1 Boezaart_CH01.qxd 4/26/06 12:30 PM Page 1 Part I General Principles
2 Boezaart_CH01.qxd 4/26/06 12:30 PM Page 2
3 Boezaart_CH01.qxd 4/26/06 12:30 PM Page 3 CHAPTER 1 Orthopaedic Anesthesia as a Subspecialty of Anesthesia JACQUES E. CHELLY In the Preface to this book, the editor has pointed out that approximately 30 percent of all major surgical procedures in the United States now involve orthopaedic surgery. If any quantitative justification for the importance of orthopaedic anesthesia is still needed, this should suffice. The comprehensive survey presented in the following pages is, therefore, timely and appropriate. Orthopaedic anesthesia has developed into a full fledged subspecialty of anesthesia and is now widely accepted. The writing of a detailed account of this development must be left to those colleagues who busy themselves with medical history. In this chapter, I can only indicate briefly and in general, a few factors which, to a large extent have contributed to this development. There can be little doubt that the growth of orthopaedic anesthesia into a subspecialty has to a large extent been promoted by developments in orthopaedic surgery. Over the past 50 years, the focus of orthopaedic surgery has shifted from trauma to joint replacement, sports medicine, and spinal surgery with several subspecializations in between. Today increasing numbers of orthopaedic surgeons restrict themselves to highly specialized fields. Surgeons who initially specialized in joint replacements now specialize, more specifically, in knee, hip or ankle replacement. Other orthopaedic subspecializations include orthopaedic oncology and pediatric orthopaedic surgery, while spinal surgery has become a subspecialty shared with neurosurgeons. Among the factors that have led to these changes are advances in endoscopic techniques as well as the development of biocompatible materials, imaging equipment, and computer-guided techniques. The increasing numbers of the elderly and the resultant greater demand for joint replacements has also had a major impact on the practice of orthopaedic surgery. Meanwhile, it has become increasingly clear that a successful outcome with many of the new operative procedures depends to a significant extent on the use of specific and specialized anesthetic techniques during surgery and in postoperative pain management. In this respect, regional anesthesia and continuous nerve blocks have been preeminent. These techniques are, for example, especially important when surgery is done on an outpatient basis. Orthopaedic surgeons and hospital administrators now increasingly acknowledge the fact that orthopaedic anesthesiologists play a key role in promoting the speedy functional recovery of patients, thus decreasing the length of their hospitalization. The use of neuraxial and peripheral nerve blocks is obviously not restricted to orthopaedic surgery. However, it often requires specialized knowledge and skills in the orthopaedic setting. For example, patients who undergo minimally invasive knee or hip surgery on an outpatient basis must be able to tolerate weight bearing during physical therapy within hours of surgery. This is made possible by using specific regional anesthetic techniques that differ from those used in, for example, cesarean sections or hysterectomies. Immediate or speedy postoperative functional recovery without any residual motor block is required in such instances. This is achieved with spinal or epidural anesthesia that utilize minidoses of local anesthetic. The complexity and unique features of many modern orthopaedic operations also require specialized knowledge
4 Boezaart_CH01.qxd 4/26/06 12:30 PM Page 4 TABLE 1-1. ORTHOPAEDIC MARKET OVERVIEW Orthopaedic procedures * Inpatient 3,795,000 3,719,100 3,644,718 3,571,824 3,500,387 3,430,379 3,361,772 3,294,536 3,228,646 3,164,073 3,100,791 3,038,775 2,978,000 Outpatient 4,200,000 4,284,000 4,369,680 4,457,074 4,546,215 4,637,139 4,729,882 4,824,480 4,920,969 5,019,389 5,119,777 5,222,172 5,326,616 Total 7,995,000 8,003,100 8,014,398 8,028,898 8,046,602 8,067,518 8,091,654 8,119,016 8,149,615 8,183,462 8,220,568 8,260,947 8,304,616 procedures Estimated number of procedures indicated for PNB 5,138,544 5,271,252 5,416,762 5,597,237 5,798,172 6,012,683 6,241,959 6,487,302 6,750,138 Shoulder procedures Hip arthroplasty Knee replacement Other fracture treatments 229, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,000 PNB = peripheral nerve blocks. *Estimates and projections based on MDI 1998 RP611117, American Academy of Orthopedic Surgeons ( ), National Center for Health Statistics ( ). Estimates generated by Medtech Insight (1/03 5/03).
5 Boezaart_CH01.qxd 4/26/06 12:30 PM Page 5 CHAPTER 1 ORTHOPAEDIC ANESTHESIA AS A SUBSPECIALTY OF ANESTHESIA 5 from the anesthesiologist. The anesthesiologist must, for example, be fully aware of and conversant with the possible complications associated with different specific orthopaedic surgical procedures, such as rimming of the bone and the use of bone cement. In addition, the difficulty involved in bone hemostasis requires special vigilance in estimating blood loss. An optimal outcome in orthopaedic surgery is very difficult to achieve if the anesthesiologist does not have a thorough understanding of the technical aspects of an operation. Knowledge of the specific positioning of the patient, the duration of the operation, and the specific complications that a given procedures may entail is therefore essential in orthopaedic anesthesia. The surgeon s choice of anticoagulant may, for instance, determine the regional anesthetic technique used for a particular operation and for postoperative pain management. Serious complications have occurred when epidural anesthesia was used without considering the pharmacokinetics of the drug used prophylactically to prevent deep venous thrombosis and pulmonary emboli. Although, there are guidelines to help the anesthesiologist. The catastrophic consequences of epidural hematomas have led many practitioners to view the use of antithrombotic drugs as an absolute contraindication to the use of epidural analgesia. In orthopaedic surgery, it is now not unusual to perform operations for hip fractures in the elderly population (85 to 90 years of age) or joint replacements in the obese population (130 kg or more). The orthopaedic anesthesiologist should be aware of the fact that, in younger patients, the use of 27-gauge needles reduces the incidence of postpuncture headache. In the very elderly, this complication occurs less frequently, so that lower-gauge needles (25 or even 22 gauge) can be used. Many elderly patients with arthritis of the hip or knee also suffer from arthritis of the spine. In these cases it is better to use sharp spinal needles. A final example of the problems that have promoted orthopaedic anesthesia as a subspecialty is the fact that given surgical protocols must consider not only the operations but also the postoperative requirements, especially those related to pain management at rest and during mobilization. Thus, in traditional hip replacement, the patient undergoes minimal physical therapy on the first postoperative day, so that speedy motor recovery is not necessary. In these cases pain is mainly managed while the patient is resting in bed. In contrast, patients who undergo minimally invasive hip replacement have to be able to tolerate extensive physical therapy within hours of surgery. Here, complete recovery of motor function is essential. This may be best achieved with a multimodal approach to pain management that commences before surgery. Because of this, it is important that anesthesiologists and acute pain specialists work closely together. Anesthesiologist groups who specialize in both orthopaedic anesthesia and acute pain management achieve this best. In our institution, one anesthesiologist is responsible for the anesthesia and another for the postoperative pain management. Because all of the anesthesiologists within our institution rotate between these two functions and follow established protocols, it is easier to distribute responsibility. This is not always possible when anesthesiologists and pain specialists work independently. In this chapter, I have attempted to indicate, by means of a few examples, some of the factors that have contributed to the development of orthopaedic anesthesia into a subspecialty. There is no doubt that this subspecialty will continue to develop and to grow in stature. The data in Table 1-1 below give a clear indication of the future of orthopaedic anesthesia and acute pain relief.
6 Boezaart_CH01.qxd 4/26/06 12:30 PM Page 6