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Respiratory Management (Rehab Phase)

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
Pre-Post
N=12 (2 with cervical SCI)

 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)
  1. In the RMW group, LVR increased respiratory system compliance 40% above baseline, no change in control group.
  2. Peak expired flow during LVR increased ~1l/s
  3. No change in unassisted PEF or PCF.
  4. LVR had no effect on lung volumes.

Jeong & Yoo, 2015; Korea
PEDro = 6
Randomized Controlled Trial
N=26

Population: N=26 with cervical SCI
Mean (SD) age*: 47.6 (11.7) years
*data prior to exclusion, N=30
Treatment:
Experimental group (14, Exp): 20 repetitions of air stacking twice a day
Control group (12, Ctrl): 20 repetitions of incentive spirometry twice a day
Outcome Measures: FVC, FEV1, peak cough flow (PCF)
  1. Between-group – significant increase in FVC and PCF in experimental group compared to controls
  2. Within-group – significant difference in FVC and PCF at 6 weeks (compared to baseline) in experimental group; only FVC significantly different at 6 weeks in controls
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
Cross-sectional
N = 15

 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)
  1. We observed significant differences in PCF while applying MEE-AC and AS-MEE compared with MEE.
  2. The difference in PCF value was greatest using the AS-MEE-AC techniques combined.
  3. The application of combined techniques (AS-MEE-AC) can reach near normal PCF values. This is a low-cost, simple and easily applied intervention that could be introduced to all patients with tetraplegia.

Pillastrini et al. 2006; Italy
PEDro = 3
RCT
N=not reported

 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
  1. EG showed significant increases in FVC, FEV1 and PEF.
  2. Use of mechanical insufflation/exsufflation is shown to be an effective adjunct to manual chest therapy techniques, since it makes it possible to achieve adequate bronco-pulmonary clearance.

Butler et al. 2011; Australia
Pre-post
N = 11

 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)
  1. Abdominal stimulation increased Pga and Pes during voluntary efforts and during coughing
  2. During cough, stimulation significantly increased PEFR by 36(SD 5)%, mean expiratory flow by 80(8)%, expired lung volume by 41(16)% and FEV1 by 39(12)%.
  3. Wearing an abdominal binder increased IC by 17% and VC by 14%.
  4. No additional improvement to any respiratory measures during cough with addition of binder to stimulation were found

Crew et al. 2010; USA
Case series
N = 40

 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)
  1. There was a non-significant reduction of respiratory hospitalization rates/year.
  2. There was one instance of pulmonary embolus hospitalization post-MIE
  3. Non-smokers averaged 0.14(0.16) respiratory hospitalizations/year, significantly different from smokers (0.41(0.36)). Post-MIE, smokers respiratory hospitalizations/year decreased significantly to 0.19(0.32).

DiMarco et al 2009; USA
Post-test
N = 9

 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
  1. Supramaximal SCS resulted in high peak airflow rates (ranging from 5.8 to 8.6L/s) and large airway pressure (ranging from120 to 144 cm H2O) during stimulation at each electrode lead
  2. Maximum airflow rates and airway pressure were achieved with combined stimulation of any two leads
  3. At TLC, mean(SD) PEFR and airway pressure generation were 8.6(1.8) L/s and 137(30)cm H2O

Gollee et al. 2008; UK
Pre-Post
N = 4

 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)
  1. Significant increase in tidal volume during quiet breathing (range 0.05-0.23 L)
  2. Significant increase in cough peak flow (range 0.04 – 0.47 L/s)
  3. Respiratory rate during quiet breathing decreased in all participants when stimulated
  4. Minute ventilation increased by 1.05-2.07 L/min
  5. No significant changes in EtCO2

Kang et al. 2006; Korea
Prospective Controlled Trial
N = 40

 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).
  1. MIP more so than MEP showed stronger relationships with peak exp flow during cough maneuvers.
  2. All three assisted techniques (2,3 & 4) showed higher PEFRs.  The combined assist (4) showed significantly higher values than the inspiratory or abdominal thrust assist.

Estenne et al. 2000; Belgium
Pre-post
N = 16

 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.
  1. Maximal stimulation increased gastric pressure to 76.0(7) in controls and 29.9(3.7) cmH2O in SCI participants.
  2. The cumulative thickness of the four abdominal muscles was 34% smaller in the people with SCI than in control participants and correlated positively with changes in gastric pressure induced by stimulation.

Garstang et al. 2000; USA
Pre-post
N = 18

 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.
  1. MI-E was less irritating, less painful, less tiring, less uncomfortable. All were clinically significant changes (except less tiring).
  2. 16 of 18 patients preferred MI-E and one preferred suctioning; 1 patient had no preference.
  3. When surveyed, average time from MI-E was 146 days and from suctioning was 253 days.

Linder 1993; USA
Prospective Controlled Trial
N = 11

 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).
  1. In group 1, the MEP significantly increased with FES (mean difference in MEP between spontaneous and FES assisted cough was 33.3 cm H2
  2. In group 2, the portable FES device increased MED from 32.3 to 58 cm H2O, when compared to spontaneous cough.

Gap: SCI Evidence on the Use of LVR (Lung Volume Recruitment) and Assisted Cough for Secretion Management

Source of evidence

We 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 clearance

Restrictive 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 cough

This 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.

There is limited evidence that suggests that improving inspiratory and expiratory muscle force is important to maximize expiratory flow during cough.

Cough effectiveness can be enhanced by a variety of methods including manual assistance by a caregiver, respiratory muscle training, and/or electrical stimulation triggered by the person with SCI.

Hand-held expiratory pressure devices may enhance secretion removal in people with SCI.

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