Surgery · Medical Literature
Pro-Con Debate for Thenar Tissue Oxygenation in Prone Position during Lumbar Discectomy.
Abstract
AIM: To compare the regional tissue oxygen saturation under general, spinal, and epidural anesthesias during the posterior lumbar discectomy procedures performed in the prone position. MATERIAL and METHODS: A total of 90 patients with an American Society of Anesthesiologists score I-III were evaluated. Using the research randomizer program, the patients were split into three groups: group of general anesthesia (GA, Group I), group of spinal anesthesia (SA, Group II), and group of epidural anesthesia (EA, Group III). Each patient received non-invasive peripheral arterial oxygen saturation (SpO2), three-lead electrocardiography, non-invasive mean arterial blood pressure (MAP), and the in Spectra TM StO2 Spot Check device with near-infrared spectroscopy (NIRS) technology. The group GA also received end-tidal CO2 monitoring and tissue hemoglobin index (THI), and StO2 monitoring. RESULTS: The data of 90 patients showed that age, weight, height, American Society of Anesthesiologists score, amount of bleeding, duration of surgery, and anesthesia were not statistically significant. Tissue oxygen saturations were detected between groups at the 15th, 30th, 45th, and 60th minutes. The values of group EA at the 15th, 30th, and 45th minutes were higher than group SA (p=0.001; p<0.05). CONCLUSION: This study shows that general anesthesia, as opposed to spinal and epidural anesthesia, offers superior thenar tissue oxygenation in a prone position during posterior lumbar discectomy surgery, despite the ongoing debate over the pros and cons of this position.
Clinical relevance
Does the type of anesthesia (general, spinal, or epidural) differentially affect regional thenar tissue oxygen saturation (StO2), as measured by near-infrared spectroscopy (NIRS), in ASA I–III patients undergoing posterior lumbar discectomy in the prone position? __SNAPSHOT__ {"studyDesign":"Prospective randomized controlled trial (3-arm parallel group)","setting":"Not reported (Turkey, based on journal; institutional setting not specified)","sampleSize":"n = 90 (Group I – General Anesthesia [GA]: n = 30 [implied]; Group II – Spinal Anesthesia [SA]: n = 30 [implied]; Group III – Epidural Anesthesia [EA]: n = 30 [implied]; exact per-group sizes not explicitly stated in abstract)","population":"Adults with ASA physical status I–III undergoing elective posterior lumbar discectomy in the prone position; key baseline characteristics (age, weight, height, ASA score, estimated blood loss, and operative/anesthesia duration) were reported as statistically similar across groups","intervention":"General anesthesia (GA) with endotracheal intubation and end-tidal CO2 monitoring (Group I); Spinal anesthesia (SA) (Group II); Epidural anesthesia (EA) (Group III). All patients monitored with SpO2, 3-lead ECG, non-invasive MAP, and thenar StO2 via the InSpectra™ StO2 Spot Check device (NIRS technology). GA group additionally received end-tidal CO2 and tissue hemoglobin index (THI) monitoring.","comparator":"Three-way comparison: GA vs. SA vs. EA; no sham or placebo arm","primaryOutcome":"Regional thenar tissue oxygen saturation (StO2) measured serially at 15, 30, 45, and 60 minutes intraoperatively across anesthesia groups","followUp":"Intraoperative only (up to 60 minutes of StO2 measurement); postoperative follow-up duration not reported","fundingSource":"Not reported"}
Key findings
The abstract reports that baseline demographic and procedural variables (age, weight, height, ASA score, blood loss, surgical duration, and anesthesia duration) did not differ significantly among the three groups, supporting adequate randomization and baseline comparability. Statistically significant inter-group differences in thenar StO2 were detected at the 15th, 30th, 45th, and 60th intraoperative minutes. However, the abstract is truncated and does not provide the specific StO2 values, direction of difference (which group was higher or lower), absolute effect sizes, relative effect sizes, confidence intervals, p-values, or information on tissue hemoglobin index (THI) results. No adverse events, hemodynamic complications, or postoperative outcomes are reported. NNT and NNH cannot be calculated from the available data. No data are available to assess clinical importance of the observed statistical differences.
Practice implications
This study establishes that the choice of anesthesia modality — general, spinal, or epidural — is associated with statistically significant differences in peripheral tissue oxygen saturation at the thenar eminence during prone lumbar discectomy, at each measured intraoperative time point. However, the clinical importance of these differences cannot be assessed from the abstract alone, as the magnitude, direction, and absolute values of StO2 differences are not reported. It is not established whether any anesthesia type is superior in protecting tissue perfusion, whether the observed StO2 changes reached clinically meaningful thresholds (e.g., StO2 < 75%, a value associated with tissue dysoxia in prior NIRS literature), or whether differences correlated with patient-centered outcomes such as hemodynamic instability, neurological recovery, pain, or postoperative complications. The findings apply to ASA I–III adults undergoing posterior (open or microscopic) lumbar discectomy in the prone position; patients with significant cardiovascular, pulmonary, or peripheral vascular disease, or those undergoing minimally invasive or endoscopic procedures, were not explicitly described as represented. NIRS-based thenar StO2 is a surrogate endpoint, and its relationship to hard clinical outcomes in this surgical context remains uncertain. Practice should not change based on this abstract alone; full-text review is required, and independent replication is needed before any anesthesia recommendation can be derived from this data. Note: this summary is based solely on the published abstract (PMID 42541779); full-text data were not available for review. __LIMITATIONS__ Only an abstract is available; critical quantitative data (exact StO2 values, effect sizes, confidence intervals, p-values, THI results) are truncated and not assessable.,Relatively small sample size (n = 90 total; approximately 30 per arm), limiting statistical power to detect modest but clinically meaningful differences and increasing risk of type I error across multiple time points.,Intraoperative-only monitoring at fixed 15-minute intervals; no continuous StO2 recording or postoperative follow-up reported, which may miss transient hemodynamic perturbations.,Thenar StO2 is a surrogate endpoint with uncertain correlation to clinical outcomes (e.g., neurological recovery, postoperative analgesia, complications) in this specific surgical context.,Prone positioning itself affects peripheral perfusion and venous drainage; the interaction between prone positioning and anesthesia type on StO2 is not disentangled.,THI and end-tidal CO2 monitoring were available only in the GA group, introducing asymmetric data collection across arms and preventing direct comparison of these secondary metrics.,The randomization method (research randomizer program) and allocation concealment strategy are not described in the abstract; blinding of outcome assessors is not mentioned.,Generalizability is limited: patient characteristics, surgeon/anesthesiologist experience, intraoperative fluid management protocols, vasoactive drug use, and specific anesthetic agents/doses are not reported.,Funding source is not disclosed; potential conflicts of interest are unknown.,Multiple comparisons across four time points without described correction for multiplicity increases the risk of spurious statistical significance. __BOTTOM_LINE_CATEGORY__ low_certainty __BOTTOM_LINE__ This small 3-arm RCT (n = 90) found statistically significant differences in thenar NIRS-derived tissue oxygen saturation among general, spinal, and epidural anesthesia during prone lumbar discectomy at all measured intraoperative time points, but the abstract is truncated and provides no quantitative effect data, direction of difference, or clinical outcome correlation. Full-text review is required before any clinical inference can be drawn, and the findings are not currently sufficient to guide anesthesia selection for this procedure.