Evaluation the Perfusion of Uterus and Lower Extremities During Cesarean Section With NIRS and Color Doppler
Evaluation the Perfusion of Uterus and Lower Extremities During Cesarean Section With NIRS and Color Doppler
Hypotension after spinal anesthesia for cesarean section is one of the most common
 perioperative issue, with an incidence up to 83%.Hypotension is mainly induced by the
 associated sympathetic blockade, with a drop of peripheral vascular resistance in the lower
 extremities and an increase in venous capacitance. Hypotension is a distress for both
 anesthesiologists and obstetricians as it endangers parturient's hemodynamics and compromises
 the uteroplacental blood flow. In clinical practice, there are several ways to treat
 hypotension after spinal anesthesia such as preloading with intravenous fluids and
 administrating ephedrine. Normotensive maternal blood pressure does neither guarantee the
 well-being of the fetus nor ensure the tissue perfusion of the parturient. Based on the
 anatomy and physiology basis, we hypothesize that uterine perfusion under spinal anesthesia
 would correlate with the perfusion of the lower extremities. To measure the perfusion of the
 lower extremities, we use a relative new tool, the non-invasive transcutaneous near infrared
 spectroscopy.
This is a prospective observational study. Parturients who are going to receive an elective
 cesarean section will be enrolled. Before entering the operating rooms, the parturient
 enrolled receives the Doppler studies. The external iliac artery is identified and color
 Doppler is activated to locate the uterine artery crossed the external iliac artery. The
 probe is stabilized to obtain the maximum flow velocity waveform.The pulsatility index of
 these three waveforms is calculated and recorded as the baseline. Three minutes after the
 anesthetics are injected, the same procedures of color Doppler are performed again, and the
 PI after the spinal anesthesia is recorded.

 Tissue (cerebral) oximeter (INVOS Cerebral Oximeter Model 5100B; Somanetics, Troy, MI, USA)
 is used for the NIRS technique. Two adhesive sensor patches are attached to the parturient.
 One sensor patch is applied over the the biceps brachii of the upper limb while the other
 adhere to the medial side of the gastrocnemius muscle. After the oximeter shows a stable
 reading, the baseline data are recorded. The parturient then receive spinal anesthesia in the
 right lateral decubitus position. The intrathecal injection consists of 0.5% hyperbaric
 bupivacaine. NIBP is monitored at 2.5 minutes interval for 30 minutes. Tissue oximeter starts
 recording every minute right after local anesthetics are injected into the intrathecal space
 for a total of fifteen minutes.
Inclusion Criteria:

 -  Parturients

 -  elective cesarean section

 -  ASA class I or class II

 Exclusion Criteria:

 -  Emergent cesarean section

 -  Skin lesions over the site of local anesthetic injection

 -  Skin lesions over the sites where NIRS patches are about to be attached

 -  Patients with history of being allergic to NIRS patches

 -  Patients with coagulopathy or other contraindications for spinal anesthesia