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Monaco et al. Vessel Plus 2023;7:23 https://dx.doi.org/10.20517/2574-1209.2023.113 Page 5 of 14

Table 1. Physiologic determinants, target values and potential therapeutic interventions to avoid spinal cord ischemia (SCI) during
thoracoabdominal aortic aneurysms (TAAA) repair
Determinant Target value Potential therapeutic intervention
MAP 85-100 mmHg • Increase volemia
• Vasoactive drugs infusion
• Reduce clamping time
• Gradual clamp release
• Avoid abrupt pressure variations
CSFP 8-10 mmHg Place external CSF drainage
CVP < 10 mmHg • Implement diuretic therapy
• If RV dysfunction is present:
Optimize gas exchange by increasing FiO
2
Moderate hyperventilation
Dobutamine/adrenaline infusion
DO 2 1,000 mL/min • Improve SaO
2
• Keep Hb > 10 g/dL
• Ensure CI > 2.5 L/min
Body temperature 32-34 °C • Mild hypothermia
• 300 mL cold saline infusion in each of the renal arteries
• Cold saline infusion with dual-lumen catheter in epidural space
MAP: Mean arterial pressure; CSFP: cerebrospinal fluid pressure; CSF: cerebrospinal fluid; CVP: central venous pressure; RV: right ventricular;
FiO : inspired fraction of oxygen; DO : oxygen delivery; SaO : arterial oxygen saturation; Hb: hemoglobin; CI: cardiac index.
2
2
2
PERIOPERATIVE MONITORING OF SPINAL CORD ISCHEMIA
Open TAAA surgery benefits from intraoperative neurophysiological monitoring (IONM) for the
identification of SCI. Descending and ascending spinal pathways are evaluated by means of motor (MEPs)
and somatosensory evoked potentials (SSEPs), respectively. SSEPs are elicited by stimulation of posterior
tibial nerves at the ankle and/or median nerves using subdermal needle electrode pairs. Similarly, MEPs are
elicited in the upper extremities with a needle electrode in the abductor pollicis brevis or the first dorsal
interosseus muscle and both tibialis anterior and abductor hallucis muscles in the lower ones. Limitations of
neurophysiologic monitoring include the inability to differentiate between medium and severe SCI and that
[17]
it can be influenced by lower limb ischemia resulting from vascular introducers .
Anesthetic agents
Anesthesia shows a profound influence on evoked potentials. Volatile anesthetics reduce the amplitude of
SSEP, increase their latency, and impair cortical waves; hence, their administration should not exceed 0.5
MAC [18,19] . Intravenous anesthetics (e.g., propofol and remifentanil infusions), combined with low
concentrations of volatile anesthetic agents if appropriate, represent the first line of choice when the
monitoring of evoked potentials is in place .
[20]

Neuromuscular blockers
Careful attention must also be given to the administration of neuromuscular blockers to safeguard
appropriate muscle relaxation and an adequate response of MEPs. IONM also proved to be beneficial for
categorizing patients based on their risk of SCI when the vascular phase of surgery is over. Bianchi et al.
used a multimodal IONM approach, combining MEP, SEP, and peripheral nerve monitoring techniques in
100 consecutive patients undergoing TAAA open repair . The study showed a notably higher rate of
[21]
immediate postoperative motor deficits consistent with SCI, particularly in cases with irreversible MEP
deteriorations compared to reversible ones. The authors concluded that implementing a multimodal IONM
protocol could improve MEP interpretation and assist surgeons in making informed decisions before
concluding vascular maneuvers. Although IONM has the potential to detect SCI during surgery, during the
timeframe between the end of the surgical procedure and the subsequent neurological clinical evaluation,
limited information about the presence of SCI is available for clinicians. In order to address this gap, von