The Effects of Temporary Clipping as an Expression of Circulatory Individuality: Online Measurement of Temporal Lobe Oxygen Levels During Surgery for Middle Cerebral Artery Aneurysms

The Importance of the Temporary Clip Removal Phase on Exposure to Hypoxia: On-Line Measurement of Temporal Lobe Oxygen Levels During Surgery for Middle Cerebral Artery Aneurysms

“…A total of 86 temporary arterial occlusion events were recorded (1-12 per patient, mean of 4.3), with an average duration of 140.8 seconds (41-238 seconds), and an aggregate recorded time of 12 111 seconds of arterial flow interruption. 10 The mean recorded amount of time after CR was 336.7 seconds, lasting from 75 to 813 seconds, and an aggregate recorded time of 28 957 seconds. 10…”

“…Measures of dispersion, when applied to both ascending P bt O 2 steepest slopes and ranges, were higher between different patients. Within single patients, there were statistically significant correlations between both steepest descending (clipping phase) 10 and ascending (CR phase) P bt O 2 slopes ( P = .001, r = −0.704), and corresponding P bt O 2 ranges ( P < .001, r = −0.690), per event (Table 2).…”

“…In addition to data from the clipping phase (number, order, and duration of clippings; preclipping P bt O 2 levels, steepest P bt O 2 descending slopes, minimum P bt O 2 level, and P bt O 2 range), 10 specific clip removal curve landmarks were acquired: P bt O 2 level at clip removal (the lowest starting point), “steepest ascending P bt O 2 slope” as the maximum (positive, percentual in relation to basal level) mean of 5 consecutive 5-second intervals, and “maximum P bt O 2 level” (Figure 2).…”

“…10 The mean recorded amount of time after CR was 336.7 seconds, lasting from 75 to 813 seconds, and an aggregate recorded time of 28 957 seconds. 10 The P bt O 2 Curve After Temporary Clip Removal On an aggregate average of all events from our sample, measuring changes in P bt O 2 as a function of time (Figure 4), the removal of a proximal temporary clip generated an ascending sigmoid-shaped curve. Temporal lobe oxygen levels started rising immediately, at a growing rate until approximately the 30-to 35second marks.…”

Letter: Commentary: The Importance of the Temporary Clip Removal Phase on Exposure to Hypoxia: On-Line Measurement of Temporal Lobe Oxygen Levels During Surgery for Middle Cerebral Artery Aneurysms

“…In their commentary, Wipplinger et al 3 derived from the findings of our study and previous literature on the subject to propose specific recommendations regarding the use of TAO. In a true spirit of contribution to the field based on a personal interpretation of our results concerning brain tissue oxygenation during the 2 phases of the temporary clip (application and removal), 1,4 we were motivated to write the present text in an attempt to both discuss and expand on those. We propose the following principles, around which our current clinical practice is established: The use of TAO in Neurosurgery is broadly justified by its unique advantages, but those must always be weighed against its potential for vascular injury and ischemia, considering the specific necessities of the patient and the intraoperative occurrences.…”