Ultrasound-guided nerve blocks benefit patients with multiple comorbidities, who fall under the high-risk category for anesthesia.
A 71year old gentleman, a known case of chronic diabetes >20yrs, hypertension >15yrs,coronary artery disease with low ejection fraction EF 25%, chronic kidney disease on medical management presented with acute lower limb ischemia. He was taken up for right popliteal tibia bypass surgery. Pre-anesthetic evaluations were done, and blood investigation results were within the normal range. The patient was on anticoagulants, cilostazol, and his other regular medications, i.e. diuretics and insulin. Anti-hypertensive medications were continued.
The plan of anesthesia was explained and informed high-risk consent was obtained because of his co-existing illness. Using sterile precautions ultrasound-guided right femoral and sciatic nerve block was administrated with these total volumes – 20ml of 0.75 % ropivacaine and 20ml of 2%xylo with adrenaline additive dexamethasone 4mg. Identification of the femoral artery at the level of the femoral crease was done using ultrasound orientation.
Typically, both the femoral and the deep artery of the thigh are seen. In this instance, the transducer was moved proximally so that only the femoral artery is visible. (Figure 1a &1b). The roughly triangular or oval-shaped femoral nerve is typically hyperechoic and is covered by 2 layers of the fascia iliaca. The femoral nerve is normally visualized to a depth obetween2 to 4 cm.
The femoral nerve block results in anesthesia of the anterior and medial thigh down to and including the knee, as well as a variable strip of skin on the medial leg and foot. The sciatic nerve block is given through the trans-gluteal approach. The sciatic nerve is approached deep within the gluteus maximus muscle, where it is identified between two osseous landmarks (the ischial tuberosity and the greater trochanter). To obtain a view of the sciatic nerve and the osseous structures at this level, a curvilinear probe is typically needed.
A sciatic nerve block results in the anesthesia of the entire lower limb below the knee (both motor and sensory blockade), except for the skin on the medial leg and foot, which is innervated by the saphenous nerve.
The left radial artery was cannulated for hemodynamic monitoring because of severe left ventricular dysfunction. During the exploration of the popliteal fossa, the vascular surgeon supplemented the local anesthetic agent which was infiltrated directly in the popliteal nerve sheath. Inj.Midazolam and Inj. fentanyl was given to alleviate anxiety and keep the patient comfortable.
The surgery lasted for two and a half hours. The hemodynamics were stable, no hypotension was observed and blood loss was less than 100ml during the 2 hours 30-minute procedure. Post-surgery, the patient was shifted to the coronary care unit for observation.
Apart from the routine, our main anesthetic concerns were hypotension, volume replacement, and post-operative pain relief. General anesthesia offers the advantage of easy hemodynamic control during surgery and no patient discomfort during long procedures; however, it does not inhibit postoperative hypercoagulability. On the other hand, a regional blockade is effective in blocking the response to surgical stress and in postoperative analgesia. However, this is a difficult technique, particularly in patients who are obese, uncooperative, with kyphoscoliosis or previous spinal instrumentation, in addition to its limited duration for long procedures, such as spinal anesthesia. Another point to be considered is the common use of antiplatelets, anticoagulants, and thrombolytics in this population that contraindicate the techniques of neuraxial blockade. For these patients, nerve blocks are the best choice of anesthesia. As there are hardly any changes in hemodynamics, hypotension is avoided. Hence there is no change in cardiac and renal blood flow. There is also no need to load fluid to maintain volume status as there is no hypotension. The patients need not be kept at nil oral post-surgery. They can be started on oral intake once they are back in the recovery room. This avoids hypoglycemia, dehydration and its side effects. Because these patients are in chronic pain, we are usually left with little choice of analgesics. Their age, reduced renal reserve, and long-term use of NSAIDS makes them resistant to analgesics. This results in the possibility of them becoming addicted to opioids. An additive along with the nerve block helps in the prolonged duration of action and an adequate immediate post-op pain relief for 12-18 hours.
In patients with complicated systemic illnesses, general anesthesia and neuraxial blockade can cause hemodynamic instabilities and adverse changes. Additionally, these patients are on anticoagulants, making nerve blocks the safest choice. In addition, this provides quality and satisfactory postoperative analgesia for the patient.
Thankful to the Department of Anesthesiology and Vascular Surgery, Kauvery Hospitals, Chennai, India. Competing Interests: The authors have no competing interests to declare. Author Contributions: The patient was under the care of Dr. Sekar, N HOD of vascular surgery department. Report written by Dr. Mahalakshmi Manoj, Consultant anesthesiologist and edited by Dr. Vel Murugan Designh,SeniorConsultant Anesthesiologist.
● Article R. Noorani, P. Rock Regional versus general anesthesia for vascular surgery patients ● Article Am Soc Anestesiol (2009) F.K. Enneking, V. Chan, J. Greger, et al. ● Article Lower-extremity peripheral nerve blockade: essentials of our current understanding Reg Anesth Pain Med, 30 (2005), pp. 4-35 ● NYSORA- New York School of Regional Anesthesia. Admir Hadzic, Ana M. Lopez, Catherine Vandepitte, and Xavier Sala-Blanch
Dr. Mahalakshmi Manoj Anesthesiologist
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