CHEST Guidelines-Response

Response_chest

Pdf Summary

In a letter to the editor published in CHEST, Dr. Michael Rodgers critiques a statement made by Dr. Paul Marik regarding septic shock in a recent article. Dr. Marik suggested that an increase in cardiac output accompanied by vasodilation and a drop in systemic vascular resistance (SVR) is observable in fluid responders. Dr. Rodgers argues against the utility of SVR, asserting that its decrease is a result of mathematical coupling rather than a true indication of vasodilation. He claims SVR is derived from Ohm’s law and lacks relevance in clinical settings. Rodgers contends that SVR’s use can lead to hazardous errors in treating patients since it does not reliably indicate vasodilation.<br /><br />In response, Dr. Marik acknowledges Dr. Rodgers’s caution regarding calculated variables but defends SVR’s theoretical value in contextualizing patient responses to interventions, particularly when observing cardiac output changes relative to mean arterial pressure. He references studies, including those by Pierrakos et al. and Monnet et al., where decreases in SVR were noted in fluid responders, reflecting vasodilation, while the phenomenon did not occur in non-responders. These studies indicate that fluid loading might adversely affect both responders and non-responders. Dr. Marik ultimately rejects the notion of discarding the concept of SVR, emphasizing its interpretive utility in clinical scenarios.<br /><br />Both physicians emphasize the need for careful consideration in applying hemodynamic measurements, highlighting the ongoing debate on the role of SVR in critical care. While Dr. Rodgers calls for a cessation of SVR’s clinical use, Dr. Marik supports its thoughtful application, backed by evidence of its relevance in specific clinical contexts.

Keywords

septic shock

systemic vascular resistance

SVR

cardiac output

vasodilation

fluid responders

hemodynamic measurements

clinical relevance

critical care

Ohm's law