Facial plast Surg 2016; 32(01): 017-021
DOI: 10.1055/s-0035-1570323
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

The Nasal Airway: A Critical Review

Capi C. Wever1
  • 1Department of Otolaryngology, Head and Neck Surgery, Leiden University Medical Center, Leiden, The Netherlands
Further Information

Address for correspondence

Capi. C. Wever, MD, PhD
Department of Otolaryngology, Head and Neck Surgery
Leiden University Medical Center, Albinusdreef 2 Leiden 2223 ZA
The Netherlands   

Publication History

Publication Date:
10 February 2016 (online)

 

Abstract

Functional nasal surgery is frequently performed and deeply embedded in otolaryngology. However, unequivocal proof of its efficacy is still pending, leading some health authorities toward restrictive policies. In this article, we review the evidence and suggest that reexamining the paradigm of functional nasal surgery may be appropriate.


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Nasal airway obstruction (NAO) is a common problem, with a population prevalence of around 30% or even higher.[1] [2] Not surprisingly, functional nasal surgery is frequently performed and generates high social costs. In the Netherlands, more than 10,000 septoplasty (and/or SMR) procedures were performed in 2014, in addition to approximately 3,000 noncosmetic septorhinoplasties.[3] This equates to approximately 30 functional nasal procedures per surgeon per year, or 75 procedures per 100,000 population. This number is approximately similar to the rate in the United States, yet almost double the rate in the United Kingdom.[4] [5] Moreover, regional variation has been shown to be rather high, with a factor of 5 to 6 between the least and most frequent operating region.[6] [7] However, there is a lack of consistent and high-level empirical evidence supporting the efficacy of functional nasal surgery.[8] This has led some health authorities to raise critical inquiry into functional nasal surgery, restricting or even abolishing it.[9] [10] As a profession, we need a better understanding of NAO surgery and its indications. This review discusses NAO surgery from the critical perspective of a high-volume rhinoplasty surgeon, with quite a few disappointing experiences in terms of surgical results. It will not bring forth the missing biologic knowledge base nor resolve the issue of bias in our studies. Rather, this review is meant to provoke debate and stimulate thought regarding a procedure that has been embraced over many generations.

Basic Fluid Aerodynamics

Velocity is a key factor affecting flow characteristics.[11] Higher speed, higher fluid density, and larger area of friction relate to higher drag. In laminar flow, drag increases linearly with velocity. In turbulent flow, drag increases squared with velocity. From static models, we know that area and air velocity differ in different parts of the nose: (1) vestibule, (2) the valve area, and (3) nasal cavity. At the level of the vestibule, velocity is around 2 to 3 m/s.[12] Beyond that point, velocity rises rapidly to its high value of 12 to 18 m/s at the level of the nasal valve.[13] Posteriorly, the speed slows down again to 2 to 3 m/s. Bernoulli's law states that an increase in fluid velocity equates to a decrease in pressure. This low-pressure area creates a pressure differential, and a resultant inward vector. In the nasal airway, this entails that a high velocity caused by the anatomic narrowing at the valve area creates an inward pressure of the compliant soft tissues. The nasal valve is the area with the smallest cross-sectional area and, conversely, the highest air velocity and drag and therefore of critical importance in nasal obstruction surgery.[14] Even small modifications to structures in the direct space of the nasal valve can have significant effect on nasal resistance, whereas changes to structures posterior to the nasal valve tend to be of lesser impact.[11]


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Measuring Nasal Patency

So how have we measured nasal patency in clinical research? Three main domains can be identified here: (1) objective measures, (2) patient response, and (3) surgeons judgment. All three have been incorporated in literally hundreds of studies over the past decades.

Objective Measures

Nasal airway surgery is, by definition, a matter of creating alterations to the physical shape of the nasal cavity that we assume lie at the basis of subjective NAO, guided by specific and universal aerodynamic principles. However, we do not fully understand these technical principles, and even lesser so how they relate to subjective sensation. Aerodynamics of the nasal cavity is multifaceted, as the shape of the nasal cavity is three dimensionally complex and different from one subject to the next. Even small irregularities can cause sudden deceleration, accelerations, eddies, turbulent flow, and drag increase. Nonetheless, research has strongly focused on finding a single objective “number” to reliably quantify nasal airflow. Rhinomanometry and peak nasal inspiratory flow (PNIF)[5] [15] [16] [17] [18] are the most commonly attributed dynamic measures of nasal patency in a clinical setting. Study results and their interpretation have been somewhat debated however, even though a few prospective studies have clearly documented improvement after functional nasal surgery.[5] [19] [20] [21] However, there are shortcomings as well. What objective measures fail to accommodate for, for example, is that although change in patency may indeed be realized, the question remains if this change is significant enough to be subjectively relevant. Missing, therefore, is an inquiry into the effect size, the magnitude of the effect, assumed an attribute of significance or meaning from a patient's perspective. We would like to see satisfied patients after all, not just improved flow characteristics.[22]


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Subjective Measures

Patient-reported outcome has also been reported on widely, based on a great number of questionnaires, with varying levels of validation.[21] Both disease-specific lists such as the NOSE scale and generic questionnaires have been used extensively. The NOSE questionnaire is being increasingly adopted as the gold standard for studies into this area.[23] In a recent systematic review, Rhee et al concluded that many studies report a positive effect of functional nasal surgery, with effectiveness ranging from 65 to 100%.[24] However, the study design is too often faulted, precluding final conclusions on the efficacy of functional nasal surgery. One of the main points of critique is the lack of correction for potential bias. As mentioned earlier, quite a few studies have reported subjective, even startling, improvements. However, our understanding of the validity and limitations of patient-reported outcome in terms of issues such as choice-supportive bias, cognitive consistency, Hawthorne effect, and question format is still rather limited.[22] [25] [26] Patients may, for example, be hesitant to admit to moderate surgical results out of loyalty to their surgeon. A 90% plus patient-reported satisfaction is in all fairness in itself enough reason to question what we are measuring really—regardless of the type of surgery.[25] Therefore, a more modest approach may be more appropriate. Intuitively many of us seem to agree as we generally find subjective benefit without any objective correlate rather unconvincing. Ideally, we would like to see a strong codependence between what we measure objectively and what patients experience.


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Relating Objective and Subjective

The relation between objective outcomes and subjective experience is rather modest.[14] [18] [27] [28] This fact is sometimes blamed on the limitations of our instruments or on the still insufficiently understood mechanism of subjective sensation, a rather common form of skepticism toward subjective factors.[26] Generally, study results have been inconclusive, with some studies reporting no correlation between objective PNIF and VAS scores (preintervention), whereas others did find such a match.[14] [27] Similar to the critique on objective measures, however, effect size remains an area of controversy. Kjaergaard et al[14] report a change of 0.5 to 2.3% in VAS scores for a 10% change in PNIF, which appears rather modest, also expressed by a relatively low correlation coefficient of 0.13 to 0.35. The question remains what this change means for our patients' experience in a clinical diagnostic or interventional setting.[18]


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Where from Here?

Clinically, a distinction can be made into pathology of the main body of the septum, the caudal septum,[29] the inferior turbinates,[30] the internal nasal valve,[31] and the external nasal valve or lateral wall. However, we know that surgeons commonly combine procedures to achieve an optimal effect. Of the 46 studies under review by Rhee et al,[24] 70% included adjunctive procedures, most importantly septoplasty and inferior turbinectomy, both of which can be considered to have an independent effect on nasal valve function. Moreover, outcome was measured through a broad range of measures, mostly not validated, thus precluding pooling of data and meta-analysis and leading the author to attribute a disappointing grade “C” to the level of evidence currently available by Oxford Centre for Evidence-Based Medicine (OCEBM) standards. Moreover, many studies are based on small samples, weakly document surgical technique, and based on relative short follow-up.[21]

So although there is, on the one hand, good evidence that functional nasal surgery can be of benefit to our patients, a solid underpinning is still pending.[14] Why are we not consistently finding subjective benefit, and why is it that we cannot strongly relate subjective benefit to objective measures? Is it because of the design of our studies? Are our objective values to technical or theoretical to be perceived by patients? Are we overestimating what our surgery can mean to patients? And what role does our indication spectrum play? In analyzing dissatisfied case narratives, it materialized too often that, in hindsight, other ills at least codetermined why patients present to our clinics. Are we perhaps overlooking the patients' motives, being too technical in our gaze?


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What Do Patients Seek?

Getting the indication right is a prerequisite for any medical success. This entails recognizing and understanding the pathology of course. Yet it also entails a profound understanding of the patient's narrative. The nature of elective surgery is, not surprisingly, that it is elective and thus by definition not driven by whatever overarching motive.[8] In nonelective surgery, the demanding discourse of “indication” or “pathology” commonly dominates the dialogue between patient and his or her surgeon. When patients are brought into the emergency department with a broken leg, for example, consent and shared decision making are rather futile. In elective procedures, this is clearly not the case. Yet as surgeons we sometimes still act differently, even in those settings. Physicians in general prefer to perceive treatments as self-explanatory and therefore “mandatory,” driven by the objective, rather than being a matter of patient narrative.[22] Given the typical imperfect surgical result, the intrinsic risks of surgery, its failure rate, and the sequels that may occur, the unequivocal sense of urgency is inappropriate. Thus, patients do very much have a choice and their voices count. In elective medicine, we treat patients primarily, not their condition.

Yet patients' stories are prestructured, which can be a caveat. To be of “use” in medicine, physical complaints need to be fitted into specific categories, in rather specific language. Patients themselves, preeducated as they are and with access to open sources on the Internet, initiate this process. Therefore, patients self-construct their complaints well in advance of a visit to their physician. Relying on patients' global initial self-report can be deceptive, and allowing this to remain unexplored throughout the consult can be a setup for failure.

So what brings our nasal patients to our practices? We assume, of course, this is nasal obstruction. But is it really? In terms of NAO, it is rather self-explanatory that patients are likely to present with “nasal obstruction” as their primary complaint. Yet some questions remain unanswered, foremost the question why people present to our care with unilateral nasal obstruction at an adult age, without any recent compromise to nasal patency. We know from other fields that chronic complaints can be set off by incidental factors.[32] This may also play a role in nasal obstruction. Aging and related cartilaginous weakening and mucosal change may be another factor. Inadequate inquiry into patient's ills, driven by fixed assumptions, may also play a part. Thus, although patients may present with unilateral nasal obstruction as their key symptom, this does not rule out a more complex nature of their complaint. Sleeping disorders, snoring, and subliminal cosmetic demands may costructure their discourse. Failure to comprehend this may lead to incomplete appreciation of the true end goals of treatment. Although a relationship may exist between NAO and such downstream complaints, the causality and magnitude of the relationship have not been quantified sufficiently to blindly rely upon them.[33]

To probe this hypothesis, we sent out a questionnaire among new patients who presented at Leiden University Medical Center over a period of 4 weeks with nasal obstruction as their primary complaint as defined by their referring physician. Our hypothesis was that many of these patients have secondary issues that may even outweigh their nasal ills in terms of significance.

Questionnaire

In total 40 questionnaires were completed ([Fig. 1]). Men and women were equally represented. The average age was 39 years, with women averaging considerably lower (30) than men (46). Though based on a small sample, our pilot study indicates that nasal obstruction is indeed a primary complaint for most of our patients. On average, our patients scored 7.8/10 on the item nasal obstruction. Yet several other items followed closely behind. The feeling of not getting enough oxygen (7.5), shortness of breath (6.7), a runny nose (6.5), and open mouth breathing (6.4) scored high averages overall. If we look at individual scores, almost all our patients scored high on at least one additional domain, sometimes even higher than on the primary complaint of nasal obstruction. Although 63% marked a 9 or 10 score on nasal obstruction, 42% ranked such high scores on shortness of breath, half of which outclassed nasal obstruction in weight. Not getting enough oxygen also yielded high marks by 42% of respondents, again outscoring nasal obstruction in 50% of cases (the two items corresponded in almost 90% of our cases). A similar pattern was seen on open mouth breathing (37%), runny nose (32%), snoring (21%), and insomnia (21%).

Zoom Image
Fig. 1 Questionnaire.

Although nasal obstruction did materialize as a primary concern for many of our patients, other complaints rose to the forefront, matching and sometimes even outweighing the primary complaint. In particular, shortness of breath or the experience of not getting enough oxygen, open mouth breathing, a runny nose, snoring, and insomnia materialized as strong factors.

The relation of such downstream complains and functional nasal surgery is rather understudied. Rotenberg and Pang studied the effect of FESS surgery on sleeping in 50 cases, and reports a positive effect.[34] The relation between nasal surgery and OSAS has been studied more extensively and shown to be moderately effective, though in many studies multiple surgical modalities are applied and patients are selected based on the likelihood of nasal etiology.[35] Similar positive effects have been reported on the relation of nasal surgery on continuous positive airway pressure (CPAP) compliance.[34] The relation between surgery and open mouth breathing seems much less likely to materialize, as is diminishing of rhinitis complaints. It appears that if secondary complains codirect patients to our offices and if we fail to understand these, the likelihood of treatment failure is real.


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Conclusion

Functional nasal surgery seems to be strongly embedded in a clinical mechanical paradigm. Yet viewing nasal patency too much from theoretical perspective may predispose to modest results in terms of patient satisfaction. A complete understanding and adequate diagnosis of NAO is essential. This includes first and foremost adequate anamnestic intake to identify potential downstream desires that may have codirected patients into our offices. Patients construct their initial narrative on a medical vignette, and unless we probe further, we may omit the full spectrum of their motives. As Becker and others argue, the surgical scope of functional nose surgery is rather narrow.[36] This implies that a modest view on what we can achieve may be appropriate, which seems to explain our tendency to perform multiple surgical steps. A more aggressive and multimodal approach may be more successful. This implies perhaps not operating on minor deformities and refocusing on significant pathology, although we lack clear criteria to identify these conditions.[21]

NAO surgery can be greatly satisfying to our patients. However, our current practice still fails the test of scientific inquiry. Changing to a more modest and patient-oriented paradigm may improve our results.


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Address for correspondence

Capi. C. Wever, MD, PhD
Department of Otolaryngology, Head and Neck Surgery
Leiden University Medical Center, Albinusdreef 2 Leiden 2223 ZA
The Netherlands   


Zoom Image
Fig. 1 Questionnaire.