National Board Ex- 6 Book .pmd - National Board Of Examination

espiratory complications due tothe presence of restrictive lungdisease, ineffective or absentcough, atelectasis and chronicaspiration. Cough is a complexphysiological reflex which protectsthe lung from inhalation ofirritants and clears the airways ofexcess secretions and particulatematter. An effective cough consistsof an inspiratory gasp, acompressive phase and an expulsivephase. The production ofcough involves coordinated activityof all the groups of respiratorymuscles. The intercostalmuscles are actively involved inall the three phases. Spinal cordinjury patients, especially thosewith higher level cord injury andparalysis of the intercostal andabdominal muscles, lack the abilityto generate an effectivecough 4 . Though the cough reflexsensitivity is preserved in thesepatients, the ineffective coughresults primarily from the loss ofinnervation of respiratorymuscles 5 . Impaired cough leadsto inability to clear tracheobronchialsecretions which becomethick and purulent leading toatelectasis. Experimental atelectasishas been created in animals byartificial instillation of bronchialsecretions and by pharmacologicalblunting of the cough reflex 6 .It has been shown that an adequateand effective cough canprevent atelectasis in these circumstances.Case 1 was not able to create anadequate blast of air via tracheostomy.Cough was severely impairedin case 2 leading to poolingof secretions in the trachea.Effective cough or an adequateair blast via the tracheostomy isessential for expectorating out thetracheobronchial secretions. Theabsence of adequate cough inthese two patients lead to mucusimpaction and atelectasis. Rarelyis this due to a central intraluminalbronchial plugthat can be visualizedbronchoscopically, rather, moretypical is obstruction of multiplesmall bronchi and bronchiolesdue to impaired clearance ofmucus 7 . Mortality among spinalcord injury patients most frequentlyfollow repeated episodesof pneumonia, bronchial mucusplugging, atelectasis and respiratoryfailure 8 . Health and survivalin these patients are strongly associatedwith meticulous and vigorouspulmonary hygiene. Thiscan be brought about by routinesecretion clearance with a strictregimen of chest physiotherapyand regular tracheal suctioning.Chest physiotherapy involves percussionand positioning for posturaldrainage. It cannot be performedin unstabilized spinalcord injury patients. In post operativepatients following thoracotomynebulised N-acetylcysteine has shown to reducesputum viscosity, reducedifficulty in expectoration, increaseweight of sputum expectoratedand improved oxygensaturation compared to nebulisednormal saline 9 . Our experience inthese two patients shows that N-acetylcysteine can be extremelyeffective in these situations.It acts by opening the disulfidebonds in mucoprotein through aspecific sulfhydryl- disulfide interchangereaction, thereby effectivelylowering the viscosity 10 . Ithas been shown that a vigorousregimen of tracheobroncheal toiletalong with routine administrationof mucolytic agent N-acetylcysteine helps in significantdecrease in post operativeatelectasis 7 . N-acetylcysteine effectsa marked liquefaction withinone minute, although the maximumeffect is not gained for 5 to10 minutes. The duration of actionafter a single endotrachealinstillation is approximately 45minutes 10 . Liquefied secretionsare more easily removed by ciliaryaction or by cough. For thispurpose it can be administered byvarious routes 2 – directly into tracheostomy,via intratracheal catheteror can be nebulised with airas oxygen inactivates N-acetylcysteine 11 or into endotrachealtube. Complications withendotracheal instillation ornebulisation of N-acetylcysteinehas been minimal 2, 7 . It can producebronchospasm in patientswith previous history of bronchialhyperreactivity. Nausea hasalso been reported which hasbeen attributed to its unpleasantsulfurous odor. No literatureexists on the use of N-acetylcysteine for the treatmentof pulmonary atelectasis producedin spinal cord injury patientsdue to inability to coughout secretions. These patients requirelife long assistance in tracheobronchialclearance of secretions.Although there are no specificrecommendations regardingthe frequency of use of N-acetylcysteine, it has been used asfrequently as 2 ml intratrachealyevery 2 hours with minimal complications7 . N-acetylcysteine canprovide these patients with asimple applied, reliable, safe andpractical method for effectiveclearance of accumulated tracheobronchialsecretions and78Journal of Postgraduate Medical Education, Training & ResearchVol. II, No. 5, September-October 2007