Compared with his ideal body weight, how is cardiac output affected in a 140 kg patient undergoing thyroid surgery?

Compared with his ideal body weight, how is cardiac output affected in a 140 kg patient undergoing thyroid surgery?

• A. Diminished by factor of 2
• B. Diminished by 10%
• C. The same
• D. Doubled

Answer: (D)

Obesity and thyroid disease create a hyperdynamic circulation, so the heart pumps more blood to meet the higher metabolic demands. Cardiac output, which is heart rate times stroke volume, is therefore increased relative to what would be expected for someone with ideal body weight. In severe obesity, this increase can be substantial, and when compared to the same person at ideal body weight, the cardiac output is often about twice as high. Thyroid factors amplify this by raising heart rate and contractility, further boosting CO. So, in a 140 kg patient undergoing thyroid surgery, the resting cardiac output is roughly doubled compared with what would be expected for ideal body weight. This reflects the need to supply more oxygen and nutrients to a larger body and a hyperactive cardiovascular state.

Obesity and thyroid disease create a hyperdynamic circulation, so the heart pumps more blood to meet the higher metabolic demands. Cardiac output, which is heart rate times stroke volume, is therefore increased relative to what would be expected for someone with ideal body weight. In severe obesity, this increase can be substantial, and when compared to the same person at ideal body weight, the cardiac output is often about twice as high. Thyroid factors amplify this by raising heart rate and contractility, further boosting CO. So, in a 140 kg patient undergoing thyroid surgery, the resting cardiac output is roughly doubled compared with what would be expected for ideal body weight. This reflects the need to supply more oxygen and nutrients to a larger body and a hyperactive cardiovascular state.