Cough Assist and Secretion Removal
People with spinal cord injury are at risk for retention of secretions because of an increased prevalence of pneumonia compounded by lower expiratory flows during cough, which is greatest during the acute phase after SCI. Increased prevalence of respiratory infections, although decreased during the rehabilitation phase of recovery, is still higher in people with SCI compared to age-matched healthy people. Reduction in expiratory flows during cough is related to the higher levels of SCI. Of considerable surprise, several devices that have been shown to be effective in people with other chronic respiratory conditions have not been evaluated in people with spinal cord injury.
Author Year; Country Score Research Design Total Sample Size |
Methods | Outcome |
---|---|---|
Seon et al. 2017; Canada |
Population: 12 people with respiratory muscle weakness (RMW, maximal inspiratory mouth pressure <30% predicted; age = 29 ± 3 yrs), including 2 with C5 SCI, and 12 healthy controls (age = 29 ± 2 yrs) Treatment: LVR with manual resuscitation bag delivered to maximum tolerated mouth pressure. Outcome Measures: Maximum insufflation capacity; respiratory system compliance (pulse method); peak cough flow (PCF); peak expiratory flow (PEF) during LVR; lung volumes (TLC, VC, IC, FRC, ERC, RV) |
|
Jeong & Yoo, 2015; Korea |
Population: N=26 with cervical SCI |
|
Effect Sizes: Forest plot of standardized mean differences (SMD ± 95%C.I.) as calculated from pre- and post-intervention data
|
||
Torres-Castro et al. 2014; Chile |
Population: Fifteen in-patients with complete tetraplegia (C4–C6, AIS A) were included. Median age was 33 years (16–56). Treatment: Peak cough flow (PCF) was measured during four different interventions: spontaneous maximal expiratory effort (MEE); MEE while receiving Assisted Cough (MEE-AC); MEE after Air Stacking with a manual resuscitation bag (AS-MEE); and MEE with AS and AC (AS-MEE-AC). Outcome Measures: Peak cough flow (PCF) |
|
Pillastrini et al. 2006; Italy |
Population: Complete cervical SCI, control group (CG) mean(SD) age 52.2(17.6) yrs; experimental group (EG) age 31.5(16.1) yrs. Number of participants not reported. Treatment: EG = Manual respiratory kinesitherapy (included chest therapy techniques such as postural drainage, assisted coughing, Ambu bag to provide positive pressure) coupled with mechanical insufflation/exsufflation (portable machine which inflates lung with positive pressure and assists coughing with negative pressure); CG = manual kinesitherapy only Outcome Measures: FVC, FEV1 and PEF |
|
Butler et al. 2011; Australia |
Population: N=11 people with SCI (8M 3F); mean(SD) age 45(5); YPI 9.2(4.1); SCI at or above T6 Treatment: Bilateral posterolateral surface electrical stimulation of abdominal expiratory muscles at 50Hz, abdominal binder Outcome Measures: Measures of lung function (IC, VC, FBC, FEV1) gastric pressure (Pga), esophageal pressure (Pes) |
|
Crew et al. 2010; USA |
Population: 40 patients with tetraplegia; 33 AIS A or AIS B; 14 acute SCI (mean (SD) age 50.3(11.2), YPI 2.3(1.7)) and 26 chronic SCI (58.3(12.9), YPI 22.5(15.1)) Treatment: Mechanical insufflation-exsufflation (MIE) device for outpatient use Outcome Measures: Medical record review (respiratory hospitalization rates/cause) |
|
DiMarco et al 2009; USA |
Population: 9 SCI patients (age range 23-52 yrs) Treatment: Lower thoracic spinal cord stimulation (SCS) at T9, T11, and L1 levels Outcome Measures: Peak airflow and airway pressure generation |
|
Gollee et al. 2008; UK |
Population: 4people with tetraplegia (ages 16, 37, 45, and 49, level of injury C4-C6) Treatment: Surface functional electrical stimulation (FES) of abdominal wall muscles Outcome Measures: Spirometry, end-tidal CO2 (EtCO2) |
|
Kang et al. 2006; Korea |
Population: 40 traumatic cervical SCI Treatment: Compared four types of cough. Unassisted peak cough flow inspiratory assist cough flow abdominal thrust cough flow inspiratory assist & abdominal thrust cough flow. Outcome Measures: Spirometry, Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP). |
|
Estenne et al. 2000; Belgium |
Population: 16 participants: (8 SCI, 8 non-SCI matched for age, sex, height and weight controls), all 8 SCI participants had complete tetraplegia, C4-C7, mean(SD) age SCI: 39(3.1) yrs; controls: 38(1.8) yrs Treatment: Magnetic stimulation of abdominal muscles. Outcome Measures: Gastric pressure. |
|
Garstang et al. 2000; USA |
Population: 18 SCI patients (C1-T3), 88% were C5 or higher Methods: Surveyed preference for: suctioning or maximal in/exsufflation (MI-E). Outcome Measures: Not Specified. |
|
Linder 1993; USA |
Population: 11 people with complete SCI (C4 and below), mean(SD) age: group 1 = 38(11.4) years, group 2 = 36.7(7.2) yrs, average time since injury: group 1 = 12.3, group 2= 18years Treatment: Group 1: assisted coughing by: 1) manual assist; or 2) functional electrical stimulation (FES). Group 2: assisted coughing by a portable abdominal binder incorporating electrodes. Outcome Measures: Maximum Expiratory Pressure (MEP). |
|
Gap: SCI Evidence on the Use of LVR (Lung Volume Recruitment) and Assisted Cough for Secretion Management |
---|
Source of evidenceWe found 1 study using LVR for people with SCI (see above Molgat- Seon et al. 2017). However, there is a large body of evidence from other populations with neurological respiratory impairment and cough impairment, predominantly Duchennes Muscular Dystrophy, Amyotrophic Lateral Sclerosis and Multiple Sclerosis. There are a variety of LVR techniques possible: using a LVR resuscitation bag, using a Mechanical Insuffalator/Exsuffalator machine (MIE) or using the Ventilator for individuals already using one. |
Recognizing risk of impaired secretion clearanceRestrictive lung disorders as a result of their decreased respiratory muscle strength, reduced vital capacity, ineffective cough and reduced lung and chest wall compliance. These acute and chronic chest changes place individuals with SCI at risk for cardiorespiratory complications such as atelectasis, secretion retention and recurrent chest infections. Mechanical in-Patients with SCI commonly develop exsufflation (e.g., cough assist machines), lung volume augmentation techniques (e.g., breath-stacking) and manual assisted cough techniques are recommended as best practice for managing acute and chronic cardiorespiratory conditions in people with SCI. Individuals with a Peak cough flow of less than 270 L/min are at risk for secretion retention and need manual or mechanical assistance to avoid serious complications or health risks. |
Management: Assisted coughThis is a manual technique used to increase expiratory pressure. It is used to compensate for the decreased intra-abdominal pressure that can be present with certain levels of SCI. Pressure is applied in the direction of the costal and abdominal areas during expiration. It can be done in lying or sitting PRN depending on need. Appropriate communication and timing is required to ensure that the manual thrust is done just at or prior to expiration. There are some precautions and contraindications mostly related to abdominal trauma, fractures etc. LVR: is also called ‘breathstacking’. It is a technique used to compensate for the decrease in inspiratory volume and to achieve maximum insufflation capacity (maximum volume of air that can be held in lungs with glottis closed). To perform this technique a LVR kit is used. It consists of a resuscitation bag and a one way valve and flex tube with a mouth piece. Breaths are then “stacked” (taken one after another) to fully inflate the lungs. There may be some tightness or feeling of stretch. An assisted cough can be done at the time of maximum inflation to assist with secretion clearance and increase peak cough flow. Although this is recommended for secretion clearance during times of congestion it is also recommended as a daily treatment to maintain chest mobility and chest hygiene. |
Discussion
Very few studies have examined the effectiveness of secretion removal techniques in people with SCI even though respiratory complications are a primary cause of morbidity and mortality in this population. With the exception of one RCT, studies performed to date are limited by a survey (Garstang et al. 2000) or lack of documentation of valid measurement technique of standard pulmonary function (Kang et al. 2006). Limited evidence supports the postulate that improving inspiratory muscle strength (Kang et al. 2006) in addition to expiratory muscle force (Estenne et al. 2000) are important to maximize expiratory flows during cough. IMT (Van Houtte et al. 2008), electrical stimulation of the expiratory muscles (Linder 1993; Estenne et al. 2000; DiMarco et al. 2009, Butler et al. 2011), and mechanical insufflation/exsufflation (the application of positive pressure to the airway, then shifting to negative pressure to produce an expiratory flow simulating a cough) as an adjunct to manual respiratory kinesitherapy (Pillastrini et al. 2006) are three potential therapies that can maximize the force produced by the inspiratory and expiratory muscles, respectively, in order to increase expiratory flows during cough. With the exception of the small RCT assessing the latter (Pillastrini et al. 2006), RCTs examining the effectiveness of airway clearance techniques in people after SCI are lacking. RMT (Van Houtte et al. 2008) and mechanical insufflations-exsufflation (Crew et al. 2010) has been shown to decrease infections and tended to decrease respiratory hospitalizations per year, respectively.
Other issues that require further study in SCI is to examine the effectiveness of hand-held devices that facilitate airway clearance, such as those that apply continuous (PeripepÒ) or oscillating positive expiratory pressure (Flutter). Of equal concern is to evaluate the comfort and preference of airway clearance techniques that are readily adhered to and performed by people with SCI. Some evidence supports the effectiveness of these positive expiratory pressure devices and other secretion removal techniques such as autogenic drainage in people with cystic fibrosis and other chronic respiratory diseases; however, the evidence to date is somewhat equivocal (Hess 2001; Reid & Chung 2004).
Conclusion
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 2 RCTs: Pillastrini et al. 2006; Jeong and Yoo 2015) 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.