a 67-year - old male ( height , 165.4 cm ; weight , 69.1 kg ) with a history of hypertension and hyperthyroidism was scheduled to excise a laryngeal mass because of right vocal fold leukoplakia . the patient 's preoperative laboratory test , chest x - ray , pulmonary function test results were unremarkable . transnasal fiberoptic laryngoscopy taken 2 months prior to the surgery showed right vocal cord palsy ( fig . the initial vital signs of patient in the operating room were systolic / diastolic blood pressure of 150/70 mmhg and oxygen saturation of 98% on room air . general anesthesia was induced with 120 mg propofol and 40 mg rocuronium , followed by preoxygenation with 5 l oxygen . two min after injecting the rocuronium , the patient was intubated with a 6.5 mm endotracheal laser tube ( medtronic , laser - shield ii 6.5 mm i.d . anesthesia was maintained with 67 vol% desflurane in an oxygen - air mixture under a 0.3 fraction of inspired oxygen ( fio2 ) . total gas flow was 4 l / min . at the end of the surgical procedure , 15 mg pyridostigmine and 0.4 mg glycopyrrolate were administered after irregular spontaneous breathing of the patient . five min after administering the anticholineasterase , we removed the tube after confirming clear consciousness of the patient and inspiratory pressure less than 40 mmhg . the patient responded well to commands and 5 sec grip strength was good on both hands . the patient was placed on a face mask for manual ventilation and inhaled racemic salbutamol sulfate ( 100 g as salbutamol ) twice through the face mask to facilitate bronchodilation . laryngeal edema , right vocal cord palsy , and paradoxical adduction of the left vocal cord during inspiration were detected by laryngoscopy . hydrocortisone sodium succinate ( 100 mg ) was administered intravenously to alleviate the laryngeal edema and 1 mg midazolam was administered intravenously twice for anxiolysis . the patient still complained of dyspnea and inspiratory stridor after 5 min so we applied 5 cmh2o manual ventilation by face mask to support the patient 's self - ventilation and the dyspnea and inspiratory stridor improved immediately . 2 ) . immediately after applying cpap , the dyspnea and inspiratory stridor were relieved . we detected left vocal fold abduction from the midline on inspiration and widening of the glottic gap on the exam . we decided to maintain 5 cmh2o cpap applied via a face mask during transport to the intensive care unit ( icu ) . an arterial blood gas analysis ( abga ) was done immediately in the icu and showed ph 7.4 , paco2 39.8 mmhg , pao2 104.2 mmhg and sao2 97.7% . he had maintained oxygen saturation > 95% on a high - flow nasal oxygen cannula system ( optiflow , fisher & paykel healthcare limited , auckland , new zealand ) under settings of fio2 0.35 and flow 35 l / min ( fig . another transnasal fiberoptic laryngoscopy was performed 9 hours after extubation and no left vocal fold adduction movement was detected on inspiration . the results of an abga at that time were ph 7.411 , paco2 43.0 mmhg , pao2 65.6 mmhg , and sao2 93.6% . no left vocal fold adduction movement was detected on inspiration during transnasal fiberoptic laryngoscopy ( fig . pvfm is a disorder that presents paradoxical adduction of the vocal fold during inspiration and abduction during expiration . it was reported first by patterson et al .   in 1974 . at that time , pvfm was considered as neurologic or psychiatric disorder , therefore it was described as " munchausen 's stridor " . the symptoms of pvfm are inspiratory stridor , shortness of breath , choking sensation , voice changes , and cough due to the limited airway opening associated with paradoxical vocal fold adduction . the major differential diagnoses are asthma , bilateral vocal cord paralysis , unilateral vocal cord paralysis , vocal cord granuloma , subglottic or glottis stenosis , laryngomalacia , tracheomalacia , benign or malignant neoplasm of the upper airway , and palatine or lingual tonsil hypertrophy . pvfm is often misdiagnosed as asthma because its clinical symptoms are similar with those of asthma . patients with pvfm are resistant to asthmatic medical therapy , therefore , they tend to be exposed to unnecessary long - term steroid therapy and escalated drug use . features that help distinguish pvfm from asthma are inspiratory stridor heard loudly over the larynx , rare sputum production , and associated voice changes . the organic causes of pvfm are brain stem compression , upper or lower motor neuron injury , and a movement disorder similar to parkinson 's disease . the functional causes of pvfm include conversion disorder , anxiety disorder , depression , personality disorder , and stress disorder . according to a 2002 study by forrest et al . patients with psychologically based pvfm present with conversion disorder alone or accompanying diseases , such as asthma , gastroesophageal reflux disease , laryngeal sicca , chronic laryngitis , and laryngeal sensory neuropathy . neurologic factors consist of focal respiratory dystonia with or without spasmodic dysphonia , multiple sclerosis , and autonomic dysfunction . the gold standard for diagnosing pvfm is direct visualization of paradoxical inspiratory adduction of the vocal fold by laryngoscopy while the patient is complaining of symptoms , such as inspiratory stridor and dyspnea . . a pulmonary function test ( pft ) can be helpful when there is a cut - off or flattening of the inspiratory limb on spirometry that suggests an extrathoracic obstruction . clinical symptoms and laryngoscopic findings are essential for diagnosing pvfm but a pft is not . typical findings on transnasal fiberoptic laryngoscopy are adduction of all parts of the true vocal cord and posterior diamond - shaped glottal chinking on inspiration . if the patient is asymptomatic at the time of laryngoscopy , some specific examination , such as metacholine challenge , exercise , histamine , and pungent smell , should be performed to trigger pvfm . treatments for pvfm include reassurance , speech therapy , psychotherapy , biofeedback , benzodiazepines , and inhaled anticholinergics . if the patient does not improve with these therapies , positive pressure ventilation , a bag - valve - mask , or cpap should be considered . in an emergency situation , such as postoperative pvfm , invasive procedures , such as endotracheal intubation or tracheostomy , are performed under a falling oxygen saturation condition due to near complete vocal cord obstruction . in this case , the patient was self - medicating with a benzodiazepine preoperatively because of concern about the right hand tremor . the spo2 of the patient was maintained > 97% after extubation , therefore , we decided to apply cpap rather than performing invasive procedures , such as re - intubation or a tracheostomy . applying cpap in a patient with pvfm lowers expiratory flow and increases lung volume , which helps the glottis to open and relieves dyspnea . cpap also reduces the effort needed for inspiration by establishing a favorable pressure gradient for inhalation . however , few patients with pvfm encounter an emergency situation , such as severe dyspnea . therefore , rapid diagnosis and treatment are very important for a patient 's prognosis . pvfm is very difficult for anesthesiologists to diagnose in the post - anesthesia care unit because the gold standard for pvfm is transnasal fiberoptic laryngoscopy . however , pvfm should be considered when patients complain of dyspnea and stridor after endotracheal extubation . in conclusion , oxygen supply and positive pressure ventilation could be applied first in a case of pvfm when the patient complains of severe inspiratory dyspnea after endotracheal extubation . if the patient continues to suffer from prolonged dyspnea after supplying oxygen and positive pressure ventilation , cpap could be effective before performing invasive procedures , such as endotracheal intubation or a tracheostomy .
paradoxical vocal fold movement ( pvfm ) is an uncommon upper airway disorder defined as paradoxical adduction of the vocal folds during inspiration . 
 the etiology and treatment of pvfm are unclear . 
 the physician should manage this condition because of the possibility of near complete airway obstruction in severe case of pvfm . 
 we report a case of successful airway management in a patient with pvfm by applying continuous positive airway pressure ( cpap ) . in this case 
 , pvfm was detected after removing an endotracheal tube from a 67-year - old male who underwent excision of a laryngeal mass . 
 the patient recovered without complications in 1 day with support by cpap .