Epidural volume extension: A novel technique and its efficacy in high risk cases.

We present a unique case series restricting ourselves only to the high-risk case of different specialities who underwent successful surgery in our Institute by using epidural volume extension's technique using 1 mL of 0.5% ropivacaine and 25 μg of fentanyl.

INTRODUCTION

Combined spinal epidural anesthesia has become very common in today's anesthetic practice. This technique where normal saline is injected into the extradural space following an intrathecal injection of local anesthetic is known as epidural volume extension (EVE) and has been shown to increase the cephalad spread of the block and thereby raising the analgesia level, mainly due to “volume effect.”[1] We in this case series are trying to highlight the efficacy of this novel technique in patients of different setting with compromised cardiac functional status.

CASE REPORTS

Case 1

A 62-year-old man presented in the casualty with hematuria and clot retention. He was a chronic smoker and had three episodes of myocardial infarction over the last 6 months and was on tablet aspirin 150 mg OD. His INR was 1.3 with hemoglobin of 7.8 gm%. Airway examination revealed Mallampati class (MPC) III airway with diffuse wheeze over the entire lung field. His investigations revealed hemoglobin 9.4 gm%, INR 1.4, sodium 145 meq/L, and potassium 4.5 meq/L. A cardiology consultation was obtained, and 2D echocardiography (ECHO) revealed global Hypokinesia with left ventricular (LV) dysfunction (ejection fraction (EF) <30%), which was due to three episodes of the myocardial infarction patient had suffered in the past. Patient was planned for an emergency clot evacuation.

Case 2

A 60-year-old man with a history of diabetes mellitus, coronary artery disease, ischemic cardiomyopathy, moderate left ventricular dysfunction, severe right ventricular dysfunction, and severe pulmonary artery hypertension had presented to orthopedic department following trauma sustained over the left leg 1 week back, which had progressed to gangrene and was planned for above knee amputation. Patient had four episodes of angina over the period of last 2 years of which the last attack was 4 weeks back, and was on tablet aspirin 75 mg OD. He was classified under American Society of Anesthesiologist (ASA) III, New York Heart Association (NYHA) grade III with MPC III. He was a chronic smoker with 40 pack years.

Laboratory parameters were within normal limits. Chest X-ray revealed bilateral nonhomogeneous opacities with enlarged cardiac shadow. Two D ECHO revealed regional wall motion abnormality along with global hypokinesia and ejection fraction of 25%, and Grade II diastolic dysfunction. Patient was started on injection furosemide 40 mg BD, tablet amiodarone 6.25 mg BD, tablet digoxin 0.25 mg BD, tablet spironolactone 25 mg OD, and injection human albumin 20%.

Case 3

A 25-year-old primigravida at 36 weeks of gestation presented in obstetric department with complaint of dyspnoea at rest, and clinical examination revealed her to be in cardiac failure. Two D Echo revealed cardiomyopathy, biventricular systolic dysfunction, Grade I diastolic dysfunction with an ejection fraction of 42%. Diagnosis of peripartum cardiomyopathy was made. Tablet furosemide and tablet Methyldopa was started, and she was planned for elective cesarean section.

Case 4

A 28-year-old primigravida presented at 37 weeks of gestation with complains of dyspnea and pedal edema. Two D Echo revealed pulmonary artery hypertension with an ejection fraction of 48%. Elective cesarean section was planned for her, and she was posted as the first case in the morning.

Case 5

A 29-year-old gravid 3 at 38 weeks of gestation presented to obstetric unit and was in congestive heart failure and pulmonary edema. Two D Echo was performed, which revealed cardiomyopathy with an ejection fraction of 42% and pulmonary artery hypertension. She was put on tablet lasix and tablet digoxin. Cardiac consult was sought and she was planned for the elective cesarean section.

Case 6

A 23-year old primigravida who was diagnosed with Takayasu arteritis Type III along with bilateral subclavian and renal artery involvement presented to the obstetric unit for safe confinement. She also suffered from renovascular artery hypertension and dilated cardiomyopathy secondary to Takayasu arteritis. Patient was on tablet nifedipine 10 mg OD, tablet digoxin 0.25 mg OD, tablet levocarnitine 500 mg OD and tablet prednisolone 30 mg OD. She was posted for elective cesarean section.

Anaesthetic plan

All the patients were assessed systematically; the investigations were assessed, and aspiration prophylaxis was administered to all of them. All these patients were administered 1 mg midazolam intravenously before shifting to the operating room (OR) and once the patients were received inside the OR non invasive blood pressure, SpO2 and electrocardiogram leads were attached, and vital parameters were recorded. A wide bore peripheral intravenous line was secured, and patients were preloaded with 500 mL of crystalloids. Under aseptic precaution, a 18 G epidural catheter was inserted using 16 G Tuhoy needle via L2-L3 interspace using the loss of resistance technique to air and fixed at 4 cm mark. This was followed by subarachnoid block with 1 mL of 0.75% of hyperbaric ropivacaine along with 25 μg of fentanyl injected intrathecally via the L3-L4 interspace using a 25 G Whitacre needle. A wedge was placed under the right hip joint in all the obstetric cases. We injected 8 mL of normal saline through the epidural catheter 5 min after giving the subarachnoid block. Right internal jugular vein was cannulated after administration of suitable dose of midazolam and after local infiltration of local anesthetic. Intraoperative fluid management was guided by central venous pressure. Direct arterial pressure was also monitored in all the patients. The dermatomal level of anesthesia was checked at 3, 5, and 10 min after administration of epidural saline [Table 1] by the pin prick method.

Table 1

Level of sensory block and grade of motor block achieved

All the patients were hemodynamically stable throughout the surgery since the density of the sympathetic blockade achieved by this technique is traditionally lesser than that achieved by classical subarachnoid blockade. Postoperatively patients were shifted to the intensive care unit for overnight observation, and the postoperative analgesia was maintained by epidural infusion of ropivacaine 0.2% at the rate of 4-6 mL/h.

DISCUSSION

Epidural volume extension (EVE's) technique is a unique regional technique, which offers the reliability and rapidity of spinal anesthesia along with flexibility of epidural anesthesia. It also avoids the degree of sympathectomy that accompanies spinal anesthesia when used alone as the dose of drug being used in EVE's technique is very less and hence the severity of hemodynamic compromise is less. At the same time, it avoids the disadvantages of general anesthesia in patients at high cardiac risk by avoiding potent cardiodepressant drugs.

The options in front of us broadly included spinal or general anesthesia. We, however, opted for EVE's technique, since it commands a unique place in the anesthetist's armamentarium. At one side, it had significant dose sparing effect providing the required level of anesthesia and analgesia and does not compromise the hemodynamic profile of the patient. Hence, we went ahead with this technique as it offered us advantage of both regional and general anesthesia, at the same time also avoided the undesirable side effect of both the techniques. Our technique provided the rapidity, density and reliability of spinal anesthesia and gave us the flexibility of epidural anesthesia as we could titrate the level of anesthesia, vary the intensity of block, extend the duration of anesthesia, and deliver postoperative analgesia. It also provided us a backup in the case if spinal anesthesia fails. At the same time, our technique had a clear edge over general anesthesia as we could avoid airway manipulation and accompanying stress response, which could have adversely affected our patient's cardiovascular status. We were also able to avoid the negative inotropic effect of anesthetic agents and the adverse effect on venous return due to positive pressure ventilation was also avoided. The mild vasodilatation that we could achieve by the subarachnoid block by EVE's technique was beneficial in patients with isolated left ventricular dysfunction.

Lew et al.[2] found that combined spinal epidural using EVE's technique proved to have a faster motor recovery profile that may have an impact on reducing or bypassing post anesthetic care unit.[234] The advantage of using saline in epidural space was that we could achieve a higher level of block using a given volume of ropivacaine, as a result of which the level of hemodynamic compromise was less. None of our patients had any complaint related to prolonged motor blockade or postoperative urinary retention.

There are several mechanisms described in the literature, which explains this phenomenon the most popular ones being “Volume effect” that postulates that saline in epidural space compresses the theca which results in “squeezing” of cerebrospinal fluid and more extensive spread of subarachnoid block.[234] This effect of injecting epidural saline is time limited and injecting saline will have no effect on the block profile, after 30 min or once two segment regression has begun.[56] This was the reason that we had opted to inject 8 mL of normal saline 5 min after intrathecal injection. This technique proved to have a faster motor recovery profile by at least 60 min.[7] This again was beneficial in our group of patients, as early ambulation decreases the risk of developing postoperative DVT. This in long term certainly is cost saving for both patient and hospital authorities along with low complication rates and better use of hospital resources.

This technique is, however, not without its disadvantages, which draws special attention from an anesthesiologist such as rapid rise of spinal block, accidental migration of catheter in intravascular and intrathecal space along with an increased incidence of meningitis.

Judicious preloading with crystalloids tailored to individual needs, along with the low dose of spinal anesthetics, which was followed by epidural saline injection, helped us to attain the desired level of block for all our high-risk cases avoiding a precipitous decrease in blood pressure. The epidural catheter placed preoperatively also helped to provide postoperative analgesia thereby decreasing any further cardiac stress arising due to postsurgical pain.

CONCLUSION

EVE's technique is a novel technique that allowed us to achieve the desired degree of surgical anesthesia using a smaller dose of local anesthetic agent which prevented adverse hemodynamic effect seen with the conventional dose. Careful fluid administration under the guidance of intensive monitoring and well tailored regional anesthesia helped us to fulfill our anesthetic aim.