Based on the following blood-gas report, what is the most likely acid-base diagnosis?
pH = 7.51
pCO2 = 44 torr
HCO3 = 35.1 mEq/L
- acute (uncompensated) metabolic alkalosis
- combined respiratory and metabolic alkalosis
- acute (uncompensated) respiratory alkalosis
- fully compensated respiratory alkalosis
The pH is above normal (alkaline). The PCO2 is in the normal range and thus not a factor in the alkalosis. The HCO3 is high, which indicates a primary metabolic alkalosis. Since the PCO2 is normal, no compensation is occurring and the problem is an acute or uncompensated metabolic alkalosis.
When reviewing the chart of a patient who presents with evidence of acute pulmonary infection, which of the following laboratory studies would provide the most useful information?
- sputum culture and sensitivity
- blood culture
- sputum acid fast stain
- sputum Gram stain
Sputum culture and sensitivity will provide not only what microbe is growing in the lung, it will provide the drug(s) that are most effective in controlling the microbe.
Characteristic of all obstructive disorders is a:
- decrease in lung volumes
- increase in lung volumes
- decrease in flow rates
- decrease in work of breathing
Whether inspiratory or expiratory in nature, all obstructive disorders are characterized by impedance to the flow of air. In the pulmonary function laboratory, this flow impedance always is seen as a DECREASE in flows, as measured during the applicable phase of breathing. If the problem is mainly expiratory obstruction, expiration time is usually prolonged beyond that of inhalation, with contraction of the upper abdomen often evident toward the end of exhalation.
The Apgar score for a normal newborn infant ranges between
At birth, an Apgar score of 7-10 is considered normal. Scores of 4-6 are intermediate and usually dictate the need for more intensive support. Infants with Apgar scores of 0-3 usually undergo aggressive resuscitation. Needed interventions should never be delayed in order to obtain the Apgar score, nor should these scores dictate resuscitation procedures.
An adult patient has an intracranial pressure (ICP) of 24 mm Hg. You can conclude that:
- the ICP is normal
- the ICP is below normal
- the ICP is abnormally high
- there is excessive CSF
In supine adults, the mean ICP normally ranges between 7 to 15 mm Hg. An ICP > 20 mm Hg for more than 5 to 10 minutes is considered abnormally high an adult, with pressures > 25 mm Hg for a prolonged period of time associated with poor patient outcomes. Excessive cerebrospinal fluid is one cause of a high ICP, but there is insufficient information to draw that conclusion.
In reviewing a transthoracic ultrasound scan you note a prominent shadow occurring beneath a rib. What does this shadow signify?
- pulmonary edema
- normal finding
A shadow beneath the ribs is an expected normal finding when performing a transthoracic ultrasound scan. The shadow (indicating a lack of echo) occurs because the sound waves cannot penetrate beyond the rib. This shadow should not be confused with the presence of liquid, which would also appear black.
Six hours after a confused 71-year-old male is admitted to the ED with dyspnea, diaphoresis and hypotension, lab results indicate elevated creatine kinase isoenzyme (CK-MB) and troponin I. These finding are most consistent with:
- myocardial infarction
- neurogenic shock
- fluid overload
- pulmonary edema
CK-MB and troponin I are biomarkers whose concentrations rise when there is damage to the myocardium. In combination, a rise in the level of these markers 6 hours after injury indicates an acute myocardial infarction (AMI), consistent with the patient's clinical signs (chest pain may not always occur in AMI). These markers do not help diagnose neurogenic shock or pulmonary edema and fluid overload would not result in hypotension.
Which of the following echocardiogram findings are consistent with a diagnosis of persistent pulmonary hypertension of the newborn (PPHN)?
- enlargement of the left ventricle
- right -to-left shunting through a PDA
- mitral valve regurgitation/insufficiency
- right bowing of the interventricular septum
On a comprehensive echocardiography exam, infants with PPHN typically will exhibit right-to-left shunting (especially during systole) at the ductus arteriosus; a high pressure gradient across the tricuspid valve with regurgitation (insufficiency); a high pulmonary artery pressure with enlargement of the RV, RA and pulmonary artery; and possible bowing of the interventricular septum to the left. To support PPHN as a diagnosis, the echo exam also should be negative for any congenital heart disease, e.g., partial/total anomalous pulmonary venous return.
The results of an arterial blood gas analysis are below:
These data indicate which of the following?
- primary metabolic acidosis
- primary metabolic alkalosis
- primary respiratory alkalosis
- primary respiratory acidosis
The pH is acidic indicating that the primary problem is the one causing acidosis. The low bicarbonate and base excess confirm that the acidosis is metabolic in origin. The low PaCO2 indicates that the patient is hyperventilating. In the presence of a primary metabolic acidosis, a low PaCO2 (same direction change as the HCO3), represents a (partial) compensation for the metabolic acidosis.
You note in the chart of a patient's who is receiving volume control ventilation that the plateau pressure has been increasing over the last 6 hours, while the PEEP levels remains constant. Which of the following would be the most likely cause of this change?
- development of pulmonary edema
- water accumulation in the ventilator circuit
- partial obstruction of the endotracheal tube
- development of bronchospasm
An increase in the plateau pressure relative to baseline (Pplat-PEEP) indicates a decrease in the patient's lung and/or thoracic compliance. Common causes of a decrease in lung compliance are pneumothorax, pulmonary edema, atelectasis and ARDS. Partial obstruction of the ET tube and development of bronchospasm would increase airway resistance and thus increase PIP and the PIP-Pplat pressure difference, but not affect Pplat.
While reviewing the chart of a patient with lobar pneumonia, you note that the respiratory rate for the last 24 hours has increased from 18 to 38/min. Which of the following is the most likely cause of the increased respiratory rate?
- metabolic alkalosis
Both hypothermia and metabolic alkalosis depress respiratory drive, and would therefore tend to decrease the respiratory rate. Hypokalemia causes muscle weakness, which also could diminish respiratory effort. On the other hand, hypoxemia (commonly seen in pneumonia) stimulates breathing. Indeed, tachypnea is one of the signs associated with hypoxemia.
An adult male patient has a hematocrit value of 59%. Which of the following problems might this finding indicate?
- impaired oxygen transport
- decreased immunity
Normal hematocrit values for males range between 40-50%. A high hematocrit (as in this case) indicates either hemoconcentration (as occurs in dehydration) or a polycythemia (as occurs with chronic hypoxemia).
An echocardiogram on a 64 year-old patient who experiences dyspnea and palpitations on exertion reveals the following left ventricular data: elevated end-diastolic pressure, elevated end-diastolic volume, and an ejection fraction of 38%. There is no evidence of valvular heart disease, intracardiac shunts, cardiac tamponade, or pericardial constriction. Which of the following is the most likely problem?
- constrictive cardiomyopathy
- diastolic heart failure
- pericardial effusion
- systolic heart failure
Heart failure can be due to decreased LV contractility (systolic failure) or abnormal LV filling (diastolic failure). In both types, the LV end-diastolic pressure is elevated. The key difference is that the LV ejection fraction is reduced (<45%) in systolic failure but normal (> 50%) in diastolic failure. In addition, whereas the LV end-diastolic volume in systolic failure is increased (causing LV dilatation), this pressure is either normal or decreased in diastolic failure.
On reviewing the results of the attending physician's physical examination of a patient's chest, you note 'a dull percussion note and bronchial breath sounds - LLL.' Which of the following is a potential problem?
A patient with a dull percussion note and bronchial breath sounds on chest examination most likely has either pulmonary infiltrates, atelectasis or consolidation of the affected area. A pneumothorax would be evident by a hyperresonant percussion note.
In which of the following conditions would a ventilation scan be normal but a perfusion scan reveal areas of absent blood flow?
- lung cancer
- pulmonary embolism
The distinguishing feature of pulmonary embolism is the presence of a perfusion defect in an area of normal ventilation. Many other conditions, such as pleural effusion, tumors, pulmonary hypertension, pneumonia, and COPD can cause perfusion defects. However, in these cases both the perfusion and ventilation scans would tend to be abnormal and—unlike pulmonary embolism—the problem usually would be evident on a standard chest X-ray.
When inspecting the X-ray of a patient with a history congestive heart failure being treated in the Emergency Department, you note patchy densities in the perihilar areas and in the gravity-dependent lower lung fields, with an increased CT ratio. Which of the following is the most likely problem?
- pleural effusion
- bacterial pneumonia
- pulmonary edema
On X-ray, fluffy or patchy densities in the perihilar areas and in the gravity-dependent lower lung fields is most consistent with pulmonary edema. Cardiomegaly and pleural effusions may also be seen, especially in severe left heart failure.
Which of the following arterial blood gas results would be most representative of a patient who has advanced, but stable, COPD breathing room air?
pH PaCO2 PaO2
A 7.37 41 55
B 7.38 59 56
C 7.41 45 79
D 7.50 56 57
A stable COPD patient typically exhibits a chronic or compensated respiratory acidosis with hypoxemia (ABG ‘B’). In compensated respiratory acidosis, over time the kidneys increase bicarbonate levels, which offsets the high Paco2 and raises the pH back into the normal or near-normal range.
All of the following are common causes of fluid depletion (dehydration) in patients EXCEPT:
- renal failure
Common causes of fluid depletion (dehydration) in patients include diarrhea, vomiting, sweating/fever, hemorrhage, diuretics and excessive urination. Renal failure typically causes fluid retention.
In reviewing the chart of a 55 year-old male patient, you note the following symptoms: obesity, loud snoring and insomnia. These findings are most consistent with which of the following diagnoses?
- pulmonary emphysema
- acute asthma
- Guillain-Barré syndrome
- obstructive sleep apnea
Loud snoring and insomnia are symptoms of obstructive sleep apnea (OSA), with obesity being a related causal factor. To confirm this suspected diagnosis, you should recommend a diagnostic sleep study (polysomnogram).
Obstructive sleep apnea is defined as:
- a decrease in breathing greater than 50% that causes desaturation
- at least 10 seconds of no airflow with increasing respiratory effort
- increasing respiratory effort that leads to an arousal from sleep
- at least 10 seconds of no airflow without respiratory effort
Obstructive apnea is defined as a cessation of airflow for at least 10 seconds during which there is continued effort to breathe. Central apnea also is characterized by a lack of airflow for 10 or more seconds, but occurs without respiratory effort. Hypopnea is a reduction in air flow of at least 30% from baseline lasting at least 10 seconds and associated with significant oxygen desaturation (> 3–4%).
Which of the following findings would you expect to see in an alert but anxious asthmatic who has just been admitted to the ED?
- respiratory acidosis
- respiratory alkalosis
- cor pulmonale
Patients suffering from an acute exacerbation of asthma typically present with respiratory alkalosis and hypoxemia. This is because anxiety and hypoxemia together cause hyperventilation. In general, once supplemental O2 relieves the hypoxemia, the patient’s PaCO2 and pH will tend to normalize. A rising PaCO2 (respiratory acidosis) is an ominous sign, indicating progression to hypercapnic respiratory failure.
In the laboratory results section of her medical record, you note an overall WBC of 22,000 for a febrile patient who appear acutely ill and in moderate respiratory distress. Which of the following is this patient’s most likely diagnosis?
- bacterial pneumonia
- pulmonary embolus
- pulmonary fibrosis
The elevated WBC suggests a bacterial infection. The respiratory distress further points to a respiratory infection such as bacterial pneumonia. In addition, the other choices are not infectious processes and therefore you would not likely see an elevated WBC.
Which of the following information in a patient's medical history would be LEAST important to consider in evaluating the patient's pulmonary condition?
- smoking history
- employment history
- prior pulmonary illnesses
- dietary habits
While knowledge of dietary habits would be helpful in some respiratory patients (e.g., cystic fibrosis), it is the least helpful of the available choices. Obviously the patient’s prior pulmonary illnesses and smoking history are essential. Employment history is also critical, since many respiratory disorders are associated with job-related exposure to toxic substances.
A patient receiving ventilatory support has a reported serum potassium of 2.1 mEq/L. Which of the following would you be on guard for with this patient?
- metabolic alkalosis
- cardiac arrhythmias
- renal failure
A low serum potassium (normal range 3.5-4.8 mEq/L) is associated with metabolic alkalosis and can result in abnormal electrical conduction in the heart, i.e., cardiac arrhythmias.
Which of the following clinical laboratory tests indicate potential renal failure?
blood urea nitrogen of 58 mg/dL
blood creatinine of 4.3 mg/dL
blood glucose of 100 mg/dL
- 1 and 2 only
- 2 and 3 only
- 1 and 3 only
- 1, 2 and 3
Both the blood urea nitrogen (normal 7–20 mg/dL) and creatinine (normal: 0.7–1.3 mg/dL) levels are used to assess renal function. As by-products of protein metabolism, the BUN and creatinine are elevated in certain forms of renal failure, such as chronic glomerulonephritis.
Which of the following basic spirometry tests would be most useful in the evaluation of an obstructive lung defect such as COPD?
- forced expiratory volume
- inspiratory capacity
- tidal volume
- expiratory reserve volume
Since obstructive disease limits expiratory airflow, a forced expiratory maneuver will help detect obstruction. Lung volume measurements may also be useful, but primarily the FRC/RV (to detect air-trapping).