What is a primary risk factor for developing respiratory complications postoperatively in cardiac patients?

Obesity is a primary risk factor for developing respiratory complications postoperatively in cardiac patients due to several physiological and mechanical reasons. Patients with obesity often have decreased lung volumes and impaired respiratory mechanics. This can lead to a higher incidence of atelectasis, reduced pulmonary compliance, and compromised gas exchange.

In obese patients, the excess weight can exert pressure on the diaphragm and thoracic cavity, making it more difficult for them to take deep breaths effectively. This mechanical disadvantage can increase the risk of postoperative respiratory complications such as pneumonia and prolonged ventilatory support. Additionally, obesity is associated with a higher likelihood of obstructive sleep apnea, which can further impair respiratory function during the recovery period.

While age over 70, a history of smoking, and diabetes mellitus are also recognized risk factors for postoperative complications, they may not have as direct or significant an impact on respiratory function compared to the effects of obesity. Each of these factors can contribute to overall health status and surgical risk but obesity particularly influences the respiratory dynamics crucial in the postoperative setting for cardiac patients.