Mode Of Breathing Research Articles

Deposition of Refractory Ceramic Fibers (RCF) in the Human Respiratory Tract and Comparison with Rodent Studies

A mathematical model has been developed to calculate the deposition of refractory ceramic fibers (RCF) in the human respiratory tract. For a typical size distribution of airborne RCF found in the work place, the fractional deposition and size distribution of deposited fibers in various regions of the respiratory tract are determined. These results are compared with those obtained earlier in rats and hamsters. The deposition fraction in the human lung is higher consisting of more coarse and long deposited fibers. This is caused by less efficient filtration of RCF in the human extrathoracic airways. Over the same exposure period however, total number of fibers deposited in the pulmonary region of the humans lung is about 5–10 times smaller per gram of lung or 1–2.5 times smaller per unit lung surface area than the rodents, depending upon the mode of breathing.

Jaw position, head position, body posture: development of an integrated system of examination, Part I

Recently in the field of clinical orthodontics, there has been increased interest in the relationship between jaw and head position, sleep apnea, and equivocal symptoms occurring in head, neck and shoulder. It has already been determined that a relation exists between head posture and mode of breathing. Since the craniofacial skeleton is supported by the cervical, thoracic and lumbar vertebrae, the head position might have some biomechanical connection to total body posture. Therefore, an integrated system of examining jaw position, head position and body posture is being developed.

Normalization of incisor position after adenoidectomy

Changes in incisor inclination and position in both jaws of children during the first 5 years after adenoidectomy were studied. The main change is a significant increased labial inclination of the incisors for the adenoidectomy groups. All variables that measure the labiolingual position of the mandibular incisors confirm a significant labial incisor positioning for both sexes. Stepwise regression analysis shows that 41% to 44% of the incisor proclination after adenoidectomy is accounted for by two regressors--sex (female) and increase in the sagittal size of the nasopharynx. The study supports the hypothesis that a changed mode of breathing after adenoidectomy is associated with significant labial positioning of the incisor teeth.

Disposition of Mulberry Pollen in the Human Respiratory System: A Mathematical Model

Abstract Inhaled particle deposition sites must be identified to effectively treat human airway diseases. We have determined distribution patterns of a selected aeroallergen, mulberry pollen, among human extrathoracic (ET: i.e., oronasopharyngeal) regions and the lung. A predictive model validated by inhalation exposure data from human subjects was utilized. Deposition locations were primarily functions of (1) mulberry particle parameters (geometric size, 11–18 μm; shape, spherical; and density, 1.14 g cm−3), and (2) mode of breathing. In the general population, two styles of inhalation are prevalent, normal augmentors (NAs) and mouth breathers (MBs). Their clinical definitions are based on intra-ET airflow divisions. For a NA-mode breathing sedentary (minute ventilation = VE = 10 L min−1) adult, 93% of inhaled mulberry pollen was removed by the ET compartment and 7% collected within the lung. For a MB, the respective deposition efficiencies were 75% and 25%. To apply the model, we used a daily springtime...

Mandibular and maxillary growth after changed mode of breathing

The amount of maxillary and mandibular growth and the direction of maxillary growth were studied in 38 children during the 5 years after adenoidectomy for correction of severe nasopharyngeal obstruction. The amount of mandibular growth measured between successive gnathion points on superimposed radiographs was significantly greater in the group who had an adenoidectomy than in the matched controls. In the boys the difference was 3.8 mm ( p < 0.001), and in the girls the difference was 2.5 mm ( p < 0.01). The boys also showed a tendency toward greater growth in the maxilla as measured between successive subnasal points (1.2 mm, p < 0.05). We detected no difference in the direction of maxillary growth between who had undergone adenoidectomy and the controls. (A M J O RTHOD D ENTOFAC O RTHOP 1991;100:1-18.)

Deposition patterns of ragweed pollen in the human respiratory tract

Abstract Inhaled particle deposition sites must be identified to effectively treat human airway diseases. We have determined distribution patterns of a selected aeroallergen, ragweed pollen, among human extrathoracic (ET: i.e., oro-nasopharyngeal) regions and the lung. A predictive model validated by inhalation exposure data from human subjects was utilized. Deposition locations were primarily functions of 1. ragweed particle parameters (size: 14–20 μm, shape: spherical, and density: 1.14 g cm-3) and 2. mode of breathing. In the general population, two styles of inhalation are prevalent: normal augmentors (NAs), and mouth breathers (MBs), their clinical definitions are based on intra-ET airflow divisions. For a NA-mode breathing, sedentary (10 L min-1) adult, 88% of inhaled ragweed pollen was removed by the ET compartment and 7% collected within the lung. For a MB, the respective deposition efficiencies were 68% and 25%. To apply the model, we used a daily springtime ragweed pollen concentration of 300 gr...

The Relationship Between Nasal Airway Size and Nasal-Oral Breathing in Cleft Lip and Palate

Clefts of the lip and palate generally result in reduced size of the nasal airway. Procedures such as the placement of a pharyngeal flap tend to further compromise nasal breathing. The purpose of this study was to determine how size of the nasal airway affects the mode of breathing in adults with cleft lip and/or palate. A heterogeneous population of 50 adult subjects with cleft lip and/or palate was studied. Nineteen of the subjects had pharyngeal flaps. Respiratory inductive plethysmography was used in combination with an integrating pneumotachograph to measure percent nasal breathing. Pressure-flow studies were used to estimate nasal airway size. The data revealed that a majority of subjects had an airway size of less than 0.4 cm2, which constitutes impairment. Mean cross-sectional area for all subjects was 0.38 cm2 +/- 0.20 SD. Seventy percent of the subjects studied were oral breathers to some extent. A Spearman rank correlation coefficient of 0.725 (p less than 0.0001) indicated that oral-nasal breathing mode was related to airway size. Airway size in the subgroup with pharyngeal flaps was even smaller (0.31 cm2), while percent nasal breathing was lower. Mouthbreathing was observed in all subjects whose airway size was less than 0.38 cm2.

Impact of Air Pollutants on Athletic Performance

Human controlled and observational studies both lead to the conclusion of air pollution adversely affecting athletic performance during training and competition. The dosage of various air pollutants during exercise is much higher due to the marked increase in ventilatory rate and concomitant nasal and oral breathing. This is particularly true for sulfur dioxide which is a highly water-soluble gas and is normally absorbed in the upper airway during nasal breathing. With heavy exercise, oral pharyngeal breathing is the predominant mode of breathing and much larger amounts of sulfur dioxide are delivered to the lower airway resulting in significant impact upon the lower respiratory tract. More recently, several controlled human studies have shown that a combination of exercise and air pollutants such as ozone (O3) or sulfur dioxides (SO2) cause a significant increase in bronchoconstriction and air flow obstruction when compared to the same exposure at rest. In strenuous athletic competition such as the Olympic Games where small increments of time often determine the ultimate success of athletes, the impact of air pollutants and subsequent adverse ventilatory changes can affect athletic performance.

Effects of cleft lip and palate on the nasal airway in children.

Clefts of the lip and palate often produce significant nasal deformities and reduced nasal airway size. The purpose of this study was to assess how type of cleft affects nasal cross-sectional area and mode of breathing. The pressure-flow technique was used to estimate nasal airway size and modified inductive plethysmography was used to determine percent of nasal breathing in 60 children with cleft lip and palate aged 6 to 15 years. Ninety-five normal children served as controls. The data demonstrate that nasal size decreased among cleft types as follows: children with bilateral cleft lip and palate had largest airway, followed by unilateral cleft lip, cleft of the hard and soft palate, cleft of the soft palate, and unilateral cleft lip and palate. The data also indicated that most subjects with cleft were mouth breathers. Results of otolaryngologic examinations suggest that septal deformities affecting nasal valve function are responsible for much of the impairment, especially in the group with unilateral cleft lip and palate. The differences among groups appear to relate to developmental differences associated with the original defect and the surgical procedures used in primary repair.

Extrathoracic and intrathoracic removal of O3 in tidal-breathing humans.

We measured the efficiency of O3 removal from inspired air by the extrathoracic and intrathoracic airways in 18 healthy, nonsmoking, young male volunteers. Removal efficiencies were measured as a function of O3 concentration (0.1, 0.2, and 0.4 ppm), mode of breathing (nose only, mouth only, and oronasal), and respiration frequency (12 and 24 breaths/min). Subjects were placed in a controlled environmental chamber into which O3 was introduced. A small polyethylene tube was then inserted into the nose of each subject, with the tip positioned in the posterior pharynx. Samples of air were collected from the posterior pharynx through the tube and into a rapidly responding O3 analyzer yielding inspiratory and expiratory O3 concentrations in the posterior pharynx. The O3 removal efficiency of the extrathoracic airways was computed with the use of the inspiratory concentration and the chamber concentration, and intrathoracic removal efficiency was computed with the use of the inspiratory and expiratory concentrations. The mean extrathoracic removal efficiency for all measurements was 39.6 +/- 0.7% (SE), and the mean intrathoracic removal efficiency was 91.0 +/- 0.5%. Significantly less O3 was removed both extrathoracically and intrathoracically when subjects breathed at 24 breaths/min compared with 12 breaths/min (P less than 0.001). O3 concentration had no effect on extrathoracic removal efficiency, but there was a significantly greater intrathoracic removal efficiency at 0.4 ppm than at 0.1 ppm (P less than 0.05). Mode of breathing significantly affected extrathoracic removal efficiency, with less O3 removed during nasal breathing than during either mouth breathing or oronasal breathing (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in lip pressure following extension and flexion of the head and at changed mode of breathing

The changes in upper and lower resting lip pressures following extension and flexion of the head and at changed mode of breathing were studied in a sample of 15 adults with Class I molar relationship. The lip pressure was measured with bonded strain gauge transducers on the upper and lower central incisors. The transducers could be calibrated directly in the subject's mouth. The upper and lower lip pressures during natural head posture had a mean value of 3.91 g/cm 2 and 8.58 g/cm, 2 respectively. The mean values of the differences between pressures obtained during natural head posture and during 5°, 10°, and 20° of extension showed a continuously, highly significant increase in pressure. During 5°, 10°, and 20° of flexion, the upper lip pressure continuously decreased with highly significant values. Changes in the lower lip pressure during flexion were difficult to measure because of intense muscle activity. A significant decrease was shown for the difference in upper and lower lip pressures between nose breathing and mouth breathing, whereas there was a significant increase in pressure when the subject extended the head 5° during mouth breathing.

Changes in postural EMG activity in the neck and masticatory muscles following obstruction of the nasal airways.

The aim of the present investigation was to induce oral respiration in human subjects and to study how this, in the short term (30 minutes), affected head posture, mandibular posture, and postural activity in the postcervical, supra- and infrahyoid, anterior temporal, masseter and sternocleidomastoid muscles. The study comprised of 30 adults. Head posture, mandibular posture and postural muscle activity were recorded: (a) during normal breathing when the subjects were standing in natural posture and with the mandible at rest, (b) immediately following obstruction of the nasal airways and then after 1, 3, 5, 10, 15, 20 and 30 minutes of obstruction, and (c) after nose breathing had been re-established. Obstruction of the nasal airways resulted in an extension of the head and a lowered mandibular posture. Postural activity decreased significantly in the postcervical and anterior temporal muscles and tended to increase in the suprahyoid muscles. In the infrahyoid, masseter and sternocleido-mastoid muscles no change in activity could be recorded. When nasal obstruction was removed and nose breathing was resumed, the readings of the variables studied did not differ significantly from the values recorded before the mouth breathing experiment. The results of the present study suggest that a change in the mode of breathing is able to influence head posture, mandibular posture and postural activity in neck and masticatory muscles.

The effect of cold air on head posture.

The effect of cold air on head posture was studied by taking profile photographs of a sample of 14 dental students indoors and outdoors at temperatures of $20° and −20 °C. The head posture of each subject was calculated from the photographs as the angle between a vertical line and a line passing through two pencil marks made on the subject's cheek. Another group of 10 subjects was photographed under similar conditions at temperatures of $20° and $10 °C. The study showed that there was a significant extension of the head when outdoors in the cold, this being greatest during the first 30 minutes. The change in head posture is probably due to a change in the mode of breathing.

Efficiency and limitations of the upper airway mucosa as an air conditioner evaluated from the mechanisms of bronchoconstriction in asthmatic subjects.

To elucidate a limit to the efficiency of the upper airway mucosa as an air conditioner, the temperatures of the inspiratory air and mucosa were measured in the cervical trachea. Both of them were affected only minimally by change of atmospheric air temperature during resting nose breathing, but were affected greatly by change of mode of breathing. During hyperventilation through the mouth, when the atmospheric air temperature was 1 degree C, a temperature difference of 9 degrees C was noted between inspiratory air in the cervical trachea and body temperature, together with a mucosal temperature fall by 1.86 +/- 0.61 degree C. Wearing of a mask caused a rise of 3 degrees C in the inspiratory air temperature in the cervical trachea.

Respiratory effects of 0.75 ppm sulfur dioxide in exercising asthmatics: Influence of upper-respiratory defenses

To determine the influence of mouthpiece breathing on respiratory responses to sulfur dioxide (SO 2), 23 young adult asthmatic volunteers were exposed in a chamber to 0.75 ppm SO 2 during heavy exercise, once with breathing unencumbered and once while they wore noseclips and mouthpieces. These conditions (more severe than in typical ambient exposures) were deliberately chosen to produce significant physiological and clinical responses. Similar exposures to clean air served as controls. Exposure studies were separated by 1-week intervals and order was randomized. The protocol consisted of 10 min on a bicycle ergometer (mean load 650 kg-m/min, mean ventilation 40 liter/min), preceded and followed by response testing (body plethysmography, symptom questionnaires, and forced expiratory function tests; the last were performed only postexposure). During clean-air exposures, specific airway resistance (SR aw) and symptoms increased significantly, but no meaningful differences between mouthpiece breathing and unencumbered breathing were observed. Exposures to SO 2 under these relatively severe conditions produced greater increases in SR aw than clean-air exposures regardless of the mode of breathing, but the excess increase was significantly greater with mouthpiece than with unencumbered breathing. Symptom changes and postexposure forced expiratory function showed qualitatively the same pattern of decrements with SO 2 as did SR aw, but the excess responses attributable to mouthpiece breathing did not attain statistical significance. Mouthpiece breathing can compromise upper-respiratory defenses against SO 2 to the extent that responses are greater than with more natural breathing. The mode of breathing should be taken in account when applying laboratory human exposure data to air-quality risk assessment.

Mouth breathing in allergic children: Its relationship to dentofacial development

While there are many claims that abnormal breathing patterns alter facial growth, there are limited controlled data to confirm this. We evaluated forty-five North American Caucasians of both sexes, ranging in age from 6 to 12 years. Thirty chronically allergic mouth-breathing subjects were selected from a pediatric allergy practice, and fifteen nonallergic nose breathers were selected from a general pediatric practice. Each subject underwent an intraoral clinical examination and a cephalometric radiograph analysis. Various skeletal and dental relationships were evaluated for statistical differences related to mode of breathing and age. The upper anterior facial height and the total anterior facial height were significantly larger in the mouth breathers. Angular relationships of the sella-nasion, palatal, and occlusal planes to the mandibular plane were greater in the mouth breathers, and their gonial angles were larger. The mouth breathers' maxillae and mandibles were more retrognathic. Palatal height was higher, and overjet was greater in the mouth breathers. Maxillary intermolar width was narrower in the mouth breathers and was associated with a higher prevalence of posterior cross-bite. Over all, mouth breathers had longer faces with narrower maxillae and retrognathic jaws. This supports previous claims that nasal airway obstruction is associated with aberrant facial growth. Longitudinal studies are needed to evaluate the effectiveness of early intervention in preventing these growth alterations.

Effects of temperature, relative humidity, and mode of breathing on canine airway secretions

Airway secretions were collected from the upper trachea of eight healthy nosebreathing mongrel dogs under general anesthesia, and the electrolytes and osmolality of these secretions were determined. Compared to plasma, secretions contained 15% higher Na+ and 33% higher Cl-, were 18% higher in osmolality, but had a lower Na+/Cl- throughout the 6-h experiments. When six nose-breathing dogs were exposed to air at 28.5 degrees C and 95% relative humidity, secretion osmolality became lower, but Na+/Cl- remained unchanged. In four other dogs, secretions approached the osmolality of plasma when inspired air was at 36.4 degrees C and 100% relative humidity. These secretions contained 22% higher Cl- and a lower Na+/Cl- than plasma. The differences between airway secretions and interstitial fluid suggest that secretions are formed by active Cl- transport. In another four dogs, secretion osmolality was higher with mouth breathing than breathing through the nose. Inasmuch as humidified and warmed air lowered and mouth breathing raised the osmolality of airway secretions, we postulate that the hyperosmolality of secretions results from water loss from the airway surface during conditioning of inspired air.

Relationship between tubal function, craniofacial morphology and disorder of deglutition.

26 children without hearing impairment have been examined by otolaryngologists and orthodontists. According to the tubal function test in a pressure chamber they were classifed into a group with good and poor tubal function. The E.N.T. examination was unconclusive for a possible relationship between rhinological findings, mode of breathing, sinusitis, size of tonsils, nasal airway resistance and tubal function. Adenoids proved to be a mechanical impairment for active tubal function as stated by many authors. The cephalometric analysis of lateral head films combined with a static and dynamic-functional evaluation of tongue posture revealed significant differences between children with good and poor tubal function. Subjects with a vertical craniofacial growth pattern seem to be predisposed for poor tubal function. Analysing static tongue posture in children with poor tubal function the tongue lies more retracted in a backward position. The back of the tongue is flattened in relation to the palatal arch. In children with good tubal function there is a much closer contact between the back of tongue and the hard palate. Subjects with poor tubal function have an increased incidence of abnormal deglutition combined with tongue-thrust, teeth-apart swallowing, lack of sealing off the anterior oral cavity and contraction of the circumoral musculature. In children with good tubal function one can find the somatic type of swallowing that means no contractions of the circumoral muscles, no tongue-thrust during deglutition but contact of the molars and contraction of the masseter muscle.

Control of Breathing in Acrochordus javanicus, an Aquatic Snake

Ventilation and oxygen uptake were measured in the elephant trunk snake, Acrochordus javanicus, during normal, undisturbed breathing. Ventilation is periodic, with ventilatory periods (VP) lasting 2.5-3.5 min, interrupted by nonventilatory periods (NVP) averaging 10 times longer at 25 C. Average tidal volumes ranged from 27.8 to 47.7 ml·kg⁻¹, while breathing frequency during VP ranged from 78 h⁻¹ to 155 h⁻¹. Total ventilation (V̇I) ranged from 250 to 543 ml·kg⁻¹·h⁻¹ BTPS (body temperature and pressure, saturated with water vapor). Oxygen uptake (V̇o2) averaged 16.6 mlO₂· kg⁻¹·h⁻¹ STPD (standard temperature and pressure, dry) at 20 C and 29.3 mlO₂· kg⁻¹·h⁻¹ at 30 C. Corresponding ventilations were 225 ml·kg⁻¹·h⁻¹ and 504 ml·2kg⁻¹· h⁻¹ BTPS. Ventilatory requirements, V̇I/V̇o2, were 13.8 and 17.2 for 20 and 30 C. Both ventilation and oxygen uptake are low in Acrochordus, compared with other reptiles. Also, the V̇I/V̇o2 ratio is much lower for Acrochordus than for most reptiles. A well-developed, richly vascularized lung and the long NVP contribute to unusually high extractions of O₂ from the ventilated air. The mode of breathing of Acrochordus allows it to stay submerged more than 90% of total lapsed time. During hypoxic breathing, ventilation is stimulated when inspired O₂ concentration is less than 10%. Large alveolar-to-blood Po2 gradients indicate that blood and lung O₂ stores are nearly exhausted when the hypoxic stimulus breaks the breath holds. The increased ventilation resulted from a shortening of NVP while tidal volumes and the frequency of breathing during VP remained unchanged. Breathing 100% O₂ significantly reduced ventilation. Hypercapnic breathing showed no ventilatory change when breathing 2% and 4% CO₂. Breathing 6% and 8/% caused an actual depression of ventilation. The results indicate an effective elimination of CO₂ by cutaneous exchange, which may account for the lack of a ventilatory response to CO₂ breathing. Ventilation in Acrochordus appears controlled for maximum utilization of oxygen stores and rapid recovery during breathing.

Active branchial and ram gill ventilation in fishes.

1. Characteristics of cyclic breathing movements have been examined in a number of fish species at rest and during swimming acceleration to velocities above those sufficient to induce transfers from active to passive gill ventilation (ram gill ventilation). They were trained to swim in one of several types of swimming tunnels after electrode implants to permit recording of ECG's and ventilatory muscle EMG's.2. Transfer to the ram mode of gill breathing is marked by a drop-out of individual cyclic breathing movements as swimming increases from rest. When the swimming speed reaches about 65 cm· sec-1, most fish that use ram gill ventilation complete conversion to the ram mode (35 to 82 cm·sec-1, range of all fish tested). This is equivalent to an across-gill differential pressure of 2.1 cm H2O as measured with a combined impact-reverse pitot tube as an approximate model. Generally, a fish must be swimming to ram gill ventilate, but some exceptions are noted such as the shark-riding remoras.3. Control of the transfer between gill ventilation modes appears basically to be a reflex shut-down of rhythmic breathing initiated by mechanoreceptive detection of water flow-velocity and the detection of swimming movements. Reflex transitions between active and passive breathing seem to happen too rapidly for a sufficient change of respiratory gas concentrations to occur and allow triggering of chemoreceptors.4. No unusual events are detectable in the ECG's of swimming fish as they reach and surpass speeds sufficient to maintain the ram mode. Cardioacceleration varies as between sluggish and active swimmers, but seems to be independent of the mode of gill ventilation used.5. Generally, demersal fishes that depend mainly upon the opercular phase for active gill ventilation, strongly aided by a well-developed branchiostegal system, do not ram ventilate. Conversely, nearly all species in which the work share of active ventilation is about equally buccal and opercular, probably use ram gill ventilation when they reach the requisite swimming speed. These are mostly midwater to pelagic in habits so for them, transfer of the muscular work of gill ventilation from the branchial to the swimming musculature seems to serve a dual function—a reduction in the cost of breathing, and an improvement in swimming efficiency.