|Year : 2021 | Volume
| Issue : 3 | Page : 131-140
Mechanical ventilation and weaning practices for adults with spinal cord injury - An international survey
Radha Korupolu1, Argyrios Stampas1, Isaac Hernandez Jimenez1, Darby Cruz2, Melina Longoni Di Giusto3, Monica Verduzco-Gutierrez4, Matthew E Davis1
1 Department of Physical Medicine and Rehabilitation, McGovern Medical School, The University of Texas, Health Science Center at Houston; The Institute of Rehabilitation and Research Memorial Hermann, Houston, TX, USA
2 The Institute of Rehabilitation and Research Memorial Hermann, Houston, TX, USA
3 Disability Department of Ituzaingó Municipality Buenos Aires, ReDel Rehabilitation Center, Buenos Aires, Argentina
4 Department of Rehabilitation Medicine, Long School of Medicine, The University of Texas Health Science Center at San Antonio, TX, USA
|Date of Submission||16-Dec-2020|
|Date of Decision||18-Feb-2021|
|Date of Acceptance||03-Mar-2021|
|Date of Web Publication||15-Jun-2021|
Assoc. Prof. Radha Korupolu
Department of Physical Medicine and Rehabilitation, McGovern Medical School, The University of Texas, Health Science Center at Houston, TX 77030
Source of Support: None, Conflict of Interest: None
Objective: There is heterogeneity in the management of spinal cord injury (SCI) patients requiring mechanical ventilation (MV). This survey's objective was to study the current practices of ventilator management and weaning in adults with SCI. Methods: We conducted a cross-sectional, self-administered global electronic survey of providers caring for adults with SCI on MV. Recruitment was accomplished through direct E-mailing, social media posting and sharing amongst qualifying providers. Respondents were divided into acute care (AC) and rehabilitation (rehab) groups based on their work setting and specialty. Results: Overall, 137 respondents with a majority from North America (50%) were included. Assist Control mode was the most frequently reported mode (33%) in AC and the rehabilitation setting (RS). Most (72%) in AC use predicted body weight (PBW) to determine the tidal volume (VT); it varies widely in the RS. The highest VT (median [interquartile range]) reported by AC was 10 (8–10) cc/kg pbw compared to 13 (10–15) cc/kg pbw (P = 0.001) in the RS. Application of positive end-expiratory pressure and keeping the tracheostomy cuff inflated are commonly reported practices in AC, whereas there is inconsistency with these practices in the RS. Regarding factors to initiate weaning, physicians in the AC mostly relied on arterial blood gas (70%) findings, whereas in the RS, physicians relied on vital capacity (73%). Conclusion: We found significant differences in practices between “AC and RS” and “within RS,” which warrants further investigation of optimal ventilator settings and weaning practices for people with SCI.
Keywords: Mechanical, mechanical ventilation, spinal cord injuries, ventilator weaning
|How to cite this article:|
Korupolu R, Stampas A, Jimenez IH, Cruz D, Di Giusto ML, Verduzco-Gutierrez M, Davis ME. Mechanical ventilation and weaning practices for adults with spinal cord injury - An international survey. J Int Soc Phys Rehabil Med 2021;4:131-40
|How to cite this URL:|
Korupolu R, Stampas A, Jimenez IH, Cruz D, Di Giusto ML, Verduzco-Gutierrez M, Davis ME. Mechanical ventilation and weaning practices for adults with spinal cord injury - An international survey. J Int Soc Phys Rehabil Med [serial online] 2021 [cited 2021 Oct 24];4:131-40. Available from: https://www.jisprm.org/text.asp?2021/4/3/131/318501
| Introduction|| |
The annual incidence of traumatic spinal cord injury (SCI) worldwide was estimated as 768,473 new cases with a 95% confidence interval (CI) of 597,000–939,732 new cases; cervical lesions resulting in complete or incomplete tetraplegia account for 46% of new cases. Respiratory complications such as pneumonia and respiratory failure requiring mechanical ventilation (MV) are the leading cause of morbidity and mortality following SCI.,,,,,,,,, Although respiratory complications requiring MV are most common with a neurological level above C5 (84%–95% incidence), they occur in 60% or more of patients with lower injury levels at some point during acute care (AC) or rehabilitation., Moreover, 19.7% of persons with tetraplegia and 5.4% of those with paraplegia were dependent on MV at the time of admission to a rehabilitation unit. Optimal ventilator settings have decreased morbidity and mortality in people who require MV support for various pathologies.,,,, Review of the current literature suggests a significant practice variation in the management of mechanical ventilator settings for patients with acute SCI. In a recently published cohort study conducted in an Intensive Care Unit setting, people with acute SCI received tidal volumes (VT) ranging from the median (interquartile range) 7.6 cc/kg predicted body weight (PBW) (6.6–8.6) in the low VT group to 10.8 cc/kg (10.2–11.3) PBW in the high VT group. In a cohort study set in an acute rehabilitation unit, VT of 10 cc/kg PBW and 20 cc/kg PBW with positive end-expiratory pressure (PEEP) were used in adults with acute SCI, along with a 14-day progressive ventilator weaning protocol. In another study performed at a different acute inpatient rehabilitation facility, people with SCI on MV received VTs ranging from 8.4 cc/kg IBW to 20 cc/kg IBW without PEEP, using a 20-day progressive weaning protocol. Though differences in protocols are apparent; a similarity is that outcomes differed based on high versus low VT ventilation. The true extent of practice variation in managing ventilator settings and weaning strategies for adults with SCI is unknown. While some can be justified based on disease severity and associated risk factors, unwarranted variation can lead to sub-optimal outcomes and increased care costs.,, Despite the wide use of MV in people with SCI, limited information exists regarding the optimal ventilator modes, the criteria that clinicians use to initiate weaning, secretion management strategies, and the approach used to wean patients with SCI from a ventilator. To address this problem, we conducted a self-administered electronic survey to explore the extent of ventilator management variations when caring for patients with SCI based on a similar approach taken by Burns et al.,
| Methods|| |
Study design and study population
We conducted a global, self-administered cross-sectional electronic survey of physicians who provide care for adult SCI patients that require MV to characterize management and practice variation. This study was classified as exempt by the institutional review board at the University of Texas Health Science Center at Houston.
Survey questionnaire development
We created survey questions in English and Spanish using The University of Texas Health Science Center secure Qualtrics software. Our authors developed a Spanish version with native/bilingual proficiency (IHJ and MLG). We developed 18 questions in the following five areas: (A) The preferred modes of ventilation, (B) The preferred ventilator settings (VT, PEEP), (C) Secretion management, (D) The criteria for initiating weaning and (E) The use of written protocols for weaning [Survey Questionnaire Provided in Supplement]. Additionally, we also inquired about factors important to physicians when considering caring for patients with SCI while on MV. Questions were revised and tested by our focus group consisting of 4 U. S. board-certified SCI physicians (RK, AS, IH, and MD) and one respiratory therapist (DC) with over 20 years of experience in managing and weaning mechanically ventilated patients with SCI. Questions inquired about the practices of individual respondents. We formatted the questions to provide a range of responses exploring weaning practices using nominal, interval, and ordinal responses within domains. We used ordinal response formats (Never, Sometimes, and Most of the time) to reflect the frequency with which tasks were performed, or techniques were used (See Appendix 1).
Recruitment for the survey was accomplished in several ways: (1) Direct E-mail with the survey link to colleagues; (2) Posting on social media groups restricted to physicians (Facebook), and (3) Survey link sent to all international members in the International Society of Physical and Rehabilitation Medicine (ISPRM); (4) Request that physicians would share the survey link with their colleagues that qualify for the survey. Participation was voluntary, and all responses were anonymous.
We presented descriptive statistics as proportions and median (25th, 75th percentile) when data was not normally distributed. We compared proportions using the Chi-square test statistic and continuous data using Wilcoxon rank-sum test. We considered P ≤ 0.05 to represent statistical significance. All data analyses were completed using StataCorp. 2015. Stata Statistical Software: Release 14. College Station, TX: StataCorp LP. We divided responses into two medical settings: AC hospital and Rehabilitation hospital. If a respondent reported their primary work setting as being at an AC hospital and belonged to a non-Physical Medicine and Rehabilitation (PM and R) specialty such as pulmonary medicine, critical care medicine, or any surgical specialty, then data was included in the AC group. All other respondents' data were grouped into the rehabilitation group.
| Results|| |
A total of 200 physicians responded to the survey; however, 63 respondents only provided demographic data and were not included in further analysis. For data reporting, we included 137 respondents who provided data on demographics and answered at least one component of the survey's ventilator management and weaning questionnaire. The majority of the respondents were from North America [Table 1]. The characteristics of respondents are presented in [Table 1].
Preweaning ventilator management
Preweaning ventilator modes
Respondents reported using assist control mode most of the time (33%) both in AC (45%) and a rehabilitation setting (RS) (30%), and SB-PS was reported as the 2nd most commonly [Figure 1] used mode (most of the time) before initiating weaning. Respondents reported SB-PS mode (42%) as a frequently used alternative (sometimes) before weaning, followed by VC-AC (35%) and VC-SIMV (33%). Half of the respondents (50%) reported that they never use pressure control modes for people with SCI before initiating weaning. Other infrequently used ventilator modes include Airway pressure release ventilation mode (n = 3), pressure regulated volume control mode (n = 1), average volume-assured pressure support mode (n = 2), continuous positive airway pressure (n = 1), bilevel positive airway pressure (n = 1), and continuous mandatory ventilation (n = 1).
|Figure 1: Most frequently used ventilator modes for people with spinal cord injury among respondents. SB: Spontaneous breathing; PS: Pressure Support; VC: Volume Control; AC: Assist Control; SIMV: Synchronized Intermittent Mandatory Ventilation; PC: Pressure Control|
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Determination of tidal volume
Approximately 48% of the respondents reported using predicted body weight for determining VT setting when volume control modes are applied [Table 2]. While most physicians (72%) in the AC setting reported using PBW to determine VT setting, there was wide variation in the method of determining VT by physicians in the RS [Table 2]. The physicians in RSs reported using higher VT than in AC [Table 2]. Among respondents who used PBW to determine VT, physicians in the RS reported using higher VTs with median: 13 cc/kg pbw, IQR:(10–15) compared to the AC physicians with median: 10 cc/kg PBW, IQR: (8-10) P = 0.001. Similarly, among those that use current body weight, rehabilitation physicians reported higher VT than AC physicians, although this did not achieve significance [Table 2]. We further evaluated the highest VT reported in cc or ml without considering body weight after dividing data into two quantiles [Table 2]. We noted 60% of physicians in the RS reported utilizing VT ≥806 cc compared to only 26% of AC physicians (P = 0.007).
Tracheostomy cuff and positive end-expiratory pressure
There was a significant difference in tracheostomy and PEEP practices between the two settings. Approximately 29 respondents from the AC setting and 98 from the RSs answered questions about tracheostomy and PEEP [Figure 2]. Among AC respondents, the majority reported keeping the tracheostomy cuff inflated (86%) most of the time compared to only 46% in the RS (P = 0.001). Similarly, most respondents in the AC setting (86%) reported using PEEP compared to only 54% in the RS (P = 0.019). Furthermore, in the RS, 46% reported keeping the tracheostomy cuff inflated sometimes, and 34% reported using PEEP sometimes, suggesting further practice variation among physicians working in the RS.
|Figure 2: Tracheostomy cuff and positive end expiratory pressure practices in spinal cord injury. *(Frequencies were reported for “most of the time” variable)|
Click here to view
Factors considered to decide readiness to initiate the weaning process
Among 137 respondents, only 116 (85%) clinicians answered factors considered to decide readiness to initiate weaning. The majority of respondents considered chest X-ray findings (65%), suction frequency (65%), vital capacity (60%), and arterial blood gas (ABG) analysis (60%) in assessing readiness for weaning [Table 3].
|Table 3: Important variables when considering weaning and secretion management|
Click here to view
There were significant practice variations to initiate MV weaning based on practice setting. In the AC setting, ABG (70%), negative inspiratory force (57%), and suction frequency (57%) were the most frequently reported factors used to assess readiness to initiate weaning. Quite differently, respondents from the RS frequently considered vital capacity (73%), chest X-ray findings (70%), and suction frequency (67%) to assess readiness for weaning. Other infrequently considered factors not reported in [Table 2] include the maximal fractional concentration of oxygen, and alertness/cognition.
Change in ventilator mode
Among 118 respondents, 33% reported “yes” to switching ventilator modes during the weaning process; 44% in the AC setting and 30% in the RS. Thirty-four applicable respondents provided details on the type of frequently switched ventilator modes. Overall, 21 (62%) reported switching to spontaneous breathing trial with PS most of the time. Alternative modes used sometimes were reported as VC-AC 10 (29%) and 10 (29%) VC-SIMV.
Tracheostomy cuff and PEEP: Among 29 AC respondents, 52% reported keeping the tracheostomy cuff inflated most of the time, and 38% reported sometimes after initiation of weaning.
However, in the RS, among 90 respondents, only 16% reported keeping the cuff inflated most of the time, 51% sometimes, and 28% reported that they never keep the cuff inflated once the weaning process is initiated. Similarly, 66% of the respondents in the AC setting reported using PEEP most of the time after initiation of weaning compared to 27% in the RS [Figure 2]. Only 3% of respondents in the AC setting and 18% in the RS reported that they never use PEEP once weaning is initiated. There was a statistically significant difference in the practice of tracheostomy cuff inflation (P = 0.001) and use of PEEP (P = 0.001) in the AC setting and the RS.
Concerning written guidelines or protocol for MV weaning for patients with SCI, 46 among 116 (40%) respondents acknowledged having written guidelines or a protocol. Among the 46 respondents who reported written guidelines in their facility, 87% had a PM and R background.
In our survey, we asked about methods used for secretion management. Among 137 respondents, 120 of them (AC = 31, Rehabilitation = 89) answered questions related to secretion management [Table 3]. Suctioning (91%) is the most commonly reported method for clearing secretions for people with SCI in both AC (84%) and the RS (93%). Hypertonic saline nebulization (61%) and intermittent positive pressure breathing (55%) are other frequently reported secretion management methods in the AC setting. In the RS, manually assisted cough (84%), manual chest percussion (73%), mechanical insufflator-exsufflator (MIE) (71%), and hypertonic saline nebulization (61%) are other frequently used methods for secretion management besides suctioning. Besides the methods listed in [Table 3], sodium bicarbonate nebulization, postural drainage, beta 2 agonist inhalation, guaifenesin, and bronchioalveolar lavage were reported as other methods of secretion management.
Factors important to clinicians
We asked respondents to rank five factors (least important to most important ) when caring for a patient with SCI on MV; (a) decreasing morbidity, (b) decreasing time to wean off ventilator, (c) patient ability to speak over the ventilator, (d) decreasing length of stay and (e) decreasing anxiety while on the ventilator. For the purpose of reporting, we combined ranks 4–5 as most important and 1–2 as least important [Figure 3]. The majority (62%) responded that decreasing morbidity was the most important factor. Most of the respondents reported decreasing anxiety (52%) and patient ability to speak over the ventilator (50%) as the least important factor among the five factors. The reporting trend was similar among AC and PM and R physicians except for “patient able to speak over the ventilator.” On the one hand, most AC physicians (64%) reported it as the least important factor (Rank 1); in contrast, only 29% of PM and R physicians reported this as the least important factor.
|Figure 3: Factors important to physicians when caring for people with spinal cord injury on mechanical ventilation. *(we combined rank 4 and 5 in each category to calculate most important and combined 1 and 2 to calculate least important; scale ranges from 5-Most important to 1 as least important)|
Click here to view
| Discussion|| |
We found significant practice variations between “the AC setting and the RS“ and ”within the RS” in the usage of ventilator modes, tracheostomy cuff inflation, use of PEEP, determination, and the dose of VTs, factors considered before evaluation of the readiness of weaning and secretion management. Variation in ventilator modes is likely due to differences in severity and acuity of SCI. The patients with severe complete injury at a higher cervical neurological level would likely require volume control modes (AC or SIMV). In contrast, patients with less severe and incomplete injury might only require a PS mode. Similarly, a higher percentage of people reported using PEEP and keeping the tracheostomy cuff inflated in AC settings, which is likely due to an inability to tolerate cuff deflation and the need for PEEP during the acute phase. However, the difference in PEEP and tracheostomy practices after initiation of weaning is likely due to practice culture and lack of robust research studies to guide weaning protocols in people with SCI.
We noticed a significant discrepancy in the determination of VT methodology in RSs. Despite current recommendations to use PBW for VT calculation, up to 28% of respondents in the RS reported using current body weight to calculate VT for volume control modes. Most importantly, most AC settings reported using lower VT compared to higher VT in the RSs. Current evidence in people without SCI suggests that lower VTs with PEEP decrease morbidity and mortality in people with and without acute respiratory distress syndrome (ARDS).,,,,,,, However, VT data in people with SCI is inconsistent and lacks evidence from large clinical trials.,,,, Larger VTs are recommended in people with SCI in the RS to overcome hypoventilation secondary to weakness of inspiratory muscles for the prevention of atelectasis., However, it is unclear at what VT setting risk outweighs benefits. Besides, we don't know if short term use of higher VTs during MV improves long term outcomes once patients are weaned off the ventilator.
After acute SCI, unopposed parasympathetic activity and an inability to clear secretions due to weakness and paralysis of abdominal muscles pose challenges with secretion management., Poor secretion management can cause mucus plugging, leading to hypoxia, the collapse of distal lungs, dilatation of airways and pneumonia.,,,, For secretion management, multiple modalities are used in the RS for aggressive pulmonary management including suctioning (93%), manually assisted cough (84%), manual chest percussion (73%), and MIE (71%). Use of the MIE was reported by only 26% of the AC respondents. In our experience, it is an effective way of secretion management in people with SCI. Perhaps using MIE in AC settings can improve secretion management and decrease mucus plugging incidence, pneumonia, and atelectasis. The last main difference was seen in reporting the “patient able to speak over ventilator” factor. The majority of the AC physicians (64%) reported it as the least important factor (Rank 1).
In contrast, only 29% reported it as the least important factor in the RS. To allow the patient to speak while on a ventilator requires deflating the tracheostomy cuff. However, it is not clear if using a speaking valve is better for patients versus keeping the tracheostomy cuff inflated during the weaning process for people with SCI.
Our survey had several limitations. It is primarily unclear how many physicians worldwide manage the ventilators in patients with SCI; therefore, extrapolating from this cohort is not possible. We also had limited response from those in the AC setting. Most of our responders were from the United States, with little comparative representation from Asia. Lower response rates from other regions (South America, Australia, and Africa) could be due to lower SCI incidence and fewer centers managing people with SCI in these regions.
The survey was only available in English and Spanish. Qualitative input from respondents could have provided important information on why a particular ventilator mode or setting was preferred over other settings. As most respondents were from the United States, our findings are likely not applicable outside the United States. Nonetheless, this survey accomplished the primary goal of highlighting the variability in MV management for people with SCI.
| Conclusions|| |
Despite the limitations mentioned above, it is clear that there is a need for further research in people with SCI to identify optimal ventilator settings (VT, use of PEEP), tracheostomy practices, optimal secretion management methods, and best weaning practices while considering factors important for these patients while on MV. We can not apply ARDS network guidelines of lower VTs without investigating it in people with SCI due to differences in respiratory failure pathophysiology in people with ARDS and SCI. Similarly, we need a large multi-center randomized control trial to test safety of higher VTs in people with SCI to generate evidence-based guidelines to improve outcomes and minimize practice variation.
We would like to thank our colleagues and friends who helped with this survey's distribution.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| Mechanical Ventilation and Weaning Practices for Adults with Spinal Cord Injury- An International Survey|| |
Start of Block: Demographics
Q1 In which country do you currently practice medicine?
Q2 In which setting do you work? (check all that apply)
□ Acute inpatient rehabilitation facility
□ Long term acute care facility
□ Acute care hospital
□ Other, please specify_______
Q3 Is your hospital affiliated with a university?
Q4 How many years have you been in clinical practice (since completing training)?
□ 0-5 years
□ 6-10 years
□ 11-15 years
□ >15 years
Q5 What specialty certifications do you hold? (Check all that apply)
□ Physical medicine and Rehabilitation
□ Spinal Cord Injury Medicine
□ Internal medicine
□ Pulmonary Medicine
□ Critical Care Medicine
□ Other, Please specify________
End of Block: Demographics
Start of Block: Ventilator management and weaning
Q1 Which modes of ventilation do you use for patients with spinal cord injury? (Please check all that apply)
Abbreviations- PS: Pressure Support; AC: Assist Control; SIMV: Synchronized Intermittent Mandatory Ventilation; PC: Pressure Control, VC: Volume Control
Q2 Do you keep the tracheostomy cuff inflated?
Q3 Do you use positive end expiratory pressure (PEEP)?
Q4 How do you determine tidal volume (Vt) settings for your patients with SCI?
Abbreviations- Vt: Tidal Volume, Kg: Kilo Gram, PBW: Predicted Body Weight
□ Vt based on current body weight (bw) in cc/kg or ml/kg body weight
□ Vt based on predicted body weight (pbw) in cc/kg or ml/kg pbw
□ Vt in cc or ml without consideration of body weight
□ Not applicable/I don't make this decision
□ Other, please specify_______
Q5 Which tidal volume range do you use for volume control modes? (Check all that apply)
Q5 Which tidal volume range do you use for volume control modes? (Check all that apply)
Q6 Which tidal volume range do you use for volume control modes in cc or ml? (Check all that apply)
Q7 What methods do you use for secretion management in patients with spinal cord injury? (Check all that apply)
□ Mechanical Insufflator-Exsufflator
□ Manual Chest percussion
□ Meta-Neb/Intermittent positive pressure breathing
□ Manually assisted cough
□ Intra pulmonary percussive ventilation (IPV)
□ Anti-cholinergic medications (oral or transdermal)
□ Hypertonic saline nebulization
□ N- acetylcysteine nebulization
□ Other, please specify_______
Q8 During the weaning process, do you use a different ventilator mode than the mode used prior to initiation of weaning?
Q9 If yes to above question, Please check all that apply. Abbreviations: PS: Pressure support; AC: Assist control; SIMV: Synchronized intermittent mandatory ventilation; PC: Pressure control, VC: Volume control
Q10 Please indicate what variables YOU typically consider for each of the following to decide readiness to undergo a weaning? (Please check all that apply)
□ Vital capacity (VC) in cc or ml
□ Vital capacity in cc/kg PBW
□ Weaned off PEEP
□ Negative Inspiratory Force
□ Minute ventilation
□ Chest x-ray
□ Chest exam
□ Suction frequency for secretion management
□ Tolerance to Passy muir valve
□ Other Factors: Please specify
Q11 In your facility, do you have a written guideline, protocol or policy for the weaning of mechanical ventilation for patients with Spinal Cord injury?
End of Block: Ventilator management and weaning
Start of Block: Post survey
Q1 Rank which factors are most important to you for people with acute SCI who are on mechanical ventilation (1- least important, 5- most important)
□ Patient able to speak over ventilator
□ Decreasing time to wean off of ventilator
□ Decreasing length of stay
□ Decreasing anxiety
□ Decreasing morbidity
End of Block: Post survey
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]