Critical Care Flashcards
What are the components of ARDS?
ARDS is a life-threatening condition associated with a severe oxygenation defect related to a noncardiogenic proteinaceous pulmonary edema.
1- Respiratory failure not explained by heart failure or volume overload
2- Decreased arterial PO2/FiO2 ratio:
mild ARDS: ratio is 201 - 300 mmHg (≤ 39.9 kPa)
moderate ARDS: 101 - 200 mmHg (≤ 26.6 kPa)
severe ARDS: ≤ 100 mmHg (≤ 13.3 kPa)
3- Lung injury of acute onset, within 1 week of an apparent clinical insult and with progression of respiratory symptoms
4- bilateral opacities on chest imaging not explained by other pulmonary pathology (e.g. pleural effusion, lung collapse, or nodules)
What is involved in LPV?
- 6 cc/kg tidal volume
- plateau pressure < 30 cm/H20
- sufficient PEEP (5-24 cm H2O) and FiO2 to maintain the SaO2 > 88%
- Note that sacrificing a higher PCO2 and therefore lower arterial pH for oxygenation is known as permissive hypercapnia
- bicarbonate infusions can be used to maintain pH > 7.2 if desired while allowing for elevated PCO2
Describe delirium.
- A disturbance of consciousness that is ACUTE in onset
- A FLUCTUATING course of impaired cognitive functioning so that a patient’s ability to receive, process, and store information is impaired.
What is Beck’s triad of cardiac tamponade?
1- Hypotension (2/2 decreased stroke volume)
2- JVD (2/2 impaired venous return)
3- Muffled heart sounds (2/2 fluid inside the pericardium)
What are negative effects associated with sodium bicarbonate therapy for the treatment of acidosis?
1- venous hypercapnia 2- decreased CSF pH 3- tissue hypoxia 4- hypernatremia 5- hyperosmolality of the CSF 6- shift in the oxygen dissociation curve
T or F: as compared to diabetic ketoacidosis, hyperglycemic hyperosmolar state is associated with higher glucose levels (usually > 600), pH > 7.3, higher serum bicarbonate, osmolality greater than 320, no serum or urine ketones, and more dehydration.
True: treatment includes hydration, insulin, and repletion of profound potassium deficits.
Acute treatment of tension pneumothorax?
Needle decompression inserted into the second intercostal space in the midclavicular line using a 14 g needle. Should be placed on the side of the tension pneumothorax.
Acute treatment of pericardial drainage?
needle decompression inserted between the xiphoid and left costal margin, passed at 30-45 degrees and angled toward the left shoulder.
Treatment of tension pneumothorax AFTER it has been urgently decompressed.
Tume thoracostomy decompression placed in the right fifth intercostal space at the midaxillary line.
Case presentation: a 35 year old woman presents with complaints of fatigue, poor appetite, weight loss, and nausea. On exam, she appears tanned but denies sun exposure. She is moderately hypotensive. Lab studies show she is mildly hyperkalemic and hyponatremic. What endocrine disorder does she have?
Addison’s disease
What is Addison’s disease?
Primary adrenal insufficiency and due to a lack of both glucocorticoid and mineralocorticoid activity. Characterized by weightloss, weakness and lethargy, hypotension, GI symptoms, hyperpigmentation, hyperkalemia, hyponatremia, and hypercalcemia. Autoimmune causes are the most common casue of Addison’s today.
Secondary adrenal insufficiency is due to failure of the pituitary and lack of ACTH. Secondary adrenal insufficiency does not show the hyperpigmentation of Addisons.
How can the adverse effects of etomidate manifest itself acutely intraoperatively?
Etomidate inhibits adrenal steroidogenesis by interaction with 11 beta-hydroxylase enzyme. This can result in reduced cortisol production in response to ACTH. Loss of adrenal responsiveness in times of stress can lead to increased resuscitation needs and poor response to pressor agents in the face of hypotension.
The effects of etomidate were thought to last for 8-12 hours after dosing, but newer studies are showing that effects may linger for longer periods, perhaps up to 48 hours.
What does the “French” in a french catheter refer to?
A catheter of 1 French has a diameter of ⅓ mm, and therefore the diameter of a round catheter in millimeters can be determined by dividing the French size by 3:
D (mm) = Fr / 3
What two things affect the flow rate in a central line?
Tube diameter and length of tubing
The diameter of the tube has a magnified effect on flow rates, but length can adversely affect flow. Given that the length of a central venous catheter exceeds the diameter, catheter length plays an important role.
http://www.teleflex.com/en/arrow-catalog/offcat38.html
What is Hagen-Poiseuille equation?
Flow through a rigid tube (ie catheter) is governed by this equation:
Q = DP x ( Pr^4/8mL)
Q = rate of flow DP = the change in pressure through the tube Pr^4 = size of the tube m = viscosity of the fluid L = length of the tube
Some key points with carbon monoxide poisoning:
- can be difficult to detect unless the diagnosis is suspected.
- CO has a higher affinity for hemoglobin than oxygen does –> displaces oxygen and diminishes the oxygen carrying capacity.
- Standard pulse oximetry does not differentiate between oxyhemoglobin and carboxyhemoglobin, so pulse oximetry readings are NOT helpful.
- headache and dizziness are common signs of mild CO poisoning.
- Classically described cherry-red pigmentation does NOT appear until high concetrations of carbon monoxide are present.
What are standard medications for the treatment of an anaphylactic reaction?
- anaphylactic reactions are characterized by IgE mediated release of histamine, leukotrienes, chemotactic factors, platelet aggregatng factor, prostaglandins.
- release of the above triggers capillary permeability leading to loss of circulating volume, hypotension, and tachycardia.
- Wheezing occurs secondary to bronchoconstriction
- skin manifestations and GI complaints may accompany the hemodynamic and pulmonary complications
- Standard therapy: epinephrine (inhibits mediator release by increasing levels of cAMP and affects symptoms by relaxing bronchoconstriction and improving hemodynamics)
- H1 blockers such as diphenydramine and H2 blockers such as famotidine blunt the response to histamine, including capillary permeability and cardiac dysfunction.
- corticosteroids increase tissue response to epinephrine and inhibit histamine synthesis.
- albuterol can help with pulmonary complications of anaphylaxis.
How does racemic epinephrine work?
- Works by stimulation of 1) the α-adrenergic receptors in the airway with resultant tightening of the mucosa (mucosal vasoconstriction) and decreased fluid in the airway (subglottic edema) and by stimulation of the 2) β-adrenergic receptors causing relaxation of the bronchial smooth muscle
- Commonly used in croup and when stridor is present after removal of an endotracheal tube (extubation).
- Side effects include increased heart rate, nausea, anxiety, heart palpitations and headache.
What is the RIFLE criteria for acute kidney injury?
In 2002, the Acute Dialysis Quality Initiative (ADQI) was created with the primary goal of developing consensus and evidence-based guidelines for the treatment and prevention of acute kidney injury (AKI). The first order of business was to create a uniform, accepted definition of AKI; hence, the RIFLE criteria were born:
Risk Injury Failure Loss End-stage renal disease
See http://emedicine.medscape.com/article/1925597-overview#aw2aab6b3
Note: Patients can be classified either by GFR criteria or by UO criteria. The criteria that support the most severe classification should be used.
Name treatments for hyperkalemia.
1- Albuterol: moves K out of serum and into intracellular space for 1-2 hours
2- Insulin/glucose: moves K intracellularly
3- Furosemide: triggers K loss in the urine
4- Sodium polystyrene sulfonate: potassium exchange resins in the GI tract
5- Calcium gluconate: changes the threshold potential of the myocardium conducting cells, blunting the ability of hyperkalemia to trigger myocardial arrhythmias
What is the progression of EKG changes in the setting of hyperkalemia?
1- T waves initially get taller and more peaked 2- PR interval lengthens 3- P wave flattens out 4- QRS widens 5- EKG assumes a sine-wave pattern 6- asystole
What are EKG changes in the setting of hypokalemia?
Development of a prominent U wave and is generally accompanied by flattening of the T waves and ST depression
True or false: intraoperative urine output is not a predictor of perioperative renal failure.
True
What is tPA used for?
As an enzyme, it catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for clot breakdown. Because it works on the clotting system, tPA is used in clinical medicine to treat embolic or thrombotic stroke.
What is the most effective method for reversing the effect of tPA?
- cryoprecipitate or fibrinogen concentrates replace fibrinogen and represent the accepted method for treating acute life-threatening bleeding after the administration of fibrinolytics.
T or F: ARDS network trial demonstrated a decrease in mortality from about 40% to 31% with the use of low tidal volume and controlling plateau pressures to less than 30 cm H2O.
True: this improved survival was accompanied by an increase in the RR, increased arterial CO2, and decrease in oxygenation.
What is a known side effect in the administration of nitric oxide?
Nitric oxide is a potent pulmonary vasodilator.
Known side effects:
platelet dysfunction
methemoglobinemia
What can cause negative pressure pulmonary edema? What is the treatment for this? How quickly does it resolve?
Negative pressure pulmonary edema is caused by a closed glottis in the spontaneously ventilating patient, with generation of significant negative intrathoracic pressure due to rib retraction from an inspiration attempt. This can also happen when an ETT becomes occluded, most commonly by a mucus plug, clot, or biting on the ETT. It follows releif of acute upper airway obstruction (postobstructive pulmonary edema) caused by postextubation laryngospasm, epiglottitis, tumors, obesity, hiccups, or OSA in spontaneously breathing patients.
The generation of significant negative intrathoracic pressure can cause increased left ventricular preload and afterload, altered pulmonary capillary permeability, a hyperadrenergic state, right ventricular dilatation, and increased hydrostatic pressure. The negative pleural pressure can result in fluid entry into the lung. Relief of the obstruction leads to decreased airway pressures, increased venous return, increase in pulmonary hydrostatic pressure, and ultimately pulmonary edema.
The time to the development of symptoms after relief of airway obstruction ranges from a few minutes to as long as 2-3 hours. Typical signs are tachypnea, cough, and failure to maintain oxygen saturation above 95%. Hypoxemia is accompanied by bilateral fluffy infiltrates on CXR, but radiographic evidence of pulmonary edema resolve within 12-24 hours.
Treatment: supportive with continuous PPV with PEEP. Typically resolves in 6-12 hours, transient and self-limited.
