From the Guidelines
Catecholamines are the primary factors that affect capillary refilling in shock, as they cause peripheral vasoconstriction, redirecting blood flow from peripheral tissues to vital organs. During shock, the body releases catecholamines like epinephrine and norepinephrine as part of the sympathetic nervous system response. These hormones constrict peripheral blood vessels, including capillaries, leading to decreased blood flow to the skin and extremities, resulting in delayed capillary refill time, which is a clinical sign used to assess perfusion status in shock patients 1.
Some key points to consider:
- The use of vasopressors, such as norepinephrine, can improve microcirculatory perfusion in severely hypotensive septic shock patients, but the optimal mean arterial pressure (MAP) and dose of vasoactive drug for optimal microcirculatory perfusion are variable and should be tailored to individuals 1.
- Norepinephrine is recommended as the first-line vasopressor agent to maintain adequate organ perfusion pressure in patients with septic shock, with a target MAP of 65 mm Hg 2.
- The effects of other vasoactive agents, such as dobutamine, levosimendan, and phosphodiesterase III inhibitors, on microcirculation are still uncertain, with beneficial effects in experimental models and scarce data in humans 1.
- Vasopressin has been shown to increase MAP, systemic vascular resistance (SVR), and urine output in patients with vasodilatory septic shock and hyporesponsiveness to catecholamines, but its clinical role is not as well defined 3.
In clinical practice, the primary goal is to restore adequate organ perfusion and prevent organ dysfunction, and catecholamines, particularly norepinephrine, are the primary agents used to achieve this goal. While other factors, such as baroreceptors, chemoreceptors, and aldosterone, play roles in the body's response to shock, they do not directly affect capillary refilling in the same immediate way that catecholamines do. Therefore, the correct answer is a. Catecholamines, as they have the most direct and significant impact on capillary refilling in shock patients 1, 2, 3.
From the Research
Factors Affecting Capillary Refilling in Shock
- Catecholamines: These are known to affect capillary refilling in shock, as they are used to treat shock and have an impact on blood pressure and oxygen supply to peripheral tissues 4, 5.
- Baroreceptors: There is no direct evidence in the provided studies to suggest that baroreceptors affect capillary refilling in shock.
- Chemoreceptors: There is no direct evidence in the provided studies to suggest that chemoreceptors affect capillary refilling in shock.
- Aldosterone: There is no direct evidence in the provided studies to suggest that aldosterone affects capillary refilling in shock.
Relationship Between Catecholamines and Capillary Refilling
- The use of catecholamines, such as epinephrine, norepinephrine, and dopamine, can impact capillary refilling in shock patients 5.
- A study found that capillary refill time was significantly higher in nonsurvivors or patients needing VA-ECMO support, suggesting a relationship between capillary refilling and shock outcomes 6.
- The addition of vasopressin to catecholamine vasopressors was associated with a lower risk of atrial fibrillation, which may indirectly affect capillary refilling 7.