A literature search was performed using the following databases: Cochrane Library, PubMed/MEDLINE, EMBASE, CINAHL, and Scopus. The following search terms were entered: (spinal cord injury OR paraplegia OR quadriplegia OR tetraplegia OR spinal cord impaired OR spinal cord lesion) AND acapello, airway, airway pressure, apnea, asthma, atelectasis, barotraumas, breathing, bronchial lavage, bronchitis, bronchoscopy, cardiopulmonary function, cardiorespiratory, COPD, cough, diaphragm, dysphagia, expiration, exsufflation, flutter, Garshick, inspiratory, insufflations, lung, percussion, phrenic nerve, pneumonia, positive airway pressure, pulmonary, pulmonary capacity, pulmonary complications, pulmonary embolism, pulmonary health, pulmonary secretions, respiration, respiratory capacity, respiratory complications, respiratory endurance, respiratory function, respiratory health, respiratory muscle, respiratory secretions, sleep apnea, smoking, spirometry, steroid respiratory, tidal volume, ventilation, ventilator weaning, ventilatory capacity, ventilatory failure, abdominal binder, assisted cough, autogenic drainage, BiPAP, breathing exercises, chest physiotherapy, cough, CPAP, diaphragmatic pacemaker, expiratory pressure device, exsufflation, futter device, flutter valve, forced expiratory technique, glossopharyngeal breathing, incentive spirometry, insufflations, intermittent positive pressure breathing, intrapulmonary percussive ventilation, IPPB stretch, manual percussion, manual vibration, mechanical vibration, paripep, PEEP, PEP, percussion, phrenic pacemaker, positive pressure breathing, postural drainage, progressive ventilatory free breathing, respiratory exercise, respiratory training, secretion removal, spirometry, synchronous intermittent mandatory ventilation, TheraPep, tracheostomy, ventilation, ventilator, or ventilator weaning. Each search term after the brackets was added separately.

The following limits to the search were applied: the article must have been published between January 1, 1990 and December 31, 2021 in English, and included humans over the age of 18 years. The search was restricted to journal articles, reviews, and systematic reviews; grey literature, conference abstracts, case reports, study protocols, and qualitative studies were excluded. The studies had to include a minimum of three patients, of which ≥50% had spinal cord injuries, unless the results stratified injury etiology. During this process, additional studies were added as a result of cross-referencing between studies. Efforts were made to focus on the most recent studies and the highest levels of evidence available.