Anesthetic Management of Surgical Vascular Access for Hemodialysis

Abstract

Patients with end-stage renal disease (ESRD) have an adjusted all-cause mortality rate significantly higher than the general population. Surgical techniques to establish hemodialysis access are common and increasing in frequency as more and more patients are diagnosed with advanced and end-stage renal disease. The purpose of this review is to focus on the fundamentals of perioperative anesthetic management of a patient who is scheduled for hemodialysis access procedure. This involves not only the choice of anesthesia method but also pre-anesthesia preparation, intraoperative and postoperative management, and the effect of choice of anesthesia on the outcomes.

1. Introduction

1.1 Pre-anesthesia preparation at anesthesia clinic

A comprehensive preoperative evaluation is mandatory for safe and effective anesthesia management since chronic kidney disease (CKD) is an independent risk factor for predicting postoperative death and cardiac events [1]. Therefore, the evaluation should be most efficiently done in a pre-anesthesia clinic. It is essential to identify the comorbidities that are common to patients with chronic or end-stage renal disease, including coronary artery disease and hypertension. Once identified, measures and treatments should be initiated to medically optimize these patients to minimize or eliminate the risk of surgery and anesthesia. Current guidelines recommend checking a baseline electrocardiogram (ECG) in those patients who have cardiovascular risk factors or documented cardiovascular disease [1]. Additionally, the patient should be scheduled to have routine hemodialysis. Ideally, hemodialysis should be done one day prior to the surgery. Basic laboratory tests including a complete blood count and metabolic and coagulation panel may also be considered in pre-anesthesia clinics.

1.2 Same day evaluation

Most procedures done to establish hemodialysis access are outpatient procedures with patients arriving a few hours prior to the planned procedure. The pre-anesthesia evaluation in the preoperative holding area is one of the most important phases in preparing the patient for the administration of anesthesia. The anesthesia team should confirm that the patient’s general condition has not changed since they are evaluated in pre-anesthesia clinic. The site of intravenous access and blood pressure measurement must be avoided in the arteriovenous (AV) access arm. Establishing peripheral intravenous access may be challenging, and an ultrasound-guided method may be helpful to identify an appropriate vein. In cases where a patient has an existing indwelling catheter, consideration can be taken to gain access. However, this is generally avoided due to fear of increased infectious complications. Routine airway examination should be done at the same time even if general anesthesia is not planned.

1.3 Special anesthetic considerations: chronic vs end-stage renal disease

For those patients with chronic renal disease but have not yet started hemodialysis. It is important to ask the patients about the volume and regularity of daily urine production with special attention to those who report a recent drop in volume and/or frequency. This may indicate a recent worsening of their renal function, which may necessitate closer attention to potassium changes or fluid management during the procedure. For those patients already on hemodialysis, it is important to establish when the patient underwent hemodialysis last. Ideally, the patient is expected to have hemodialysis 12 to 24 hours prior to the procedure to facilitate their physiologic status to completely or near completely return to normal at the time of anesthetic administration. Additionally, whether the patient has routine hemodialysis regularity or not is also important since a single session of dialysis may not normalize the patient who does not undergo regular hemodialysis, particularly the fluid status. Similarly, it is important to ask if the patient is well tolerated during the last hemodialysis session. If the patient felt uncomfortable during hemodialysis, the session was not completely terminated, or the patient skipped a regular session because of feeling ill, it may indicate other factors that must be seriously considered. These factors, combined with laboratory abnormalities, may necessitate canceling/rescheduling the procedure.

1.4 Which laboratory data are important?

Verification of certain laboratory data is critical to check on the day of the procedure as these patients are subject to day-to-day changes.

1.4.1 Potassium

The serum potassium levels in patients with chronic renal or end-stage renal disease are typically elevated. Hyperkalemia is potentially life-threatening and must not be neglected. There are no “cut off” levels of preoperative potassium levels to consider for canceling the case or proceeding the procedure safely. Therefore, the potassium level used to determine “go or not go” may vary among hospitals. It should be noted that the serum potassium level is closely related to serum pH. Therefore, if the patient is acidotic, re-evaluation of serum potassium level must be considered after serum pH is corrected. In our institution, a potassium level higher than 6.0 mmol/L prompts a discussion between the anesthesia and surgical teams regarding the need for urgent hemodialysis prior to the procedure. One additional consideration is that venous potassium levels can sometimes falsely be higher than arterial levels. Obtaining and checking an arterial blood sample may be useful in confirming the correct true potassium level [2]. Occasionally, patients can have a lower preoperative potassium level (<3.5 mmol/L). Hypokalemia is not as dangerous for patients as hyperkalemia. Therefore, correction is required if it is associated with frequent cardiac arrhythmias or with significant EKG changes such as QT prolongation. It is extremely difficult to correct hypokalemia in a patient with ESRD. Therefore, consultation with a nephrologist or a cardiologist is safer to avoid overcorrection with possible cardiac complications.

1.4.2 Hemoglobin and hematocrit

Patients with chronic or end-stage renal disease are mostly status of “chronic anemia” due to lower erythropoietin activity as well as the effect of uremic toxic metabolites on bone marrow. Anemia does not need to be corrected routinely since it is well tolerated by patients due to the gradual progression of anemia. There are no definite guidelines regarding the hematocrit level below which blood products should be transfused. However, previous studies have reported increased intraoperative complications in patients with end-stage renal disease and preoperative hematocrit levels ranging from 20–26% [3]. Hemodialysis access surgery itself is usually not a procedure with significant surgical blood loss. Therefore, more flexible criteria may be accepted for transfusion. However, transfusion should be considered if the patient is symptomatic or has significant comorbidities such as history of coronary artery disease and/or cerebrovascular disease beyond specific objective criteria of hemoglobin and hematocrit. It should be noted that transfusion of blood products may increase the patient’s potassium level [4] as well as induce antibody formation which may decrease a patient’s chances of successful renal transplantation in the future [5].

1.4.3 Coagulation panel

Patients with chronic or end-stage renal disease may have coagulopathy due to platelet dysfunction, decreased coagulation factors, and/or fragile capillary vessels. Additionally, if the patients have uncontrolled atrial fibrillation and cerebrovascular and/or peripheral vascular disease, they have chronic anticoagulation treatment such as warfarin and/or antiplatelet therapy such as aspirin or clopidogrel. Patients are usually instructed to temporally hold oral anticoagulants prior to the procedure, but occasionally it is not carried out. In this situation, there may be additional limitations to the surgery or could necessitate canceling/rescheduling the procedure. In the case of a prolonged bleeding time or elevated INR, a regional nerve block may be contraindicated due to risk of bleeding complications with hematoma formation and nerve compression.

2. Choice of anesthesia

After the evaluation of the patient’s physical condition, anesthesia method should be decided. Anesthetic options include local anesthetic (LA) infiltration around the operative site provided by the surgical team in combination with monitored anesthesia care and sedation (MAC (Monitored Anesthesia Care)) provided by the anesthesia team, regional anesthesia (RA), and general anesthesia (GA). Choice of anesthesia also depends on the surgical site and the type of surgery. The surgery for vascular access for hemodialysis can essentially be categorized into two basic types such as arteriovenous fistulas (AVF) and arteriovenous grafts (AVG).

For AVF, a fistula is created between an artery and a vein. There are two common sites in the upper extremity where a fistula is created: between the radial artery and cephalic or basilic vein at the wrist and between the brachial artery and cephalic or basilic vein in the upper arm. For AVF created with the basilic vein, transposition of the vein is required, affecting the chosen anesthesia method. Alternatively, AVG is placed using prosthetic material between an artery and vein in the forearm or upper arm. Any of the three options (LA, RA, and GA) are acceptable for both AVF and AVG. However, the patient’s medical comorbidities, the anatomic location (wrist/forearm, antecubital fossa, and upper arm), and the surgeon’s preference are to be considered when selecting the anesthesia method.

Choice of anesthetic options can be determined based on the anatomic location of surgical incision. LA with MAC can be considered suitable for the procedures performed at the wrist and the antecubital fossa. RA is a viable option for procedures performed at the antecubital fossa and distal upper arm. GA or RA with an interscalene block can be considered when procedures involve the proximal upper arm for AVG and transpositions, which require tunneling.

2.1 Local anesthesia

Infiltration of LA in the surgical field by the surgeon provides stable analgesia with minimal to no hemodynamic and respiratory changes and is, therefore, often used in patients who have severe cardiopulmonary co-morbidities. The specific LA selected depends on the surgeon’s preference, but many surgeons prefer 1% lidocaine as the onset is faster compared to others. In some patients experiencing agitation or anxiety during the procedure, LA alone is not well tolerated. This situation should be overcome with additional sedation and/or analgesia such as propofol infusion or fentanyl provided by the anesthesia team. The other problem for LA is the lack of a preventive effect on the spasm of the artery, in contrast to RA and GA. Previous reports have revealed that the use of a brachial plexus block with a supraclavicular approach provided dilatation of both the veins and arteries of the ipsilateral extremity immediately following the block, reduced the incidence of arterial spasm during and after the surgery, and significantly decreased the rate of immediate AVF failure postoperatively when compared to those that were performed with LA [6, 7, 8].

2.2 Regional anesthesia

RA of the upper extremity is primarily achieved through a brachial plexus block. RA offers many advantages over other anesthetic methods, including intraoperative hemodynamic stability and good postoperative analgesia. There is also evidence that it improves vascular flow via regional sympathectomy, although evidence of improved graft survival is lacking yet [6, 7, 8]. There are several ways to perform a brachial plexus block, including supraclavicular or infraclavicular and axillary approaches. Complications of RA include infection, hematoma, local anesthetic toxicity, and nerve injury. There are also complications that are specific to each approach, such as total spinal anesthesia, Horner syndrome, hemi diaphragmatic paralysis, and pneumothorax during supraclavicular blocks. There is not enough published data, but the use of ultrasound-guided nerve blocks certainly appears to have made these blocks easy and decreased the incidence of complications [9]. It should be noted that following a brachial plexus block supplementation with LA by the surgeon may be required and LA dose calculations are to be kept in mind to avoid local anesthetic toxicity.

2.2.1 Supraclavicular block

The supraclavicular block is performed around the brachial plexus and passes with the subclavian artery, which is an exceptionally good anatomical landmark. The subclavian artery crosses over the first rib between the insertions of the anterior and middle scalene muscles, posterior to the midpoint of the clavicle. A high frequency (10–15 MHz) ultrasound beam due to the superficial location of the brachial plexus at this level should be used to improve the quality of visualization of all structures in this area. The subclavian artery is readily apparent as an anechoic round structure, while the parietal pleura and the first rib can be seen as a linear hyperechoic structure immediately lateral and deep to the subclavian artery. Supraclavicular brachial plexus can be visualized slightly superficial and posterolateral to the subclavian artery. Local anesthetic solution is given over the trunks of the brachial plexus above the formation of musculocutaneous and axillary nerves [10]. The supraclavicular block is preferred in many institutes because the brachial plexus is tightly packed at this level allowing for an intensive block. Also, this block provides adequate anesthesia for the entire arm and allows for surgical site flexibility. The major disadvantage is relatively higher risk for pneumothorax due to its proximity to the pleura, but it can be overcome with use of ultrasound technique. Also, phrenic nerve blockade is likely (reported up to 50% incidence) with this approach and close observation should be performed especially in patients with compromised respiratory function. The supraclavicular block should be avoided in patients who are unable to withstand up to 30% reduction in pulmonary function resulting from ipsilateral phrenic nerve block.

2.2.2 Infraclavicular block

The infraclavicular block is performed around the brachial plexus, which is below the level of the clavicle and in proximity to the coracoid process. Local anesthetic solution is deposited over the cords of the brachial plexus, which lie circumferentially around the artery at this level. This block is indicated for distal arm surgery at the elbow, forearm, and hand. Due to the relatively deep location of the brachial plexus at this level, lower frequency of ultrasound beam (5–12 MHz) is helpful for better tissue visualization, especially in obese patients whose plexus is extremely deep [11]. Maneuvers to decrease the depth of the target may be worth trying for success. Some patients may feel uncomfortable with this block since the needle should penetrate through the thicker muscles such as pectoralis major and minor. The patients may require more sedation, which may be respiratory depression or apnea. It should be noted that supplementation of LA provided by the surgeon, additional sedation, or conversion to general endotracheal anesthesia may be required if additional high surgical approach of forearm is needed. In some institutes, this block is considered as an alternate for supraclavicular when there is a relative contraindication to supraclavicular block (e.g., subclavian artery pathology or arteriovenous communication around the trunks, which makes it difficult to pass the needle without puncturing the vessels; severe chronic obstructive pulmonary disease).

2.2.3 Axillary block

The axillary block performed under ultrasound guidance is highly recommended and successful. Due to the superficial location of the brachial plexus, high-frequency ultrasound beam (10–15 MHz) can provide an excellent visualization of all structures where local anesthetics are injected. The axillary artery is a very good landmark to find the spot to find location of the median, ulnar, radial, and median nerves. An additional block of the musculocutaneous nerve off the axillary artery is required to achieve complete analgesia for distal arm. However, it should be noted that there are significant variations between the anatomical positions of the nerves relative to the axillary artery [12]. More analgesic effect is achieved by multiple injections rather than a single injection for axillary approach. Retzl and colleagues observed that the position of the nerves relative to the axillary artery at this level changes significantly with application of varying pressures [13].

2.3 General anesthesia

Almost all patients with CKD and ESRD have multiple comorbid risk factors for GA due to the nature of the conditions that led to the renal insufficiency. Previous clinical research has reported that approximately 25% of the patients who undergo renal replacement therapy have ischemic heart disease, 10% have cerebrovascular disease, and 12% have peripheral vascular disease [14]. Therefore, anesthesiologists consider avoiding GA, if possible, but this may not always be feasible for patients with a history of psychological disorders or those who need more complicated procedures, such as an upper arm transposition or AVG, which may not be amenable to RA. Modes of GA delivery include endotracheal tube (GETA) and laryngeal mask (LMA). There are some advantages of GETA over LMA. GETA provides a more secure airway and controls PaCO₂ easily. It results in minimal aspiration risk and avoids respiratory acidosis that can contribute to increase the potassium level rapidly. However, usage of LMA does not require muscle relaxants, which can delay emergence from GA at the conclusion of the case.

During anesthesia induction, hemodynamics should be maintained with titrating doses of inductions agents such as propofol and prompt use of narcotics. However, blood pressure tends to decrease significantly after induction due to lower vascular compliance and/or lower cardiac reserve function. In these cases, a bolus or a continuous infusion of vasoactive medications such as ephedrine and phenylephrine intravenously should be initiated at the same time as general anesthesia induction to keep the perfusion pressure adequate. Also, selection for induction drugs such as etomidate or midazolam combined with fentanyl, which do not decrease blood pressure as much as propofol, may be a good idea. As to pain control during the surgery, the use of LA by the surgeon can contribute to reducing the intraoperative use of inhalational anesthetics and narcotics.

3. Intraoperative anesthesia management

3.1 Monitoring

Standard monitoring recommended by the American Society of Anesthesiologists, such as two leads ECG, every 3 to 5 minutes measurement of noninvasive blood pressure and pulse oximetry is mandatory for intraoperative monitoring, especially if either LA or RA is primary anesthesia. If GA is an initial plan or required in the middle of the case for several reasons, close monitoring of BP (Blood Pressure) by invasive arterial line may be required due to cardiopulmonary comorbidities.

As to fluid administration, potassium-free crystalloids such as normal saline must be the first choice to reduce the possibility of intraoperative increases in potassium. It should be noted that potassium may increase so suddenly in the middle of the case even if preoperative potassium is at an acceptable level and/or the patient has a full HD one day before the surgery.

The surgery for HD access is not a major surgery and it barely loses blood. However, if the patient is anemic and vital signs become very unstable, especially in the case of GA, blood transfusion should be considered.

3.2 Potassium level

Any type of anesthesia may raise potassium to a critical level suddenly. Therefore, it is particularly important to pay close attention to ECG changes even for minor changes in the QRS complex or the height of the T wave. If recognized, the potassium level must be checked immediately. If elevated, immediate treatment to decrease the potassium should be initiated. Treatment for hyperkalemia starts with immediate administration of calcium (10 ml of 10% calcium chloride). A bolus dose of insulin (5–10 units while checking serum glucose simultaneously) should be followed by a continuous infusion of D10W with 5–10 units of regular insulin per 25–50 g of glucose. After this, sodium bicarbonate (50 to 100 mEq) and furosemide (if the patient still can make urine) should be administered. Other methods to decrease the potassium level includes increasing the respiration rate (if the patient’s respiration is controllable under GA). Frequent checks of the potassium level should be performed until it is normalized.

3.3 Heparin

The surgeon will request heparin prior to clamping the artery. It is important to verify the dose of heparin by asking the surgeon again immediately before giving and flushing the lines to confirm the administration. We should inform the surgeon every hour after the initial and/or additional heparin is administered.

3.4 Oxygenation status

In cases undertaken with LA or RA where a patient is requiring high doses of sedatives, it can become difficult to maintain the patient of the airway. This can expose the patient to risk of hypoxia. In this situation, an adjunctive airway device can be placed with use of an oral or nasal airway or a conversion to GA with endotracheal tube or LMA should be considered to secure the airway. Since inserting an airway instrument, without muscle reluctance, is sometimes enough to stimulate the patient to move suddenly, the procedure should be paused during the intervention. It should be noted that the risk of bleeding during laryngoscopy and intubation is potentiated if the security of the airway is needed after heparin is administrated. Also, the possibility of potassium increase caused by respiratory acidosis during the patient’s spontaneous respiration should be considered.

3.5 Choice of sedatives

A choice for sedatives during monitored anesthesia care is up to the anesthesiologist. However, we should consider the renal function of the patients is significantly impaired and that respiratory depression due to the sedatives may enhance to increase potassium due to respiratory acidosis. In addition to traditional sedatives, such as midazolam and fentanyl, relatively newer sedatives such as propofol, dexmedetomidine and remifentanil have been used to keep the patients calm and comfortable. The metabolism of propofol is not significantly affected by renal dysfunction and it remains a very popular one. However, it may cause respiratory depression if given at higher doses such as 100 micrograms/kg/min. If you need a higher dose, adding midazolam and/or fentanyl may be to reduce the dose. In terms of avoiding respiratory depression, dexmedetomidine is an excellent choice but may make systemic blood pressure lower than expected by decreasing HR. Even if lower BP may not happen during the surgery, it may happen in postoperative period due to a longer half-life of dexmedetomidine. A lower dose of remifentanil (less than 0.5 microgram/kg/min) can sedate the patients without inhibiting spontaneous respiration, but it may cause apnea if it is accidentally flushed. As described, any sedative has advantages and disadvantages of which the selection must be based on each individual patient’s demand and background.

4. Postoperative anesthesia care

Anesthesia management does not discontinue at the end of the surgical procedure but when the patient is discharged from the postanesthesia care unit. It should be noted that potassium levels may increase suddenly even in the perioperative period. Therefore, the recovery nurse should pay close attention to ECG changes and possibly check the serum potassium if increase in potassium is suspected. Occasionally the timing of the next HD session may need to be advanced, especially for the patient that missed their regular HD session prior to the procedure. The criteria are varied between hospitals but consulting a nephrologist should be considered and common for any institute.

5. Updated topic: comparison of anesthesia type for patency, complications, and economy

Recently, the effect of anesthesia type on the patency of fistula, complications, and economy has been highlighted.

A previous retrospective study has reported that GA decreased early failure within 120 days after dialysis creation, while RA may decrease postoperative infection and bleeding [15]. On the other hand, a very recent study in 2022 did not show significant superiority of GA for fistula maturation [16].

The retrospective multivariable analysis has indicated that GA compared with RA/LA was independently associated with increased postoperative admission and decreased three months access utilization but similar 1-year access occlusion and intervention of which subgroup analysis of the RA/LA cohort showed RA was associated with increased three months access utilization but had similar 1-year access occlusion compared to LA [17]. A systematic review and meta-analysis comparison between RA and LA has indicated the superiority of RA over LA in terms of primary patency of fistula, brachial artery diameter, and operation duration [18]. A prospective study of the research group of Scotland, United Kingdom has indicated that RA significantly improved both primary and functional AVF patency at one year and cost compared to LA [19].

The topic of “which anesthesia is the best” has not been concluded yet. Most of the previous studies were retrospective or some were prospective but not enough of the subjects to conclude. Very recently, the new protocol of randomized, prospective, large-number study has been published [20]. The result of this study, which has not been opened yet as of November 2022, maybe promising and conclusive.