Time to recovery PPNI (secondary outcome)
From various definitions of persistent phrenic nerve injury (beyond procedure/discharge), we established the definition as impairment of diagrammatic stimulation beyond the time of hospitalization. In 37 studies with 194 cases it was decided that after recalculating those occurrences after the procedure but not after hospitalization to define that group as transient PNI. Eighty-one persistent PNI after CB-1 and 113 after CB-2 generation were noted. In the CB-1 group, almost half of the nerve injuries (40 PPNI; 49,4%) were associated with 23 mm, although the use of CB1-23 mm accounted for almost a quarter of the total first generation (n = 1164; 25.9%). In CB-2, the use of 23 mm significantly decreased to n = 192 (3.3%) after which the incidence with 23 mm became statistically insignificant. In CB-2, CMAP usage became a marker. Seventy-three (64.6%) PPNI occurred without the CMAP, and 40 (35.4%) occurred with CMAP use (p < 0.05).
We investigated the time to recovery based on the registries. The information was found in 27 studies by observing 150 PPNI, 66 from CB-1 and 84 from CB-2. Precise data with time to resolution were collected from 138 PNI and divided into persistent PNI-CMAP and persistent PNI non-CMAP protection groups. The median time to recovery in the persistent PNI with CMAP group was three months (standard deviation [SD] 3.45; 95%CI 1.9–4.1) while without CMAP protection, this time was prolonged to six months (SD 4.1; 95%CI 5.2–6.8) with statical significance based on Wilcoxon Peto’s log-rank test (p = 0.012) as shown in Figure 5. Only 12 results were described as unresolved ranging over 24 months beyond the observation period. The longest time of observation of unresolved persistent PNI reach over 36 month [46]. Detailed information of PNI follow-up can be found in the supplemental publication material.