Phrenic Nerve Injury Management

Pathophysiology and Etiology

Phrenic nerve injury during cardiac surgery can occur through direct trauma, traction, thermal injury, and is more common during redo operations and concurrent Cox-maze procedures 2

Hemidiaphragmatic paralysis presenting as immobility or elevation of the diaphragm on imaging 2
Respiratory distress with increased work of breathing 2
Difficulty weaning from mechanical ventilation 3
Paradoxical abdominal motion during inspiration (abdominal paradox) 4

Chest X-ray showing elevated hemidiaphragm on the affected side 2
Diaphragmatic ultrasound at bedside to assess diaphragmatic function, particularly during weaning from mechanical ventilation 3
Phrenic nerve stimulation techniques (electrical or magnetic) to provide objective assessment of diaphragm function independent of patient effort 1, 3
Measurement of twitch transdiaphragmatic pressure (Pdi,tw) following phrenic nerve stimulation to specifically assess diaphragm strength 1
Negative gastric pressure to transdiaphragmatic pressure ratio indicating severe diaphragmatic dysfunction or paralysis 3

Initiate non-invasive ventilation promptly in patients showing signs of respiratory distress or hypercapnia 3
Consider controlled ventilation modes as patient triggering may be ineffective 3
Target oxygen saturation of 88-92% in adults to avoid worsening hypercapnia 3
Monitor CO2 levels closely with transcutaneous monitoring or arterial blood gases 3

Ensure the precipitant cause of respiratory failure is treated and pH is normalized before initiating weaning 3
Implement physiotherapy treatment before and after extubation to reduce weaning duration 3
Consider prophylactic non-invasive ventilation after extubation for patients at high risk of reintubation 3
Plan extubation carefully and perform in a specialized setting with non-invasive ventilation support available 3

Most adult patients can be managed conservatively with respiratory support 2
Most phrenic nerve injuries will recover within 3-6 months if the nerve is not transected 2
Physiotherapy and respiratory muscle training 3
Nocturnal non-invasive ventilation for patients with sleep-disordered breathing 3

Diaphragm pacing may be considered for long-term management in selected patients 1
Patient selection criteria for diaphragm pacing include no or mild intrinsic lung disease, non-obese status, and intact phrenic nerve-diaphragm axis 1

Identify patients at high risk for phrenic nerve injury and monitor diaphragm function closely post-operatively 2
Implement preventive strategies during surgery, including careful pericardial incision and visual identification of the nerve during dissection 2
Ensure an individualized emergency healthcare plan is in place for future hospital admissions 3
For patients with cardiac pacemakers requiring diaphragm pacing, ensure the cardiac pacemaker is bipolar to minimize potential electromagnetic interference 1