Differences in cardiac responses to resuscitation from burn shock

Area of Science:

• Cardiovascular Physiology
• Gerontology
• Burn Injury Research

Background:

• Aging is associated with intrinsic changes in cardiac function.
• Burn shock can lead to significant cardiovascular compromise.
• The impact of aging on myocardial response to burn shock is not fully understood.

Purpose of the Study:

• To investigate if aging alters the intrinsic contractile response of the left ventricle (LV) to burn shock.
• To assess the effects of fluid resuscitation on LV function in young versus aged burned guinea pigs.

Main Methods:

• Isolated perfused guinea pig hearts were used to measure LV pressure (LVP) and its derivatives (+dP/dt max, -dP/dt max) at a constant preload (LVEDP).
• A third-degree burn model (Walker) was applied to young and aged guinea pigs.
• Hearts from burned animals were analyzed for contractile function, with and without fluid resuscitation.

Main Results:

• Aged control hearts exhibited significantly lower LVP, +dP/dt max, and -dP/dt max compared to young controls.
• Burned aged hearts showed reduced LVP and -dP/dt max compared to burned young hearts.
• Contractile deficits in aged burned hearts persisted despite fluid resuscitation, with uniformly depressed peak LVP and maximal relaxation rate.

Conclusions:

• Aging exacerbates myocardial contractile dysfunction following burn shock.
• Intrinsic cardiac deficits in aged individuals limit the response to burn injury and resuscitation.
• Severe myocardial contractile changes in aged subjects with compromised hearts are a significant factor in burn shock outcomes.