TABLE 2.
Practical questions regarding βB use in critical illness.
| 1. Are βB safe in critical illness? Yes, βB appear to be safe in the setting of critical illness. Adequate volume resuscitation should be a target prior to βB initiation to ensure appropriate preload |
| 2. What are the hemodynamic effects of βB in critical illness? |
| a. HR: reduce heart rate |
| b. SV: decreased inotropy is expected; however, in a patient with adequate preload, increased diastolic times may improve filling and improve SV |
| c. CO: decreased inotropy and chronotropy are expected effects; however, due to potential increases in SV/cardiac efficiency, βB effect on CO can be neutral to improved |
| d. MAP: Blood pressure is the product of CO and systemic vascular resistance (SVR). βB have no notable effects on SVR, but potential improvements in CO can be observed, especially in the setting of mitigating arrhythmias (e.g., atrial fibrillation). As such, cardioselective βB use may be associated with neutral to positive effects on MAP. |
| 3. How does βB use effect vasoactive agents like norepinephrine? |
| When used at the appropriate time (i.e. if persistent tachycardia remains despite fluid resuscitation and control of pain and agitation), βB can be norepinephrine-sparing allowing for decreases in norepinephrine dosages without a higher need for inotropic support. βB allow decreased HR which facilitates increased ventricular filling times during diastole, subsequently increasing SV, SVR, and left ventricularLV stroke work to maintain MAP and lower catecholamine requirements |
| 4. Should pulmonary conditions like COPD or asthma preclude βB use in critically ill patients? In the setting of a compelling indication (e.g., atrial fibrillation), no, βB should not be withheld due to this co-morbidity. Further, continuation of home βB use even in the setting of pulmonary conditions appears safe and associated with improved outcomes. In particular, cardioselective βB (e.g., esmolol) appear to be the lowest risk |
| 5. How should βB be dosed in different types of critical illness? |
| a. Sepsis: Data are mixed; however, esmolol 0.5 mg/kg/min or 25 mg/h IV continuous infusions are the two most frequent published approaches. In most studies, infusions were titrated to achieve a 20% HR reduction |
| b. Burns: Dosing ranges of propranolol 0.5–3 mg/kg/day IV or PO divided three to four times per day were most prevalent in the existing literature |
| c. TBI: A wide variety of agents and doses have been studied with most robust data reporting use of atenolol, esmolol, propranolol, metoprolol, or labetalol, but failing to mention dosing strategies |
| d. Cardiac Arrest: IV esmolol loading doses were reported as 300–500 μg/kg as well as 300–500 mg/kg. Propranolol, metoprolol, and bisoprolol were also utilized |