Phrenic Nerve Injury Following Cardiac Surgery: A Review

Abstract

Phrenic nerve injury following cardiac surgery is variable in its incidence depending on the diligence with which it is sought. Definitive studies have shown this complication to be related to cold‐induced injury during myocardial protection strategies and possibly to mechanical injury during internal mammary artery harvesting. The consequences are also variable and depend to a large extent on the underlying condition of the patient, particularly with regard to pulmonary function. The response of the patient may range from an asymptomatic radiographic abnormality to severe pulmonary dysfunction requiring prolonged mechanical ventilation and other associated morbidities and even mortality. Two cases are presented to demonstrate the variability in clinical responses to diaphragmatic dysfunction secondary to phrenic nerve injury from cardiac surgery. In addition, treatment strategies are reviewed including early tracheostomy and diaphragmatic plication, which appear to be the most effective options for patients who are compromised by phrenic injuries.

An anatomical study of the full-length phrenic nerve and its blood supply: clinical implications for endoscopic dissection

“…The above discussion notwithstanding, there have been some anatomic studies on thoracic phrenic nerve and its precise relation with adjacent anatomical structures (Fell 1998;Tripp and Bolton 1998;Deng et al 2003). However, there is currently insufficient appreciation of the morphological features of the nerve in terms of descending trajectory, blood supply and anatomical relationships.…”

“…Furthermore, it is generally acknowledged that the nerve carries its accompanying arteries and veins throughout its course in the thoracic cavity. As indicated by the relevant literature, some attention has been paid to the anatomy of the phrenic nerve in the thoracic cavity, but the focus has been mainly on its anatomical protection (Tripp and Bolton 1998;Deng et al 2003). Therefore, it is imperative that the precise course of the phrenic nerve, and close correlation with its adjacent tissues and organs be fully appreciated to assist surgeries aimed at dissecting the whole nerve together its accompanying vessels, especially for endoscopic manipulations, as a transition from endoscopic to open thoracic surgery is, to some extent, often considered as a failure.…”

Current trends in preoperative, intraoperative, and postoperative care of the adult cardiac surgery patient

“…Many patients fully recover the function of the nerve with time. 137 The injury appears to be caused by hypothermia during CPB, as the nerve courses over the pericardium and is subjected to cold cardioplegia and ice. Postoperatively, the diagnosis of phrenic nerve injury can be made by bedside ultrasound, fluoroscopy, or electrophysiology.…”

“…This has been noted in 10-20% of patients following cardiac surgery, depending on the series. 137,138,215 Patients who have injury bilaterally will often need long term ventilator support.…”

Routine Postoperative Care of Patients Undergoing Coronary Artery Bypass Grafting on Cardiopulmonary Bypass

“…Phrenic nerve damage due to cold or mechanical trauma of this extrapericardial structure is also possible; however, it should rarely preclude extubation. 13,14 Intensive care physicians often employ measurements such as generation of negative inspiratory force (NIF), vital capacity, and rapid shallow breathing indices (RSBI) to evaluate candidates for extubation. These measurements are generally applicable to longer-term ICU patients who experience significant diaphragmatic and skeletal muscle atrophy during hospitalization and provide objective evidence of residual muscle strength, endurance, and respiratory system compliance.…”