Table 1.

Main characteristics of protocols for assessment of dynamic CA. Note that this list is not exhaustive, and that the use of the method in the literature (* rating) is based on subjective assessment by the authors (given the complexity of the methods and combinations used).

Method	Principle	Subject cooperation required?	Test duration (min)	Main limitations	Literaturea	Key references
Spontaneous fluctuations	Rest	N	5	Reduced BP variability	*****	10,44
Thigh cuff release	Bilateral leg compression	N	1	Discomfort (pain), SA, SM	***
Head up tilt	Induced hypotension	N	5	Equipment costs, SM	**
Fixed breathing	6 breaths/min	Y	5	Hypocapnia	**
Sit-to-stand	Repeated manoeuvre	Y	5	Exercise	**	83
Squat-to-stand	Repeated at 0.05 or 0.10 Hz	Y	5	Exercise	**
Hand grip	3 min submaximal exercise	Y	5	SA, exercise, hyperventilation	**	84
Leg raising	Repeated passive movement	N	5	Exercise (when performed by subject)	*
Valsalva manoeuvre	Forced expiration	Y	1	ANS activation, intrathoracic pressure rise, SM	*
Carotid artery compression	Finger compression for 5 s	N	1	Carotid artery disease, SM	*
Random repetitive thigh cuff compression	Multiple inflation/deflation for 5 min	N	5	Equipment costs, SA	*	82
Rapid head elevation	Repeated 0° – 30° - 0° head position 4x in 60 s	N	5	Light discomfort	*
Cold pressor test	Hand in ice water	N	1	Pain, SA, SM	*	84
Lower body negative pressure	Pressure reduction by suction from waist down	N	5	Discomfort, SA	*	84,85

SA: sympathetic activation; SM: single measurement; ANS: autonomic nervous system.

^aApproximate relative number of references found in the literature, subjectively estimated by the authors, based on their experience of the literature ¹⁶ . For spontaneous fluctuations (*****) this number is of the order of 300–500 studies.