This section describes efficacy outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
4.1 In a systematic review of 148 patients with traumatic high cervical spinal injuries and ventilator-dependent respiratory failure (from 12 studies), intramuscular diaphragm stimulation systems were implanted successfully in all patients except 1. This was because of a false positive preoperative phrenic nerve conduction test in this patient.
4.2 In the systematic review of 148 patients, the mean delay in inserting diaphragm pacing wires ranged from 40 days to 9.7 years. In 1 study in the systematic review (Posluszny 2014) in which devices were implanted early at a mean of 40 days, the highest percentage of patients fully weaned from a ventilator (73% [16/22]) was reported at a mean of 10 days.
4.3 In the systematic review of 148 patients, half of the patients (range 40% to 72%) could be weaned from ventilators after the procedure and most could use the diaphragm stimulator instead of the ventilator for several hours per day. The largest study (Onders 2009; 50 patients) reported that more than 50% were using diaphragm pacing 24 hours per day and up to 96% were able to use pacing for 4 hours continuously. Other studies also described similar rates.
4.4 The specialist advisers listed key efficacy outcomes as reduction in dependency on external mechanical ventilation, survival and quality of life.