TY - CHAP M1 - Book, Section TI - Nasal Function and the Evaluation of Taste/Smell A1 - Chan, Yvonne A1 - Goddard, John C. Y1 - 2019 N1 - T2 - K.J. Lee’s Essential Otolaryngology: Head and Neck Surgery, 12e AB - Warming and humidificationAir is humidified to high relative humidityAir is warmed through heat diffusion and convectionOptimum mucociliary clearance is facilitating by temperature of 37°CRegulation of nasal secretions and airway resistanceProteins in nasal secretionsPlasma proteinsAlbuminImmunoglobulins (IgG, IgM, IgA)Serous cell productsAntibacterial defense moleculesLysozymesLactoferrinSecretory componentMucous cell productsMucoglycoproteinsMucinsEpithelial goblet cell productsMacromolecules and ionsProteins are dissolved or suspended in epithelial lining fluidModified by epithelial ion pumpsPlasma extravasation controlled by interepithelial tight junctionsDependent on rate of blood flow and plasma transudationArterial vasodilation and filling of venous sinusoidal vessels results in plasma extravasation, thickened nasal mucosa, increased airway resistance.Vasoconstriction reduces mucosal blood flow, reduces plasma extravasation, relieves venous sinusoidal congestion.Autonomic innervationVidian nerveFormed at junction of greater superficial petrosal (preganglionic parasympathetic fibers) and deep petrosal nerves (postganglionic sympathetic fibers)Postganglionic sympathetic and parasympathetic fibers carried in the nerve of the vidian canal and join branches of sphenopalatine nerveParasympathetic neuronsCotransmitter to acetylcholine (vasointestinal peptide [VIP])Vasodilation at arterial and sinusoidal vesselsEnhanced secretory activityMast cell degranulation– Release of histamine, bradykinin, arachidonic acid metabolites, ionsSympathetic fibers join branches of sphenopalatine nerve and arteryCotransmitter to noradrenaline (neuropeptide Y)Vasoconstriction of venous sinusoidal vesselsNonadrenergic, noncholinergic responsesTrigeminal sensory neurons use peptides as neurotransmittersSecreted by macrophages, eosinophils, lymphocytes, dendritic cellsSubstance P, neurokinin A, calcitonin gene-related peptide (CGRP)Induce vasodilationIncrease vascular permeabilityIncrease nasal resistanceStimulate glandular secretionLeukocyte chemotaxisMast cell degranulationNasal cycleCyclical vascular phenomenon that occurs in 80% of normal individualsAlternating congestion/decongestion every 3 to 7 hoursCentrally mediated autonomic tone of capacitance vessels of erectile mucosaOther influences on nasal resistanceExercise decreases nasal resistanceIrritants (dust, smoke), cold/dry air, alcohol, pregnancy, hypothyroidism, and medications can cause congestion of capacitance vesselsMedications that can cause nasal congestionAntihypertensives (alpha and beta blockers)Oral contraceptivesAntidepressantsNonsteroidal anti-inflammatory medicationsDecongestants in excess may result in rhinitis medicamentosaAtrophic rhinitisChronic, degenerative disorder characterized by nasal crusting, malodorous discharge, and nasal obstructionAtrophy of serous and mucinous glandsLoss of cilia and goblet cellsInflammatory cell infiltratesPossible causesUnderlying chronic inflammatory diseaseGranulomatous disordersIrradiationBacterial and viral infectionExcessive nasal surgeryNasal airflowAt low flow rates, airflow is laminar.Maximum velocity occurs in the nasal valve region.Bernoulli principleAirflow velocity is greatest at the narrowest segment.Increased airflow velocity leads to negative pressure and nasal valve collapse.Poiseuille lawAirflow resistance is inversely proportional to fourth power of the radius.Small decrease in cross-sectional area produces large increase in airway resistance.Relatively slow flow rates found in olfactory region with quiet breathingDuring inspiration, main flow stream occurs in the lower and middle airway (space between middle meatus and nasal septum)During expiration, maximum velocity is lower but expiratory air is evenly distributed across inferior, middle, and olfactory regionsDiagnostic testing of nasal airflowObjective diagnostic tools of nasal airflow often poorly correlate with patient reported symptomsNasal inspiratory peak flowObjective, physiologic measurement of nasal airflow during maximal forced nasal inspirationAdvantages: portable equipment, easy to useDisadvantages: test-retest variability, influenced by the lower airway, influenced by nasal valve collapseRhinomanometryPressure sensors placed with and without decongestion to develop flow-pressure curvesMeasurements calculated to determine airflow resistanceAdvantages: functional test, may be done on both sides simultaneouslyDisadvantages: time, expense, inability to identify site of obstructionAcoustic rhinometrySound waves transmitted into nasal cavity, which is reflected back and converted into digital impulses constructed on ... SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accesssurgery.mhmedical.com/content.aspx?aid=1172370240 ER -