[The clinic experience of implantable diaphragm pacer in a patient with high cervical spinal cord injury and literature review].

Objective: To report the use of implantable diaphragm pacer (IDP) in a patient with high cervical spinal cord injury(HCSCI). Methods: A 14-year-old male patient, who suffered from a HCSCI at C2 neurological level and had been on a ventilator for 2 years, received IDP in August 2017 at China Rehabilitation Research Center. A systematic literature review was performed on IDP in patients with HCSCI in Pubmed, CNKI, and Wanfang databases, using the keywords: phrenic nerve and electrical stimulation and spinal cord injury; IDP and spinal cord injury; breathing pacemaker system and spinal cord injury. All fields were covered from 1970/01/01 to 2018/01/01 in Pubmed, from 1981/01/01 to 2018/01/01 in CNKI, and from 1900/01/01to 2018/01/01 in Wanfang. Results: No spontaneous breathing was observed preoperatively in the patient. The electrical response of phrenic nerves was intact on the right, but unresponsive on the left. We got started with the IDP at 4 weeks after surgery. The threshold voltage of the right hemidiaphragm pacing was 0.1 V and at the level of 0.7 V with an optimal effect. No significant diaphragmatic contraction was found at left side with the extent up till 0.7 V. The maximum tidal volume was 840 ml when electrical stimulation was given at an intensity of 0.7 V bilaterally. The bilateral stimulation voltage at 0.1-0.2 V, pacing frequencies at 9 beats/min in bed, or at 12 beats/min on wheelchair, were set to maintain the tidal volume at the level of (435±32) ml. After 2-week adaptive training, the patient could wean from the ventilator for 12 hours and had a normal blood gas analysis. At 6 week after surgery, with the aid of IDP, the patient could get out in wheelchair for outdoor activities. By literature review, we found 78 English papers, including 6 clinical trials, 10 reviews, and 11 Chinese papers, consisting of 8 reviews, 1 study in animal, and 2 news reports. Extensive contents, such as preoperative evaluation, preoperative preparation, surgical procedures, complications, surgical outcomes, and animal model studies of IDP were involved. The indications of IDP reported by literature were: (1) central alveolar hypoventilation; (2) Sleep apnea syndrome (Biot's respiration); (3) Respiratory failure induced by brainstem injury or disease; (4) Respiratory failure induced by spinal cord injury or disease above C3 level. Conclusion: Our case study confirmed the therapeutic effect of IDP on patients with respiratory failure caused by HCSCI.