Physiology of the nose and paranasal sinuses

Impact of posterior septectomy on olfaction in endoscopic endonasal transsphenoidal surgery

BACKGROUND

Endoscopic endonasal transsphenoidal surgery is widely used to resect pituitary adenomas, yet its impact on olfactory function after resection of the posterosuperior nasal septum remains a concern. To optimize surgical techniques to preserve olfactory function, it is essential to understand the relationship between the extent of septal resection and olfactory outcomes.

METHODS

This retrospective study analyzed 295 patients who underwent pituitary adenoma surgery. The extent of nasal septum resection was quantified and its impact on olfactory function was assessed using the Cross-Cultural Smell Identification Test (CCSIT), Sino-Nasal Outcome Test-22 (SNOT-22), and a Visual Analog Scale (VAS) for olfactory loss. Preoperative and 6-month postoperative scores were compared to evaluate changes in olfactory function.

RESULTS

There was a significant correlation between larger septal resections and greater reductions in CCSIT scores, indicating a decline in olfactory function. Furthermore, patients with more extensive septal resections reported increased discomfort and olfactory loss, as evidenced by higher SNOT-22 and VAS scores. These findings highlight the importance of the nasal septum in maintaining laminar airflow and its role in olfactory function.

CONCLUSION

Study underscores the adverse effects of extensive posterior septectomy on olfactory outcomes. Minimizing the extent of septal resection may help preserve olfactory function, suggesting a need for surgical strategies that maintain septum integrity to reduce the risk of postoperative olfactory impairment.

Maxillary Sinus Anatomy and Physiology

This study summaries the anatomy, including neurovascular anatomy, and physiology of the maxillary sinus. As the maxillary sinus is intimately related to the maxillary dentition, the maxillary sinus is the first paranasal sinus to become involved in infections of dental origin. Not only are these infections often very symptomatic but also spread to neighboring paranasal sinuses and extrasinus tissues such as the skin and the orbit.

Rapid, selective and homogeneous brain cooling with transnasal flow of ambient air for pediatric resuscitation

Neurologic outcome from out-of-hospital pediatric cardiac arrest remains poor. Although therapeutic hypothermia has been attempted in this patient population, a beneficial effect has yet to be demonstrated, possibly because of the delay in achieving target temperature. To minimize this delay, we developed a simple technique of transnasal cooling. Air at ambient temperature is passed through standard nasal cannula with an open mouth to produce evaporative cooling of the nasal passages. We evaluated efficacy of brain cooling with different airflows in different size piglets. Brain temperature decreased by 3°C within 25 minutes with nasal airflow rates of 16, 32, and 16 L/min in 1.8-, 4-, and 15-kg piglets, respectively, whereas rectal temperature lagged brain temperature. No substantial spatial temperature gradients were seen along the neuroaxis, suggesting that heat transfer is via blood convection. The evaporative cooling did not reduce nasal turbinate blood flow or sagittal sinus oxygenation. The rapid and selective brain cooling indicates a high humidifying capacity of the nasal turbinates is present early in life. Because of its simplicity, portability, and low cost, transnasal cooling potentially could be deployed in the field for early initiation of brain cooling prior to maintenance with standard surface cooling after pediatric cardiac arrest.

Deviated Nasal Septum a Risk Factor for the Occurrence of Chronic Rhinosinusitis

The aim of this review article is to determine whether a deviated nasal septum (DNS) is a potential risk factor for the occurrence of chronic rhinosinusitis (CRS). Nasal septal deformities include spur, deviated nasal septum, thickening, and dislocation. Deformities of the nose tip and columella are examples of external deformities, together with the deviated part of either cartilage or both the bony and cartilage part of the dorsum of the nose. Various symptoms of chronic rhinosinusitis include nasal obstruction, nasal or post-nasal drainage, facial pain and pressure, and smell disturbances. For a long time, the deviation of the nasal septum is related to the pathogenesis, progression, and severity of chronic rhinosinusitis. Mechanisms involving mechanical and aerodynamics theory may be used to explain this relationship. Etiology in the occurrence of CRS are allergy, asthma, tooth Infection, immunodeficiency, mucociliary disorders, anatomical irregularities like DNS, concha bullosa, septum spurring, or an expanded cystic middle turbinate or prominent agger nasi cells that compromise the osteomeatal complex. The computed tomography (CT) scan imaging of the nasal cavity and paranasal sinuses has dramatically improved especially since the use of coronary CT scans. These scans make it simple to find even minute changes and abnormalities in bony structures and mucosal pathologies. An increase in the angle of DNS is significantly linked to specific disease patterns in the osteomeatal complex. This review shows that not all subtypes of DNS always result in the development of CRS. Only extremely severe DNS appears to contribute to the etiology of CRS.

Nasal Irrigation as Treatment in Sinonasal Symptoms Relief: A Review of Its Efficacy and Clinical Applications

Nasal irrigations have been used for centuries without any scientific data to determine its efficacy. Despite their widespread use, much confusion exist about the mechanism of action, preparation, indications and therapeutic advantage of nasal irrigations. Anecdotal evidence and poorly controlled studies add to the confusion. Recent evidence provides strong scientific justification of the benefits and advantages of using nasal irrigations in sinonasal symptoms relief. The present review of the evidence based literature highlights its efficacy and clinical applications.

Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air

Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C ± 0.3°C, 1.03°C ± 0.6°C, and 1.3°C ± 0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C ± 0.35°C vs. 0.21°C ± 0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA.

Impacts of fluid dynamics simulation in study of nasal airflow physiology and pathophysiology in realistic human three-dimensional nose models

During the past decades, numerous computational fluid dynamics (CFD) studies, constructed from CT or MRI images, have simulated human nasal models. As compared to rhinomanometry and acoustic rhinometry, which provide quantitative information only of nasal airflow, resistance, and cross sectional areas, CFD enables additional measurements of airflow passing through the nasal cavity that help visualize the physiologic impact of alterations in intranasal structures. Therefore, it becomes possible to quantitatively measure, and visually appreciate, the airflow pattern (laminar or turbulent), velocity, pressure, wall shear stress, particle deposition, and temperature changes at different flow rates, in different parts of the nasal cavity. The effects of both existing anatomical factors, as well as post-operative changes, can be assessed. With recent improvements in CFD technology and computing power, there is a promising future for CFD to become a useful tool in planning, predicting, and evaluating outcomes of nasal surgery. This review discusses the possibilities and potential impacts, as well as technical limitations, of using CFD simulation to better understand nasal airflow physiology.

Ozone-induced Nasal Hyperresponsiveness to Tachykinins in Guinea Pigs

Objective

To assess role of hydroxyl radials in the ozone-induced upper airway hyperresponsiveness to tachykinins.

Methods

A prospective, controlled, animal model (n = 96) was performed. Half of them exposed to air (A-group, placebo) and the other half exposed to 3 ppm ozone (O-group) for 2 h. Two hours post air/ozone exposure, animals were anesthetized and equally randomized to be pretreated with one of the three treatments, including saline vehicle, dimethylthiourea (DMTU; 500 mg/kg m, a hydroxyl radical scavenger), or phosphoramidon (Phos; 2 μg/kg, an inhibitor for neutral endopeptidase). Ten minutes after pretreatment, half of the animals in each group were i.v. injected with capsaicin (2 μg/kg), and the other half were i.v. injected with substance P (10 μg/kg) to produce Evans blue dye extravasation.

Results

Nasal exudative response to capsaicin or substance P in O-group was found to be significantly greater than that in A-group. This ozone-induced nasal airway hyperresponsiveness was largely prevented by DMTU. Phosphoramidon produced a similar nasal airway hyperresponsiveness in the A-group, but failed to alter ozone-induced nasal airway hyperresponsiveness in O-group. In sharp contrast, only substance P, but not capsaicin, produced a laryngeal exudative response in the A-group, which was similar to that in the O-group. The laryngeal exudative response to substance P was not significantly affected by DMTU or Phos.

Conculsion

In the guinea-pig model, hydroxyl radicals play a vital role in the development of ozone-induced nasal airway hyperresponsiveness to tachykinins. It is possibly mediated through the suppressive action of ozone on the tachykinin degradation.

The effects of nasal histamine challenge on cough reflex in healthy volunteers

The aim of the study was to investigate the effects of nasal histamine on the intensity of cough reflex and the effects of intensified nasal breathing following the nasal histamine challenge on cough sensitivity (CS) in humans. 20 volunteers (mean age 23, nonsmokers, no history of nasal or respiratory system diseases and atopy) were recruited to the study. Baseline CS was determined in all subjects. 2 days later the subjects (n = 20) were challenged with nasal histamine (8 mg/ml, 0.1 ml) and the number of coughs was determined after four consecutive single-breath inhalations of capsaicin C2 concentration during the period of the most intensive nasal symptoms (sneezing, itching of the nose). The same capsaicin C2 challenge was performed after nasal saline challenge two days later. One week later CS was determined after nasal histamine challenge with subsequent 10 min of intensified breathing (5-6 sniff-like aspirations to total lung capacity per minute) through the nose and mouth in randomized order in ten volunteers, and with a two-day interval between the challenges. The same manoeuvres after intranasal saline challenge were performed in volunteers of the control group (n = 10). The number of coughs after nasal histamine was significantly higher than that after intranasal saline challenge (8(6-10) vs 5(3-7); p = 0.038(. CS was not significantly different between the baseline challenge and challenges after nasal histamine followed by the intensified nasal and mouth breathing ((2.21 (1.8-2.62) vs 2.04 (1.57-2.51) vs 2.05 (1.6-2.5) log(10) of capsaicin concentration in mumol.l(-1); p = 0.09).

CONCLUSIONS

During the period of maximum nasal symptoms after nasal histamine challenge the cough response to inhaled capsaicin was enhanced. Capsaicin cough sensitivity measured after a 10-min. intensified nasal breathing after nasal histamine challenge, compared to a previous measurement of CS, remain unchanged.

The nose and paranasal sinuses physiology and anatomy

The paranasal sinuses and nose are much more than two cavities behind a projection on the centre of the face. They humidify, filter, warm, and sense what we breathe. The anatomy and physiology interact forming a dynamic system. The anatomy, airflow, nasal resistance, its turbulence, the nasal cycle - a process by which the turbinates or cushions lining the nose alternatively swell and congest from side to side, can all potentially influence the nasal delivery of drugs. Along with these factors mucus rheology and mucociliary clearance influence the removal of substances delivered to the nose. The health of the nose and its immunological response to what is inhaled, be it pollutants, allergens, drugs or vaccines, all need to be considered. It is a fascinating sensor for the body, not only detecting the potentially harmful substances such as smoke, but its psychosexual aspects have far reaching implications and the olfactory pathway has potential as a pathway for the delivery of drugs.

The effect of nasal patency on the clearance of radiolabeled saline in healthy volunteers

PURPOSE

The objective of this study was to investigate the effect of nasal cavity patency on the penetration, deposition, and clearance of an aqueous isotonic saline solution.

METHODS

The study was carried out as a single center, open, randomized, 2-way cross-over in healthy volunteers. Nasal patency was assessed using misting patterns on a cold metal surface at the beginning and end of study. 100 microl of technetium-99m radiolabeled saline solution was introduced into either the most or least patent nasal cavity using a purpose designed spray device. The distribution and residence time of the radiolabel was followed for 2 hours using gamma scintigraphy.

RESULTS

The mean times to 50% clearance were 34+/-7 and 28+/-12 minutes (+/- s.d.) for the side view of the least and most patent nasal cavity respectively. Total clearance of the radiolabelled saline from the nose was not affected by patency. Between 7 and 35% of the radiolabelled saline solution remained in the nasal cavity at the end of imaging. Using endoscopy to track the clearance of an aqueous solution of food dye using the same delivery procedure, identified this region as hair in the nasal vestibule. The dye was seen to dry in this region along with the mucus.

CONCLUSIONS

Nasal patency affects the initial, but not total clearance of solutions, however, the remaining solution may not be available for drug delivery.