Nursing

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PART 19 Consultative Medicine

465 Approach to Medical Consultation Jack Ende, Jeffrey Berns

Effective health care requires teams of generalists and specialists with complementary expertise. Many clinical conditions require the input of more than one clinical provider, either because the diagnosis and recommended treatment is uncertain or because a patient may have multiple diseases that may be best managed by involving multiple specialists.

To consult is to seek advice from someone with expertise in a particular area, whereas consultation refers to the meeting or comparable outcome arising from that request. Medical consultation takes several forms. Its most traditional forms include in-hospital consultation in which physicians provide recommendations or perform procedures for a hospitalized patient, and out-patient consultations, in which patients are seen in the office setting. More contemporary forms of consultation include e-consultations, telemedicine evaluations (see “Consultation Involving Telemedicine,” below), and remote medical second opinions. In these forms, the consultant may not actually see the patient but, nonetheless, assumes the responsibility of evaluating the patient’s clinical condition, assessing and analyzing pertinent clinical data, and offering a synthesis and appropriate recommendations.

While forms of medical consultation evolve, basic responsibilities associated with medical consultation endure. These responsibilities can be divided into those that fall to the requesting physician or non-physician practitioner; the consultant, who provides the consultation; and the health system, hospital, or organization that must support this important medical encounter (Table 465-1).

TABLE 465-1 Stakeholder Responsibilities in the Medical Consultation Process

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RESPONSIBILITIES OF THE REQUESTING PRACTITIONER Before requesting a consultation, the provider should ensure that the patient endorses the purpose of the consultation, understands the role of the consultant, and anticipates the likely outcomes of the encounter. Further responsibilities of the requesting practitioner include being specific and communicating clearly the reason for the consultation. Vague messages such as, “Please evaluate” are not as helpful as more specific inquiries such as, “What is the cause of the declining kidney function?” or, “How should this asymptomatic pulmonary nodule be evaluated?” To the extent possible, the requesting practitioner should provide the relevant clinical information, summarized as succinctly as possible. Urgency should be clearly conveyed, typically with a phone call or other direct communication.

The requesting practitioner should be explicit regarding the intended outcome of the consultation, i.e., is this for a single evaluation or ongoing co-management? Communication between the requesting and the consulting providers is paramount. Whether this communication includes direct contact is less important than that the relevant information and desired outcome be explicit and clear, regardless of communication medium. Consultations should be requested for clinical purposes and always directed to qualified consultants; they should not be driven by entrepreneurial or relationship-building purposes. Another responsibility of the referring provider is not to “over- consult.” Medical care should be focused on value, not volume.

RESPONSIBILITIES OF THE CONSULTANT Just as the referring provider should attend to clear and explicit communication, so too should the consultant follow the precepts of effective interactions between professionals, which include courtesy, availability, and clarity. Particularly on the inpatient service, where consultants may receive several requests each day, it is important that the incoming consultations are triaged and dispatched as clinically appropriate. Consultants also need to determine the requested level of involvement going forward and not assume that long-

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term co- management is being sought. While consultants can and should make use of available clinical data, they should also assemble independently their own database, including taking a history, performing a physical exam, and reviewing pertinent clinical studies. Absent that, they may be unable to provide an independent and actionable synthesis. Just as the referring provider needs to be clear and concise, so too should the consultant be specific and focused in the recommendations provided. “Possible malignant ascites” is less helpful than, “I will arrange for paracentesis to exclude the possibility of malignant ascites.” For the most part, recommendations to “consider” some diagnosis or test are less helpful than more specific and concrete advice. Some referring practitioners wish to be called after a patient is seen; others prefer that communication be handled as part of the medical record. How this communication is handled must also align with the complexity and urgency of the consultation and clinical circumstances.

RESPONSIBILITIES OF HEALTH SYSTEMS, HOSPITALS, AND MEDICAL ORGANIZATIONS Health systems, hospitals, and medical organizations also have responsibilities in the consultation process. This responsibility includes ensuring that qualified consultants are accessible and available on the medical staff. Consultations within a single system are aided by common shared electronic medical records, particularly when consultations originate in the hospital, but can also involve care in the outpatient setting. Finally, health care entities should strive to foster a culture of team-based care and collegiality.

SPECIAL ISSUES IN MEDICAL CONSULTATION

Curbside Consults        Curbside consults are requests from one practitioner to another for an informal and unwritten opinion about a specific patient care matter. They are typically limited in scope, mostly regarding management or questions regarding procedures, and developed from information provided by the consulting practitioner and perhaps the medical record (such as labs and imaging studies), but without a comprehensive review of the record or any direct contact with the patient. Although often viewed as convenient, efficient, and a common aspect of clinical care, by their very nature, curbside consults have been found to often be incomplete or even flawed. It is not uncommon for the question being asked to be deemed too complex for a curbside consult, or for it not to be the actual or only issue the consultant feels needs to be addressed. As a general rule, curbside consults should be avoided. While medicolegal liability is often cited as a reason to limit curbside consults, the risk is actually negligible as U.S. courts have ruled that curbside consults do not establish a doctor-patient relationship necessary for creating the basis for medical malpractice litigation. An important exception, however, is when a curbside consult is provided by a resident or fellow in training; in this circumstance the trainee’s supervising physician, whether aware of the curbside consult or not, is responsible for the recommendations of the trainee.

Second Opinions    Physicians may find themselves providing consultations requested by patients who have already been evaluated for the same problem by another physician. Not a “consult” in the usual context of one physician referring a patient to another, the service provided by the consultant here is, nonetheless, very much aligned with a physician- referred consult. Second opinions, which often are encouraged by the patient’s physician, may be sought by patients for reassurance that a diagnosis and treatment

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recommendation is correct, out of dissatisfaction with the initial physician, or with the hope of an entirely different opinion and recommendation. The physician providing the second opinion should strive to understand the patient’s motivations for seeking the additional opinion. While a second opinion may have been initiated by the patient rather than referral from another physician, it is recommended that the consulting physician communicate with the patient’s primary physician or specialist as would be done following a standard consultation unless the patient insists otherwise. In addition, professional behavior in how the consulting physician refers to the recommendations or actions of previously consulted physicians is important, even when there is disagreement. Likewise, it is important that a transfer of care from prior consultants to the one providing a second opinion be enacted only if specifically requested by the patient or the physician who encouraged the second opinion.

Consults Involving Mid-Level Providers Increasingly, specialist physicians may find themselves being consulted by nurse practitioners and physician assistants rather than other physicians. Whether the quality of the information provided to the consultant physician by a mid-level provider is different from physician-to-physician referrals has not been studied. Consulting physicians should know whether they should respond back to the mid-level provider or to the supervising physician. As with physician-to-physician consults, it is also important for the consultant to know whether the individual calling for the consult has an ongoing role in the care of the patient or is simply covering for a limited period of time. Finally, the consultant, if responding back to the mid-level provider, should make sure that the information provided meets the needs of that provider, and that questions are answered as they would be if responding back to another physician.

Consultation Involving Telemedicine        Consultations making use of electronic health records, patient portals, and various forms of telecommunication technology, including video conferencing or cell phone communication, can improve access to care, reduce cost, and improve outcomes. This is particularly true when employed in geographic areas of health care shortage and when the clinical issues can be handled without direct contact with the patient, e.g., radiology or dermatology. However, the absence of direct contact between patient and consultant introduces special issues related to diagnostic accuracy and physician-patient relationship. Regulatory issues, liability, security, and confidentiality issues arise as well. Consultation via telemedicine holds considerable promise, but the aforementioned concerns will need to be better understood.

FURTHER READING DANIEL H, SULMASY LS: Policy recommendations to guide the use of telemedicine in

primary care: An American College of Physicians Position Paper. Ann Intern Med 163:787, 2015.

PEARSON SD: Principles of generalist-specialist relationships. J Gen Intern Med 14(Suppl 1):S13, 1999.

466 Medical Disorders During Pregnancy Robert L. Barbieri, John T. Repke

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Each year, approximately 4 million births occur in the United States, and more than 130 million births occur worldwide. A significant proportion of births are complicated by medical disorders. Advances in medical care and fertility treatment have increased the number of women with serious medical problems who attempt to become pregnant. Medical problems that interfere with the physiologic adaptations of pregnancy increase the risk for poor pregnancy outcome; conversely, in some instances, pregnancy may adversely impact an underlying medical disorder.

HYPERTENSION (See also Chap. 271) In pregnancy, cardiac output increases by 40%, with most of the increase due to an increase in stroke volume. Heart rate increases by ~10 beats/min during the third trimester. In the second trimester, systemic vascular resistance decreases, and this decline is associated with a fall in blood pressure. During pregnancy, a blood pressure of 140/90 mmHg is considered to be abnormally elevated and is associated with an increase in perinatal morbidity and mortality. In all pregnant women, the measurement of blood pressure should be performed in the sitting position, because the lateral recumbent position may result in a lower blood pressure. The diagnosis of hypertension requires the measurement of two elevated blood pressures at least 4 h apart. Hypertension during pregnancy is usually caused by preeclampsia, chronic hypertension, gestational hypertension, or renal disease.

PREECLAMPSIA Approximately 5–7% of all pregnant women develop preeclampsia, the new onset of hypertension (blood pressure >140/90 mmHg) and proteinuria (either a 24 h urinary protein >300 mg/24 h, or a protein- creatinine ratio ≥0.3) after 20 weeks of gestation. Recent revisions to the diagnostic criteria include: proteinuria is no longer an absolute requirement for making the diagnosis; the terms mild and severe preeclampsia have been replaced; and the disease is now termed preeclampsia either with or without severe features and fetal growth restriction is no longer a defining criterion for preeclampsia with severe features. Although the precise pathophysiology of preeclampsia remains unknown, recent studies show excessive placental production of antagonists to both vascular endothelial growth factor (VEGF) and transforming growth factor β (TGF-β). These antagonists to VEGF and TGF-β disrupt endothelial and renal glomerular function resulting in edema, hypertension, and proteinuria. The renal histological feature of preeclampsia is glomerular endotheliosis. Glomerular endothelial cells are swollen and encroach on the vascular lumen. Preeclampsia is associated with abnormalities of cerebral circulatory autoregulation, which increase the risk of stroke at mildly and moderately elevated blood pressures. Risk factors for the development of preeclampsia include nulliparity, diabetes mellitus, a history of renal disease or chronic hypertension, a prior history of preeclampsia, extremes of maternal age (>35 years or <15 years), obesity, antiphospholipid antibody syndrome, and multiple gestation. Low-dose aspirin (81 mg daily, initiated at the end of the first trimester) modestly reduces the risk of preeclampsia in pregnant women at high risk of developing the disease.

Preeclampsia with severe features is the presence of new-onset hypertension and proteinuria accompanied by end-organ damage. Features may include severe elevation of blood pressure (>160/110 mmHg), evidence of central nervous system (CNS) dysfunction (headaches, blurred vision, seizures, coma), renal dysfunction (oliguria or creatinine >1.5

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mg/dL), pulmonary edema, hepatocellular injury (serum alanine aminotransferase level more than twofold the upper limit of normal), hematologic dysfunction (platelet count <100,000/L or disseminated intravascular coagulation [DIC]). The HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) is a special subtype of severe preeclampsia and is a major cause of morbidity and mortality in this disease. Platelet dysfunction and coagulation disorders further increase the risk of stroke.

TREATMENT

Preeclampsia Preeclampsia resolves within a few weeks after delivery. For pregnant women with preeclampsia prior to 37 weeks of gestation, delivery reduces the mother’s morbidity but exposes the fetus to the risk of premature birth. The management of preeclampsia is challenging because it requires the clinician to balance the health of the mother and fetus simultaneously. In general, prior to term, women with preeclampsia without severe features may be managed conservatively with limited physical activity, although bed rest is not recommended, close monitoring of blood pressure and renal function, and careful fetal surveillance. For women with preeclampsia with severe features, delivery is recommended unless the patient is eligible for expectant management in a tertiary hospital setting. Expectant management of preeclampsia with severe features remote from term affords some benefits for the fetus, but significant risks for the mother. Postponing delivery beyond 34 weeks gestation in this group of patients is not recommended. In preeclampsia without severe features delivery at 37 weeks is recommended.

The definitive treatment of preeclampsia is delivery of the fetus and placenta. For women with preeclampsia with severe features, aggressive management of blood pressures >160/105 mmHg reduces the risk of cerebrovascular accidents. IV labetalol or hydralazine is most commonly used to acutely manage severe hypertension in preeclampsia; labetalol is associated with fewer episodes of maternal hypotension. Elevated arterial pressure should be reduced slowly to avoid hypotension and a decrease in blood flow to the fetus.

Magnesium sulfate is the preferred agent for the prevention and treatment of eclamptic seizures. Large, randomized clinical trials have demonstrated the superiority of magnesium sulfate over phenytoin and diazepam in reducing the risk of seizure and, possibly, the risk of maternal death. Magnesium may prevent seizures by interacting with N-methyl-D-aspartate (NMDA) receptors in the CNS. The universal use of magnesium sulfate for seizure prophylaxis in preeclampsia without severe features is no longer recommended by most experts. There is consensus that magnesium sulfate should be used in all cases of preeclampsia with severe features, or in cases of eclampsia. Women who have had preeclampsia appear to be at increased risk of cardiovascular and renal disease later in life.

CHRONIC ESSENTIAL HYPERTENSION Pregnancy complicated by chronic essential hypertension is associated with intrauterine growth restriction and increased perinatal mortality. Pregnant women with chronic

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hypertension are at increased risk for superimposed preeclampsia and abruptio placentae. Women with chronic hypertension should have a thorough prepregnancy evaluation, both to identify remediable causes of hypertension and to ensure that the prescribed antihypertensive agents (e.g., angiotensin-converting enzyme [ACE] inhibitors, angiotensin- receptor blockers) are not associated with an adverse outcome of pregnancy. Labetalol and nifedipine are the most commonly used medications for the treatment of chronic hypertension in pregnancy. The target blood pressure is in the range of 130–150 mmHg systolic and 80–100 mmHg diastolic. Should hypertension worsen during pregnancy, baseline evaluation of renal function (see below) is necessary to help differentiate the effects of chronic hypertension from those of superimposed preeclampsia. There are no convincing data that the treatment of mild chronic hypertension improves perinatal outcome.

GESTATIONAL HYPERTENSION The development of elevated blood pressure after 20 weeks of pregnancy or in the first 24 h post-partum in the absence of preexisting chronic hypertension or proteinuria is referred to as gestational hypertension. Mild gestational hypertension that does not progress to preeclampsia has not been associated with adverse pregnancy outcome or adverse long- term prognosis.

RENAL DISEASE Normal pregnancy is characterized by an increase in glomerular filtration rate and creatinine clearance. This increase occurs secondary to a rise in renal plasma flow and increased glomerular filtration pressures. Patients with underlying renal disease and hypertension may expect a worsening of hypertension during pregnancy. If superimposed preeclampsia develops, the additional endothelial injury results in a capillary leak syndrome that may make management challenging. In general, patients with underlying renal disease and hypertension benefit from aggressive management of blood pressure. Preconception counseling is also essential for these patients so that accurate risk assessment and medication changes can occur prior to pregnancy. In general, a prepregnancy serum creatinine level <133 μmol/L (<1.5 mg/dL) is associated with a favorable prognosis. When renal disease worsens during pregnancy, close collaboration between the internist and the maternal-fetal medicine specialist is essential so that decisions regarding delivery can be weighed to balance the sequelae of prematurity for the neonate versus long-term sequelae for the mother with respect to future renal function.

CARDIAC DISEASE

VALVULAR HEART DISEASE (See also Chaps. 256–263) Valvular heart disease is the most common cardiac problem complicating pregnancy.

Mitral Stenosis    This is the valvular disease most likely to cause death during pregnancy. The pregnancy-induced increase in blood volume, cardiac output, and tachycardia can increase the transmitral pressure gradient and cause pulmonary edema in women with mitral stenosis. Women with moderate to severe mitral stenosis (mitral valve area ≤1.5 cm2) who are planning pregnancy and have either symptomatic disease or pulmonary

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hypertension should undergo valvuloplasty prior to conception, preferably with percutaneous balloon valvotomy (PBV). Pregnancy associated with long-standing mitral stenosis may result in pulmonary hypertension. Sudden death has been reported when hypovolemia occurs. Careful control of heart rate, especially during labor and delivery, minimizes the impact of tachycardia and reduced ventricular filling times on cardiac function. Pregnant women with mitral stenosis are at increased risk for the development of atrial fibrillation and other tachyarrhythmias. The immediate postpartum period is a time of particular concern secondary to rapid volume shifts. Careful monitoring of cardiac and fluid status should be observed.

Mitral Regurgitation and Aortic Regurgitation and Stenosis        The pregnancy-induced decrease in systemic vascular resistance reduces the risk of cardiac failure with these conditions, especially in women with chronic lesions. Acute onset of mitral or aortic regurgitation may not be well tolerated during pregnancy. For women with severe aortic stenosis, treatment before pregnancy should be considered for a peak-to-peak valve gradient >50 mmHg. In women with aortic stenosis and a mean valve gradient <25 mmHg, pregnancy is likely to be well tolerated. For women with mitral or aortic regurgitation and left ventricular dysfunction (LVEF <30%) pregnancy should be avoided.

CONGENITAL HEART DISEASE (See also Chap. 264) Reparative surgery has markedly increased the number of adult women with surgically repaired congenital heart disease. Maternal morbidity and mortality are greater among these women than among those without surgical cardiac repair. When pregnant, these patients should be jointly managed by a cardiologist and an obstetrician familiar with these problems. The presence of a congenital cardiac lesion in the mother increases the risk of congenital cardiac disease in the newborn. Prenatal screening of the fetus for congenital cardiac disease with ultrasound is recommended.

OTHER CARDIAC DISORDERS Supraventricular tachycardia (Chap. 241) is a common cardiac complication of pregnancy. Treatment is the same as in the nonpregnant patient, and fetal tolerance of medications such as adenosine and calcium channel blockers is acceptable. When necessary, pharmacologic or electric cardioversion may be performed to improve cardiac performance and reduce symptoms. This intervention is generally well tolerated by mother and fetus.

Peripartum cardiomyopathy (Chap. 254) is an uncommon disorder of pregnancy and its etiology remains unknown. Approximately 10% of women with peripartum cardiomyopathy carry a truncating mutation in the gene encoding the titin sarcomere protein. Treatment is directed toward symptomatic relief and improvement of cardiac function. Many patients recover completely; others are left with progressive dilated cardiomyopathy. Recurrence in a subsequent pregnancy has been reported, and women who do not have normal baseline left-ventricular function after an episode of peripartum cardiomyopathy should be counseled to avoid pregnancy.

SPECIFIC HIGH-RISK CARDIAC LESIONS

Marfan Syndrome (See also Chap. 406)        This autosomal dominant disease is associated with an increased risk of aortic dissection and rupture. An aortic root diameter

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<40 mm is associated with a favorable outcome of pregnancy; conversely, an aortic root diameter >40 mm is associated with an increased risk of aortic dissection. Prophylactic therapy with beta blockers has been advocated to reduce aortic dilation and the risk of dissection. A “cardiac delivery” with reduced pushing and early intervention with operative delivery is often recommended to reduce increases in aortic wall stress caused by the Valsalva maneuver.

Ehlers-Danlos syndrome (EDS) may be associated with premature labor, and in type IV EDS there is increased risk of organ or vascular rupture that may cause death. For women with vascular EDS, pregnancy is relatively contraindicated because of the high risk of vascular and uterine rupture.

Pulmonary Hypertension (See also Chap. 277)        Maternal mortality in the setting of severe pulmonary hypertension is high, and primary pulmonary hypertension is a contraindication to pregnancy. Termination of pregnancy may be advisable in these circumstances to preserve the life of the mother. In the Eisenmenger syndrome, i.e., the combination of pulmonary hypertension with right-to-left shunting due to congenital abnormalities (Chap. 264), maternal and fetal deaths occur frequently. Systemic hypotension may occur after blood loss, prolonged Valsalva maneuver, or regional anesthesia; sudden death secondary to hypotension is a dreaded complication. Management of these patients is challenging, and invasive hemodynamic monitoring during labor and delivery is recommended in severe cases.

In patients with pulmonary hypertension, vaginal delivery is less stressful hemodynamically than cesarean section, which should be reserved for accepted obstetric indications.

DEEP VENOUS THROMBOSIS AND PULMONARY EMBOLISM (See also Chap. 273) Pregnancy is associated with venous stasis, endothelial injury and a hypercoagulable state. Inherited thrombophilias and the presence of antiphospholipid antibodies increase the risk of venous thromboembolism (VTE) in pregnancy. Deep venous thrombosis (DVT) or pulmonary embolism (PE) occurs in about 1 in 500 pregnancies, with DVT being three times more common than PE. VTE occurs more commonly in the 6 weeks post-partum than antepartum. In pregnant women, most unilateral DVTs occur in the left leg because the left iliac vein is compressed by the right iliac artery and the uterus compresses the inferior vena cava.

TREATMENT

Deep Venous Thrombosis Aggressive diagnosis and management of DVT and suspected pulmonary embolism optimize the outcome for mother and fetus. In general, all diagnostic and therapeutic modalities afforded that the nonpregnant patient should be utilized in pregnancy except for D-dimer measurement, in which values are elevated in normal pregnancy. Anticoagulant therapy with low-molecular-weight heparin (LMWH) or unfractionated heparin is indicated in pregnant women with DVT. LMWH may be associated with an increased risk of epidural hematoma in women receiving an epidural anesthetic in labor and must be discontinued at least 24 h before placement of an epidural catheter.

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Warfarin therapy is contraindicated in the first trimester due to its association with fetal chondrodysplasia punctata. In the second and third trimesters, warfarin may cause fetal optic atrophy and mental retardation. In pregnancy the use of warfarin is restricted to women with mechanical heart valves. Warfarin is not contraindicated in breast-feeding women. For women at moderate or high risk of DVT who have a cesarean delivery, mechanical and/or pharmacologic prophylaxis is warranted.

ENDOCRINE DISORDERS

DIABETES MELLITUS (See also Chaps. 396–398) In pregnancy, the fetoplacental unit induces major metabolic changes, the purpose of which is to shunt glucose and amino acids to the fetus while the mother uses ketones and triglycerides to fuel her metabolic needs. These metabolic changes are accompanied by maternal insulin resistance caused in part by placental production of steroids, a growth hormone variant, and placental lactogen. Although pregnancy has been referred to as a state of “accelerated starvation,” it is better characterized as “accelerated ketosis.” In pregnancy, after an overnight fast, plasma glucose is lower by 0.8–1.1 mmol/L (15–20 mg/dL) than in the nonpregnant state. This difference is due to the use of glucose by the fetus. In early pregnancy, fasting may result in circulating glucose concentrations in the range of 2.2 mmol/L (40 mg/dL) and may be associated with symptoms of hypoglycemia. In contrast to the decrease in maternal glucose concentration, plasma hydroxybutyrate and acetoacetate levels rise to two to four times normal after a fast.

TREATMENT

Diabetes Mellitus in Pregnancy Pregnancy complicated by diabetes mellitus is associated with higher maternal and perinatal morbidity and mortality rates. Preconception counseling and treatment are important for the diabetic patient contemplating pregnancy and can reduce the risk of congenital malformations and improve pregnancy outcome. Folate supplementation reduces the incidence of fetal neural tube defects, which occur with greater frequency in fetuses of diabetic mothers. In addition, optimizing glucose control during key periods of organogenesis reduces other congenital anomalies, including sacral agenesis, caudal dysplasia, renal agenesis, and ventricular septal defect.

Once pregnancy is established, glucose control should be managed more aggressively than in the nonpregnant state. In addition to dietary changes, this enhanced management requires more frequent blood glucose monitoring and often

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