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Blood Pooling Prevention in Management of OH in SCI

The application of external counter pressure through devices such as abdominal binders or pressure stockings is thought to decrease capacitance of the vasculature beds in the legs and abdominal cavity, both major areas of blood pooling during seating or standing.

Table 6: External Pressure Interventions for Management of OH in SCI

Author Year; Country
Score
Research Design
Total Sample Size
MethodsOutcome
Wadsworth et al. 2012;

Australia

PEDro=4

RCT

N=14

 

Population: 14 adults with recent complete SCI (C3-T1; mean (SD) age: 32(16), range 18-73.

Treatment: Abdominal binder (AB) on/off while seated in an upright wheelchair, with three repeated measures at 6 weeks, 3 months, 6 months after commencing daily use of an upright wheelchair.

Outcome measures: Forced vital capacity, forced expiratory volume, peak expiratory flow, max inspiratory and expiratory pressures, mean arterial pressure (MAP), max sustained vowel time, sound pressure level.

1.     No statistically significant improvement in mean arterial pressure (MAP) with use of the abdominal binder.

2.     Variable responses: MAP greater with the AB at the 1st and 3rd time points; MAP was less with the AB at the 2nd time point.

3.     Measures of supine and seated blood pressure were taken (allowing diagnosis of OH) but this was not a key outcome. 7 occasions of OH found across subjects as indicated by systolic blood pressure changes; 4 had OH regardless of AB application and 3 had OH without the AB only.

Hopman et al. 1998a; The Netherlands

PEDro=5

RCT

N=9

Population: 9 males, 5 with tetraplegia, 4 with paraplegia; 8 complete, 1 incomplete.

Treatment: 5 discontinuous submaximal arm ergometer exercise tests on different days at 20, 40 and 60% of maximum power output while: 1) sitting, 2) supine, 3) sitting plus an anti-G suit, 4) sitting plus stockings and abdominal binder, and 5) sitting plus FES of the leg muscles.

Outcome measures: Oxygen uptake (VO2), carbon dioxide output, respiratory parameters, HR, BP, stroke volume, cardiac output.

1.    Both FES and anti-G suit increased BP in subjects with tetraplegia whereas binders and stockings reduced HR in those with tetraplegia

2.    The interventions did not improve BP responses in subjects with paraplegia however FES and anti-G suit lowered HR.

Hopman et al. 1998b; USA

PEDro=4

RCT

N=9

Population: same subjects as above study.

Treatment: 5 conditions as above except at maximal power output.

Outcome Measures: VO2, carbon dioxide output, respiratory parameters, HR, BP, stroke volume, cardiac output.

1.    The supine posture increased peak VO2 in subjects with tetraplegia, but reduced HR in subjects with paraplegia compared to sitting.

2.    The relatively low pressure generated by stockings and bindings did not improve the venous system or cardiovascular responses during exercise. The positive circulatory benefits from FES and the anti-G suite observed in submaximal exercise (Hopman et al. 1998a) was not found for maximal exercise.

Helmi et al. 2013;

The Netherlands

Case report

N=1

Population: 61-year-old male with C3/C4 traumatic SCI with symptoms of presyncope as a result of severe OH after 60° head-up tilt.

Treatment: inflatable external leg compression (ELC); minimal ELC pressure to prevent OH (15 mmHg) found via tolerability test then applied in different positions (supine, 45°, and 60° head-up tilt).

Outcome measures: external leg compression (ELC) pressure, mean arterial pressure (MAP), cardiac index, stroke volume index, heart rate, perfusion index (PI), peripheral tissue oxygen saturation (StO).

1.   A 28% decrease in MAP when pressure decreased to 7 mmHg, below this level, dizziness rapidly occurred.

2.   With the application of ELC 15 mmHg pressure during 45° and 60° head-up tilt:

a. stroke volume index and heart rate were maintained with no presyncopal symptoms.

b. global and peripheral perfusion parameters improved.

Rimaud et al. 2012; France

Pre-post

N=9

 

Population: 9 SCI men (8 were highly-trained athletes who competed regularly at the national or international level); Level of lesion: >T6 (n=4), <T6 (n=5); age in yrs: 34±12 years; range 24-53; duration of injury: 10±10 years; range 2-34.

Treatment: Two maximal wheelchair exercise tests with and without graduated compression stockings (GCS).

Outcome measures: Heart rate variability (HRV): high frequency (HF), low frequency (LF), and LF/HF ratio; Norepinephrine (NOR) and epinephrine (EPI); BP, heart rate, max power output, oxygen uptake, stroke volume, cardiac output.

1.     Increase in sympathetic activity and decrease in parasympathetic activity after maximal exercise in subjects when wearing GCS as shown by the increase in LF and decrease in HF components; results further supported by an enhanced sympathetic activity at rest in SCI, as demonstrated by a significant increase in noradrenergic response when wearing GCS.

2.     When wearing GCS: LF increased significantly and HFpost decreased significantly leading to an enhanced LF/HF ratio  and a significant increase in resting NOR.

Rimaud et al. 2008;

France

Pre-post

N=9

Population: 9 men with chronic traumatic SCI, were divided into 2 groups: high paraplegia with lesion levels between T4 and T6 (n = 4), and low paraplegia with lesion levels between T10 and L1 (n = 5)

Treatment: 2 plethysmography tests: with and without graduated compression knee-length stockings (GCS) at rest.

Outcome Measures: venous capacitance (VC); venous outflow (VO); heart rate; blood pressure.

1.    No significant difference in HR or BP for either group or either treatment.

2.    In both groups, VC values were lower with GCS than without.

3.    VC and VO did not differ significantly with or without GCS.

Krassioukov & Harkema 2006;

Canada

Prospective controlled trial

N=20

Population: 6 subjects with complete tetraplegia; 5 with complete paraplegia; AIS A; 9 able-bodied controls.

Treatment: With and without harness for locomotor training during supine, sitting and standing (within subject analysis).

Outcomes measures: BP and HR.

1.     Orthostatic stress significantly decreased arterial BP only in individuals with cervical SCI.

2.     Harness application had no effect on cardiovascular parameters in able-bodied individuals, whereas diastolic BP was significantly increased in those with SCI.

3.     Orthostatic changes in cervical SCI when sitting were ameliorated by harness application. However, while standing with harness, individuals with cervical SCI still developed OH.

Kerk et al. 1995;

USA

Prospective controlled trial

N=6

Population: Chronic complete paraplegia.

Treatment: Crossover design: with and without an abdominal binder.

Outcome Measures: BP, HR, VO2max, respiratory parameters, and wheelchair propulsion.

1.     5/6 subjects demonstrated a mean increase of 31% in forced vital capacity with binder compared to without, which was not significant but this may be because the sixth subject showed an 18% decrease in forced vital capacity when wearing the binder.

2.     BP, HR, VO2max increased significantly with increased exercise intensity and during maximal exercise, but these variables were not significantly affected by the use of the binder.

Discussion

The studies examining external pressure interventions generally test different pressure conditions with the same group of individuals (e.g. with and without stockings) either in a randomized order (RCT) (Wadsworth et al. 2012; Hopman et al. 1998a,b) or assigned order (non-RCT) (Helmi et al. 2013; Rimaud et al. 2012, 2008; Krassioukov & Harkema 2006; Kerk et al. 1995).

The application of these interventions must be interpreted with caution, as none of these studies assessed more than the effect of pressure application during acute phase. Whether these effects would persist with chronic use or cause any detrimental effects upon removal after extended use is unknown. Rimaud et al. (2008), after observing a decrease in venous capacitance, suggested that graduated compression stockings worn by individuals with paraplegia may prevent blood pooling in the legs. However, these effects were observed when the subjects were at rest and in the absence of orthostatic stress. Rimaud et al. (2012) found that with the graduated compression stockings, sympathetic activity increased and parasympathetic activity decreased after maximal exercise in men with SCI. Kerk et al. (1995) reported that application of an abdominal binder did not significantly improve cardiovascular or kinematic variables at submaximal or maximal levels of exercise. A single RCT (n=14) by Wadsworth et al. (2012) found that abdominal binders did not significantly affect mean arterial pressure. In his review, Bhambhani (2002) concluded that the use of abdominal binders does not influence cardiovascular responses. Conversely, in another RCT (Hopman et al. 1998b), demonstrated in a small group of subjects with SCI (n=9) that stockings and an abdominal binder have an effect on cardiovascular responses during submaximal exercises, but not during maximal exercises (Hopman et al. 1998a). Krassioukov & Harkema (2006) found that the use of a harness (which applies abdominal pressure) during locomotor training increased diastolic BP in those with SCI, but not in able-bodied individuals. Therefore, there is level 2 evidence (from 1 RCT) that pressure from elastic stocking and abdominal binders may improve cardiovascular responses during submaximal, but not maximal, arm exercise.

Conclusion

There is conflicting evidence based on limited research that elastic stockings/abdominal binders have any effect on cardiovascular responses in individuals with SCI.

There is level 2 evidence (Krassioukov & Harkema 2006) that application of a harness in individuals with SCI could alter baseline cardiovascular parameters and orthostatic responses.

There is insufficient evidence that elastic stockings or abdominal binders have any effect on cardiovascular responses to orthostasis in SCI.