Patients undergoing regional or general anesthesia are at increased risk because normal muscle tone and pain sensations that enable the body to adjust itself in response to excessive pressure are disabled. Patients often are placed in positions that they would not be able to tolerate comfortably if they were awake or even asleep without the use of anesthetics. Anesthesia also causes hypotension, which can reduce tissue perfusion and thus reduce the exchange of oxygen and carbon dioxide. Connor and colleagues (2010) found that prolonged hypotension is a valid predictor of pressure ulcer risk in the OR. All these anesthetic effects can heighten the effect of pressure forces, particularly if other comorbid conditions are present.

A study by Fred and colleagues (2012) shows that patients with at least a 1° F (1.8° C) drop in temperature may be at increased risk for intraoperatively acquired pressure ulcers. Hypothermia is the frequent result of the cooler OR environment, exposure of external and internal body surfaces, and infusion and irrigation with unwarmed solutions. This causes peripheral vessels to constrict to conserve core temperature and increases the patient’s heat metabolism. This increased metabolism leads to increased tissue needs for oxygen, nutrients, and metabolic waste-product removal. When tissue is under pressure, these needs are not easily met. When hypothermic patients later emerge from general anesthesia, they often shiver, which further increases their oxygen requirements and may increase their risk for pressure ulcers as well as myocardial infarction. Minimizing intraoperative hypothermia thus is imperative.

Ways to offset hypothermia in the OR and to reduce its detrimental effects include using forced-air warming therapy over the patient. Avoid placing a warming blanket under the patient in the area where pressures are greatest because tissue requirements tend to increase there and the effect of tissue ischemia may be more profound. Minimize unnecessary skin exposure and use warm irrigation fluids, especially deep inside the body cavity. To warm IV fluids, insert a fluid-warming coil or place most of the IV fluid tubing under the forced-air warming blanket.

The type of surgery performed can affect pressure ulcer development. Patients who undergo cardiac, general, thoracic, and vascular procedures tend to be at greater risk, possibly because these cases immobilize patients for long periods (Denholm, 2008). In addition, procedures that involve significant blood loss, extracorporeal circulation, and clamping of major vessels can contribute to the lack of blood flow to tissue under pressure.

The type of positioning devices used can increase pressure ulcer development risk as well. Rigid, unpadded objects that press against a body surface, such as stirrup bars, compressed beanbags, or rolled sheets, can cause tissue injury if pressure is not relieved periodically.

Negativity, as explained earlier, can override the pressure-relieving capabilities of mattresses and padding. Placing a warm blanket under a patient may be soothing initially, but if a surgical procedure is long, pressure to the bony prominences resting on the blanket will be greater than if only a sheet and drawsheet are used. Additionally, wrinkles and folds can cause further pressure points.

When a patient is moved into a shear-producing position (e.g., from supine to semi-Fowler) before being prepped and draped, the OR team can take measures to reduce shear forces. One technique is to slightly move the patient’s back away from the mattress momentarily to allow the skin to realign with its surrounding skeletal structures. When the patient is placed in these positions during a surgical procedure, however, interventions to reduce shear forces are limited. Reducing the time that shear forces are in place is the best measure to reduce tissue injury.

Intrinsic factors lower a patient’s tissue tolerance to pressure and decrease the time and pressure required for tissue breakdown. Certain preexisting conditions are regarded as intrinsic risk factors for OR-induced pressure ulcer development. These conditions include diabetes mellitus, smoking, peripheral vascular disease, cerebral vascular disease, urinary or fecal incontinence, anemia, malignancy, sepsis, steroid use, morbid obesity, malnutrition (serum albumin levels less than 3.5 g/dL), advanced age, body size (obesity as well as thin, frail build), and impaired mobility (Connor et al, 2010; Cox, 2011; Denholm, 2008; Lyder and Ayello, 2008; Munro, 2010; Primiano, 2011; Walton-Geer, 2009).

Various scales exist to determine pressure ulcer potential. One widely used is the Braden Scale, which scores a patient’s potential for pressure sore development based on various intrinsic factors. It is valid and reliable in acute care and long-term care settings and has been used for many years to guide nursing interventions. It does not take into account, however, various extrinsic factors patients are subjected to in critical care areas such as the OR or the intensive care unit (ICU), in both of which immobile patients are completely dependent on caregivers to sustain their fragile hemodynamic status and where routine, timely repositioning may be contraindicated.

Recent studies have tested the relevance of the Braden Scale in the perioperative setting (Connor et al, 2010; Galvin and Curley, 2012) and the medical-surgical ICU setting (Cox, 2011, Suriadi et al, 2008). These studies concluded that not all Braden Scale risk factors are predictable in these patients and that other significant risk factors are not identified on Braden or other pressure ulcer predictive scales used in hospital settings. The Braden score may be used as a preoperative baseline, but the OR is unique when compared with other areas of the hospital. Typical predictors of pressure ulcer risks may not work once anesthetized, immobile patients are put in atypical positions for varying lengths of time, which may disrupt their cardiovascular, hemodynamic, and thermoregulation statuses. This potential disruption underscores the suggestion by Walton-Geer (2009) and others that all surgical patients should be considered at risk to develop pressure ulcers. Some patients are at a higher risk than others, and risk assessment scales need to be developed specific to the perioperative patient. Several nursing studies (Connor et al, 2010; Galvin and Curley, 2012; Primiano et al, 2011) have yielded perioperative variables usable to predict pressure ulcer development (Research Highlight). Some OR teams have developed their own perioperative risk assessment tools (Mathias, 2008; Munro, 2010), but these have not as yet been widely tested for validity and reliability.

Over the past decades multiple other studies with surgical patients have attempted to determine risk factors specific to this patient population. The problem with attempting to draw out distinct perioperative risk factors for pressure ulcer development that would apply on a general scale is that so many exist; risk factors vary substantially from hospital to hospital as to type and length of procedures, types of anesthesia, positions, positioning devices, mattress surfaces, patient warming methods, and unplanned surgical and anesthetic events, along with multiple and varying intrinsic factors such as age, weight and comorbidities. Even so, given our extant knowledge coupled with future research, a baseline perioperative pressure ulcer risk scale that could be individualized for each patient and situation would serve as a useful guide to perioperative nurses to plan and care for this patient population. Development of such a prospective scale, particularized for each surgical patient, remains an incomplete goal and unmet need of perioperative nursing.

Assessment for pressure ulcer risk factors and development nevertheless should be done consistently and aimed at three periods: preoperative, intraoperative, and postoperative. Such assessments should accompany the hand-off report to the nurse in the postanesthesia care unit (PACU) receiving the patient (see Chapter 10). Included in postoperative assessment is inspection for changes in skin temperature, color, moisture level, turgor, and integrity. These inspections start in the preoperative area and OR, continue in the PACU, and go beyond to discharge. It is in the early postoperative phase that many small problems picked up by astute assessments can be treated to avert bigger problems.

Stage I or stage II pressure ulcers (Figures 6-2 and 6-3) may be evident immediately after surgery. These areas must be kept free from additional pressure for healing to occur and to keep them from advancing to higher stages. Such ulcers are sometimes misidentified and treated inappropriately. Stage I pressure ulcers can look like normal erythema, a reaction to pressure in which the healthy tissue blanches when compressed and generally fades on its own in half to three quarters of the time that the area was under pressure, with little or no permanent tissue damage. Stage I pressure ulcers do not blanch when compressed. Failure to blanch is a serious sign, indicating that the compromised tissue is not receiving adequate oxygen and nutrients. The blistering or partial dermal loss that occurs in stage II pressure ulcers is often misidentified as a chemical or thermal burn. The lack of contact with a chemical or thermal agent in that area and its location under a bony prominence or near where a hard surface had been during surgery can help distinguish it as a serious stage II pressure ulcer.

Deep tissue injury (DTI) (Figure 6-4) must also be differentiated from a stage I or II pressure ulcer. Stage I ulcers present with discolored, nonblanchable, but intact skin, which is also true of a DTI. Instead of pink or red, however, the DTI is purple or maroon in appearance, like that of a deep bruise. Stage II ulcers present as an intact or open/ruptured serum filled blister, whereas a DTI blister fills with blood. The NPUAP added the DTI category to help identify a dangerous form of pressure ulcer in which deeper tissues are subjected to such a long duration of ischemia that reperfusion causes additional microvascular injury (reperfusion injury). What began in appearance as a closed discolored area rapidly deteriorates to a full-thickness stage III or IV pressure ulcer, even with optimal treatment. The epidemiology, clinical course, and efficacious treatment of DTIs require more research (NPUAP, Deep Tissue Injury, 2013).

Upper extremity neuropathies generate from lesions to the brachial plexus and the nerves that emerge from it. The brachial plexus consists of a bundle of nerve cords that run through the shoulder and innervate the lower shoulder, arm, and hand (Figure 6-5). This bundle originates from cervical spinal nerves C5-C8. The nerve cords emerge to form peripheral nerves. The axillary nerve innervates the deltoid muscle. The musculoskeletal nerve innervates the biceps muscle. Three main peripheral nerves run down the arm to the fingers: median, radial, and ulnar (Figure 6-6).

The median nerve runs through the antecubital space to the fingers and provides sensory and motor ability to the distal and palmar surfaces of the thumb and adjacent two fingers. A normally perceived pinprick to the palmar surface of the distal index finger generally would show that the median nerve was intact (Figure 6-7).

The radial nerve loops around the posterior humerus before it runs through the antecubital space to the fingers. It provides motor and sensory function to the triceps and the muscles of the posterior forearm and hand. Injury to this area can cause difficulty extending the wrist and thumb. If the distal thumb can be actively extended, this generally indicates an intact radial nerve (see Figure 6-7).

The ulnar nerve runs behind the elbow and innervates the third, fourth, and fifth fingers and the muscles of the medial forearm. It is responsible for wrist flexion and, along with the radial nerve, enables the thumb to oppose the other four fingers. A normally perceived pinprick over the plantar surface of the distal fifth finger generally indicates an intact ulnar nerve (see Figure 6-7).

The most common OR-related nerve injuries are to the ulnar nerve and brachial plexus. There is a good reason for this. As the ulnar nerve circles behind the elbow, it lies superficially in the shallow cubital tunnel of the humerus, where it is subject to pressure and to stretching from flexion of the elbow (Figure 6-8). The brachial plexus resides in the shoulder, which is subject to abduction, manipulation, and sometimes pressure, depending on position. The use of shoulder braces, to reduce sliding while in Trendelenburg position, should be avoided because braces can compress proximal nerve roots and stretch the brachial plexus. Arm abduction on armboards should be limited to 90 degrees or less. Avoid excessive head rotation, especially away from the abducted arm because doing so can stretch and compress the nerves between the clavicle and the first rib (Figure 6-9).

The brachial plexus can also suffer injury by the separation of the sternum during open cardiac procedures that require a median sternotomy. When splitting the sternum, a retractor is used to separate it, allowing access to the heart. This separation forces the ribs to move laterally. If internal mammary artery dissection occurs as part of the procedure, there is additional asymmetric retraction of the rib cage. The first rib compresses the brachial plexus nerve bundles and, in particular, the nerve cord that emerges into the ulnar nerve. If brachial plexus and ulnar neuropathies develop as a result, they generally are not preventable by proper positioning of the patient’s arm (Warner, 2009). Improper arm positioning, however, may worsen the insult of the injury.

Isolated ulnar nerve injuries arise primarily from pressure on the vulnerable location of that nerve. The ulnar nerve becomes superficial as it runs behind the elbow, nesting in the epicondyle groove of the humerus, which makes up the cubital tunnel. Ulnar nerve injuries occur primarily in male patients. Warner (2009) offers three anatomic differences between the elbows of men and women, which probably account for this gender anomaly:

The main goal in protecting the ulnar nerve is to eliminate pressure on it. Pressure on the medial aspect of the elbow may compress the ulnar nerve (see Figure 6-8, C). Figure 6-10 illustrates ways to prevent this pressure. Supination (palms up) of the forearms on an armboard (see Figure 6-10, A) places the olecranon of the elbow on the flat surface instead of the cubital tunnel, which contains the ulnar nerve. When the arm of a supine patient rests on the trunk, direct trauma can occur to the ulnar nerve as the weight of the arm presses the flexed elbow against the surface of the bed. Padding placed under the upper arm, proximal to the elbow, leaves a free space under the elbow, eliminating pressure on the nerve (see Figure 6-10, B). When a patient is prone (abdomen facing down) with arms pronated on armboards, the ulnar nerve is vulnerable to pressure from the elbow. Padding placed proximal and distal to the elbow frees the nerve from pressure (see Figure 6-10, C).

Many OR-induced peripheral upper extremity nerve injuries can be avoided by properly securing the arms when they are tucked at the patient’s side. The arms should be tucked in a way that prevents them from sliding down the side of the OR bed and contacting the bed edge or rigid bed attachments. An effective technique to prevent arm slippage during surgery is to wrap the drawsheet smoothly around the arm and then tuck the drawsheet under the patient’s body instead of under the mattress (Figure 6-11). This technique is useful in the supine and prone positions. It is best accomplished with an assistant on the other side of the OR bed, who rolls the patient’s body over enough to tuck the drawsheet underneath it. Care should be taken to ensure that the drawsheet is not tucked too tightly as to cause pressure to the arms. A tight fold pressing on the elbow could cause an isolated ulnar nerve injury.

Complete and thorough documentation of intraoperative measures taken to protect vulnerable nerves should include the following:

The common peroneal nerve branches from the sciatic nerve behind the knee and becomes superficial as it wraps around the lateral head of the fibula (Figures 6-12, 6-13, and 6-14). At this level, it is vulnerable to direct compression by stirrup bars. This risk may be increased in extremely thin patients who have minimal overlying tissue in this area. It is important to ensure that the lateral head of the fibula does not rest against stirrup bars or any other rigid surface. Compressive leg wraps (i.e., intermittent pneumatic compression devices, graduated compression stockings) also can put pressure on this nerve if the wrapping is too tight in this area. In addition, pressure behind the knee can compress the common peroneal and tibial nerves where they run through the popliteal fossa, so only soft padding or pillows should be used for knee support. The patient’s ability to dorsiflex the great toe (point it upward) indicates that the common peroneal nerve is intact.

The sciatic nerve originates from the L4-S3 spinal nerve roots and travels down the buttock and posterior thigh before it divides into the common peroneal and tibial nerves (see Figure 6-12). The stretching that occurs during hyperflexion of the hip may injure it. A patient who has had a total hip replacement may have some preexisting sciatic nerve damage as a result of the excessive rotation of the femur that is part of that operative procedure. Additionally, patients with a history of hip trauma who have required surgery such as open reduction and internal fixation may be at increased risk for sciatic neuropathy because of the potential presence of scar tissue around the nerve area. Because the branches of the sciatic nerve run from the thigh to the hamstring, the patient’s ability to flex the thigh generally indicates an intact sciatic nerve.

The femoral nerve arises from the L2-L4 spinal nerve roots and runs through the medial thigh. Injury to the deep femoral nerve may occur more as a result of inappropriate placement of abdominal pelvic retractors and vaginal retractors in the pelvic cavity than by virtue of inappropriate positioning (Cassorla and Lee, 2010). The femoral nerve and obturator nerve can be subjected to excessive stretching and injury, however, as a result of inappropriate lithotomy positioning (see Figure 6-14). The patient’s ability to flex the thigh to the trunk generally indicates an intact femoral nerve.

The obturator nerve originates from the L2-L4 nerve roots. It runs through the obturator foramen of the ischium to innervate the adductor group of muscles in the inner thigh (see Figure 6-14). It can be subjected to excessive stretching when the patient is in lithotomy position. Scrubbed personnel may lean against the inner thigh while holding vaginal or anal retractors, causing additional stretching and compression of the nerve. The patient’s ability to adduct the leg generally means the obturator nerve is intact.

The tibial nerve branches from the sciatic nerve behind the knee and runs along the posterior tibia to the foot (see Figure 6-12). From there it branches into the medial and lateral plantar nerves. The patient’s normal sensation at the plantar surface of the foot and ability to curl the toes downward generally indicate an intact tibial nerve.

The perioperative nurse should document measures taken to protect the lower extremities from injury, such as:

The use of intraoperative neurophysiologic monitoring is demonstrably an effective method to prevent peripheral nerve injuries in the upper and lower extremities during procedures in which there is otherwise a high risk of such injuries. A common method of monitoring in the OR is somatosensory-evoked potential (SSEP). Its goal is to establish a baseline of the patient’s normal nerve function along selected pathways and then to monitor those pathways at continual intervals during the procedure. Any emerging insult to these nerve structures or pathways will appear and corrective measures taken before permanent nerve injury occurs (Chung et al, 2009).

The Association of periOperatve Registered Nurses (AORN, 2013) offers specific recommendations to prevent nerve injuries during surgery. They are listed in the Evidence for Practice box.