Cardiovascular chronobiology: implications for critical care nursing

Abstract

Critical care clinicians must consider known expected circadian rhythms when interpreting fluctuations in patients' hemodynamic values. As noted in the case study, knowledge of circadian rhythmicity in cardiovascular variables may help clinicians anticipate hemodynamic changes and develop and evaluate chronobiologically sensitive interventions, including prescriptions for activity, modification of the timing of medications, and provision of protective interventions for patients with disrupted rhythms. Felver provides excellent guidelines for the systematic review of possible causes for overt changes in circadian patterns. This review highlights the need to evaluate (1) the effect of disease progression on temporal patterns, (2) the patient's underlying endogenous rhythms, (3) the zeitgebers that may entrain the patient's biological rhythms (e.g., light, social cues, and sleep-wake cycles), and (4) how the zeitgebers change in a critical care environment. The body of literature on the rhythmic fluctuation of cardiovascular variables in healthy, young subjects is extensive. During the past 10 years, research on the chronobiologic fluctuations of numerous physiological variables (cardiovascular, pulmonary, hematologic, and endocrine) in critical illness has increased. As information on the fluctuations in critically ill patients increases, critical care clinicians will be challenged to develop and evaluate a chronobiologically sensitive plan of care for these patients.

Cardiovascular Chronobiology: Do You Know What Time It Is?

“…If the zeitgebers are altered (e.g., awakening a patient at 4 a.m. for a blood draw), or if age, 95 disease, or a surgical event desynchronizes or blunts these rhythms, the patient may have altered adaptation to stressors 93 . For example, in the elderly, there is uncoupling of the heart rate and blood pressure, which may place these individuals at increased risk for orthostasis, 95 due to an inability to physiologically adapt to the orthostatic stress 91 …”

“…2) Are there external factors that may be contributing to the observed changes (e.g., altered sleep‐wake cycle or social interaction in the middle of the night)? 3) Is the patient tolerating the observed changes, or are the changes contributing to patient compromise (e.g., increased heart rate and blood pressure precipitating ischemia)? 3,91 …”

Circadian Rhythms in Sudden Cardiac Arrest

“…It is well appreciated by emergency and critical care nurses (Bridges & Woods, 1998, 2001) as well as paramedics that there is a significant circadian rhythm to the incidence of SCA. However, some discrepancy on circadian timing exists, which may be dependent upon patient characteristics (sex, age, etc.)…”

Entering a World with No Future: A phenomenological study describing the embodied experience of time when living with severe incurable disease

“…Nature’s time appears in cycles and rhythms that continuously repeat themselves, while at the same time never returning, each day, we become 1 day older. Life is a permanent process of breathing and digesting that re‐establishes itself in a cyclic manner that rapid in a linear way moves towards annihilation (1, 15, 24, 49, 64). In the rhythms of nature, repetition and change are conjoined (1).…”