Perioperative assessment of diaphragmatic dysfunction in cardiac surgery patients and its effect on outcome; a prospective observational study

Abstract

Objectives: While the assessment of the diaphragm in different clinical scenarios is quite frequent, there remains a scarcity of studies focused on assessing diaphragm dysfunction using ultrasound in cardiac surgery patients. We investigated the impact of cardiopulmonary bypass (CPB) surgery on diaphragm function and evaluated its effects on mechanical ventilation.

Methodology: A prospective cohort study, on 100 consecutive adult cardiac surgery patients, was conducted at National Heart Institute. Diaphragmatic displacement (DD) or excursion and diaphragmatic thickening fraction (DTF) were measured using motion-mode ultrasound during quite normal breathing pre-operatively (the day before surgery) and post-operatively on mechanical ventilation, while the patient was fully conscious and spontaneously breathing on continuous positive airway pressure (CPAP) mode + pressure support 10 cmH₂O. Then, the results were correlated to CBP time and important patient outcomes.

Results: Post-operative DD was significantly less as compared to the pre-operative reading; (1.39 ± 0.42 cm vs. 2.3 ± 0.52 cm; P < 0.001), as was DTF (23% ± 10% vs. 40% ± 13%; P < 0.001). The incidence of diaphragmatic dysfunction post-cardiac surgery was 17% by the definition of DD < 1 cm, and 49% by the definition of DTF ≤ 20%. DD was positively correlated with CBP time, as well as total ventilation time and ICU stay, indicating a negative impact on overall patient outcomes.

Conclusion: The results suggest that diaphragmatic dysfunction is positively correlated with CPB time, total ventilation time and ICU stay, underscoring the importance of monitoring diaphragmatic function in post-operative patients, who are difficult to wean from mechanical ventilation with apparently normal chest X-ray, particularly those with prolonged CPB time.

Keywords: cardiac surgery; cardiopulmonary bypass; diaphragm dysfunction; diaphragmatic displacement; diaphragm ultrasound; mechanical ventilation.

Citation: Omara ISM, Nagi HK, Mohamed KAA, Abd El Haq HH, Awdallah FF. Perioperative assessment of diaphragmatic dysfunction in cardiac surgery patients and its effect on outcome; a prospective observational study. Anaesth. pain intensive care 2024;28(5):816−823; DOI: 10.35975/apic.v28i5.2555

Received: June 28, 2024; Reviewed: September 04, 2024; Accepted: September 06, 2024