Ch01-2-4-9781975113285

Introduction and Objectives

1

Thomas M. Ciesielski

INTRODUCTION

Welcome to your intern year. This is a transformative time, and you will likely not forget the first time you walk into a patient’s room, whether it’s the operating room, emergency room, or hos- pital ward, and introduce yourself as a physician. It is also a time when you will encounter many new challenges. These will range from very simple to the most complex. You have acquired the tools to address this adversity. Even when you feel most overwhelmed, you are undoubtedly surrounded by a wealth of available resources that include ancillary and nursing staff, fellow interns, senior residents, and attending physicians. As I think back to my intern year, I recall the sage advice from my chief resident, “Intern year Although the year ahead of you may now seem long and daunting, your tasks are quite achievable. The following rotation objectives were copied from the curriculum for the inpatient general medicine rotation for the internship program at Washington University School of Medicine and Barnes-Jewish Hospital. You can see that not only are the objectives quite simple, but also your rigorous work in medical school has prepared you well to master many of your goals. Your pro- gram likely has a similar document, whether in medicine or another specialty. Use these objectives throughout the year as a checklist to remind yourself of your accomplishments and to guide your learning in potential areas of weakness. • Patient care • Gather and synthesize essential and accurate information to define each patient’s clinical problems, including performing a thorough history and physical examination. • Synthesize data into a prioritized problem list and differential diagnosis, and then develop and achieve comprehensive man- agement plans for patients. is only one year!” OBJECTIVES

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• Manage patients with progressive responsibility and independence. • Monitor and follow up patients appropriately. • Know the indications, contraindications, and risks of some invasive procedures and competently perform those invasive procedures. • Request and provide consultative care. • Prioritize each day’s work (if you’re an intern, for yourself; if you’re a resident, for your entire team). • Medical knowledge • Demonstrate an increasing fund of knowledge in the range of common problems encountered in inpatient internal medicine and utilize this knowledge in clinical reasoning. If you’re a resident, while on service you should become familiar with the diagnostic and therapeutic approach to patients with chest pain, shortness of breath, deep vein thrombosis/pulmo- nary embolism, nausea/vomiting/diarrhea, fever, mental status changes, abdominal pain, gastrointestinal bleeding, syncope and lightheadedness, renal failure (acute and/or chronic), anemia, hypertension, diabetes mellitus, pneumonia, urinary tract infection, soft tissue infections (e.g., cellulitis, diabetic foot infection, decubitus ulcer), and alcohol withdrawal. You should also demonstrate an increasing ability to teach others on these and other topics. • Increase your knowledge of diagnostic testing and procedures. • Practice-based learning and improvement • Understand your limitations of knowledge and judgment, ask for help when needed, and be self-motivated to acquire knowledge. ■■ Monitor practice with a goal for improvement. ■■ Learn and improve via performance audit. ■■ If you are a PGY2 or PGY3, you should learn how to use knowledge of study designs and statistical methods in the critical appraisal of clinical studies and apply to the care of patients. ■■ Use information technology to manage information and access online medical information. • Accept feedback, learn from your own errors, and develop self-improvement plans. • Learn and improve via feedback. • Learn and improve at the point of care.

Introduction and Objectives   3

• Interpersonal and communication skills • Communicate effectively with patients and caregivers. For example: ■■ Demonstrate caring and respectful behaviors with patients, families—including those who are angry and frustrated— and all members of the healthcare team. ■■ Counsel and educate patients and their families. ■■ Conduct supportive and respectful discussions of code status and advance directives. • Communicate effectively with interprofessional teams. • Facilitate the learning of students and other healthcare professionals. • Ensure appropriate utilization and completion of health records. Demonstrate ability to convey clinical information accurately and concisely in oral presentations and in chart notes. • Professionalism • Display respect, compassion, and integrity. • Demonstrate a commitment to excellence and ongoing profes- sional development. • Have professional and respectful interactions with patients, • Develop an appreciation for the ethical, cultural, and socio- economic dimensions of illness, demonstrating sensitivity and responsiveness to each patient’s culture, age, gender, and disabilities. • If you are a resident, display initiative and leadership; be able to delegate responsibility appropriately. • Exhibit integrity and ethical behavior in professional conduct. • Demonstrate a commitment to ethical principles pertaining to provision or withholding of clinical care, confidentiality of patient information, informed consent, and other aspects of clinical care. • Systems-based practice • Work effectively with an interprofessional team (such as with nurses, secretaries, social workers, nutritionists, interpreters, physical and occupational therapists, technicians). ■■ If you’re a resident, you should develop proficiency in leading the healthcare team and organizing and managing medical care. caregivers, and members of the interprofessional team. • Accept responsibility and follow through on tasks.

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• Advocate for quality patient care and assist patients in dealing with system complexities. • Recognize system errors and advocate for system improvements. • Identify forces that affect the cost of healthcare and advocate for and practice cost-effective care. • Transition patients effectively within and across the healthcare delivery system. For example, understand and appreciate the importance of communicating with the primary care physician at the time of admission or soon thereafter.

Keys to Survival

2

Thomas M. De Fer

1. DON ’ T PANIC ! Keep your sense of humor. A positive attitude will take you far. 2. Ask questions and ASK FOR HELP! Believe it or not, you are not actually expected to know everything. 3. TAKE CARE OF YOURSELF. Sleep when you can, remember to eat, and be mindful of your own health. Don’t forget your family and friends. 4. Work hard, stay enthusiastic, and maintain interest. But try not to burn yourself out in the first month. 5. Take care of your patients. You’re finally using your expensive education and training. Keep your patients at the center of what you do, and keep their best interests in mind. 6. Be organized and prioritize your tasks. Keep checklists of your tasks and cross them off once you complete. The one with the most checkmarks wins! 7. Verify everything yourself (e.g., lab tests, plain radiographs, ECGs). Any test worth ordering is worth knowing the results of. Never but never make it up! If you don’t know, you should say so. 8. Scut happens. Try hard not to leave it to someone else. If you do, they’ll return the favor someday. 9. Be kind to the nurses and other ancillary staff. They can make your life much better… or much worse. The choice is mostly yours. 10. When in doubt, go and see the patient! 11. Choose your battles very carefully. Even in the name of patient care, ugly behavior is ugly. You will be remembered for violation. Don’t get a reputation! 12. Call for consultations on your patients early in the day and have a specific question you want answered from the consultant. 13. Start thinking about discharge/disposition planning from day 1. Although discharge isn’t the goal of all patient care, it should be on your radar screen most of the time. 14. Complete discharge summaries the day the patient leaves.

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Useful Formulae

4

Thomas M. De Fer

INTRODUCTION

• The most important formula for the intern year:

(discharges + transfers) (admissions + cross cover) 2

Sleep (h) =

× number of interns

• Many of these formulae can be found on applications for your electronic devices or on Web sites. A-a O 2 GRADIENT

− Pa O

A-a gradient = PA O 2

2

2  × 713) −  (PaCO 2

PAO

 = (FiO

/0.8)

2

( all units in mm Hg )

• Estimate for upper limit of normal in room air (in mm Hg) by age (years) = (age/4) + 4. • Causes of increased A-a gradient: V/Q mismatch, intrapulmonary right-to-left shunt, intracardiac right-to-left shunt, impaired diffu- sion (room air only) ANION GAP (SERUM)

AG = [Na + ]  −  ([Cl − ] + [HCO 3 – ])

( all in mmol/L )

• Normal = 8 to 12 mmol/L • See Chapter 15, Acid-Base Disorders, for differential diagnosis.

1 0

Useful Formulae   1 1

ANION GAP (URINE)

) − U

UAG = (U

 + U

[Na + ]

[K + ]

[Cl − ]

( all in mmol/L )

• Normal = slightly positive • UAG is negative in diarrhea-induced nongap metabolic acidosis ( enhanced urinary NH 4 + excretion). • UAG is positive in distal RTA-induced nongap metabolic acidosis ( impaired urinary NH 4 + excretion). • See Chapter 15, Acid-Base Disorders, for differential diagnosis. BODY MASS INDEX

BMI = wt/(ht) 2 ( wt in kg, ht in m )

• <18.5 = underweight • 18.5-24.9 = normal weight • 25-29.9 = overweight • >30 = obese • >40 = morbidly obese CREATININE CLEARANCE/GLOMERULAR FILTRATION RATE

Estimated (Cockcroft-Gault Formula) CrCl = [(140  −  age) × weight]/[serum Cr × 72] × 0.85 ( if female ) ( weight in kg, Cr in mg/dL) Estimated (MDRD) eGFR = 175 × (SCr) − 1.54  × age −0.203 × 0.742 ( if female ) × 1.21 ( if black ) ( eGFR in mL/min per 1.73m 2 , Cr in mg/dL )

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• Um, yeah, like you’re going to calculate those exponents in your head. Obviously, this is too complicated without a calculator. • If you care, MDRD stands for Modification of Diet in Renal Disease (study). • MDRD is fairly accurate for patients with known chronic kidney disease and who are not hospitalized. Estimated (The Chronic Kidney Disease Epidemiology Collaboration) eGFR = 141 × min (SCr/ κ , 1) α  × max (SCr/ κ , 1) −1.209  × 0.993 age

× 1.018 ( if female ) × 1.159 ( if black ) ( eGFR in mL/min per 1.73m 2 , Cr in mg/dL )

• Again, ain’t no way anyone can calculate that in his/her head. • More accurate when GFR is close to normal. Measured (24-h) CrCl = (U [Cr]  × U volume )/(P [Cr]  × 24 × 60) ( Cr in mg/dL, volume in mL, and time in min )

CORRECTED SERUM CALCIUM

Corrected serum Ca = [Ca +2 ] +  [ 0.8 × (4.0  −  [albumin]) ] ( [Ca +2 ] in mg/dL, albumin in g/d )

CORRECTED SERUM SODIUM

Corrected serum Na = [Na + ] +  [ 0.016 × ([glucose]  −  100) ] ( [Na + ] in mmol/L, [glucose] in mg/dL )

FRACTIONAL EXCRETION OF SODIUM

FE

 = (U

 × P

)/(P

 × U

) × 100

Na

[Na + ]

[Cr]

[Na + ]

[Cr]

(U

and P

in mmol/L; U

and P

in mg/dL)

[Na + ]

[Na + ]

[Cr]

[Cr]

Useful Formulae   1 3

• FE Na <1% in prerenal states, early acute tubular necrosis, contrast or heme-pigment nephropathy, and acute glomerulonephritis. • Not valid when diuretics have been given. • See “Acute Kidney Injury” section in Chapter 12, Top 10 Workups.

FRACTIONAL EXCRETION OF UREA

FE

 = [(U

 × P

)/(P

 × U

)] × 100

urea

[urea]

[Cr]

[urea]

[Cr]

( all units in mg/dL )

• FE

<35% in prerenal states.

urea

• Not affected by diuretics. • See “Acute Kidney Injury” section in Chapter 12, Top 10 Workups.

MEAN ARTERIAL PRESSURE

Mean arterial pressure = [SBP + (2 × DBP)]/3

MODEL FOR END-STAGE LIVER DISEASE

MELD = (3.78 × Ln[bilirubin]) + (11.2 × Ln INR) + (9.57 × Ln[SCr]) + 6.43 ( [bilirubin] and [Cr] in mg/dL ) • Who remembers what a nature log is? Rhetorical… Only included to provide the interpretation (Table 4-1).

OSMOLALITY (SERUM, ESTIMATED)

Calculated serum osm = (2 × [Na + ]) + ([glucose]/18) + ([BUN]/2.8)

( [Na + ] in mmol/L; [glucose] and [BUN] in mg/dL )

• To correct for methanol + ([MeOH]/3.2). • To correct for ethanol + ([EtOH]/4.6).

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MORTALITY BASED ON MODEL FOR END-STAGE LIVER DISEASE (MELD) SCORE

TABLE 4-1

MELD Score

Observed Mortality (over 3 mo) (%)

>40

71.3 52.6 19.6

30-39 20-29 10-19

6.0 1.9

<9

Adapted from Wiesner R, et al. Model for end stage liver disease (MELD) and allocation of donor livers. Gastroenterology 2003;124:91-6, with permission.

• To correct for isopropyl alcohol + ([IPA]/6). And in this case, IPA does not stand for India pale ale.

• To correct for ethylene glycol + ([EG]/6.2). • To correct for mannitol + ([mannitol]/18.2). OSMOLAL GAP

−  calculated S

Osmolal gap = measured S osm

osm

• Causes of increased osmolal gap: decreased serum water, hyper- proteinemia, hypertriglyceridemia, and presence of unmeasured osmoles (e.g., sorbitol, glycerol, mannitol, ethanol, isopropyl alco- hol, acetone, ethyl ether, methanol, and ethylene glycol) • Every time you drink alcohol you have an osmole gap! Unless you correct for it as mentioned. RETICULOCYTE INDEX Reticulocyte index = [reticulocyte count × (Hct/45)]/maturation factor Maturation factor = 1 + (0.5 × [(45  − Hct)/10]) • Good marrow response = 3.0-6.0. You go marrow! • Borderline response = 2.0-3.0 • Inadequate response = <2.0. Gosh marrow, is that the best you can do?

Useful Formulae   1 5

MEDICAL EPIDEMIOLOGY

• Yeah, can you believe this stuff actually matters? • The letters in the following refer to a standard 2 × 2 table presented in Figure 4-1. • Sensitivity: the percentage of patients with the target disease/ condition who have a positive result [A/(A + C)]. The greater the sensitivity, the more likely the test will detect patients with the disease. High sensitivity tests are useful clinically to rule OUT a disease (SnOUT) (i.e., a negative test result would virtually exclude the possibility of the disease). • Specificity: the percentage of patients without the target disease/ condition who have a negative test result [D/(B + D)]. Very spe- cific tests are used to confirm or rule IN the presence of disease (SpIN). • Positive predictive value : the percentage of persons with positive test results who actually have the disease/condition [A/(A + B)]. • Negative predictive value : the percentage of persons with negative test results in which the disease/condition is absent [D/(C + D)]. • Number needed to treat : the number of patients who need to be treated to achieve one additional favorable outcome; calculated as 1/absolute risk reduction, rounded up to the nearest whole number • Number needed to harm : the number of patients who, if they received the experimental treatment, would lead to one additional person being harmed compared with patients who receive the con- trol treatment; calculated as 1/absolute risk increase

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All with positive test = A + B Positive predictive value (PPV) = [A/(A + B)] All with negative test = C + D

Negative predictive value (NPV) = [D/(C + D)]

D

B

Disease No disease

False positive (FP)

True negative (TN)

All without disease = B + D Specificity = [D/(B + D)]

A

C

Positive test True positive (TP)

Negative test False negative (FN)

All with disease = A + C Sensitivity = [A/(A + C)]

Figure 4-1. Medical epidemiology.