Christina M. Spofford, Peter Foldes, and John Laur
An increasing number of patients are undergoing surgical procedures in hospital outpatient departments (HOPDs) or ambulatory surgery centers (ASCs). Outpatient surgical procedures have become more complex, and patients are presenting for surgery with a greater number of comorbid conditions than in the past. Regional anesthesia (RA) and peripheral nerve blocks (PNBs) can help meet the goals of caring for these patients in the outpatient setting.
In 1976, there were 67 Medicare-certified ASCs in the United States, and in 2011, there were 5,344. In 1982, 30 ambulatory surgical procedures were covered by Medicare; today there are hundreds. In an analysis of National Survey of Ambulatory Surgery (NSAS) data, Tighe et al. found that 15% of an estimated 4 million orthopedic outpatient cases implemented a “regional block” as part of the anesthetic used. Over 580,000 PNBs were performed in HOPDs or ASCs in 2006.
From 2006 to 2010, outpatient services per Medicare enrollee increased by 5.7% annually. In 2011, the rate increased by 1.9%, accounting for $3.4 billion in charges, a 2.2% increase from 2010. Currently, about 57 million outpatient procedures (surgical and nonsurgical) are performed in the United States at a cost of $3.2 billion. In 2014, over 3 million of these cases are estimated to be orthopedic procedures. At some institutions, including the authors’, most PNBs are performed for orthopedic cases. Based on NSAS data from 1996 through 2006, arthroscopic knee procedures in the U.S. increased by 49%. As minimally invasive surgery becomes available for surgeries that require an inpatient stay due to the severity of postoperative pain, RA can allow for safe same-day discharge. A study by Koenig and Gu indicated that the growth of ASCs may reduce Medicare spending due to lower reimbursements relative to number of hospitals. There is preliminary evidence that outcomes at ASCs are better than those at in-hospital settings for similar otolaryngologic surgical cases. Future research in this area needs to be completed for other services.
With the growth in both complex outpatient surgeries and ASCs, there is a need for more anesthesiologists with specific training in the use of acute pain medicine with integrated RA and PNB techniques. With the use of these techniques, the first priority should be on safety, the second on reducing patient pain and minimizing opioid and general anesthesia (GA) side effects, the third on economics, and the fourth on efficiency.
Outpatient Surgery Stakeholders
Patients, providers, payers, and “internal customers,” including anesthesiologists, nurses, and support staff,may have differing views on the value on the various outpatient operational and clinical outcomes. In healthcare, value is defined as patient outcome per costs used to achieve those outcomes. For payers, value consists of providing a service with good outcome at a lower cost than competitors. Typically, a standalone outpatient surgery center can provide patient care with greater patient convenience and lower overhead costs than a hospital outpatient surgery department. Busy surgeons focus on ASC efficiency and understand the value of RA and PNBs, but they may object to additional procedures that could delay surgery. The available data, however, point out that greater than half of surgery-start delays are caused by the surgeon rather than nerve block placement. Factors that contribute to delays include the need for surgical consent, updating the patient’s medical history and performing the physical examination, the patient’s desire to speak with the surgeon prior to going to the operating room (OR), and the need for additional preoperative testing.
Anesthesiologists work to provide safe high-quality care by applying methods that reduce or prevent adverse events and side-effects. Minimizing or eliminating nausea, vomiting, and pain are important for maintaining patient satisfaction. Secondary goals for anesthesiologists include accurate and fast RA placement and nerve block onset, sufficient duration of analgesia, avoidance of “rebound pain” when the nerve block resolves, post-anesthesia care unit (PACU) bypass, and rapid patient discharge from the facility. Avoiding side effects, hence bypassing the PACU, can reduce hospital costs by an estimated 12% while still meeting the goals of the surgeons, anesthesiologists, payers, and patients.
Patients fear nausea, vomiting, gagging on the endotracheal tube, surgical pain, recall, residual weakness, shivering, sore throat, and somnolence. They wish to experience restful sleep and then return to work and physical function with little pain or motor block. Most of these patient-centric goals can be achieved by designing an appropriate anesthesia regimen tailored to the patient and surgical procedure(s). In many cases, the use of RA achieves these goals.
- The anesthesiologist’s priorities are (1) safety; (2) reducing patient pain and minimizing opioid and GA side effects; (3) economics; and (4) efficiency.
- Factors that contribute to surgery-start delays include the need for surgical consent, updating the patient’s medical history and performing the physical examination, the patient’s desire to speak with the surgeon prior to going to the OR, and the need for additional preoperative testing.
- Hospital costs can be reduced by bypassing the PACU while meeting the goals of the surgeon, anesthesiologist, payers, and patient through the avoidance of side effects.
- Most patient-centric goals can be achieved by designing an appropriate anesthesia regimen tailored to the patient and surgical procedure(s).
Defining Outpatient Regional Anesthesia Success
There are multiple, and possibly overlapping, metrics defining outpatient RA success. A single set of outcomes may not please all stakeholders. In randomized, controlled trials (RCTs), success is determined by avoiding the following: conversion to GA, loss of sensation to pin-prick or cold, loss of motor function, and time to first pain medication request. Many RCTs ask about patient satisfaction with RA, and it is important to understand what patients prefer with respect to outcomes after RA. Recently, a validated, multidimensional, self-reported questionnaire was created to assess RA in the outpatient surgery setting.
Factors included avoiding RA-related delays and complications, providing anesthesia during the surgical procedure and continuing adequate postoperative analgesia, reducing the costs of drugs and equipment, reducing patient time spent in the healthcare facility, avoiding unplanned hospital admissions, ensuring patient satisfaction, maintaining postoperative function (particularly with a partially or wholly insensate body region), safety at home, and other clinical and economic outcomes. Motor weakness can be desirable for surgery yet is often undesirable afterward when physical therapy is necessary or patients want to walk or hold an object. While acknowledging that RA is superior to GA in terms of pain control and reduction of postoperative nausea and vomiting, orthopedic surgeons often report avoiding RA due to case-start delays and unpredictable RA success.
Numerous factors must be taken into account in the outpatient surgery setting, including avoiding RArelated delays and complications, providing anesthesia during the surgical procedure and continuing adequate postoperative analgesia, reducing the costs of drugs and equipment, reducing patient time spent in the healthcare facility, avoiding unplanned hospital admissions, ensuring patient satisfaction, maintaining postoperative function (particularly with a partially or wholly insensate body region), safety at home, and other clinical and economic outcomes.
Peripheral Nerve Blocks and Multimodal Analgesia
Managing postoperative pain with minimal side effects is an important factor in determining if a surgical case can proceed in an outpatient setting. An anesthesiologist has an armamentarium of agents and methods to provide multimodal analgesic therapy. Boezaart and Tighe contend that PNBs are an inherent part of the rapidly developing field of acute pain medicine that they remark should focus on the patient and his or her pain control. In an outpatient setting, RA with PNBs is a cornerstones of multimodal analgesia and opioid-sparing strategies. High-dose opioids can cause hyperalgesia by activating neurons and glial cells. Furthermore, potent opioids, such as remifentanil and fentanyl, can cause hyperalgesia and rapid tolerance in humans. Other undesirable side effects are nausea, somnolence, and respiratory depression, all which are highly undesirable in the outpatient setting.
Well-planned multimodal analgesia is important in the ambulatory surgery setting for several reasons. First, patients prefer to avoid side effects such as nausea, vomiting, and somnolence. Second, uncontrolled side effects can result in unplanned hospital admission, which is costly and inconvenient for all parties. Third, the use of multimodal analgesia has the potential for real synergistic positive effects while also reducing the likelihood of serious side effects. Lastly, multimodal analgesic regimens improve the likelihood of early recovery.
One example is the same-day discharge of patients undergoing unicompartment knee replacement surgery. By utilizing a continuous femoral nerve block and minimizing opioids as part of a multimodal analgesia regimen, these patients can safely undergo surgery in an ASC.
Used in a multimodal analgesic regimen, gabapentinoids, nonsteroidal anti-inflammatory drugs (NSAIDs), acyclooxygenase-1 and -2 (COX-1 and COX-2) inhibitors, glucocorticoids, ketamine, clonidine, and lidocaine infusions can reduce postoperative opioid use by 20%–60%. Intravenous lidocaine infusions have demonstrated a preventive analgesic effect lasting from 8.5 to 72 hours, which is greater than 5.5 lidocaine half-lives. Local anesthetics may reduce pain scores and opioid consumption when administered via PNB or the intravenous route (using lidocaine), although the evidence for this is sometimes contradictory.
Some facilities are performing “fast-track” total hip and knee replacement surgeries in an outpatient setting with 23-hour observation. The American Academy of Orthopaedic Surgeons guidelines on preventing venous thromboembolism recommends neuraxial anesthesia during hip and knee replacement procedures to reduce blood loss. In fact, due to its superior analgesia in joint replacement surgery, RA is the centerpiece of a multimodal analgesia algorithm in such surgeries.
- PNBs have progressed to become a component of the larger field of acute pain medicine that focuses on the patients and their pain control.
- In the outpatient setting, RA with PNBs is the cornerstone of multimodal analgesia.
Nerve Blocks in Outpatients
A wide variety of PNBs can be used in the ambulatory setting, including upper and lower extremity blocks, truncal blocks, and head-and-neck PNBs (Table 1). Moreover, neuraxial RA techniques can achieve outpatient anesthesia goals. In an ambulatory setting, surgeon-performed blocks can also be timely, cost-effective, and remarkably safe. Done at the time of the procedure, they often include rapidly acting local anesthetics. Some of the most commonly used peripheral nerve blocks are listed in Table 2.
TABLE 1. Peripheral nerve blocks.
|Upper Extremity PNBs||Lower Extremity PNBs||Truncal Blocks|
|Cervical paravertebral||Subgluteal sciatic||Thoracic paravertebral|
|Interscalene||Femoral||Transverse abdominis plane
TABLE 2. Commonly used regional anesthesia blocks.
|Service||Type of Block|
|Orthopedics||Joint injections, local infiltration|
|Vascular surgery||Cervical plexus blocks|
One strategy to decrease onset time is to add mepivacaine to the longer-acting local anesthetics that are traditionally used (eg, ropivacaine, bupivacaine), albeit at the cost of shortening the duration of the block. The best strategy is to have one provider perform the nerve block in the block room and have the other providers remain in the operating room. This procedure prevents delays in turnover, optimizes care by having a dedicated person providing specialized care, and creates a team atmosphere. This model can either be expensive or pay for itself, depending on the system and methods of reimbursement for care. For example, it can be cost prohibitive in practices where there are too few blocks placed in a single day or too few personnel trained in peripheral nerve block.
Peripheral Nerve Blocks and Adjuvants
Regional anesthesiologists combine local anesthetics with adjuvant drugs to achieve prolonged analgesia, reduce local anesthetic dose to avoid toxicity, and potentially reduce motor block. Clinical doses of clonidine, buprenorphine, dexamethasone, and midazolam have no neurotoxicity in vitro. These drugs are thought to act through an indirect mechanism without influencing the potency or duration of the local anesthetic, specifically ropivacaine or lidocaine.
Providing surgical anesthesia and then maintaining the patient’s motor strength while achieving postoperative analgesia may be difficult with single local injections. Adjuvants can prolong analgesia duration with single-injection PNBs. This application reduces the mechanical, logistical, billing, and clinical management hurdles associated with outpatient indwelling PNB catheters and improves patient convenience. While clonidine and dexmedetomidine may prolong analgesic duration in some blocks, these agents may not have the same benefit in other blocks (eg, sciatic) when combined with a long-acting local anesthetic. The undesirable side effects of clonidine (and other alpha-2 blockers) include hypotension, bradycardia, orthostatic hypotension, and sedation. Clonidine increases the duration of motor block, which may or may not be desirable depending on the type of surgery.
Dexamethasone is an adjuvant that can enhance or prolong the duration of analgesia when injected perineurally or intravenously. Recent work suggests that perineural adjuvants can control post-surgical pain while sparing motor strength. However, safety data on perineural injections in animals are limited, and human safety data are also lacking. Most PNB adjuvant drugs are used off label in the U.S. Learn more following the link to Analgesic Adjuvants in the Peripheral Nervous System.
- Clinical doses of clonidine, buprenorphine, dexamethasone, and midazolam have been shown to have no neurotoxicity in vitro.
- Adjuvants may prolong analgesia duration with ssingle injection PNBs. Dexamethasone enhances and prolongs analgesia injected perineurally or intravenously.
Sedation for Ambulatory Peripheral Nerve Blocks
Patients having surgery on an outpatient basis are typically healthier than patients having surgery as inpatients and may have limited or no previous experience with surgery. Many patients undergoing surgical procedures experience preoperative anxiety. In an effort to improve the perioperative experience, short-acting anxiolytic agents and/or other medications (eg, midazolam, opioids, ketamine, gabapentinoids) are often given before a PNB is placed. Historically, the placement of a PNB using anatomical landmarks has led to multiple attempts at nerve location (ie, seeking a specific motor response to electrical nerve stimulation). Adding nerve stimulation can help confirm proper needle location but may cause considerable discomfort to the patient. Even with ultrasound guidance and the use of local anesthetics to anesthetize the needle pathway, many patients benefit from judicious premedication before undergoing PNB. Heavy premedication, however, may lead to loss of airway tone and subsequent hypoxia and hypercapnia.
Premedicating patients judiciously while maintaining a meaningful patient contact may improve the patient’s experience and allow for beneficial patient feedback during the procedure.
From a cost perspective, premedicated patients require bedside monitoring, and more personnel may be required depending on the physical layout, surgical case workload, and current staffing levels. Furthermore, heavily premedicated patients may take longer to recover and need to remain within the surgical center longer, resulting in patient dissatisfaction. Lastly, from a patient satisfaction perspective, patients may appreciate ongoing dialogue and reassurance as the block is being placed and the opportunity of being an active participant in their care.
In an effort to reduce patient wait times, patients are instructed to arrive close to the time of surgical start based on mathematical principles.
The Block Team and Block Nurse
In academic training centers, residents and fellows can be organized into block teams. These teams can provide safe and efficient RA while allowing trainees to focus on a single aspect of their education. A multidisciplinary group at Duke University initiated a “block nurse” team in 2010. Block nurses completed a focused training program that emphasized patient flow, educating and preparing patients, assisting anesthesiologists, monitoring patients, and enhancing safety during the pre, intra- and post-procedure periods. Within a year, rapid OR turnover time increased by 26%, OR on-time starts increased by 7%, orthopedic cases receiving preoperative blocks increased by 19%, and patient safety (eg, no wrong-sided blocks) improved. While resources are lean at free-standing ASCs, the block nurse concept could perhaps be incorporated into an existing nursing team, thus potentially improving a facility’s processes by increasing the number of patients who can benefit from preoperative PNB, increasing PACU bypass rates, and improving patient satisfaction.
PACU Bypass Criteria
Fast-tracking patients is an important goal of ambulatory anesthesia strategy. In a meta-analysis by Liu et al. of 15 trials including 1003 patients given central neuraxial block (CNB) and 7 trials of 359 patients given PNB, for RA versus GA, induction time was increased 9 minutes. There was a greater PACU bypass with PNB versus CNB, perhaps due to lack of a formal PACU bypass criteria for CNB patients. The odds of bypassing PACU using PNB was 14 times greater compared to GA. Both PNB and CNB patients reported an increased satisfaction level compared to GA patients, though PNB patient satisfaction was much higher than those having CNB. Patients receiving regional anesthesia reported lower pain scores, had less need of analgesics, and experienced less nausea and vomiting.
Williams et al. and others who matched interventional technique to surgical pain have remarked on the possibility of “rebound pain,” that is, pain above baseline that patients experience after a nerve block resolves.
Breast surgery on an outpatient basis using thoracic paravertebral blocks is another good example of the benefits of PNBs. A review article by Thavaneswaran et al. has shown that length of stay was reduced for breast surgery when using paravertebral block versus GA alone. Length of hospital stay, postoperative nausea and vomiting, and patient satisfaction were improved over GA (relative risk 0.25; 95% CI 0.13–0.50).
Read more about Developing Regional Anesthesia Pathways.
- In the fast-paced outpatient setting, assistance in setting up equipment, preparing and positioning patients, monitoring patients after block, and educating patients regarding safety and protection of insensate body regions are important.
Through 2007, most literature reports on RA outcomes were based on neuraxial techniques. Since 2007, more literature has been published focusing on PNBs in outpatient surgery settings.
Improved outcomes from neuraxial use in the outpatient surgery setting include improved short-term and long-term pain control, reduced surgical stress, improved gastrointestinal function, lower rates of postoperative nausea and vomiting, and fewer unplanned admissions or readmissions. More physiologically significant outcomes include reductions in perioperative myocardial infarction, pulmonary complications, and mortality. However, a systematic study of these outcomes in ambulatory patients has not been published, and it is unclear whether outpatient surgical patients would achieve the same benefit.
In an effort to improve care after colorectal surgery, a working group analyzed outcomes from randomized controlled trials published through 2007 for colorectal surgeries and created recommendations for the use of thoracic epidural catheters, avoiding long-acting opioids, reducing the amount of time under GA, and preventing gut paralysis. Epidurals provide efficient analgesia, reduce surgical stress responses, and minimize the side effects of systemic opioid administration (pulmonary, gastrointestinal, and cognitive dysfunction). Once RA methods are discontinued, the use of NSAIDs further reduces or avoids the need for opioid administration and their side effects. RA has been demonstrated to improve outcomes such as mortality, major morbidity, and rehabilitation.
Since superior pain control has been shown with the use of RA, focus on functional outcome improvement has become paramount. This requires the ability to measure outcomes accurately. For outpatient RA outcomes, some measures include electromechanical dynamometer, which measures motor contraction; the 36-item Short Form Health Survey (SF-36), which measures physical and mental status before and after surgery; and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), which assesses pain and stiffness in the hips and knees. The recently validated Patient Reported Outcome Measurement Information System (PROMIS) is a computerized, adaptive test that provides an excellent method for assessing outcomes in patients who have had a foot or ankle surgery.
In recent years, functional outcome studies comparing RA to GA have shown a tendency toward improved early outcomes with RA. Patients undergoing stable fixation of distal radius fracture under brachial plexus block demonstrated improved pain scores and better wrist and finger motion at all time points during follow-up compared to GA. Disabilities of the Arm, Shoulder and Hand (DASH) scores also demonstrated higher function at both 3 and 6 months (P = 0.04 and P = 0.02, respectively).
Spinal anesthesia is used for outpatient lower extremity surgery. Compared to GA, patients undergoing ankle fracture fixation under spinal anesthesia reported improved early pain scores and function as measured by the American Orthopaedic Foot and Ankle Society Clinical Rating Scale at 3 months (mean [SD] 81.7 [11.9] vs 78.1 [15.2], P = 0.02). At 6 months, spinal patients had lower pain scores (P = 0.04). Functional outcomes for the spinal group were not statistically significant by 6 and 12 months.
RA has been demonstrated to improve outcomes such as mortality, major morbidity, and rehabilitation.
Complications in the Ambulatory Setting
Complications of regional anesthesia range from minor sensory deficits that resolve within weeks to devastating injuries that result in permanent nerve injury, strokes, and on occasion, death. Cardiac dysrhythmias can occur as late as 30–75 minutes after the injection of local anesthetics and may be intractable despite adherence to advanced cardiac life support guidelines. This delayed response highlights the need for continuous monitoring of patients in the block area as well as the operating room. Although uncommon, local anesthetic systemic toxicity (LAST) can be a life-threatening complication for patients. Guidelines on the care of patients with LAST include airway management, prevent hyperventilation (to avoid an increase in seizure threshold), and treating a seizure if it occurs, intravenous lipid emulsion therapy, and transfer to a tertiary care setting with cardiopulmonary bypass capability. Ambulatory facilities should consider creating LAST kits with checklists that are housed in the areas where blocks are performed. Fortunately, ultrasound guidance coupled with decreasing doses and volumes of local anesthetics required for successful nerve block have resulted in a substantial decrease in the risk of LAST, a trend likely to continue as ultrasound-guided techniques become more refined.
Other complications, such as wrong-sided blocks, can be greatly reduced by adherence to established time-out policies. Block site marking, as well as encouraging patients to engage in dialogue during block placement, can reinforce a culture of safety. Permanent nerve injuries, with subsequent long-term morbidity and/or disability, are uncommon. The development of more objective methods of monitoring needle placement and administering local anesthetics, such as ultrasound guidance, low-current nerve stimulation, and opening injection pressure monitoring are likely to even further decrease the risk of intrafascicular injection and neurologic injury. When present, however, intrafascicular injections and neurologic injuries require a thorough evaluation, and expert consultation by a neurologist should be considered.
When an RA complication occurs, prompt and well-planned disclosure is warranted. When possible, a quiet, private area is required for patient and family disclosure. Anesthesiologists should have another member of the healthcare team present during the disclosure. The provider should investigate how much is known about the adverse event and how much detail the patient and family require. With empathy, knowledge of the event needs to be conveyed in a manner that is clear and understandable. This often requires planned pauses, repetition of information, reassurance, and open body language. Saying “I’m sorry this event happened to you” does not imply fault; rather, it is a statement of empathy about the adverse event and the subsequent pain, suffering, or other inconvenience that may have been experienced. Lastly, all disclosure discussions need to be documented and patients and/or family need to have a mechanism for further follow-up. Several studies suggest that thoughtful and prompt disclosure of adverse events or complications results in less legal action and possibly less emotional impact on the provider.
- Guidelines on the care of patients who experience toxic reactions from local anesthetics include airway management, hyperventilation on prevention, seizure control, intravenous lipid emulsion therapy, and consideration of transfer to a tertiary care setting with cardiopulmonary bypass capability.
- Ambulatory facilities should develop LAST kits with checklists that are housed in the area where blocks are performed.
- Thoughtful and prompt disclosure of adverse events or complications may prevent or lessen the legal action and diminish the emotional impact on all parties.
Objective monitoring of the needle–nerve relationship and injection process during PNB, such as via ultrasound guidance, low-current intensity nerve stimulation, and avoidance of high opening injection pressures (> 15 psi), can further decrease the risk of already uncommon neurologic complications.
Peripheral Nerve Blocks and Outpatient Surgery Economics
Patient satisfaction, while perhaps intuitive in some ways, is not easily measured in a scientifically valid manner. In the United States, patient satisfaction and whether patients would recommend their family or friends to have surgery at a facility or institution are correlated with improved operating revenue margins. A new patient-centered assessment by Szamburski et al. is the first psychometrically evaluated, internally and externally validated patient satisfaction instrument developed to date. This new measure may prove useful in future work investigating linkages between RA and outcomes or economic indicators.
Physician-owned free-standing ASCs, through a profit motive, may be an incentive for physicians to divert cases from hospital operating rooms to their own centers. ASCs have lower overhead than hospitals but are paid less by Medicare.
Physicians may also choose to steer their patients toward ASCs based on nonfinancial factors, such as convenience, enhanced patient experience, ease of scheduling, and the ability to complete more cases per day than in a hospital environment. An analysis of the 1996 and 2006 NSAS data found that a 10% increase in profit (facility fees, not professional fees) was associated with a 1.2%–1.4% increase in the probability that a surgery would be performed at an ASC.
The presence and type of insurance also influ ence the choice to provide a PNB. When compared with self-pay patients or those receiving charity care, patients with government-paid care or private insurance were roughly 2.5 times more likely to receive a nerve block. However, this association is not necessarily causal, and other confounding factors are likely to be involved. Hospital revenue streams may be reduced as patients are recruited to have surgery at nonhospital ASCs. This may lower societal healthcare costs since ASCs are reimbursed at lower rates and have lower overhead costs than hospitals for a given procedure.
By implementing RA techniques, facilities can potentially lower costs and enhance efficiency. One report demonstrated that when RA is used in a hospital at a rate higher than the median of its competing hospitals, that hospital can reduce patient length of stay and increase profit per diagnosis-related group (DRG) while also increasing patient satisfaction and reducing complications.
- By implementing RA techniques, facilities may be able to lower costs and enhance efficiency.
- Hospitals that use RA at a rate higher than the median of competing hospitals may reduce patient length of stay and increase profit per DRG while increasing patient
satisfaction and reducing complications.
Outpatient surgical cases are increasing, and regional anesthetic techniques, including PNB, are amenable to the types of cases performed in the outpatient setting. RA and PNBs can benefit patients by avoiding the side effects of GA and opioids. RA techniques and the use of local anesthetics are a major component of a multimodal analgesia and anesthesia plan. RA techniques offer improved patient outcomes, do not disproportionately delay case start time, can improve fast-tracking of patients, and may enhance economic outcomes for a facility. Complications may occur, however, and providers should be prepared to handle these situations appropriately, particularly in a standalone ASC with fewer resources than hospitals.
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