An improved method for airway assessment in children.

Respiratory mode determination using the simultaneous nasal and oral respirometric technique (SNORT) or a head-out body plethysmography can be time-consuming, expensive, and intimidating to children. We have developed an improved method for assessing respiratory mode that uses inductive plethysmography linked to a menu-driven computer program that circumvents some of these problems. An assessment of 29 subjects over as many as nine separate time points suggests that respiratory mode measurements remain fairly uniform in some children, but can vary significantly in others.

Nasal airway impairment: the oral response in cleft palate patients.

The purpose of this study was to assess the oral response to severe nasal airway impairment in patients with cleft palate. Inductive plethysmography was used to measure the percent of nasal breathing, and the pressure-flow technique was used to estimate nasal area in 15 persons with severe nasal airway impairment. Mean nasal area was 0.17 cm2, and the average percent of nasal breathing was 20%. Analysis revealed a strong correlation (0.87) between nasal size and percent of nasal breathing in this selected group. Modeling studies based on the mean values from the subjects' data indicated that the model "mouth" would have to open 0.5 cm2 to shunt 80% of the airflow orally, an amount equivalent to the mean value of the subjects' respiratory mode. More important, the extrapolated data revealed that upper-airway resistance decreased in the model from 8.7 cm H2O/L/sec to a level of 3.2 cm H2O/L/sec, which is an average value for healthy adults. These data support the concept that the mouth acts as a variable resistor to maintain an optimal respiratory tract resistance when the nasal airway is impaired.

The effect of cleft palate speech aid prostheses on the nasopharyngeal airway and breathing.

This study determined the effect of a speech aid prosthesis on resting breathing. Nasal cross-sectional area was measured during inspiration and expiration in eight cleft palate patients. The measurements were made for the unobturated defect during both phases of respiration and then repeated while the defect was obturated by a speech aid prosthesis. The results of the study revealed that the presence of a speech aid prosthesis significantly decreased the cross-sectional region of the nasal airway. In 50% of the subjects, the cross-sectional region was less than 0.40 cm2 with concomitant impairment in nasal respiration when the speech aid prosthesis was present in the oral cavity. The data suggest that the design of these prostheses should account for breathing requirements as well as for speech.

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.

Effect of age on nasal cross-sectional area and respiratory mode in children.

Although nasal cross-sectional size has been reported for adults, no information is available concerning the effects of age on nasal area and breathing mode in children. Determination of the effect of age on nasal size is necessary in order to define nasal airway impairment in children. The purpose of this study was to determine mean nasal cross-sectional size in children between the ages of 6 and 15 years. One hundred two children were assessed during resting breathing. The pressure-flow technique was used to estimate nasal cross-sectional size, and inductive plethysmography was used to assess nasal-oral breathing. The results indicate that nasal airway size increased approximately 0.032 cm2 each year. Mean nasal cross-sectional area increased from 0.21 +/- 0.05 cm2 at age 6 to 0.46 +/- 0.15 cm2 at age 14. The percentage of nasal breathing also increased with age.

The speech regulating system: temporal and aerodynamic responses to velopharyngeal inadequacy.

Temporal and respiratory responses to a loss of velar resistance were measured in 107 subjects demonstrating varying degrees of velopharyngeal inadequacy. The subject data were compared to data generated by a mechanical model representing a passive system. The pressure-flow technique was used to estimate velopharyngeal orifice size and measure respiratory and temporal characteristics of aerodynamic events associated with the production of the nasal-plosive blend /mp/ in the word "hamper". Subjects were categorized as having adequate closure (less than 0.05 cm2), adequate/borderline closure (0.05-0.09 cm2), borderline/inadequate closure (0.10-0.19 cm2) and inadequate closure (greater than or equal to 0.20 cm2). The data revealed that intraoral pressure fell 10-fold in the model as velopharyngeal orifice area changed from adequate closure to inadequate. The subject data demonstrated only a 1.4-fold drop in pressure. Airflow data indicated that there was a 10-fold increase in respiratory volume in the subject data corresponding to the change from adequacy to inadequacy. When respiratory and temporal responses were assessed together, the findings revealed that airflow and temporal changes minimized the fall of pressure as velar resistance declined across groups.

Dimensions of the cleft nasal airway in adults: a comparison with subjects without cleft.

The prevalence of mouthbreathing among individuals with cleft lip and palate is significantly higher than in the normal population. This has been attributed to nasal deformities that tend to reduce nasal airway size. The purpose of the present study was to determine how a heterogeneous adult group with cleft lip and palate differs in terms of nasal airway cross-sectional area from an adult group without cleft during the inspiratory and expiratory phases of breathing. The pressure-flow technique was used to estimate nasal airway size in 15 adults without cleft (15 years or older) and 37 adults with cleft lip, cleft palate, or both. Mean areas and standard deviations for subjects without cleft were 0.63 cm2 +/- 0.17 during inspiration and 0.56 cm2 +/- 0.14 during expiration. This difference is statistically significant (p less than 0.01). Mean areas and standard deviations for all subjects with cleft were 0.37 cm2 +/- 0.18 during inspiration and 0.40 cm2 +/- 0.20 during expiration. This difference is not statistically significant (p greater than 0.15). Twenty-two of the subjects with cleft had nasal areas considered to be impaired (below 0.40 cm2) as compared with only three of the subjects without cleft. A two factor analysis of variance (ANOVA) demonstrated that area changes during respiration are different for subjects with and without cleft (p less than 0.005), and that cleft nasal areas are smaller than noncleft areas for both phases of breathing (p less than 0.001). Inspiratory-expiratory differences between subjects with and without cleft are probably the result of developmental defects, reparative surgery or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoral pressure, nasal pressure and airflow rate in cleft palate speech.

We have suggested that compensatory behaviors associated with cleft palate may be strategies developed for the purpose of satisfying the requirements of a speech regulating system. The purpose of the present study was to test this hypothesis in subjects demonstrating various degrees of velopharyngeal inadequancy. The pressure-flow technique was used to assess aerodynamic responses to a loss of velar resistance in 74 subjects compared to a control group of 137 subjects with adequate velopharyngeal closure. The results of this study demonstrate that as degree of inadequacy increased, airflow rate also increased. Although intraoral pressure fell as inadequacy increased, many subjects were able to maintain pressures above 3.0 cm H2O by increasing airflow rate. Nasal pressure increased in proportion to the decrease in intraoral pressure while combined nasal plus oral pressure remained constant across groups. These findings suggest that a loss of resistance at the velar port is compensated by an increase in resistance at the nasal port. Airflow rate appears to be adjusted to total upper airway resistance. These findings support our contention that the speech system is constrained to meet aerodynamic requirements.

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.

The relationship between nasal airway size and nasal-oral breathing.

Most clinicians agree that impaired nasal breathing results in obligatory mouth breathing. Some believe that mouth breathing influences dentofacial growth; others disagree. The term mouth breathing is confusing because total mouth breathing rarely occurs. A combination of nasal and oral breathing is more usual. The purpose of the present study involving 116 adult subjects was to (1) assess the relationship between nasal impairment and nasal-oral breathing, (2) determine the switching range from nasal to nasal-oral breathing, and (3) quantify the term mouth breathing. The pressure-flow technique was used to estimate nasal airway size; inductive plethysmography was used to assess nasal-oral breathing in normal and impaired breathers. Analysis of the date showed a Pearson rank correlation of 0.545 (P less than 0.001) between nasal area and nasal-oral respiration. Ninety-seven percent of subjects with a nasal size less than 0.4 cm2 were mouth breathers to some extent. About 12% of subjects with an adequate airway were assumed to be habitual mouth breathers. The findings indicate that the switching range from nasal to nasal-oral breathing is very narrow (0.4-0.45 cm2). These results also confirm our contention that in adults an airway less than 0.4 cm2 is impaired.

Prevalence of mouthbreathing in cleft lip and palate.

The purpose of the present study was to determine the prevalence of mouthbreathing in the cleft population. Percent nasal breathing was assessed in 85 children and adults using a pneumotachograph to measure nasal volumes and an inductive plethysmograph to measure tidal volumes. Breathing mode was defined using the following classifications of percent nasal breathing: 80 to 100 percent, nasal; 60 to 79 percent, predominantly nasal; 40 to 59 percent, mixed oral-nasal; 20 to 39 percent, predominantly oral; 0 to 19 percent, oral. Results demonstrate that 68 percent of the subjects were oral, predominantly oral or mixed oral-nasal breathers, and 32 percent were predominantly nasal or nasal breathers. Adults had the same prevalence of mouthbreathing as children. These findings demonstrate that cleft lip/palate and its treatment frequently compromise nasal respiration.

The relationship between nasal airway cross-sectional area and nasal resistance.

Mouth breathing in response to an impaired nasal airway is thought to have clinical consequences. Physiologically, mouth breathing occurs whenever the body senses that nasal resistance is inappropriately high. In physical terms mouth breathing is a response that enlarges the upper airway and, by doing so, reduces airway resistance. In the past measurements of nasal resistance have been used as an index of airway impairment. Recently, we introduced a technique that estimates cross-sectional size of the airway, a variable that directly determines the magnitude of airway resistance. The purpose of the present study was to determine the precise effects of nasal airway size on nasal airway resistance so that the relationship between the two could be described in mathematic terms. There were two phases to the study--one involving a model and simulated breathing, and the other involving 100 subjects demonstrating normal and impaired nasal airways. The pressure-flow technique for estimation of nasal airway size and nasal airway resistance was used. The following equation was generated from the data: Resistance = 1.9 + (Formula: see text). The relationship between the two variables is nonlinear--that is, size of the airway has its greatest effect on resistance when the airway is less than 0.4 cm2 and a much lesser effect at larger airway sizes. The study also showed that nasal airway resistance generally does not fall very much below 1.9 cm H2O/L/S during breathing even when the airway is very large. This probably relates to the need to maintain an adequate level of airway resistance for alveolar gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between nasal cross-sectional area and nasal air volume in normal and nasally impaired adults.

The controversy concerning the effects of nasal airway impairment on facial growth has stimulated renewed interest in upper airway respiratory function. The subjective manner in which airway impairment and mouth breathing have been assessed is, in our opinion, responsible for the differences observed among investigators and for their conclusions. We have been involved in a series of studies dealing with airway impairment and have report modifications of two techniques for objectively assessing respiration. The purpose of the present study was to examine a large population of adults, with and without nasal airway impairment, and assess the relationship between nasal cross-sectional area and nasal air volume to determine at what point airway size controls the passage of air during breathing. Statistical analysis of the data demonstrates that airway size alters air volume when nasal cross-sectional area is less than 0.4 cm2. The relationship between area and volume is very linear below 0.4 cm2, with air volume decreasing with decreased size. Although the data do indicate some influence over volume at sizes greater than 0.4 cm2, the effect is very slight. These findings support the prediction that upper airway impairment is present at nasal airways less than 0.4 cm2 in adults.

Inspiratory and expiratory effects of nasal breathing.

The purpose of the present study was to assess quantitatively the nasal valve area during normal inspiratory and expiratory maneuvers. The pressure-flow technique of Warren was used to estimate nasal size in 15 adult subjects who had no previous history of nasal surgery or abnormality. Cross-sectional size of the nasal airway was also assessed (1) after insertion of tubing to eliminate alar effects, (2) after administration of 0.1% Otrivin decongestant to eliminate mucosal effects, and (3) by blocking each nostril individually. Mean areas of 0.63 cm2 +/- 0.17 during inspiration and 0.56 cm2 +/- 0.14 during expiration. This difference is statistically significant (less than 0.01) and the effect was maintained under conditions of occlusion of either nostril, insertion of tubing, and administration of Otrivin. These findings suggest that the nasal valve acts as a respiratory brake during expiration possibly to allow adequate time for gas exchange at the alveoli.

Effects of size of the nasal airway on nasal airflow rate.

The controversy concerning the effects of nasal airway impairment on facial growth has stimulated renewed interest in upper airway respiratory function. We assessed the relationship between nasal airway patency and nasal airflow rate, using the pressure-flow technique to estimate nasal cross-sectional size and nasal airflow rate in 30 normal and 82 nasally impaired adults. Groups were categorized according to otolaryngologic examination results and pressure-flow measurements. The results clearly demonstrate that size of the airway influences airflow rate when the smallest nasal cross-sectional area is under 0.4 cm2. The data suggest that the nose becomes flow-limiting when it is less than 0.18 cm2. These data support our contention that nasal airway impairment in adults occurs when the airway is less than 0.4 cm2 in size.

The nasal airway following maxillary expansion.

There have been suggestions that maxillary expansion may be justified on the basis of airway considerations alone. The present study assessed the effects of rapid maxillary expansion and surgical expansion on nasal airway size to determine how useful these techniques are for breathing purposes. The results demonstrate that both procedures generally improve the nasal airway. However, approximately one third of the subjects in both groups did not achieve enough improvement to eliminate the probability of obligatory mouth breathing. These findings suggest that maxillary expansion for airway purposes alone is not justified.

Measurement of nasal and oral respiration using inductive plethysmography.

The role of nasal respiratory function in oral and facial development remains unclear in spite of the long-standing interest of clinicians. Much of the current controversy stems from our inability to define mouth breathing in objective terms and evaluate nasal airway impairment quantitatively. Recent advances in respiratory monitoring technology provide new opportunities to assess upper airway breathing more objectively. The purpose of this study was to describe a new approach for measuring oral and nasal respiration and to test its reliability. The technique involves inductive plethysmography and the data provide an assessment of respiratory mode without the need to enclose the subject's head in an airtight box. The data were compared to pneumotachography and the results demonstrate the reliability of the technique.

Upper airway pressures during breathing: a comparison of normal and nasally incompetent subjects with modeling studies.

Although there has been considerable interest in the effects of nasal airway impairment on facial growth, the relationship is still unclear. This study examined the effect of nasal airway size on upper airway pressures during breathing. Three phases of data collection were involved. The first phase used a model to describe pressures during simulated normal and impaired respirations. The second phase involved subjects with normal airways, and the third used persons who were judged by an otolaryngologist to be nasally impaired. Aerodynamic assessment techniques were used to measure airway pressures during breathing and to assess nasal airway size. Results of the modeling study suggest that when nasal cross-sectional area is greater than 0.1 cm2, pressures associated with breathing are not excessive. These findings also suggest that slight lip opening (2 to 3 mm) would significantly reduce airway pressures. In addition, pressure magnitudes of the normal and nasally impaired groups were similar to the modeling data, and no significant difference in pressures was observed between the two groups. Accordingly, the assumptions that nasally impaired persons generate abnormal breathing pressures and that these pressures directly influence facial growth are questionable.

Disabled adults in sheltered employment: an assessment of dental needs and costs.

In this dental survey of a multi-disability sheltered industry, 233 adults were examined. When compared to adjusted North Carolina values, the workers exhibited poorer oral hygiene with higher rates and severity of periodontal disease. DMF-T totals were equal to those statewide; however, workers had more decayed and fewer missing teeth. Significant unmet restorative and prosthodontic needs were found. Treatment cost estimates at 1983 fees were $421 per capita, with a median fee of $240.