The incidence of first-time venous thromboembolic (VTE) events is approximately 70–113 cases per 100,000 people per year. Approximately one-third of these cases are due to pulmonary embolism (PE). Venous thromboembolism will recur in approximately 7% of patients at 6 months, with patients presenting with PE more likely to have recurrent PE. Thirty-day mortality following PE is approximately 12%. While anti-coagulation remains the gold-standard therapy for VTE, patients who have recurrent PE despite adequate anticoagulation, high-risk patients with contraindications to anticoagulation, or patients who have bleeding complications while on anticoagulation therapy meet criteria for inferior vena cava (IVC) filter placement. Inferior vena cava filter placement is contraindicated in patients with complete thrombosis of the IVC, or with an IVC that is otherwise inaccessible by percutaneous means.

Inferior vena cava filters are inserted percutaneously under local anesthesia via the femoral or jugular vein, with fluoroscopic or ultrasound guidance. The procedure usually takes less than 30 minutes, and consists of obtaining central venous access under ultrasound guidance. Venography is performed; fluoroscopic guidance may be used to measure the IVC, locate the renal veins, and identify any possible aberrant anatomy. Procedural morbidity is extremely rare and consists primarily of complications at the insertion site. Long-term complications are more significant and need to be considered when placing filters in young patients. Such complications include device migration, device fracture, caval thrombosis, IVC perforation, and post-thrombotic syndrome.

Otologic surgery encompasses a wide variety of surgical procedures with the main goals being elimination of chronic or acute ear infections and/or restoration of hearing. The various types of otologic procedures can best be divided based on the anatomic location of the disease or impairment. Working from lateral to medial, the external auditory canal (EAC) is the first landmark which can be subject to injury; this is followed by the tympanic membrane, then the middle ear space, and finally the inner ear.

1. External Auditory Canal – EAC stenosis is an infrequent but challenging problem often found as a result of previous surgery or as an idiopathic phenomenon in the immunocompromised patient. A stenotic canal prevents adequate evaluation of the tympanic membrane; cerumen impacted deep to the stenosis often creates hearing impairment as well. A canaloplasty, which involves remodeling the EAC to widen its lumen, is the surgery of choice for this problem.

2. Tympanic membrane – Perforation of the tympanic membrane is a relatively common finding and can often be dealt with asymptomatically for decades in certain patients. However, a majority of patients will suffer either persistent ear drainage or hearing loss as a result of a perforation. Subsequently, a tympanoplasty can be performed. A tympanoplasty uses autologous tissue, either temporalis fascia or perichondrium, as a graft to replace the injured tympanic membrane.

3. Middle ear space – A cholesteatoma is a benign but destructive and expanding growth of keratinizing squamous epithelium, which can fill the middle ear space and cause hearing loss and ear drainage. While this is the most common mass found in the middle ear, other etiologies such as a glomus tumor or even malignant carcinomas can be identified here. A mastoidectomy is the surgery of choice for removal of these tumors, especially if they extend into the mastoid bone. A canal-wall up mastoidectomy keeps the EAC intact and allows the mastoid to drain through the middle ear in the usual fashion, while a canal-wall down mastoidectomy (used for more severe disease) exteriorizes the mastoid cavity through an enlarged EAC.

4. . . .

Calcium is an abundant mineral and has diffuse cellular functions in bone metabolism, cell division, coagulation, enzyme regulation, glycogen metabolism, muscle contraction, neurotransmission, protein synthesis, and degradation. Calcium is ingested in the diet and absorbed in the small intestine. It is distributed throughout the body, but 99% appears in the bone [1–3]. Adult humans contain more than 1 kg of calcium, of which over 99% is skeletal and dental and only 0.1% is in extracellular fluids. About half the calcium in serum is bound to protein, primarily of which is albumin. Decreases in serum albumin are accompanied by decreases in calcium (a drop of 1 g/dL of albumin lowers the calcium by about 0.8 mg/dL). Several calcium determinations and measurement of ionized (physiologically active) calcium levels may be needed to accurately assess calcium status..

Calcium is maintained in a very narrow range by a redundant system of parathyroid hormone (PTH), vitamin D, and calcitonin; all acting at multiple target organs, including bone, kidneys, and the gastrointestinal tract. As ionized (free, metabolically active) calcium levels decrease, the parathyroid glands secrete PTH, which raises calcium levels by stimulating bone resorption, renal calcium reabsorption, phosphate excretion, and renal 1,25-dihydroxycholecalciferol (1,25-[OH]2D3) synthesis. Vitamin D, in turn, promotes bone resorption, increases intestinal absorption of dietary calcium and phosphate, and inhibits PTH secretion [1,4–14]. Finally, calcitonin, released by parafollicular cells of the thyroid in response to hypercalcemia, has been shown to transiently inhibit bone resorption [5].

Data on the prevalence of intracranial aneurysms in the general population come from autopsy and from angiography series. A recent review found that the prevalence of intracranial aneurysms for adults without a history of subarachnoid hemorrhage (SAH) is approximately 2%, with a male to female ratio of approximately 1 to 1.3. The same analysis found that the prevalence of aneurysms increases with age, peaking in the 69–79 year age group. Nearly half of all intracranial aneurysms become symptomatic during the patient's lifetime, usually presenting as subarachnoid hemorrhage. In North America, approximately 28,000 cases of aneurysmal SAH occur each year, mostly in adults.

As opposed to fusiform aneurysms, which are encountered in the extracranial peripheral vasculature, intracranial aneurysms are typically saccular in morphology. Intracranial aneurysms possess a well-defined neck and sac distinct from the lumen of the parent vessel and are frequently located at proximal intracranial arterial branching points. Although the pathophysiology of intracranial aneurysms is controversial, they are thought to arise from defects (congenital or acquired) in the muscularis media. Once an aneurysm has developed, conditions such as hypertension and tobacco smoking will likely increase the risk of rupture, leading to SAH. Certain conditions (e.g., autosomal dominant polycystic kidney disease, Ehlers-Danlos syndrome type IV, Alpha-1 Antitrypsin Deficiency (A-1ATD)) are associated with the formation of cerebral aneurysms, presumably from the predisposition for the development of focal weak spots in vessel walls near arterial branch points.

The perioperative period is a dynamic and risky time for patients. After complications related directly to the surgery itself, medication complications are the next most common adverse events in hospitalized patients [1]. This chapter will address patient safety related to medication practices around surgery, excluding anesthesia and intraoperative medication use. A discussion of general principles will be followed by a focus on the more common complications and high-risk medication groups.

Medication history and reconciliation

Recording a full and accurate medication list is an essential part of a thorough patient history, yet doing so presents a time-consuming challenge in a patient on multiple medications. Reasons for the challenge include the plethora of medications that have been developed and marketed in the last decades that may be unfamiliar to the physician, the difficulty for the patient to remember the full medication list and details of use, and the immature state of electronic health information that does not yet allow universal sharing of data about patients' medical history between multiple health information platforms. As a result, a significant proportion of patients in hospital have incomplete or inaccurate medication histories.

Anterior cranial base surgery has been greatly enhanced with new advances in diagnostic and surgical techniques. These new advances incorporate a comprehensive, multidisciplinary approach to the removal of anterior skull-base lesions. Approaching the anterior cranial base from anterior and below has gained increasing popularity. The principal advantage is the minimal amount of frontal lobe retraction. In addition, this approach eliminates the need for facial incisions and therefore eliminates facial scarring. It also allows for the preservation of smell, depending on the location of the lesion, in contradistinction to more traditional techniques that often ensure anosmia. With the advent of improved endoscopic equipment and surgical techniques, endoscopic approaches have gained increased popularity in certain surgical cases as a different approach when compared with open surgical techniques.

Imaging plays an important role in the surgical and reconstructive planning of craniofacial tumors. It allows for assessment of the extent of the disease process and determination of the operability of the lesion. If the lesion is operable, the extent of the disease will also determine whether the surgical procedure is best done through an endoscopic or open approach. This chapter will focus on the open approach. The imaging modalities commonly employed include axial and coronal two-dimensional, three-dimensional, and interactive three-dimensional CT imaging, MR imaging, and angiography.

Cholecystectomy is indicated for symptomatic calculous cholecystitis (acute or chronic); acalculous acute cholecystitis; a gallbladder that releases stones into the common bile duct (obstructive jaundice, gallstone pancreatitis, cholangitis); carcinoma of the gallbladder; traumatic perforation of the gallbladder; and biliary dyskinesia (low gallbladder ejection fraction). It is also performed after right hepatic artery ligation for hepatic trauma and in preparation for infusion of the hepatic artery with chemotherapeutic agents for metastases. It is included as part of a pancreatoduodenectomy and may be necessary for exposure of the porta hepatis in some patients undergoing portacaval shunt procedures.

Cholecystectomy can best be performed within 48 hours of admission for patients with acute cholecystitis documented on ultrasonography or radionuclide scanning (i.e., HIDA scan) unless general anesthesia is contraindicated. In patients with acute cholecystitis of longer duration, the extent of inflammation may make a laparoscopic approach difficult. If cholecystectomy is to be scheduled electively for acute cholecystitis, it is appropriate to give antibiotics until the time of surgery to help the inflammation subside. Patients with obstructive jaundice, gallstone pancreatitis, or cholangitis undergo cholecystectomy after observation to determine whether the bilirubin level will fall, when the amylase level returns to normal, and when hemodynamic stability has been restored, respectively.

Benign hematologic diseases are second only to trauma as the most common indication for splenectomy. Immune thrombocytopenic purpura (ITP) is the most common indication for splenectomy and comprises greater than 70% of patients undergoing splenectomy for benign disease. Additional benign hematologic conditions that are indications for splenectomy include patients with congenital hemolytic anemia; metabolism abnormalities; hemoglobinopathies and erythrocyte structure abnormalities (e.g., hereditary spherocytosis and elliptocytosis).

Splenectomy may be indicated as a diagnostic tool or for palliation in patients with malignant hematologic disease. Surgical staging is utilized most often in Hodgkin's disease, resulting in a change in diagnosis and subsequent impact on therapy and prognosis in up to 30–40% of patients. Splenectomy can also provide relief to patients with symptomatic splenomegaly, which may or may not be accompanied by hypersplenism. Patients with malignant hematologic diseases are more likely to have massively enlarged spleens (> 1,000 g), resulting in significant discomfort and pain as well as early satiety. When splenomegaly is accompanied by cytopenias (hypersplenism), the cytopenia often improves or sometimes is even cured by removal of the spleen.

Obstructive sleep apnea (OSA) is a serious and chronic condition affecting as many as 15–20 million American adults. Resulting sleep deprivation has been linked to motor vehicle and workplace accidents. The incidence of OSA is increasing with the obesity epidemic, and it is increasingly recognized as a mediator of cardiovascular disease including atrial fibrillation, stroke, myocardial infarction, and sudden cardiac death. The importance of appropriate diagnosis and timely treatment thus cannot be overstated.

Obstructive sleep apnea manifests by repeated episodes of apnea or hypopnea during sleep. During deeper levels of sleep, especially that characterized by rapid eye movement (REM), there is loss of the normal tone of the pharyngeal and tongue muscles that keep the pharynx open, resulting in collapse of the oropharyngeal and nasopharyngeal airway. In the majority of the population this decrease in airway diameter is clinically insignificant. However, in OSA patients the varied degree of airway obstruction can have clinical consequences. Narrowing of the airway causes increased velocity of inspiratory airflow in the pharynx, causing decreased intraluminal pressure, further tissue collapse, and increased airway obstruction (Bernoulli's principle). In instances of complete airway obstruction, the patient will experience apnea, a cessation of breathing for at least 10 seconds. Incomplete obstruction may result in hypopnea, a reduction in airflow with associated oxygen desaturation, which is more common. Each apnea or hypopnea episode continues until the patient awakens to a more shallow level of sleep, which results in a recovery of pharyngeal muscle tone and recovery of airway integrity. The more frequent the apnea and hypopnea, the more fragmented the sleep, which results in greater sleep deprivation due to the lack of adequate REM activity.

Transurethral resection of the prostate (TURP), developed in the 1920s, remains the gold standard surgical treatment for benign prostatic hyperplasia (BPH) throughout the world. Over the years, the procedure has undergone significant modifications that improved its efficacy and safety. The most significant recent improvement is bipolar TURP. Conventional monopolar TURP employs hypo-osmolar fluids for irrigation during the procedure. As a result, patients are at risk of developing perioperative dilutional hyponatremia and TUR syndrome, which is a severe form of serum electrolyte and osmolar derangement. Since the new bipolar TURP system utilizes normal saline for irrigation, these risks and complications are completely eliminated. Bipolar TURP thus allows for safer resection.

Indications for transurethral resection of the prostate

Transurethral resection of the prostate is the treatment of choice in patients with moderate to severe BPH symptoms and significant compromise to their quality of life who:

• Are unable to tolerate or do not respond to other forms of management (e.g., watchful waiting, medical therapy and/or minimally invasive thermal therapy).

• Are experiencing urinary retention thought to be secondary to BPH.

• Have recurrent urinary infection secondary to BPH.

• Have bladder stones secondary to BPH.

• Have renal failure secondary to BPH.

• Have recurrent bleeding (gross hematuria) secondary to BPH.

Introduction

Hypertension affects an estimated 76 million persons in the USA, including one in three adults and more than 65% of individuals over age 65 years [1]. Thus, it is a very common disorder affecting many surgical patients. Hypertension often causes end-organ damage of the brain, heart, and kidneys, with important implications for surgical risk and perioperative management. Patients with chronic hypertension will often have perioperative episodes of hypertension that will require intervention. In addition, postoperative hypertension is common even without preexisting hypertension, especially in patients undergoing cardiac or carotid surgery. This chapter concentrates on the preoperative risk assessment and management of hypertensive patients and on the perioperative management of hypertension.

Hemodynamic response to anesthesia

A discussion of perioperative hypertension requires a basic understanding of the physiologic responses to anesthesia in normotensive and hypertensive patients. There are four main periods during anesthesia: induction, intubation, maintenance, and recovery periods. During induction, most patients' blood pressure falls. During laryngoscopy and intubation, the sympathetic nervous system is activated and blood pressure and heart rate rise. With deepening anesthesia, a decline in mean arterial pressure and heart rate occur due to the effects of pharmacologic agents, a decrease in sympathetic nervous system activity, and loss of the baroreceptor reflex. During recovery from anesthesia around the time of extubation, blood pressure and heart rate slowly increase in the first 15 minutes, and are accompanied by general arousal.

Total knee replacement is indicated for end-stage degeneration of the knee joint with loss of articular (joint surface) cartilage. The most common reasons for this operation are osteoarthritis (idiopathic or post-traumatic) and inflammatory arthritis (rheumatoid, psoriatic, etc.). Total knee replacement is typically considered once all other conservative modalities (oral medications, intra-articular injections, physical therapy, weight loss, etc.) have failed to relieve the pain and dysfunction associated with knee degeneration.

The natural knee joint consists of three compartments: lateral, medial, and patellofemoral. A total knee replacement is designed to resurface the damaged articular surfaces of these compartments. Both the femoral and tibial components are typically made from metal. A high-density plastic (polyethylene) insert is placed between the metal components to serve as the artificial cartilage of the joint. Highly crosslinked polyethylene may be utilized as a more wear-resistant bearing surface; however, long-term results with this type of plastic are not yet available. Most total knee replacements also resurface the patella with an all-polyethylene component. Fixation of the metal components to the bone is typically done with bone cement, but some designs allow for fixation by bony ingrowth into porous metal surfaces applied to the surface of the implant, which is placed against the bone. By removing all damaged surfaces of the knee, pain can be alleviated and function restored.

The epidemic of human immunodeficiency virus (HIV) infection that began in the late twentieth century has become one of the dominant health issues worldwide for the early twenty-first century. Advances in the prevention of HIV infection have reduced the global incidence of infection and advances in treatment have dramatically extended the lifespan of infected patients. In the developed world a 20-year-old who begins antiretroviral therapy is estimated to have a life expectancy of an additional 43.1 years while a treated patient in the developing world has an additional life expectancy of 26.7 years [1,2]. In 2009 of the estimated 33.3 million people worldwide living with HIV approximately 5 million were on antiretroviral therapy [3]. Since an additional 1.8 million people become infected with HIV each year, the effect of increased longevity will produce increasing opportunities for internists and surgeons to collaborate in the management of HIV-infected patients.

The clinical course of HIV infection has been well described and should be familiar to most physicians. HIV infection is associated with abnormalities in the number and function of CD4-positive T-lymphocytes. Because the CD4-positive T-lymphocytes are essential to the regulation of the human immune system, progressive immune dysfunction is a natural consequence of HIV infection in most patients. This progressive immune dysregulation is associated with decreased cell-mediated immune function, alterations in the humoral immune response, chronic inflammation and depressed mucosal immunity. The late stages of HIV infection are associated with pathologic processes in many organ systems and eventual death due to opportunistic infections or tumors. This natural history of the disease has been dramatically altered by the widespread use in the developed world of highly active antiretroviral therapy (HAART). HAART is an acronym that refers to combinations of antiretroviral agents that have been shown in clinical trials to result in undetectable plasma HIV RNA levels in the majority of patients. These combinations may include two nucleoside analogs plus either a protease inhibitor, an integrase inhibitor or a non-nucleoside reverse transcriptase inhibitor. Guidelines for the use of these agents in HIV-infected adults and children have been developed, are frequently updated, and are available through the Internet [4].

Endovascular repair of abdominal aortic aneurysms (EVAR) was introduced in the US market in 1999 and has gained rapid popularity because of decreased perioperative morbidity, shorter length of stay, and rapid recovery compared with open repair. Currently, more than 60% of AAAs are repaired endovascularly. However, there are possible issues of magnetic resonance imaging (MRI) compatibility. While all stent grafts cause image artifacts, the Zenith graft, made of ferro-magnetic stents, is incompatible with MRI. Also, there is increased cost with EVAR when compared with open repair.

The anatomic morphology of the aneurysm and the aortoiliac system proximal and distal to it is the most important criterion in determining if the patient is a candidate for EVAR.

Anatomic criteria for suitability for EVAR:

• Proximal landing zone (the “neck”): The aortic wallimmediately distal to the lowest renal artery and proximal tothe aneurysm is the proximal landing zone. The instructionsfor use (IFUs) for current commercially available graftsspecify that the “neck” should be at least 15mmlong; 40% ofcandidates for EVAR do not meet this criterion.

• Distal landing zone: This is the seal area in the common orexternal iliac artery where the iliac limbs of the endograftend; it should be at least 10 mm.

• Access vessels: Endovascular devices are inserted into theaorta from the groin, traversing retrograde through thecommon femoral and iliac arteries. To allow access withoutrupture, these vessels have to be a minimal diameter thatvaries according to each device manufacturer and the sizeof the endograft required.

• Status of critical side branches: The endovascular approachentails occlusion of the inferior mesenteric artery, and mayalso require the sacrifice of one or more accessory renal orinternal iliac arteries. The suitability and configuration ofan endovascular approach is thus predicated by theadequacy of collateral supply and the acceptable extent ofend-organ ischemia.

The number of non-cardiac surgeries in patients with cardiovascular diseases has been steadily rising. As perioperative myocardial infarctions are the leading cause of death after anesthesia and surgery, it is not surprising that patients with coronary artery disease (CAD) have an increased risk of perioperative morbidity and mortality. Therefore, the determination of cardiac risk generally implies a determination of “coronary risk.” Although this is suitable for the vast majority of cases due to the high prevalence of CAD, other cardiac conditions, such as heart failure, arrhythmias, valvular disease, and congenital heart disease, also increase perioperative complications and require distinct perioperative management.

A team approach to patients with cardiovascular disease who undergo non-cardiac surgery is the ideal way to expedite perioperative care. It is essential to assess patients’ risk of cardiac complications and to identify those risk factors that may be reversed or ameliorated if time allows before surgery. The most likely cardiovascular problems that patients may encounter in the perioperative period should also be anticipated and an approach to these problems planned in advance. For the patient who undergoes surgery on an emergency basis, preoperative evaluation may be limited to those components that are critical and essential for the surgical procedure. In these circumstances the consultant may well perform a more detailed evaluation in the postoperative period. For many patients the preoperative evaluation is their only opportunity for medical assessment. The consultant should bear this in mind and consider the preoperative evaluation visit as an opportunity for assessment of general cardiovascular risk and development of a plan for cardiac risk reduction.

The term “Endourology” has been adopted for the minimally invasive endoscopic surgery of upper urinary calculus disease. Since the introduction of shock wave lithotripsy, this modality has become the most common form of stone therapy, allowing an almost completely hands-off treatment for radio-opaque calculi. Due to the technological advances of endourologic procedures such as ureteroscopy and percutaneous nephrolithotomy (PCNL), the incidence of open kidney stone surgery is almost non-existent. Due to the popularity of the daVinci robot (Intuitive, CA), traditional open calculus surgeries are being performed robotically for stones that would otherwise require several endoscopic procedures. It is important to note that as advanced as surgical intervention has evolved for nephrolithiasis, medical management and prevention of complicated urolithiasis still fall short of the ideal.

Nephrolithiasis affects as much as 12% of the population in industrialized nations. Urolithiasis patients will agree that the sensation of stone passage is perhaps the most painful and intense experience of their lives, surpassing even childbirth. Urolithiasis may present as hematuria (ranging from asymptomatic microscopic hematuria to painful gross hematuria), abdominal/flank/back pain, urinary tract infection, renal failure, or as an incidental radiologic finding.