preceded by sips from high-resistance straws. Weak correlations were observed between tongue MIP and linguapalatal pressures during effortful swallows. After training, anterior linguapalatal pressures significantly increased, with training effects more dramatic for effortful swallows. Anterior tongue MIP also significantly increased. Gains in anterior linguapalatal pressure were not correlated with gains in tongue MIP. Training effects did not vary across exercise condition. The study failed to find a training advantage of pairing the effortful swallow with a precursor movement. The results demonstrated specificity of training, with more dramatic benefits observed for effortful swallows relative to noneffortful swallows. Further investigation is needed to characterize training effects in older adults and patients with dysphagia.     

Intraventricular Flow During Isovolumic Relaxation: Comparison of Normal and Paced Ectopic Excitation Under Varied Loading Conditions

In this study, isovolumetric relaxation time (IVRT) flow velocities recorded by pulsed Doppler were induced or augmented in nine patients (aged 60 +/- 20 years) with permanent pacemakers. Six subjects had evidence of IVRT flow (>/=0.2 m/sec) during native rhythm, only three of whom exhibited cavity obliteration. Mean +/- SD left ventricular (LV) ejection fraction and end-diastolic and end-systolic volumes were 60% +/- 5%, 104 +/- 50 mL, and 39 +/- 27 mL, respectively. IVRT flows were induced or augmented (P < 0.003) in all patients during paced ectopic stimulation of the right ventricle and during pacing combined with sublingual nitroglycerin (NTG; 0.4 mg). However, IVRT flows were not significantly increased with NTG alone. IVRT flow duration was prolonged >50% by pacing (P < 0.05). These data suggest that IVRT flows may be present in patients without cavity obliteration and may be accentuated by asynchronous LV relaxation. (ECHOCARDIOGRAPHY, Volume 13, January 1996)     

Origin of the Sound Components During Pharyngeal Swallowing in Normal Subjects

The aim of this study was to identify the origin of swallowing sound components by using modern techniques that can provide numeric, synchronized acoustic-radiologic data. We enrolled 15 volunteer subjects (10 men and 5 women, average age = 29.5 +/- 8 years) and used an X-ray camera connected to a video acquisition card to obtain synchronized acoustic-radiologic data (25 images/s). The subjects were asked to swallow 10 ml of a barium suspension. Each sound component was associated with a specific position of the bolus and the anatomic structure that was moving. The average duration of the pharyngeal sound was 690 +/- 162 ms. The durations of the laryngeal ascension sound and the laryngeal release sound were significantly different (72 +/- 38 ms and 106 +/- 47 ms, p < 0.001). The upper-sphincter opening sound was present in 100% of the recordings. Its duration was 185 +/- 103 ms and was significantly different from the two other sounds. The duration of the first interval was 108 +/- 44 ms and the duration of the second was 236 +/- 139 ms. This study allowed us to determine the origin of the three main sound components of the pharyngeal swallowing sound with respect to movements in anatomic structures and the different bolus positions.     

Laryngeal Penetration During Deglutition in Normal Subjects of Various Ages

This study examined the frequency of penetration of liquid, paste, and masticated materials into the airway during videofluoroscopic studies of normal swallow in 98 normal subjects who were from 20 to 94 years of age. The purposes of the study were to define frequency and level of penetration using the penetration-aspiration scale as a result of age, bolus volume, viscosity, and gender, and to describe the body's sensorimotor response to the penetration based on audible coughs or throat clearing on the audio channel of each videotaped fluoroscopic study. Frequencies of penetration were defined in relation to bolus volume, age, gender, and bolus viscosity from swallows of 1, 3, 5, and 10 ml and cup-drinking of thin liquids; 3 ml of pudding; (1/4) of a Lorna Doone cookie; and a bite of an apple. Results showed that penetrations were significantly more frequent after age 50 and thick viscosities penetrated only in subjects age 50 and over. For persons under 50, 7.4% of swallows exhibited penetration, while for people age 50 and over, 16.8% of swallows showed penetration. Significantly more penetration occurred on larger liquid boluses. There was no relationship between gender and frequency of penetration. None of the subjects that penetrated showed a sensorimotor response to the penetration, which may relate to the relatively shallow depth of the penetration.     

Studies in Desferrioxamine and Ferrioxamine Metabolism in Normal and Iron-Loaded Subjects

Plasma concentrations of desferrioxamine and ferrioxamine were measured following bolus injections of desferrioxamine and during 24 h infusions of the drug. [59Fe]ferrioxamine clearance and urinary iron excretion were also measured. Higher plasma ferrioxamine concentrations were found in iron loaded subjects and higher desferrioxamine concentrations in subjects with normal ironloads. There is a correlation between the circulating concentration of ferrioxamine during an infusion and the 48 h urinary iron excretion. The data suggests that the amount of iron chelated in vivo is related to an increase in the size of an intermediate chelatable pool rather than the total amount of the iron load. The well-recognized delay in urinary iron excretion appears to be related to active tubular reabsorption of ferrioxamine.     

Effect of the Effortful Swallow and the Mendelsohn Maneuver on Tongue Pressure Production against the Hard Palate

Although effortful swallow and the Mendelsohn maneuver are commonly used in dysphagia rehabilitation, little is known about their effects on tongue-palate pressure production. The purpose of this study was to investigate the effects of effortful swallow and the Mendelsohn maneuver on tongue pressure production. Fourteen healthy volunteers (10 men, 4 women; age range = 21–41 years) participated. Tongue pressures during dry swallow, water swallow, effortful swallow, and the Mendelsohn maneuver were measured using a sensor sheet system with five measurement points on the hard palate. Sequential order, duration, maximal magnitude, and the integrated value of tongue pressure at each measurement point were compared among the four tasks. Onset of tongue pressure at the posterior-circumferential parts occurred first in the Mendelsohn maneuver; that at the anterior-median part was earlier than at other parts in the effortful swallow. At all measurement points, tongue pressure duration was significantly longer in the Mendelsohn maneuver than in other tasks. Effortful swallow was most effective in increasing tongue pressure. The integrated value of tongue pressure at the posterior-circumferential parts in the Mendelsohn maneuver and at the median parts in the effortful swallow showed a tendency to increase. These results suggest that tongue pressure increases along a wide part of the hard palate in effortful swallow because the anchor of tongue movement is emphasized at the anterior part of the hard palate. The Mendelsohn maneuver provides prolonged and accentuated tongue-palate contact at the posterior-circumferential parts, which might be important for hyoid-laryngeal elevation during swallowing.     

Relationship Between Plasma Catecholamines and the Renin-Aldosterone System During Exercise in Normal and Essential Hypertensive Subjects

Interrelations were investigated between blood pressure, plasma epinephrine (E), norepinephrine (NE), dopamine (D), aldosterone, cortisol concentrations, active and inactive plasma renin activity (PRA), and age in 21 normotensive subjects (aged 20–60 years) and in 25 patients (aged 20–63 years) with essential hypertension (EH). These parameters were measured at rest and during exercise on a bicycle ergometer. In normotensive subjects basal and exercise-stimulated levels of plasma NE increased with age which was not observed in EH. In hypertensive patients there was a higher plasma D concentration under the exercise as compared with normotensive controls. In the normotensives, basal active PRA was inversely related to age (p<0.05), and during initial 8 min of exercise active PRA significantly correlated with plasma E and plasma NE. Moreover, absolute changes from basal to acutely stimulated values of active PRA were directly related to the changes of plasma E and NE (p<0.001). In hypertensive patients these relationships were not found. However, in the hypertensives there were significant positive correlations between the increases of active PRA, plasma E, plasma NE on the one hand and their respective basal values on the other hand.

The results indicate very strong functional relationship between the sympathetic-adrenomedullary and renin-angiotensin systems during initial interval of acute stimulation in normotensive subjects. Essential hypertension is not a pathophysiologically homogenous disease with respect to reactivity and interaction of plasma catecholamines and PRA. Separate regulatory pathways exist for plasma active and inactive renin. During short-time exercise aldosterone secretion is related rather to the renin-angiotensin system than to the hypothalamic-pituitary axis.     

Effect of Viscosity on Food Transport and Swallow Initiation During Eating of Two-Phase Food in Normal Young Adults: A Pilot Study

When eating food containing both liquid and solid phases (two-phase food), the liquid component frequently enters the hypopharynx before swallowing, which may increase the risk of aspiration. We therefore tested whether preswallow bolus transport and swallow initiation would change as the viscosity of two-phase food was increased. Fiberoptic endoscopy was recorded while 18 adult subjects ate 5 g of steamed rice with 3 ml of blue-dye water. Liquid viscosity was set at four levels by adding a thickening agent (0, 1, 2, and 4 wt%, respectively). We measured the timing of the leading edge of the food reaching the base of the epiglottis, as well as the location of the leading edge at swallow initiation. As viscosity increased, the leading edge of the food reached the epiglottis significantly later during chewing and was higher in the pharynx at swallow onset. The time after the leading edge reached the epiglottis did not vary among the viscosities of the two-phase food. This study found that the initial viscosity of two-phase food significantly altered oropharyngeal bolus flow and the timing of swallow initiation. Accordingly, increased two-phase food viscosity may delay food entry into the pharynx and be of use in dysphagic diets.     

Effects of Milrinone on Atrioventricular Conduction in the Canine Heart Under Normal Conditions,During Atrial Flutter and After Ligation and Reperfusion of the Septal Artery

Milrinone and AV Conduction. Milrinone, in addition to its vasodilatory and inotropic actions, has been shown to enhance or restore electrical activity in depolarized tissues and to improve conduction in isolated cardiac tissues depressed by exposure to an ischemic environment. These electrophysiological actions of the drug are thought to be secondary to milrinone's ability to enhance the transmembrane calcium current (I_Ca). The present study was designed to evaluate the effectiveness of milrinone (10–100 μg/kg, IV bolus) to modulate atrioventricular (AV) nodal conduction in anesthetized dogs under normal conditions, after ligation and reperfusion of the septal coronary arteries and during atrial flutter. All dosage regimens (10–100 μg/kg milrinone) produced a positive inotropic effect with no significant changes in blood pressure. Under normal conditions, 100 jig/kg of milrinone significantly reduced the PR interval, Wenckebach cycle length and AV nodal refractory period without causing a significant change in heart rate. The improvement in AV conduction and decrease in AV nodal refractoriness led to significant dose-dependent increases in ventricular rate during atrial flutter. Low doses of milrinone also accelerated the flutter rate. Ligation of the septal coronary arteries for 2 to 6 hours produced stable atrioventricular conduction disturbances in six of the 11 dogs studied: complete AV block (n = 1), second-degree AV block (n= 2) and first-degree AV block (n= 3). Milrinone (100 μg/kg) improved AV conduction in five of the six dogs. Reperfusion of the septal arteries following 6 hours of ligation produced a sustained high degree AV block in two out of five dogs. Milrinone promptly restored 1:1 conduction in both cases. Our results suggest that milrinone may be of benefit in the treatment of some cases of AV conduction disturbance and that the drug, through its effects to facilitate AV conduction and abbreviate AV refractoriness, can lead to a significant and perhaps dangerous increase in ventricular rate in patients with atrial flutter or fibrillation. (J Cardiovasc Electrophysiol, Vol 1. pp. 93–102. 1990)     

Serological Studies of Seromucoids from Normal Subjects and Patients with Malignant and Non-Malignant Diseases

During investigations of serum from patients with carcinoma, elevated levels of two proteins were observed. The larger (MW approximately 44,000) was identified as (alpha-acid glycoprotein. The smaller MW approximately 20,000) has not yet been identified. Further investigation of alpha-acid-glycoprotein-containing seromucoid showed that many red blood cell and tissue antigens were present, for example, I, i, P1, Tja (P+P+Pk), H, A, B, Lea, Leb1, M and N. Differences in antigen content between normal serum and serum from carcinoma patients could be demonstrated quantitatively and qualitatively. Seromucoid preparations from patients with Hodgkin's lymphoma inhibited phytohaemagglutinin-induced lymphocyte transformation more often than seromucoid preparations from normal subjects.     

Initiation and Duration of Laryngeal Closure During the Pharyngeal Swallow in Post-Stroke Patients

As a bolus enters the pharynx during the swallow, the airway is protected by laryngeal closure, a process characterized by approximation of the vocal folds plus approximation of the arytenoid cartilages to the base of the epiglottis. The purpose of this study was to measure initiation of laryngeal closure (ILC) and laryngeal closure duration (LCD) in three groups of subjects: (1) ten stroke patients who aspirated before and during the swallow (aspirators), (2) ten stroke patients who did not aspirate (nonaspirators), and (3) ten normal control subjects. Means and standard deviations of ILC and LCD were analyzed for both 5-ml and 10-ml thin-liquid boluses using a 100-ms timer during subsequent analysis of videofluoroscopic swallowing examinations. There were significant differences between aspirators and control subjects for both ILC and LCD, and significant differences between aspirators and nonaspirators for ILC. There were no significant differences between aspirators and nonaspirators for LCD. Both delayed ILC and reduced LCD were associated with post-stroke aspiration. Delayed ILC is a significant indicator of overall risk of aspiration. Clinical implications for these findings are discussed.     

Accuracy of a Novel Noninvasive Multisensor Technology to Estimate Glucose in Diabetic Subjects During Dynamic Conditions

The purpose of this study was to determine whether an approach of multisensor technology with integrated data analysis in an armband system (SenseWear® Pro Armband, SWA) can provide estimates of plasma glucose concentration in diabetes. In all, 41 subjects with diabetes participated. On day 1 subjects underwent an oral glucose tolerance test (OGTT) and on day 2 a 60-minute treadmill test (TT). SWA plasma glucose estimates were compared against reference peripheral venous glucose concentrations. A continuous glucose monitoring device (CGM) was also placed on each subject to serve as a reference for clinical comparison. Pearson coefficient, Clarke error grid (CEG), and mean absolute relative difference (MARD) analyses were used to compare the performance of plasma glucose estimation. There were significant correlations between plasma glucose concentrations estimated by the SWA and the reference plasma glucose concentration during the OGTT (r = .65, P < .05) and the TT (r = .91, P < .05). CEG analysis revealed that during the OGTT, 93% of plasma glucose concentration readings were in the clinically acceptable zone A+B for the SWA and 95% for the CGM. During the TT, the SWA had 96% of readings in zone A+B, compared to 97% for the CGM. During OGTTs, MARDs for the SWA and CGM were 26% and 18%, respectively. During TTs, MARDs were 16% and 12%, respectively. Plasma glucose concentration estimation by the SWA’s noninvasive multisensor approach appears to be feasible and its performance in estimating glucose approaches that of a CGM. The success of this pilot study suggests that multisensor technology holds promising potential for the development of a wearable, noninvasive, painless glucose monitor.     

Influence of Chin-down Posture on Tongue Pressure during Dry Swallow and Bolus Swallows in Healthy Subjects

The purpose of this study was to investigate the influence of chin-down posture and bolus size on tongue pressure during swallowing. Eleven healthy volunteers (7 men, 4 women; age range = 26–59 years) participated in the experiments. Tongue pressure during dry and 5- and 15-ml water swallows in neutral and chin-down postures was measured using a sensor sheet system with five measuring points on the hard palate. Sequential order, maximal magnitude, duration, and integrated value of tongue pressure at each measuring point were compared between postures and bolus sizes. Onset of tongue pressure at posterior-circumferential parts occurred earlier in dry swallow than in 5- and 15-ml water swallows in each posture. Chin-down posture was most effective for increasing tongue pressure in the 5-ml water swallow compared with dry swallow and the 15-ml water swallow, but it had almost no influence on tongue pressure with the 15-ml water swallow. These results suggest that chin-down posture increases the tongue driving force for small boluses in healthy subjects, which can be interpreted to mean that oropharyngeal swallowing in a chin-down posture requires more effort.     

Diurnal Levels of Immunoreactive Erythropoietin in Normal Subjects and Subjects with Chronic Lung Disease

S ummary . Serum levels of immunoreactive erythropoietin (Ep) were measured in 48 normal male and female volunteers, ages 20-60 years, to establish a control value for Ep of 18·5±5·0 ( SD) mU/ml. Levels of the hormone were also measured sequentially over a 24 h period of time in an additional 17'normal'volunteers with no diurnal variation. Diurnal levels of immunoreactive Ep were also measured in 30 subjects with chronic lung disease. These patients, in contrast to normal subjects, exhibited a diurnal variation in the level of immunoreactive Ep with peak levels occurring at midnight. The only variable measured which correlated with the serum immunoreactive Ep level in subjects with chronic lung disease was the level of carboxyhaemoglobin ( P <0·02).     

Fructosamine in Obese Normal Subjects and Type 2 Diabetes

The effect of various grades of obesity on serum fructosamine concentrations was studied in Type 2 diabetic (n = 105) and non-diabetic (n = 128) subjects. In obese diabetic and non-diabetic subjects (body mass index ≥ 30 kg m^?2), the concentration of fructosamine was markedly lower than that obtained for lean diabetic and non-diabetic subjects with similar glycaemic control. Stepwise multiple-regression analysis showed that fructosamine was associated with glycaemic control (as indicated by fasting plasma glucose and glycated haemoglobin), fasting triglycerides, and body mass index in both diabetic and non-diabetic subjects. In vitro studies showed marked decreases in both the extent of [¹⁴C]-glucose incorporation into plasma proteins and fructosamine production by incubated sera of obese patients whether diabetic or non-diabetic, with obese subjects with body mass index > 40 kg m^?2 exhibiting the greatest decrease. In conclusion, serum fructosamine concentrations are shown to decrease in obese diabetic and non-diabetic subjects with body mass index ≥ 30 kg m^?2 giving rise to the underestimation of glycaemic control as indicated by fructosamine measurement. A change in the glycation reaction itself may be partly responsible for such decrease.