Phases of Surgery
The Preoperative Period
In an ideal situation, patients undergoing surgery will have adequate time before the operation to prepare themselves emotionally and physically. This preparation will likely include dietary supplementation, as well as mental and emotional preparation. The healthier patients are when they go into surgery, the healthier they are likely to be during the postoperative phase.
Each of the three phases of a surgical procedure poses different threats to the patient’s well-being, although there may be considerable overlap. The most variable phase is the preoperative, or preparatory phase. In the case of emergency surgery, this period may be limited to a few hours (and in the case of trauma a few minutes). In most cases, however, both the patient and surgical team have longer to prepare, and it is during this period that many nutritional interventions can be made. One overlooked statistic is that up to 50% of patients admitted to hospitals are malnourished (Patel 2005). This startling statistic underscores the critical importance of proper nutritional intervention.
Two significant threats to the patient’s well-being during the preoperative period are continued progression of the disease that has made the operation necessary (for instance, a growing cancer) and the patient’s degree of apprehension and anxiety. Certain preoperative procedures, such as prolonged fasting, may also exert negative effects.
Disease progression. Virtually all disease processes that require surgery, including traumatic injury, impose substantial oxidative threats to tissue (DeWeese 2001). For instance, initial oxidative (free radical) damage can be caused by impaired blood supply as a tumor presses on major vessels or diverts blood from healthy tissues. Toxins may be released from infected or malignant tissue or by release of intracellular contents, including protein-damaging enzymes, from dying cells (Michalik 2006).
Blood released from normal circulation into various body compartments, such as the abdomen, can itself produce oxidative damage (Potts 2006). An early response to oxidative damage is inflammation, which is aimed at destroying unhealthy tissue or invading infectious agents. As inflammation grows, however, additional oxidant damage is produced by white blood cells that are attracted to the area by signaling chemicals called cytokines and chemokines (Ceriello 2006). Many of these cells, particularly white blood cells called neutrophils, release toxic reactive oxygen species, which cause further tissue damage (De la Fuente 2005).
Similarly, in the case of infections, the body’s powerful immune response calls inflammatory cells to the infected tissue, where they release agents that oxidize lipids in cell membranes, causing the membranes to leak and cells to die (Stark 2005). Inflammation also changes blood vessel walls, making them “leaky” and allowing blood components to seep into tissues, causing swelling and loss of plasma proteins (Thurston 2000). These oxidative and inflammatory reactions impair local tissue function and sap the body of proteins, minerals, and other substances necessary for maintaining normal blood pressure and overall tissue health (Fall 2005).
A healthy diet and appropriate nutritional supplements can help prepare a patient for surgery by maximizing reserves of proteins, essential fatty acids, vitamins and minerals. Specific nutrient and supplements can also help bolster the immune system, minimize oxidative damage, and keep inflammation under control.
Psychological stress. Psychological and emotional stress reduces the body’s immune function and renders people more vulnerable to disease. Scientists today understand that much of this effect is mediated by brain structures that influence production of stress-induced hormones (eg, corticosteroids) (Leonard 2005; Straub 2005). Every person who will be undergoing a surgical procedure, no matter how minor, has some degree of anxiety about the procedure, its outcomes, and potential complications. Outcomes of surgical procedures are almost always improved by a reasonably long preoperative planning period, which gives the surgical team and patient a maximum opportunity for physical and technical preparation. Excessively long preoperative periods, however, may be associated with increased amounts of worry, anxiety, and stress; these factors can have a negative impact on surgical outcomes (Pucak 2005).
The often repeated phrase “just relax” is not only entirely ineffective, but there is even evidence that patients “ordered” to relax actually experience increased stress levels. Instead, one of the most effective interventions to reduce patient stress levels is communication; patients with a high degree of so-called health literacy are known to have shorter hospital stays, fewer complications, and better overall outcomes (Wolf 2005; Schillinger 2002). Health literacy is easy to attain; the Partnership for Clear Health Communication promotes a program called “Ask Me 3,” which recommends that patients get the following 3 questions answered by a physician regarding any disease or treatment:
- What is my main problem?
- What do I need to do?
- Why is it important for me to do this?
Getting these questions answered is a major step in improving health literacy and reducing stress levels. Also, many physicians appreciate being asked to present information to patients in this format.
Other nonmedical strategies for reducing preoperative anxiety and stress have been shown to be helpful in varying degrees. Hypnosis has been found to be effective in reducing both preoperative anxiety and postoperative complications (Lambert 1996; Rapkin 1991). A related technique called guided imagery, in which a skilled therapist works with the patient to envision low-stress and positive concepts, has also been documented to reduce anxiety, safely lower pulse and blood pressure, and shorten hospital stays (Halpin 2002; Norred 2000). In other studies, patients using guided imagery required 50% less pain medication than controls (Tusek 1997a,b).
Preoperative fasting. Practically since the inception of general anesthesia for surgery, doctors have worried about the effects of a full stomach on an unconscious patient. The chief risk is aspiration of stomach contents into the lungs, which can cause severe inflammation, infection, and death. Modern anesthesia practices, however, such as careful control of the patient’s airway, close monitoring, and selective use of appropriate anesthetic drugs has dramatically reduced this risk (Brady 2003). Periods of fasting, such as the traditional “nothing by mouth (or NPO) after midnight” on the night before surgery can produce dehydration, low blood sugar, and a variety of other complications. Increasingly, anesthesiologists are recognizing both the biological and psychological value of permitting patients a reasonable oral intake, at least of liquids, until about 4 hours before the surgical procedure. Patients are encouraged to discuss this practice with their physicians well in advance of surgery.
Glucose control. Life Extension also suggests that patients with poor glucose control discuss intensive insulin therapy with the surgeon before surgery. Studies indicate that surgery-induced insulin resistance, leading to elevated glucose levels during surgery, raises the risk of complications and death. Intensive insulin therapy, a procedure in which glucose levels are closely monitored during surgery, can help reduce complications and lower the risk of death (van den Berghe 2001). The recommended glucose range is 80 – 120 mg/dL. However, this practice is not standard in hospitals and requires intensive monitoring from nurses and other members of the surgical team. Nevertheless, because of the benefits, patients may want to discuss intensive insulin therapy with their surgical team to see if it is warranted.
Aspirin therapy. Patients may also want to discuss aspirin therapy before surgery. Aspirin is a well-known antiplatelet used for prevention of heart attack and to mitigate damage of ongoing heart attacks. Some studies suggested that aspirin therapy may benefit certain patients before surgery, especially heart patients and those undergoing carotid endarterectomy (Mangano 2002). However, because aspirin affects the blood’s ability to clot, no surgery patients should begin aspirin therapy unless under the direct supervision of their surgical team.
The Operation Itself
The surgical procedure itself is the phase over which patients have the least control. From the moment the patient enters the operating room, virtually all vital functions are taken over by members of the surgical team. The “ABCs,” or airway, breathing, and circulation, are typically managed by the anesthesiologist. While many anesthetic agents are aimed at attaining unconsciousness and managing pain, many other medications are given to support pulse and blood pressure, prevent infection and blood loss, and counter the side effects of other medications. It is not unusual for a patient to experience the effects of more than 10 medications during a major surgical procedure. Blood transfusions can also have untoward effects, especially with regard to calcium status (Spiess 2004).
While each medication has its purpose, they also have inevitable unwanted effects, with many medications being potent oxidants and others stimulating immune or inflammatory responses, particularly in the lungs, which are directly exposed to inhaled anesthetic gasses (Patel 2002; Yang 2001). Most medications have effects on the liver’s ability to detoxify other drugs and toxins. Anesthesiologists typically plan the array of medications carefully to minimize these effects. It has recently been shown that certain of the most commonly used anesthetic gasses actually provide some protection against oxidative damage (Sivaci 2006; Johnson 1996).
The oxygen provided during the procedure is itself a mixed blessing. Critical for maintaining normal cellular processes and proper wound healing, supplemental oxygen also produces increased levels of reactive oxygen species that can damage tissues. Surgical procedures themselves are known to reduce circulating levels of vitamins A, E, and other naturally occurring antioxidants (Luyten 2005; Schindler 2003). Good pre- and postoperative nutrition, with special attention to maintaining adequate antioxidant status, can help minimize these effects; studies of administration of antioxidants during surgery are showing some promise (Canbaz 2003; Xia 2003).
The majority of physiological stress produced by an operation is the result of direct tissue damage from cutting, clamping, suturing, and otherwise manipulating organs and other structures. Reduced blood flow produces ischemia (lack of oxygen), resulting in cell death and release of intracellular components that produce an acidic environment. Enzymes released from injured cells can further damage adjacent tissue.
When blood flow is restored to an ischemic area, reperfusion injury occurs, with suddenly elevated oxygen levels causing transient oxidative damage and the restored blood flow sweeping tissue toxins into general circulation (Michalik 2006). Oxidant molecules produce the same sort of damage to cell membranes (lipid peroxidation) as the disease process itself (Stark 2005). Similarly, oxidant damage results in stimulation of inflammatory processes and release of cytokines, with further oxidant injury caused by inflammatory cells attacking injured tissue (Michalik 2006; Potts 2006; De la Fuente 2005). While this inflammatory response represents the first stages of healing, it can often become exaggerated and contribute to both local and systemic stressors that impede, rather than improve recovery (Angele 2005).
Finally, although not a major factor during the operation, bacterial and fungal organisms may gain access to normally sterile body areas, especially during so-called dirty cases, in which the bowel or other naturally contaminated organs must be opened. Drainage of abscesses and other infected tissue can also allow infectious organisms entry into otherwise sterile tissue, setting the stage for a postoperative infection, with its attendant oxidative and inflammatory consequences (Angele 2005).
Oxidant and inflammatory stresses are not limited to the surgical region. Surgery itself is now widely recognized as a systemic inflammatory stress that can cause injury in areas far removed from the surgical site (Frass 2001; Kawahito 2000). For example, surgery can impact the function of blood vessels during the procedure, causing blood pressure instability (Williams 1999).
Some of the most profound effects of surgical procedures may impact the gastrointestinal tract. There is now good evidence that surgery (and anesthesia) may produce “leaky gut” effects, permitting entry of toxins and microorganisms into circulation and affecting long-term outcomes (Mangiante 2005). Many surgeons and anesthesiologists are now interested in the use of antioxidant and immune-modulating nutrients during surgery to ameliorate these effects (Angele 2005; Calder 2004).
The Postoperative (Recovery) Period
During the postoperative phase, the patient and surgical team have many opportunities to collaborate in maximizing nutrient contributions to the healing and recovery process. As in the preoperative period, considerable benefit has been demonstrated from nonmedical interventions such as hypnosis and guided imagery. The latter, in particular, has been shown to reduce pain, anxiety, and length of stay in patients undergoing diverse surgical procedures (Antall 2004; Halpin 2002; Lambert 1996).
The greatest biological threats to the postoperative patient arise from intricate relationships between regrowth of healing tissue, inflammation, and infection. A certain amount of inflammation is necessary for proper wound healing—cytokines and other inflammatory mediators are required for the production of vascular endothelial growth factor, which is vital for assuring a strong blood supply to new tissue (Khanna 2001, 2002). Inflammatory cells and their chemical products are also required to fight the ever present threat of infection; however, excessive inflammation can also impair the healing process.
Supplemental oxygen is a very frequent part of the postoperative treatment regimen; surgeons are naturally anxious to provide adequate oxygen to meet the increased metabolic demands of rapidly healing tissue (Alleva 2005; Gottrup 2004). Wound healing is known to be accelerated by moderately elevated tissue oxygen levels. In fact, hyperbaric oxygen therapy (oxygen treatment at higher-than-normal pressures) is now used for treatment of slow-healing wounds and many burns (Gajendrareddy 2005), where it has been shown to increase vascular endothelial growth factor levels (Patel 2005).
As with intraoperative oxygen therapy, however, this benefit is not without its costs in terms of increased tissue levels of reactive oxygen species. A judicious mix of increased oxygen supply with antioxidant supplementation seems to provide maximum wound healing benefits with minimum systemic exposure to free oxygen radicals (Alleva 2005; Patel 2005; Muth 2004; Sen 2002).
In addition to wounds and tissue damage inflicted by surgery itself, postoperative patients are at risk for a number of complications caused by decreased mobility. Early complications include partial lung collapse that results from shallow, painful breathing (Westerdahl 2005), bladder infections from indwelling catheters (Green 1995), local inflammation of the healing wound (Larsen 2003), and inflammation caused by blood clots developing in nonmoving lower extremities (Vucic 2003). These complications are so common, in fact, that surgical interns are taught the mnemonic “wind, water, wound, walk” when considering likely sources of a fever in the first few postoperative days (Pile 2006). All of these complications are the result of inflammatory processes amplified by surgery. Nutritional modulation of the inflammatory response may help blunt these complications (Calder 2004).
Perhaps the most severe postoperative complication is development of pressure ulcers, or bedsores. These ulcers develop at pressure points in patients who are unable or unwilling (because of pain) to shift their positions in bed; early signs of their development can be present within two hours of pressure being applied (Bansal 2005). Constant pressure reduces local blood flow, producing ischemia (reduced oxygen levels) and lack of nutrients. This situation rapidly produces increased tissue levels of metabolic waste products (eg, lactic acid) and eventually results in cell death, with release of toxins and enzymes into adjacent tissue. Once again, inflammation is triggered in previously healthy tissue, attracting inflammatory cells that cause further tissue damage. Necrosis (cell death) can occur very rapidly in these ulcers, resulting in the development of potentially large masses of dead and dying tissue, which are a breeding ground for bacteria.
For these reasons, bedsores can be life-threatening. Their prevention is one of the chief priorities of the surgical team in the postoperative period. Poor nutritional status is a major risk factor for their development (Domini 2005), and many nutritional interventions are known to be helpful (Desneves 2005; Breslow 1993).
Proper wound healing also requires both energy and an adequate supply of the chemical building materials of new tissue. Requirements for calories, protein, and vitamins in the postoperative period are higher than practically any other period in the lifetime of an adult (Ellis 1991). Formerly, surgeons sharply limited the amount and pace of postoperative feedings, believing the gut needed a lengthy recovery period from anesthesia and surgery. Today, most surgeons recognize the critical nature of early restoration of feedings, preferably by the gastrointestinal route (Grimble 2005; Fearon 2003). This practice has been shown not only to maximize nutritional intake, but also reduce “leaky gut” effects produced by systemic inflammation in response to surgery (Mangiante 2005).
Finally, surgery suppresses immune response (Angele 2005). For this reason, the risk of infection, already elevated by the operation itself, rises still higher in the postoperative period as all branches of the immune system slowly emerge from their depressed state. Many nutrients contribute to the postoperative recovery of the immune system, and the new field of immunonutrition has developed around a growing understanding of the effects of certain nutrients on immune and inflammatory responses (Alvarez 2003).