Accuracy of acoustic rhinometry

OBJECTIVES: The objective of this study was to evaluate the ability of acoustic rhinometry (AR) (Rhin2100, Rhinometrics, Lynge, Denmark) to accurately determine the dimensions (cross-sectional areas and volumes) of the curved and complex slit-like geometry of the nasal airway. MATERIALS AND METHODS: A plastic model representing the replicate of a decongested nasal airway was produced by stereolithographic techniques from a 3-D MRI-scan. The exact dimensions of this model was determined from a high resolution CT-scan. Dimensions perpendicular to the curved course of the acoustic pathway were compared with dimensions inferred from parallel sections. The impact of sound loss to the paranasal sinuses and the ability to detect posterior volume changes was tested in the same model. RESULTS: The error in volume determination was < 14% for the MCA and < 8% for the volumes, whereas the error reached 52% for dimensions calculated from parallel sections in the coronal plane. The influence of the simulated maxillary sinuses depend primarily on the size of the ostia and may represent an important source of error for posterior measurements, in particular after decongestion. CONCLUSIONS: The accuracy of acoustically derived dimensions of the 3-D model depend on the orientation of the planes used to calculate the dimensions of the model. Volume estimates based on the smallest cross-sectional areas in points along the acoustic pathway correlate well with acoustically derived volumes, whereas single cross-sectional areas are more susceptible to error. Sound leakage to patent sinus ostia reduce the accuracy of posterior measurements.     

Modified method of acoustic rhinometry

Acoustic rhinometry is a well-known method for evaluating nasal cavity patency using sound waves. The method produces graphical information on cross-sectional areas, the distances between these areas and the nostril and the nasal volume. We used this method to evaluate 40 children aged between 7 and 13 years old with complaints of nasal obstruction. All patients underwent endoscopic examination of the nasal cavity, and only children presenting with hypertrophic inferior nasal turbinates and with no history or clinical evidence of infectious rhinitis were included in the study. Using a modified method we obtained four distinct and constant cross-sectional areas along the nasal cavity and four corresponding distances from these areas to the nostril.     

麻黄碱试验在鼻声反射中的临床应用

目的：探讨麻黄碱试验在鼻声反射（AR）中的临床应用,研究定量评价鼻腔黏膜状态的方法和鉴别单纯性鼻炎与肥厚性鼻炎的客观指标。方法：利用AR测试单纯和肥厚性鼻炎患者,并设正常对照,通过麻黄碱试验深入分析试验前后鼻气道通气阻力（NAR）、鼻腔容积（NCV）、鼻腔最小截面积（NMCA）和NMCA所处的位置相对于鼻腔入口处的距离（DCAN）以及上述参数的变化量和变化率,定量分析3类受试者的鼻黏膜舒缩状态。结果：麻黄碱试验前后成对资料比较,各基本参数均差异有统计学意义（均P〈0．01）,麻黄碱试验后NAR减小,NCV增加,并伴有NMCA扩大和DCAN的“前移”。麻黄碱试验前后各组各参数的均数多组间的均差异有统计学意义（均P〈0．01）。2个患者组之间相比,麻黄碱试验前只有NCV有统计学意义（P〈0．05）,而麻黄碱试验后所有参数（包括变化量和变化率）的均差异有统计学意义（P〈0．05或P〈0．01）。与正常对照,单纯性鼻炎所有参数（包括变化量和变化率）的均差异有统计学意义（P〈0．05或P〈0．01）,而肥厚性鼻炎的某些参数的变化量和变化率的差异则无统计学意义。结论：AR能客观的判断鼻黏膜的状态,结合麻黄碱试验能提供更多的信息,扩大了AR的临床应用,建议作为常规配套检查。     

鼻声反射在射频治疗鼻阻塞中的价值

目的：探讨鼻声反射在射频治疗鼻阻塞中的价值。方法：根据鼻声反射测试结果定位,应用射频治疗46例鼻阻塞患者。结果：射频治疗前,鼻腔最小横截面积、下鼻甲前端截面积、鼻腔容积和鼻阻力分别为（0．37±0．16）cm^2、（1．10±0．17）cm^2、（5、76±2．81）cm^3和（5．96±2．24）kPa·s／L;射频治疗后分别为（0．68±0．18）cm^2、（1．76±0．19）cm^2、（9．10±2．10）cm^3和（2．42±0．86）kPa·s／L。射频治疗前后对比差异有统计学意义（P〈0．05）。46例患者中,治愈27例,好转19例,有效率为100％。结论：鼻声反射指导射频治疗鼻阻塞有助于鼻阻塞的定位及提高疗效。     

The combination of acoustic rhinometry, rhinoresistometry and flow simulation in noses before and after turbinate surgery: a model study

BACKGROUND: Especially to young examiners, the interpretation of rhinometric findings seems to be difficult. In order to understand rhinometric assessments precisely, knowledge of airflow behavior in the nose is necessary. We therefore investigated the influence of nasal concha surgery on acoustic rhinometry and rhinoresistometry in a model. METHOD: Six nose models were examined with acoustic rhinometry and rhinoresistometry, each of these models with its lateral wall altered to represent various conditions after nasal concha surgery. Besides, all models were rinsed with water and the flow was visualized for observation. RESULTS AND CONCLUSIONS: The normal nose presented an even flow distribution over the entire nasal cavity. After nasal concha resection, though, an unfavorable flow course and a strong increase in turbulence were seen. Additionally, flow resistance decreased considerably. In the model with general lateral wall hyperplasia, reduction of the inferior and even of the middle nasal concha showed good functional results. The model revealed a good correlation between the result of flow observation and findings in acoustic rhinometry and rhinoresistometry. Both methods complement one another in their diagnostic outcome.     

The magnitude of random errors in acoustic rhinometry and re-interpretation of the acoustic profile

By measuring the effect of incomplete acoustic seal and increasing nosepiece insertion depth on the derived nasal acoustic profile, this study quantifies the random errors that may arise in the course of the clinical practice of acoustic rhinometry using the insert nosepiece. The relative movement of the nose and nosepiece also enables us to separate the contribution of each to the acoustic curve. Sixteen volunteers were tested using a commercial rhinometer. As a consequence of this study we are able to formulate the following conclusions: (1) The first minimum of the nasal acoustic profile is due to the end of the nosepiece, but may be further diminished by the position of the nosepiece tip on or within the nose. (2) The second minimum is due to the nasal valve, to which the head of the inferior turbinate contributes. (3) Acoustic rhinometry is extremely sensitive to acoustic leaks and results obtained without a fluid acoustic sealant cannot be considered valid. (4) The errors associated with the nosepiece insertion technique are very small unless the nosepiece is forced into the nasal vestibule.     

鼻声反射结合鼻内镜检查评价功能性鼻内镜手术对慢性鼻窦炎的疗效

目的：运用鼻声反射结合鼻内镜检查评价功能性鼻内镜手术对慢性鼻窦炎的疗效。方法：分别于术前及术后4周对60例接受FESS的慢性鼻窦炎患者,使用鼻声反射仪器检测手术治疗前后鼻腔最小横截面积（MCSA）、鼻腔容积（NV）及鼻气道阻力（NAR）的变化,结合鼻内镜的检查,评估手术治疗慢性鼻窦炎的效果。结果：功能性鼻内镜手术后,鼻内镜下见患者各组鼻窦开放良好,同时MCSA、NV增加,NAR降低,与术前相比具有显著的统计学意义。结论：鼻声反射结合鼻内镜检查作为手术前后鼻功能的检测手段,可对手术疗效进行客观的综合评价。     

Evaluation of postoperative pain after sinonasal surgery

BACKGROUND: Pain after sinonasal surgery concerns both patients and surgeons. Factors affecting sinonasal postoperative pain have not been examined extensively. METHODS: Using a prospective survey design, sinonasal surgery patients evaluated postoperative pain (on a scale of 0-10), pain location, and medication use. RESULTS: One hundred twenty-seven patients consented to participate. One hundred fifteen patients returned surveys, with 100 patients appropriate for analysis over the 6-day postoperative period. Pain score and medication use were evaluated with respect to sex, primary/revision case, nasal packing, and other factors. Repeated measures analysis of variance and chi-square analysis were conducted (p < 0.05). Pain ratings and analgesic use declined significantly over the postoperative period (p < 0.05). Mean pain score on postoperative day (POD) 1 was 3.61 and on POD 6 was 1.72. Mean medication use was 1.37 tablets on POD 1 and 0.55 tablets on POD 6. Additionally, a significant interaction existed, such that narcotic medication use declined from 1.91 tablets on POD 1 to 0.52 tablets on POD 6, whereas nonnarcotic medication use remained steady (p < 0.05). Periorbital pain was most frequent (46.3%), with unilateral facial pain reported least (4.1%). A significant difference existed for distribution of pain location (p < 0.05). Finally, the difference in pain rating between primary and revision procedure for women (0.65) was less than for men (1.12); this interaction was significant (p < 0.05). CONCLUSION: Multiple patient and operative factors affect pain rating and medication use after sinonasal surgery. Generally, pain level should be low with little analgesic use postoperatively.     

The effects of endoscopic sinus surgery on the nasal cycle as assessed by acoustic rhinometry.

Previous studies have demonstrated that acoustic rhinometry (AR) has a considerable utility in measuring nasal patency and in detecting the nasal cycle. This study was performed in 10 patients with chronic rhinosinusitis who were submitted to endoscopic sinus surgery. AR was used to determine minimum nasal cross-sectional area and volume as the indices of the nasal patency in all patients on the day before the surgery and 3 months postoperatively. We did not find any significant alteration when comparing the pattern of fluctuation, the periodicity, and the amplitude of the nasal cycle demonstrated by patients in the pre and postoperative periods, confirming that this surgery does not have any adverse effect on this physiologic cycle.     

Two-year follow-up with acoustic rhinometry in children

BACKGROUND: This is an explorative study of growth-related nasal geometry in healthy children. METHODS: A total of 88 girls and boys between the ages of 4 and 16 years were followed over a period of 2 years by acoustic rhinometry. The registrations were correlated to height at each occasion. RESULTS: Although both the minimal cross-sectional area and the nasal volume increased in all age groups over 7 years, large individual variations in nasal geometry led to a weak relationship with growth. CONCLUSION: In the undecongested nasal cavity in children, correlation of nasal geometry makes sense for height but not for age.     

声反射鼻测量曲线类型及其临床应用

目的明确９种鼻腔及鼻咽部疾病的声反射鼻测量曲线类型及其在估价腺样体切除术前后鼻咽部容积变化中的意义。方法应用声反射鼻测量计测量了１５１例鼻腔及鼻咽部疾病患者，包括鼻炎、鼻息肉、阻塞性睡眠呼吸暂停综合征（ｏｂｓｔｒｕｃｔｉｖｅｓｌｅｅｐａｐｎｅａｓｙｎｄｒｏｍｅ，ＯＳＡＳ）、腭裂、萎缩性鼻炎、腺样体肥大、鼻中隔穿孔、鼻咽癌、鼻阈狭窄患者。对其中１５例腺样体肥大患儿在行腺样体切除术前后鼻咽部容积进行测量，将此差值与排水法测得手术切除的腺样体实际体积相比较。结果声反射鼻测量曲线可分为正常曲线及异常曲线，根据曲线变化部位将异常曲线分为４种，即鼻腔段曲线突然显著增高和显著降低、曲线后段显著增高和低平。经手术或药物治疗后疗效良好者曲线可基本恢复正常。腺样体肥大患儿鼻咽部容积明显低于同年龄对照组，术后鼻咽部容积明显增高。手术前后声反射鼻测量计所测得的鼻咽部容积改变与排水法测得的腺样体体积之间显著相关（ｒ＝０．８７，Ｐ＜０．００１）。结论声反射鼻测量曲线对于多种鼻腔及鼻咽部疾病的协助诊断及疗效判定具有重要的意义，并可为估价腺样体体积提供参考。     

Evaluation of nasal volume by acoustic rhinometry before and after physical exercise

BACKGROUND: The nasal structures generate airflow resistance that can reach -50% of the total respiratory resistance. There are a series of factors that can alter the volume of these structures, among them physical exercise. The objective of this study was to determine the degree of changes in nasal volume at different levels of physical exercise, evaluating the influence of exercise intensity and duration, as well as the duration of the effect of exercise on the nasal mucosa. METHODS: Nineteen individuals were submitted to three distinct physical tests on a cycle ergometer: test 1, exercising for 5 minutes on a cycle ergometer at 50% the maximal load; test 2, exercising for 10 minutes on a cycle ergometer at 50% the maximal load; and test 3, exercising for 5 minutes on a cycle ergometer at 75% the maximal load. In each test, nasal volume was measured by acoustic rhinometry immediately after the end of exercise and 10 and 20 minutes thereafter. RESULTS: The rhinometry results showed a significant increase (p < 0.001) in nasal volume after physical exercise for all tests performed. At 20 minutes, nasal volume had returned close to resting levels in all three tests. Comparison of the degree of improvement of nasal volume between the three physical tests showed a significant difference (p < 0.05) between T1 and T2 (T2 presented gain of 8.3% more in nasal volume than T1). Test 3 showed no significant difference (p > 0.05) compared with the other two tests, with 5.8% higher gain in nasal volume observed compared with T1, while the increase was 2.5% lower than in T2. CONCLUSION: Physical exercise in general causes a significant increase in nasal volume, with the duration of exercise exerting a greater effect on the degree of improvement than intensity.     

The accuracy of acoustic rhinometry using a pulse train signal

The signal used in the original acoustic rhinometers was an impulse of short duration and wide energy spectrum. A rhinometer utilizing a new signal of a similarly broad energy but different time course has been developed. We investigated the accuracy of area reconstructions computed using this signal by comparing them with the original areas of simple models. This study demonstrates that, at present, acoustic rhinometry using a pulse train signal is subject to significant systematic errors. Some of these are intrinsic to the rhinometer. Others are caused by the geometry of the models. Area reconstructions beyond narrow constrictions are particularly inaccurate. The findings are significant because the nasal valve can act as such a constriction. The errors can cause the parameters used in the clinical application of acoustic rhinometry to deviate substantially from the true values.     

The influence of septal perforation on measurement by acoustic rhinometry

The influence of septal perforation on results of acoustic rhinometry was studied using cases of septal perforation and a human-nose model. Acoustic rhinometry was conducted before and after closing the perforation (average 16 mm in diameter, 23 mm from the nostril) by thin cotton patches in 33 cases (19 men and 14 women). The decrease in cross-sectional area and volume after closure was statistically significant. A human-nose model with septal holes ranging from 5, 10, 15, to 20 mm and locations ranging from 20, 40, to 50 mm from the nostril was studied by acoustic rhinometry. Our results suggest that the effect of perforations on the measurement is much greater in anterior perforations than in posterior perforations.     

Evaluation of rhinostereometry compared with acoustic rhinometry

Measurement of the nasal mucosa is a challenging task. There are many different methods; each with advantages and disadvantages. In the last decade two new methods have been used extensively: acoustic rhinometry and rhinostereometry. Many studies with rhinostereometry have shown interesting results. However, there have been doubts about this method, since only a few investigators have used it, and it has never been compared with other methods. On the other hand, the acoustic rhinometer has been compared with many other methods. In this study, we compare the results of measurements with acoustic rhinometry and rhinostereometry. Thirty patients with vasomotor rhinitis participated in the study. They were challenged with three histamine concentrations on two occasions. resulting in 180 observations with each method. The results were compared with each other using the linear correlation test, and showed a poor but significant correlation (p < 0.01. r = 0.25). We conclude that acoustic rhinometry and rhinostereometry are sensitive methods for studying nasal mucosal swelling, but that there is poor correlation between the two methods.