kettering section c: general critical care Flashcards
identify the quantitative markers of acute hypoxemic respiratory failure
- PaO2 <= 50-60mmHg on room air
- SpO2 < 93% on room air
- PaO2/FiO2 ratio < 300
- A-aDO2 > 200 mmHg
Name five hypoxemic mechanisms.
- V/Q mismatch
- Decreased diffusion of oxygen across the alveolar-capillary membrane
- Alveolar hypoventilation (hypercapnia)
- High altitude with low inspired PO2
- Shunt / refractory hypoxemia / venous admixture
Identify quantitative markers of hypercapnic respiratory failure.
- PaCO2 >= 50 mmHg
- FVC < 10 mL/kg
- NIF less negative than -20 cmH2O
Name the ATS/ERS criteria for ARDS.
- P/F ratio < 200
- PCWP < 18 mmHg
- Diffuse bilateral infiltrates
Name the phases of ARDS
- Exudative
- Proliferative
- Fibrotic
Characterize the exudative phase of ARDS.
Starts within 12-36 hours of insult to lung
Lasts 1 - 7 days
Features alveolar and leukocytic inflammation with hyaline membranes from diffuse alveolar damage–more prevalent in gravity-dependent portions of the lungs
Features hypoxemia, tachypnea, and progressive dyspnea
Features increase in physiologic deadspace that leads to hypercarbia
Appears on CXR as bilateral, diffuse alveolar and interstitial opacities
Characterize the proliferative phase of ARDS.
Lasts 7-21 days
Features persistent dyspnea and hypoxemia
May develop in some patients progressive lung injury and fibrosis
Characterize the fibrotic phase of ARDS.
Leads to recovery for most patients in 3 - 4 weeks
Means for some patients progressive fibrosis with prolonged mechanical ventilation and/or supplemental oxygen therapy
Name a bunch of risk factors for acute coronary syndrome.
Family history of MI
Hypertension
History of smoking
Hyperlipidemia
Increasing age
Post-menopausal state
Obesity
DM
Other vascular diseases
Sedentary lifestyle
Cocaine/amphetamine use
What information do you need to gather to form a diagnosis of ACS?
History
Clinical assessment
Electrocardiogram (12-lead ECG)
Serum biomarkers
Name clinical presentations of ACS.
SOB
CP
Fine basilar crackles on auscultation
Diaphoresis
Nausea & vomiting
What’s the leading cause of death from ACS?
Cardiogenic shock.
For patients who don’t tolerate aspirin for anti-platelet aggregation therapy, what should be offered to them?
Clopidogrel
Ticlopidine
Name the anti-ischemic meds.
Nitroglycerin
Morphine
Beta blockers
Diltiazem
What class of medication is Diltiazem?
Calcium-channel blocker
Name a calcium-channel blocker?
Diltiazem.
Clinical presentation of NSTEMI.
- Angina at rest, new-onset angina, or increasing angina
- Prior history of CAD
- S/T segment depression on serial EKGs
- Elevated biochemical markers (troponin, CK-MB)
How to manage NSTEMI.
–Admit to unit with cardiac monitoring
–Provide oxygen for anyone with dyspnea, SpO2 < 90% on RA, evidence of heart failure, evidence of shock
–Correct any precipitating factors, such as fever, anemia, anxiety, hypertension
–Control pain with analgesia–nitroglycerin, morphine
–Supply anti-ischemic medications
–Provide medication to combat platelet aggregation/thrombosis
–Provide anticoagulation agents
–Consider reperfusion procedures
Describe clinical presentation of STEMI.
Prolonged chest pain
S4 heart sound
Bibasilar crackles
Serial EKG with S/T segment elevation
Elevated biochemical markers–troponin, CK-MB
How to manage STEMI.
Supply blood flow to affected area
Oxygen
Aspirin/Clopidogrel
Nitroglycerin / morphine
Heparin
Beta-blocker
Invasive reperfusion in the cath lab
Okay–slog through the steps for the apnea test.
Hyperoxygenate patient to reach PaO2 > 200 mmHg
Disconnect patient from ventilator while monitoring SpO2
Administer 100% oxygen
Observe closely for chest or abdominal movements which produce an adequate Vt.
–** presence of respiratory movements indicates a negative apnea test
–absence of respiratory movements indicates a positive test and supports a diagnosis of brain death
Obtain an ABG after 8 minutes and reconnect patient to ventilator
Criteria for diagnosis of brain death
–Total cessation of cerebral function while somatic function is maintained by artificial means and the heart continues to beat
–Lack of response to all forms of stimulation (showing widespread cortical destruction)
–Absence of brainstem reflexes (showing global brainstem damage)
–Apnea (showing destruction of medulla)
–Exclusion of hypothermia and drug toxicity (prior to brain death diagnosis)
What definitive test confirms diagnosis of brain death?
Cerebral perfusion scan (cerebral angiogram)
Formula for cerebral perfusion pressure
MAP - ICP
Cerebral perfusion pressure normal values
60 - 100 mmHg
Critical values cerebral perfusion pressure
20 - 40 mmHg
Why would we place an ICP monitor?
–To detect life-threatening elevations of ICP
–To assess effectiveness of therapy
–To drain CSF to therapeutic effect
What are contraindications to placing an ICP monitor?
–Coagulopathy (low platelets, APTT 2x normal)
–Immunosuppressive therapy (particularly steroids)
Name six non-surgical strategies to reduce and/or maintain low ICP.
Maintain low jugular venous pressure.
Provide sedation and analgesia.
Remove fluid from brain with osmotic agents.
Hyperventilate.
Avoid hypoventilation and hypoxemia.
Use normal saline as primary maintenance fluid.
How does one maintain low jugular venous pressure to keep ICP from climbing?
Position patient carefully to avoid threats to venous drainage–
* Avoid neck flexion
* Avoid head turning
* Ensure trach tube ties are not too tight
Minimize increase in central venous pressure–
* Keep head of bed elevated to 30 degrees
* Minimize straining, retching, coughing
* Minimize PEEP
What osmotic fluids can help reduce fluid from the brain?
Mannitol
Hypertonic saline
Kettering on hyperventilation for reducing ICP
–PaCO2 of 25 - 30 mmHg
–Works only temporarily
–Results temporarily in vasoconstriction
–May be effective for acute elevations in ICP
–Many not be considered a standard of care
After seizure activity, return to consciousness is delayed. What conditions should be on differential diagnosis?
Stroke
Subarachnoid hemorrhage
Subdural hematoma
Tumor
Underlying metabolic disorder (e.g., hypoglycemia, toxin ingestion, electrolyte disturbance)
Kettering on pharmacological treatment of progressive ischemic stroke
tpa
Aspirin
Which tests confirm an SAH?
CT scan
Lumbar puncture
What’s the window for vasospasm following SAH?
3-5 days.
In cardiogenic shock, low cardiac output could be caused by what two factors?
• Intravascular volume depletion (e.g. hemorrhage)
• Cardiac dysfunction
Types of shock—four
Cardiogenic
Hypovolemic
Obstructive
Distributive
Mechanisms of shock—three
Failure of pump
Failure of vascular tone
Failure of fluid volume
Divide the shocks into two varieties.
Low cardiac output (cardiogenic, hypovolemic, obstructive)
High cardiac output (distributive)
Name that shock:
High cardiac output
Decreased MAP
Decreased SVR
Normal to low CVP
Normal to low PCWP
Increase pulse pressure
Distributive shock
Name six conditions that could lease to distributive shock.
- Sepsis
- Adrenal insufficiency
- Hyperthyroidism
- Anaphylaxis
- Hepatic failure
- Neurologic dysfunction—post-anesthesia, spinal cord injury
What is the mortality rate of acute renal failure?
60%!
Three urine output markers for oliguria
< 400 mL/day (UTD)
< 17-40 mL/hr
< 0.5 mL/kg/hr (UTD)
Name 7 potential causes of oliguric renal failure.
- Low cardiac output from hypovolemia
- Mechanical ventilation
- Aortic stenosis
- End-stage cardiomyopathy
- Drug therapy (ACE inhibitors)
- Renal injury
- Post-renal obstruction
In cases of traumatic myoglobinuric renal failure, what should you see?
CPK >5000 IU/L
Brown urine
Causes of myoglobinuric renal failure—K’s bumper sticker list
Trauma
Infection
Immobility
Drugs
Hypophosphatemia
Excessive exercise
What values should be watched closely in cases of myoglobinuric renal failure?
Potassium
Phosphate (PO4-3)
Evaluate oliguria with these six pointers
CVP may overestimate cardiac filling volume in critically ill patients.
For patients on mechanical ventilation, CVP levels as high as 10 to 20 mmHg can still indicate hypovolemia.
Respiratory variation in blood pressure (pulsus paradoxus) May be evidence of hypovolemia.
Decreases in blood pressure shortly after lung inflation can be used as evidence of decreased preload and inadequate cardiac filling.
Central venous saturation (SvO2) of 25-30% would indicate low cardiac output.
In patients with systemic sepsis, SvO2 < 70% is considered abnormal.
What conditions call for aborting an apnea test for brain death evaluation?
–Systolic BP slides below 90 mmHg.
–Significant oxygen desaturation occurs.
–Cardiac arrhythmias appear.
Obtain ABG immediately.
Evaluate PaCO2:
–PaCO2 > 60 mmHg or 20 mmHg above baseline supports a positive test for brain death
–PaCO2 <= 60 mmHg shows inconclusive results
Name pre-requisites for apnea brain death evaluation.
–Core body temperature >= 36.5degreesC
–Systolic BP > 90 mmHg
–Normal PaCO2 on mechanical ventilation
Six keys to management of oliguria
- Identify and correct volume deficits
- Discontinue any drugs that may cause oliguria
- Fluid challenge, especially in patients with reduced preload (0.5-1L crystalloid; 300-500mL colloid for patients with sepsis)
- Avoid low dose dopamine (dopamine makes patients pee–even when they shouldn’t–EMCRIT 138)
- Diuretics (furosemide) via continuous IV infusion (intermittent doses are less effective)
- Hemofiltration may be indicated for patients with high BUN, serum creatinine, and positive fluid balance
Define anorexia
“Lack of desire to eat despite physiologic stimuli that normally produce hunger” (UP)
What s/s are associated with anorexia?
Associated with nausea, abdominal pain, diarrhea
What is vomiting?
Forceful emptying of the stomach and intestinal contents through the mouth.
What may stimulate vomiting?
Severe pain
Distension of the stomach or duodenum
Trauma
Ipecac or copper salts in duodenum
What is retching?
Stomach and duodenum contract
but upper esophageal sphincter remains closed
material is maintained in esophagus
What is projectile vomiting?
Vomiting not preceded by nausea or retching
What is constipation?
Difficult or infrequent defecation
or
decrease in the number of bowel movements
or
hard stools
What may cause constipation?
Enlarged or dilated colon
Abdominal muscle weakness
Low-residue diet
Emotional depression
Medications such as opiates, anticholinergics, antacids
What is diarrhea?
Increase in the frequency of defecation and the fluidity and volume of feces
Name three types of diarrhea
Osmotic diarrhea
Secretory diarrhea
Motility diarrhea
What is osmotic diarrhea?
Diarrhea arising from a nonabsorbable substance in the intestine that draws excess water into the intestine and increases stool weight and volume (producing large-volume diarrhea). (UP 7th)
What is secretory diarrhea?
Large-volume diarrhea resulting from excessive mucosal secretion of fluids and electrolytes. (UP 7th)
What is motility diarrhea?
Diarrhea arising–roughly–from conditions where shortened gut or excessive motility decrease digestion transit time and the opportunity for fluid absorption. (UP 7th)
What is upper GI bleeding?
Bleeding in the esophagus, stomach, or duodenum