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Summary

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Pulmonary function alteration and respiratory complications continue to be a major cause of morbidity and mortality in patients with SCI.  There are currently no widely accepted clinical practice guidelines for the long-term respiratory management of the SCI patient.  Much of the SCI-respiratory literature focuses on the acute care of the SCI patient.  However, given that long-term survival rates following SCI injury have increased in recent years, a greater understanding of the effects of chronic SCI on the respiratory system is necessary.  Moreover, identifying interventions that can improve (or minimize the decline in) pulmonary function and reduce respiratory complications are of great importance.  Despite this need there are also no widely accepted clinical practice guidelines available for the respiratory management of the SCI patient following hospital discharge.  This is largely due to the fact that there have been relatively few well designed studies that point to effective management strategies.  Interpretation of the available literature is difficult because many studies have a least one, and more often multiple methodological or research design concerns.  Specific major concerns include an overall lack of RCTs; patient sample sizes are often small with little or no consideration for statistical power; lack of appropriate control or placebo groups; and inadequate characterization of the SCI.  In addition, most studies do not take into account gender, time since injury, smoking history and other respiratory complications.  As such, the amount and quality of the literature can be considered modest at best and the ability to generalize is limited.

Despite the above caveats and research design shortcomings, some conclusions can be cautiously drawn regarding commonly used respiratory intervention strategies.

(i) Exercise Training.  The evidence that the respiratory system is positively influenced by exercise training is not strong.  There is some evidence that rigorous training can improve respiratory muscle strength, endurance and efficiency in SCI.  There have been no reports of negative consequences of exercise training.  Exercise training should be encouraged for maintenance of general cardio-respiratory health in people with SCI.

(ii) Respiratory Muscle Training.  Specific training of the respiratory muscles in SCI is well supported by level 1a evidence that demonstrates improved respiratory muscle function and a lowering of respiratory infections.   Other studies are limited by their design, sample size or use of a less effective training device.  From the available literature on other subject groups (healthy, lung disease) it appears that training of the respiratory muscle may improve ventilation, decrease dyspnea and improve daily respiratory function.  Consistent improvement in respiratory function following respiratory muscle training has not been demonstrated in people with SCI.

(iii) Pharmaceutical Interventions.  Restrictive ventilatory impairment is common in SCI and is dependent on lesion level and degree of completeness.  Obstructive ventilatory impairment is present with cervical injury.  There is some evidence to show that use of bronchodilators can elicit a positive response in pulmonary function.  Bronchodilators can be recommended for short-term use in patients with obstructive impairment.  The long-term effects are unknown.  There is limited evidence to support the use of anabolic steroids for improvement in pulmonary function.

(iv) Assistive Devices.  Ventilatory weaning in SCI is important but there is no consensus on the ideal weaning protocol.  There is some evidence that progressive ventilator free breathing is more effective than intermittent mandatory ventilation in cervical SCI.  There is insufficient research to advocate the long-term use of abdominal binding or vibration to improve indices of pulmonary function.

(v) Obstructive Sleep Apnea.  There is a higher prevalence of sleep apnea in SCI relative to able-bodied individuals.  Treatment options include CPAP and weight loss but there is limited research evidence to suggest positive long-term benefits.  Anecdotal and patient reports suggest that therapy for sleep apnea is beneficial.

(vi) Secretion Removal.  Retention of secretions is common in SCI because of a diminished capacity for cough generation.  Elimination of secretions is commonplace in clinical practice and is generally considered an integral part of maintaining respiratory health in SCI.  There areseveral commonly used secretion removal techniques but there is no consensus on their effectiveness.

(vii) Phrenic Nerve Stimulation.  Several different devices for phrenic nerve pacing have been developed and long-term stability of this method has been recently reported. Many of the reported studies are level 4 case series or pre-post study designs looking at the feasibility of phrenic nerve stimulation devices. Long-term partial or total independence from mechanical ventilation can generally be interpreted as a successful intervention with these devices.

There is level 2 evidence (based on 1 prospective controlled trial) (de Carvalho et al. 2006) and level 4 evidence (based on 4 pre-post studies) (Silva et al. 1998; Sutbeyaz et al. 2005; Le Foll-de-Moro et al. 2005; Fukuoka et al. 2006) to support exercise training as an intervention that might improve resting and exercising respiratory function in people with SCI.

There is level 4 evidence (based on 1 pre-post study) (Janssen and Pringle 2008) that computer controlled electrical stimulation induced leg cycle ergometry (ES-LCE) increases the peak values of oxygen uptake, carbon dioxide production, and pulmonary ventilation.

There is level 1b evidence based on 1 RCT (Van Houtte et al. 2008), level 2 evidence based on 4 RCTs (Mueller et al. 2012/2013; Loveridge et al. 1989; Liaw et al. 2000; Derrickson et al. 1992), and level 4 evidence from several pre-post and case studies to support IMT as an intervention that will improve inspiratory muscle strength and might decrease dyspnea and respiratory infections in some people with SCI.

There is level 4 evidence (based on 3 pre-post studies) (Almenoff et al. 1995; Spungen et al. 1993; Schilero et al. 2004) that ipratropium and metaproterenol have a positive effect on pulmonary function in subjects with tetraplegia.

There is level 1 evidence (based on 1 RCT) (Barratt et al. 2012) that salbutamol has a beneficial effect on respiratory function in subjects with new onset of tetraplegia.

There is level 1 evidence (based on 1 RCT) (Grimm et al. 2006) that salmeterol has a positive effect on pulmonary function in subjects with tetraplegia.

There is level 2 evidence that chronic oral baclofen and chronic oxybutynin (from 2 prospective controlled trials and 1 pre-post study) (Dicpinigaitis 1994b; Grimm et al. 1997; Singas et al. 1999) and level 4 evidence that ipratropium bromide (Dicpinigaitis 1994a) decrease or block hyperresponsiveness to methacholine, but not histamine in tetraplegia.

There is conflicting evidence (Spungen et al. 1999, Halstead et al. 2010) that the short-term use of oxandrolone improves pulmonary function in subjects with tetraplegia.

There is level 1b evidence (based on 1 RCT) (Li et al. 2012) that high-dose IV ambroxol after surgery increases blood oxygenation in cervical spinal cord injured patients with motor complete injuries.

There is level 3 evidence (from 1 retrospective analysis) (Wong et al. 2012) that the implementation of specialized respiratory management (HVtV, HFPV, MIE) resulted in improvement of respiratory status in all study subjects.

There is level 4 evidence (from 1 case series study) (Peterson et al. 1994) that progressive ventilator free breathing (PFVB) protocol is more successful for weaning subjects with C3 and C4 spinal cord injuries than intermittent mandatory ventilation (IMV).

There is level 4 evidence (from 1 case series study) (Onders et al. 2010) that DP serves as an effective weaning protocol in all subjects.

There is level 4 evidence (from 1 pre-post study) (Gutierrez et al. 2003) that a resistive and endurance protocol increases inspiratory pressure, expiratory pressure and VC especially in low tetraplegia (C4-C7).

There is level 2 evidence (from 1 cohort study) (Cameron et al. 2009) that the Tracheostomy Review and Management Service (TRAMS) reduces length of stay (LOS), duration of cannulation (DOC) and saves costs, while increasing speaking valve usage.

There is level 4 evidence (from 2 case series) (Romero et al. 2009, Ganuza et al. 2011) that early tracheostomy, performed within a week of intubation, is beneficial. 

There is level 4 evidence (from 1 case series study) (Ross & White 2003) that decannulation can be successful in subjects with evidence of aspiration.

There is level 2 evidence (from 1 RCT) (Laffont et al. 2008) that intermittent positive-pressure breathing (IPPB) has no short-term or long-term effects on lung function within one year of SCI.

There is level 4 evidence (from 1 Pre-post trial) (Stiller et al. 1992) that IPPB has no effects on lung function immediately following onset of SCI.

There is level 2 evidence evidence (Wadsworth et al. 2012) that abdominal binding in tetraplegic individuals can improve respiratory function, and longer term use can continue to be effective.

There is level 4 evidence (based on 1 pre-post study) (Homma et al. 1981) that the use of chest wall vibration increases tidal volume and minute ventilation in subjects with tetraplegia. 

There is level 4 evidence (based on 1 pre-post study) (Thomaz et al. 2005) that the use of immersion to shoulder-deep 33-34° C water improves pulmonary function immediately in persons with tetraplegia but longer terms effects have not been evaluated.

There is level 4 evidence (based on 2 case series and 1 pre-post study) (Stockhammer et al. 2002; Burns et al. 2005; Biering-Sørensen et al. 1995) to support therapies to treat obstructive sleep apnea in people with SCI.

Secretion removal techniques are common practice in people with spinal cord injury and yet there is predominantly only level 4 evidence to support the use of some airway clearance techniques to facilitate secretion removal in this population.  There is level 2 evidence (based on 1 RCT) (Pillastrini et al. 2006) in support of mechanical insufflation/exsufflation coupled with manual chest therapy kinesitherapy techniques.

There is no evidence in support of one airway clearance technique over another, and there are no criteria available to indicate when to implement the various airway clearance techniques.

There is a need to determine the most efficient and effective techniques that are comfortable and readily adhered to for people with SCI in order facilitate airway clearance, to improve their quality of life, and decrease health care costs.

There is level 3 evidence (from 1 case control study) (Carter 1993) that suggests a higher survival rate in a phrenic nerve paced group compared to a mechanically ventilated group.

There is level 3 evidence (from 1 case control study) (Esclarin et al. 1994) that suggests better power wheelchair management, phonation success, patient satisfaction and hospital discharge in phrenic paced subjects compared to mechanically ventilated subjects.

There is level 4 evidence (from 8 pre-post studies) (see Table 18) that phrenic nerve stimulation can be used as a long-term alternative to mechanical ventilation for subjects with injuries at C2 or above.

There is level 4 evidence from (1 pre-post study) (Alsheklee et al. 2008) that diaphragm pacing system (DPS) can help cervical SCI patients breathe without a mechanical ventilator.

There is level 4 evidence (Tedde et al. 2012; DiMarco et al. 2005a; Onders et al. 2004) that diaphragmatic stimulation via laparoscopic placement of electrodes can be used as a long-term alternative to mechanical ventilation for subjects with high cervical spinal cord injuries.

There is level 4 evidence from 1 study (DiMarco el al. 2005b) that unilateral phrenic stimulation in combination with intercostals stimulation can be used as an alternative to mechanical ventilation for subjects with a single intact phrenic nerve.

There is level 4 evidence from 1 study (DiMarco et al. 1994) to show that intercostal muscle pacing via upper thoracic ventral root stimulation cannot be used as a long-term alternative to mechanical ventilation (DiMarco et al. 1994).

There is level 2 evidence (McBain et al. 2013) that abdominal electrical stimulation during cough improved cough pressure. After cough training, pressure was improved in unstimulated voluntary cough.

There is level 2 evidence (Hascakova-Bartova et al. 2008) that abdominal neuromuscular electrical stimulation (ES) decreases the FVC.

There is level 4 evidence (Spivak et al. 2007) that EMG-activated FES significantly improves both PEF and FVC in tetraplegia patients, when compared to patient-activated FES.