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Respiratory Management (Rehab Phase)

Mechanical Ventilation and Weaning Protocols

The indications for mechanical ventilation and the acute management of respiratory issues in SCI are outside the scope of this review which focuses on rehabilitation. However, the long-term complications associated with chronic ventilator dependency need to be mentioned in order to highlight their importance. The overall life expectancy for individuals with SCI who are ventilator dependent has been increasing, especially for those individuals who survive the first year following injury (DeVivo and Ivie 1995). Despite advances, mortality for individuals with ventilator dependency remains high (DeVivo and Ivie 1995).

In general, subjects with complete neurologic injuries at C2 and above have no diaphragmatic function and are ventilator dependent. Subjects with complete neurologic injuries at C3 or C4 have variable diaphragmatic function. Although they may have the potential for ventilator weaning, it is difficult to predict whether they will ultimately be successfully weaned. Subjects with complete injuries at C5 and below have intact diaphragmatic function. They may require ventilatory support initially post-injury, but are usually able to wean from the ventilator.

The approach to ventilator weaning in SCI remains an important and somewhat neglected issue. The PVA “Consortium for Spinal Cord Medicine — Respiratory management following spinal cord injury: a clinical practice guideline for health-care professionals (2005)” suggests the consideration of “progressive ventilator free breathing over synchronized intermittent mandatory ventilation”.

Authors Year; Country
Score
Research Design
Total Sample Size
Methods Outcomes
Fenton et al. 2016;
United States
PEDro=6
Randomized Controlled Trial
N=33
Population: N=33 cervical SCI patients on mechanical ventilation (25M, 8F)
Mean (SD) age:  33.1 (11.7) years
Treatment: control – standard mechanical ventilation tidal volume (10 ml/kg); experimental – higher ventilation tidal volume (20 ml/kg)
Outcome Measures: Days to ventilator weaning, FVC, peak inspiratory pressure (PIP); plateau pressure (Pplat), pulmonary adverse events, Borg scale
  1. No significant between group difference in number of days for ventilation weaning, even after controlling for age.
  2. No significant between group difference in increase of FVC.
  3. Significant between group difference in increase of PIP and Pplat each day.

Kornblith et al. 2013; United States
Retrospective Multicenter Review
N=344

Population: N=344 ventilator-dependent SCI patients with phrenic nerve lesions (277M, 67F)
Median (range) age: 43 (18-82) years
222 cervical, 90 thoracic, 32 lumbar
172 complete SCI; 72 concomitant TBI
Treatment: Mechanical ventilation
Outcome Measures: Need for mechanical ventilation at discharge, tracheostomy history, development of acute lung injury (ALI) and ventilator-associated pneumonia (VAP)
  1. Majority of patients weaned from mechanical ventilation at discharge.
  2. Significantly fewer patients who underwent tracheostomy weaned from ventilator, compared to those who did not.
  3. Significantly higher frequency of ALI & VAP, and fewer ventilator-free days in those who underwent tracheostomy, compared to those who did not.
  4. “Tracheostomy after cervical SCI was an independent predictor of ventilator dependence” (p.1061).

Romero-Ganuza et al. 2015; Spain
Retrospective Review
N=228

Population: N=228 patients
Group 1: acute phase SCI patients from ICU with respiratory failure (N=68; 49M 19F); mean age (SD): 53.8(16.6); AIS-A/B/C/D: 42/13/10/3; cervical/thoracic: 55/13; traumatic/nontraumatic: 40/28
Group 2: SCI patients from community with respiratory complications or scheduled follow-ups (N=160)
Treatment: Mechanical ventilation (MV)
Outcome Measures: Institutionalization status, duration of MV, length of stay
  1. At discharge* of acute phase patients: 20 with permanent MV, 23/26 succeeded in weaning after a mean of 47.3(49.3) days, 13/22 already weaned patients received tracheostomy closure, 5 expired; mean length of stay 195.6(110.4) days.
  2. At discharge* of patients with complications: 9 patients admitted with MV, 6 weaned after a mean of 17.2(19.3) days; mean length of stay 53.1(56.3) days.
  3. MV patients significantly more likely to be institutionalized after discharge*

*discharge from intensive respiratory care unit (IRCU)

Roquilly et al. 2014; France
Retrospective Multicenter Review
N=164

Population: N=164 acute traumatic tetraplegic SCI patients from ICU (125M 76F)
Median age (IQR): 44(27-59)
AIS-A/B/C/D/E: 102/21/25/13/1
Median lesion level (IQR): C5(C4-C6)
Treatment: Mechanical ventilation (MV)
Outcome Measures: Duration of MV, ASIA motor score
  1. “The duration of MV was associated with ISS (Injury Severity Score), medical history of respiratory failure, tracheal intubation, tracheotomy, HAP (hospital-acquired pneumonia), atelectasis, tidal volume in the first 24 hours, and PEEP (lower positive end-expiratory pressure) in the first 24 hours” (p313.e9)
  2. “The duration of MV was positively associated with HAP, lung atelectasis, and tracheotomy” (p313.e10)

Wong et al. 2012; USA
Retrospective comparison of pre-post treatment
N=24

Population: N=24 individuals with high cervical (C1-4) SCI (22M 2F); mean(SD) age: 33.4(16.6); DOI before transfer to SCI specialty unit (and start of treatment): 33.8(24.4) days.
Treatment: High Tidal Volume Ventilation (HVtV) treatment; High Frequency Percussive Ventilation (HFPV) treatment; and Mechanical Insufflation-Exsufflation (MIE) treatment
Outcome measures: TV; days before being weaned to room air; peak inspiratory pressure (PIP); plateau pressure (Pplat).
  1. The respiratory status of all of the study patients improved with the specialized respiratory management administered in the SCI specialty unit. For a majority of these patients, respiratory improvements were noted within 1 week of admission to the SCI unit.
  2. Tidal volume for all patients was stabilized at 12-15mL/kg ideal body weight (mean (SD) tidal volume = 1037.5 (140.8)).
  3. Nine (37.5%) patients were weaned to room air in ≤7 days, and another 5 patients were weaned to room air in ≤14 days. The average time for 23 out of the 24 participants to be weaned to room air was 16.3 days (SD 8).
  4. 23 (96%) patients were transitioned to portable ventilators (average time 7.7 days post admission SD 5.0).
  5. 14 patients were weaned from the ventilator (average time 27.6 days post admission SD 12.9 days).

Onders et al. 2010; USA
Case series
N=20

Population: N=20 people with SCI (17M 3F); 16-61 years old; all with internal cardiac pacemakers; all tetraplegia; 0.5-24 YPI
Treatment: Implantation of DP electrodes
Outcome Measures: Hours of daily use of DP, implantation, negative interactions between cardiac pacemaker and DP (device-to-device interaction), conditioning, ability to wean from Mechanical Ventilation
  1. There were no peri-operative complications in any patients, nor device-to-device interactions in 19/20 patients.
  2. There was device-to-device interaction in 1 patient, which was resolved by disabling the interacting electrode in question.
  3. All patients achieved diaphragm paced tidal volumes necessary to meet their basal metabolic needs. 14/20 patients finished conditioning with their diaphragm and reached their maximal goal.
  4. Ten of the above 14 use DP 24 hours a day with no mechanical ventilation.
  5. Three other patients use DP 8-12 hours during the day, with 1 reaching a maximum of 4 hours by choice.
  6. The remaining 5 participants (excluding the early death), were still increasing their DP sessions through conditioning at the end of the study.

Gutierrez et al. 2003; USA
Pre-post
N=7

Population: 7 tetraplegia: C2(n=2), C4-C7(n=5), incomplete, all male, age range: 45-68 years, time on ventilator: 4-36 months
Treatment: Implementation of an evidence-based resistive endurance protocol (REP) designed to help discontinue mechanical ventilation by improving ventilatory muscle strength and endurance
Outcome Measures: Pulmonary function tests; on-ventilator endurance and off-ventilator endurance.
  1. Participants with low tetraplegia achieved significant gains in inspiratory & and expiratory muscle strength, VC, mean on-ventilator endurance & off-ventilator endurance.
  2. Participants with high tetraplegia had non-significant improvements in inspiratory and expiratory muscle strength and VC and were able to discontinue mechanical ventilation.
  3. 4/5 participants with low tetraplegia were weaned from the ventilator. 1/5 low tetraplegic participants died.
Peterson et al. 1994; USA
Case Series
N=52
Population: Tetraplegia (C3-C4), ventilator dependent
Treatment: Retrospective review of 82 ventilator weaning attempts in 52 participants using intermittent mandatory ventilation (IMV), progressive ventilator free breathing (PVFB) or a combination of other ventilator weaning techniques
Outcome Measures: Successful ventilator weaning.
  1. 26/82 weaning attempts used IMV, 34/82 used PVFB and 22/82 used a combination of various techniques.
  2. PVFB weaning success rate was 67.6 % (23/34) and IMV was 34.6% (9/26) and other techniques was 11/22.
  3. Overall 43/52 (83%) of participants were successfully weaned. 6/52 were partially weaned. 2/52 participants died.

Discussion

Peterson et al. (1994) retrospectively compared weaning methods in 52 subjects with C3 and C4 SCI. Overall 83% of subjects were successfully weaned with progressive ventilator free breathing (PVFB, also known as T-piece weaning) being the most successful technique. However, most of the PVFB trials occurred at a single institution and in subjects who were longer post-injury whereas most of the intermittent mandatory ventilation trials (IMV) occurred in a variety of institutions in subjects who were earlier post-injury.

Gutierrez et al. (2003) developed an evidence based resistive and endurance protocol to improve ventilatory muscle strength and endurance in subjects with ventilator-dependent cervical SCI. The evidence was based on SCI literature where possible, but was also derived from the general respiratory literature where required. The protocol included 4 daily phases with rests in between each phase: pre-training optimization (Trendelenberg positioning, trachea suctioning, bronchodilator use, and lung hyperinflation); inspiratory/expiratory resistive training; on-ventilator endurance training; and off-ventilator endurance training. Although the pilot study only included 7 subjects, it did show promising results with respect to increasing inspiratory pressure, expiratory pressure and VC and ultimately ventilator weaning, especially in subjects with low tetraplegia (C4-C7) (Gutierrez et al. 2003).

Onders et al. (2010) evaluated diaphragm pacing (DP) as a weaning method in 20 subjects who also had cardiac pacemakers, and found no immediate or long-term device-to-device interactions. All patients could go >4 hours without mechanical ventilators, and 71% could go 24 hours continuously with DP.

Wong et al. (2012) retrospectively analyzed the charts of 24 individuals with high cervical SCI (C1-C4) who underwent high tidal volume ventilation (HVtV) treatment, high frequency percussive ventilation (HFPV) treatment and/or and mechanical insufflation-exsufflation (MIE) treatment in a specialized SCI treatment unit. All patients showed improvements in their respiratory status with implementation of these treatments. Overall, 14 patients were successfully weaned from their ventilators. Prospective studies on weaning protocols are required to determine the best way to assess, treat and wean subjects requiring mechanical ventilation following SCI.

Mechanical insufflation-exsufflation (e.g., using a “Cough Assist machine”) is a therapy in which the device gradually inflates the lungs (insufflation), followed by an immediate and abrupt change to negative pressure, which produces a rapid exhalation (exsufflation), which simulates a cough, and helps to clear secretions.

Conclusion

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 4 evidence (from 2 retrospective case series: Kornblith et al. 2013; Romero-Ganuza et al. 2015) that though many people with SCI will required Mechanical Ventilation (MV) they can be successfully weaned from it.

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