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Three Part Question

In [individuals who suffer from orthostatic hypotension], does [leg-crossing] prevent [transient loss of consciousness or syncope]?

Clinical Scenario

A 70-year-old man encountered several episodes of hypotension when standing after bending over to tie his shoes. Last time, he lost consciousness transiently. He asks you for an easy way to prevent passing out, as he lives alone. You once heard about the effect of leg crossing and you wonder if leg crossing actually prevents syncope caused by orthostatic hypotension.

Search Strategy

1. The Cochrane library - including the Cochrane Central Register of Controlled Trials (CENTRAL) - from date of inception to end of August 2012 using the Wiley interface: (MeSH descriptor Syncope explode all trees OR MeSH descriptor Hypotension, Orthostatic explode all trees OR fainting) AND leg
2. MEDLINE from date of inception to end of August 2012 via Pubmed interface: (\"Hypotension, Orthostatic\"[Mesh] OR “syncope”[Mesh]) AND leg AND cross*
3. EMBASE from date of inception to end of August 2012 via Embase.com interface: (‘syncope’/exp OR ‘orthostatic hypotension’/exp) AND leg AND cross*

Search Outcome

1. The Cochrane library: 34 Cochrane reviews and 0 clinical trials were found. None of them were relevant to the clinical question.
2. MEDLINE: 35 studies were found, 9 of which were relevant to the clinical question.
3. EMBASE: 69 studies were found, no additional paper was selected.

In total, 9 papers were retained and summarised in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Krediet et al, 2006, The Netherlands	9 healthy subjects (median age: 25 yr [range: 20 - 41]) subjected to the induction of presyncope via head-up tilting with incremental lower body negative pressure	Randomised crossover trial with comparison a) leg crossing without muscle tension vs. b) standing (level of evidence: 2b)	Orthostatic tolerance	34 ± 2 min vs. 26 ± 2 min (P < 0.001) (Mean ± SEM)	Small and young study population; mode of randomisation is not described (unclear randomisation)
			Blood pressure	Systolic: 81 ± 4 mm Hg vs. 72 ± 7 mm Hg (NS) (mean ± SEM); Diastolic: 55 ± 2 mm Hg vs. 48 ± 5 mm Hg (NS) (mean ± SEM)
			Heart rate	116 ± 7 beats/min vs. 107 ± 10 beats/min (P = 0.001) (mean ± SEM)
van Dijk et al, 2005, The Netherlands	88 patients with vasovagal syncope (median age 38.5 yr [range: 16 - 85])	Within subjects design with comparison a) leg crossing with muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Systolic: 130.9 ± 16.9 mm Hg vs. 125.3 ± 16.1 mm Hg (P < 0.001) (mean ± SD); Diastolic: 75.0 ± 10.7 mm Hg vs.73.8 ± 10.3 mm Hg (P < 0.01) (mean ± SD)	Young study population; patients diagnosed for vasovagal syncope; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
			Heart rate	82.2 ± 14.9 beats/min vs. 82.8 ± 15.3 beats/min (NS) (mean ± SD)
Krediet et al, 2002, The Netherlands	21 patients with vasovagal syncope (mean age 41 yr [Range: 17 – 74])	Within subjects design with comparison a) leg crossing with muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Systolic: 106 ± 16 mm Hg vs. 65 ± 13 mm Hg (P < 0.001) (mean ± SD); Diastolic: 65 ± 10 mm Hg vs. 43 ± 9 mm Hg (P < 0.001) (mean ± SD)	Small and young study population; patients diagnosed for vasovagal syncope; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
			Heart rate	82 ± 15 beats/min vs. 73 ± 22 beats/min (P < 0.01) (mean ± SD)
Groothuis et al, 2007, The Netherlands	13 healthy subjects (age 23.6 yr ± 1.0) (mean ± SEM)	Within subjects design with comparison a) leg crossing with muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Mean arterial pressure: 102.5 ± 3.4 vs. 89.3 ± 2.5 (P < 0.05) (mean ± SEM)	Small and young study population; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
			Heart rate	86.4 ± 3.3 beats/min vs. 91.8 ± 3.2 beats/min (P < 0.05) (mean ± SEM)
Ten Harkel et al, 1994, The Netherlands	13 subjects in total: 5 patients with orthostatic hypotension (age 45 yr [range 20 - 65]) and 8 healthy subjects (age 30 yr [range 28 - 34])	Within subjects design with comparison a) leg crossing without muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Systolic: increase with 18 ± 18 mm Hg in patients with orthostatic hypotension (P < 0.05) and increase with 4 ± 7 mm Hg in healthy subjects (NS); Diastolic: increase with 10 ± 11 mm Hg in patients with orthostatic hypotension (P < 0.05) and increase with 0 ± 3 mm Hg in healthy subjects (NS)	Small and young study population; indirect outcome (cardiovascular responses instead of orthostatic tolerance); possible carry-over effect since 2 counter-pressure manoeuvres (tiptoeing and leg crossing) were performed in random order with 1 minute of quiet standing in between)
			Heart rate	Decrease of 4 ± 5 beats/min in patients with orthostatic hypotension (NS) and decrease with 6 ± 4 beats/min in healthy subjects (P < 0.05)
Harms et al, 2010, The Netherlands	16 subjects in total: 8 patients with sympathetic failure (age range 37 – 67 yr) and 8 healthy subjects (age-matched)	Within subjects design with comparison a) leg crossing without muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Mean arterial pressure: 72 mm Hg [52 ; 89] vs. 58 mm Hg [42 ; 79] in patients with orthostatic hypotension (P < 0.05) and 90 mm Hg [74 ; 94] vs. 84 mm Hg [70 ; 95] in healthy subjects (NS) (Median [range])	Small and young study population; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
			Heart rate	75 beats/min [59 ; 92] vs. 75 beats/min [64 ; 97] in patients with orthostatic hypotension (NS); 71 beats/min [58 ; 79] vs. 74 beats/min [72 ; 86] in healthy subjects (NS) (Median [range])
van Lieshout et al, 1992, The Netherlands	13 subjects in total: 7 patients with orthostatic hypotension (age range 18-65) and 6 healthy subjects (age range 28 -34 yr)	Within subjects design with comparison a) leg crossing without muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Systolic: 95 ± 13 mm Hg vs. 75 ± 13 mm Hg in patients with orthostatic hypotension (P = 0.006) and 120 ± 7 mm Hg vs. 116 ± 15 mm Hg in healthy controls (P = 0.55) (mean ± SD); Diastolic: 60 ± 7 mm Hg vs. 50 ± 7 mm Hg in patients with orthostatic hypotension (P = 0.01) and 71 ± 3 mm Hg vs. 71 ± 8 mm Hg in healthy controls (P = 0.56) (mean ± SD)	Small and young study population; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
Bouvette et al, 1996, USA	9 patients with orthostatic hypotension (age range 58 ± 18 yr) (mean ± SD)	Within subjects design with comparison a) leg crossing with muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Systolic: increase with 24.8 ± 19.0 mm Hg (P = 0.001) (mean ± SD)	Small and young study population; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
Kim et al, 2005, Korea	48 subjects in total: 27 patients with vasovagal syncope (age 44.5 ± 15.3 yr) and 21 healthy subjects (age 28.6 ± 6.3 yr) (mean ± SD)	Within subjects design with comparison a) leg crossing with muscle tension vs. b) standing (level of evidence: 2b)	Blood pressure	Net change of systolic: 8.0 ± 5.8 mmHg for patients with vasovagal syncope (P < 0.05) and 8.7 ± 5.7 mmHg for healthy subjects (P < 0.05) (mean ± SD); Net change of diastolic: 1.6 ± 4.8 mmHg for patients with vasovagal syncope (NS) and 1.1 ± 4.9 mmHg for healthy subjects (NS) (mean ± SD)	Small and young study population; no clear description of body posture of study population when measuring baseline measurement; indirect outcome (cardiovascular responses instead of orthostatic tolerance)
			Heart rate	Change with 5.7 ± 10.5 beats/min for patients with vasovagal syncope (NS) and 3.7 ± 5.3 for healthy subjects (P <0.05) (mean ± SD)

Comment(s)

Syncope is usually of rapid onset, short duration and spontaneous complete recovery. Although squatting might be beneficial to prevent syncope, it is may not be suitable for old people. In contrast, leg crossing is easy to perform.

Clinical Bottom Line

Leg crossing is a simple manoeuvre that has clinical benefit for people who experience orthostatic hypotension.

Level of Evidence

Level 2 - Studies considered were neither 1 or 3.

References

1. Krediet CT, van Lieshout JJ, Bogert LW et al. Leg crossing improves orthostatic tolerance in healthy subjects: a placebo-controlled crossover study. Am J Physiol Heart Circ Physiol 2006 Oct;291(4):H1768-H1772.
2. van Dijk N, de Bruin IG, Gisolf J et al. Hemodynamic effects of leg crossing and skeletal muscle tensing during free standing in patients with vasovagal syncope. J Appl Physiol 2005 Feb;98(2):584-90.
3. Krediet CT, van DN, Linzer M et al. Management of vasovagal syncope: controlling or aborting faints by leg crossing and muscle tensing. Circulation 2002 Sep 24;106(13):1684-9.
4. Groothuis JT, van DN, Ter WW et al. Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances leg blood flow. Clin Sci (Lond) 2007 Feb;112(3):193-201.
5. Ten Harkel AD, van Lieshout JJ, Wieling W. Effects of leg muscle pumping and tensing on orthostatic arterial pressure: a study in normal subjects and patients with autonomic failure. Clin Sci (Lond) 1994 Nov;87(5):553-8.
6. Harms MP, Wieling W, Colier WN et al. Central and cerebrovascular effects of leg crossing in humans with sympathetic failure. Clin Sci (Lond) 2010 May;118(9):573-81.
7. van Lieshout JJ, Ten Harkel AD, Wieling W. Physical manoeuvres for combating orthostatic dizziness in autonomic failure. Lancet 1992 Apr 11;339(8798):897-8.
8. Bouvette CM, McPhee BR, Opfer-Gehrking TL et al. Role of physical countermaneuvers in the management of orthostatic hypotension: efficacy and biofeedback augmentation. Mayo Clin Proc 1996 Sep;71(9):847-53.
9. Kim KH, Cho JG, Lee KO et al. Usefulness of physical maneuvers for prevention of vasovagal syncope. Circ J 2005 Sep;69(9):1084-8.