Intensive Care Flashcards
Parameters to follow in patients with septic shock (per the surviving sepsis campaign)
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Lactate
- target value < 1.0 mmol/L
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CVP (from central venous catheter)
- target value 8-12 mmHg
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MAP (from aterial catheter)
- target value >65 mmHg
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Urine output from Foley catheter
- target value >0.5 mL/kg/hr
Reasons serum lactate might be elevated
- Poor end-tissue oxygen delivery
- Inadequate renal clearance
- Metabolic changes (as in metformin-induced lactic acidosis)
In whom would you place a pulmonary artery catheter?
In someone who you want to measure left ventricular function (LVEDP), such as a patient in the ICU with known cardiac issues and cardiogenic shock on inotropic agents
Classification of shock
Physiologic parameters of different etiologies of shock
When there is clinical uncertainty about the etiology of hypotension, these tests are extremely helpful
- Central venous pressure measurement
- Echocardiography
Patient in shock responds to fluids initially, but then has a decrease in BP and becomes hypotensive again. What should you be thinking?
Ongoing bleeding
Effects of excessive administration of fluids and blood products
Excess crystalloid administration to a bleeding patient can cause dilution of clotting factors and thrombocytopenia, which can cause further bleeding and create a vicious cycle of worsening hypotension, coagulopathy, and hypothermia.
Patient in shock responds poorly to initial fluids and then has a continued slow drop in blood pressure. What should you be thinking?
Distributive shock.
Here the changes are due to microvascular leak syndrome or excess vasodilation
Appropriate therapy:
- Norepinephrine for septic shock
- Phenylephrine for neurogenic shock
- NOT continued fluid administration!!!
Sepsis spectrum
- Sepsis: Hyperdynamic and febrile response to infection
- Severe sepsis: Infection with septic host response and evidence of organ dysfunction in at least one organ system
- Septic shock: Sepsis with persistent hypotension despite fluid administration
Two major goals of treating sepsis
- Obtain source control
- Restore tissue perfusion
Hypotensive shock management algorithm (from pressure perspective)
- Fluids
- Norepinephrine OR Epinephrine (if alpha or beta effect is desired)
- Vasopressin
- Phenylephrine
- Dopamine
Physiologic effects of dobutamine
- Inotropy
- Modest peripheral vasodilation (decreased afterload)
What “source control” often means in sepsis
Abx alone are unlikely to be enough: drainage, debridement, necrotic tissue resection
Signs of an urgent airway
- Airway that is at risk of potential compromise
- Expanding hematoma
- Cutaneous emphysema
- Inhalation burn (ex, smoke from burning building)
- Not compromised yet, but may need to be intubated pretty soon.
Signs of an emergent airway
- “GCS < 8, intubate”
- Gurgling
- Gasping
Signs of emergent breathing
- Apnea
- Insufficient o2 sats
*
Ventilation problems are managed with ___. Oxygen exchange problems are managed with ___.
Ventilation problems are managed with intubation and mechanical ventilation. Oxygen exchange problems are managed with PEEP and FiO2.
__ indicates a problem with ventilation, while __ indicates a problem with oxygen exchange.
High pCO2 indicates a problem with ventilation, while low pO2 in the context of normal pCO2 indicates a problem with oxygen exchange.
Interpretation of end-tidal CO2
Should be 40 mmHg.
NOT a measurement of blood pCO2.
It is best utilized to determine if your endotracheal tube (both sides being adequately ventilated).
If there is something that prevents you from using an endotracheal tube in a patient with an emergent airway (mouth full of blood, face smashed up, etc) then you need to . . .
. . . perform cricothyrotomy
Can be done emergently at the bedside in the ER
When these patients get to the OR, they will have a nonemergent tracheostomy.
Tracheostomy is a ____ procedure. Cricothyrotomy is a ____ procedure.
Tracheostomy is a non-emergent procedure. Cricothyrotomy is an emergent procedure.
Three most important causes of obstructive shock
- Tension pneumothorax (obstructs flow to R ventricle)
- Pericardial tamponade (obstructs flow to R ventricle)
- Massive pulmonary embolism (obstructs flow to L ventricle)
Ventilator bundle
- Interventions to improve ventilator outcomes:
- Elevation of head of bed
- Stress ulcer ppx (with PPI)
- DVT prophylaxis (with LMWH)
- Daily sedation interruption
- Daily assessment of readiness for weaning/removal of ventilatory support
Ventilator-induced Lung Injury
- From barotrauma of PPV and high FiO2
- Strategies to reduce:
- Low tital volume (5-7 mL/kg)
- Reduction of FiO2 to <60% within 72 hours
- Application of PEEP (start w/ 5 cm water)
High-frequency ventilation
High frequency, low-tidal volume ventilation that also requires an endotracheal tube to facilitate gas exchange. Can reach rates of 100-400 breaths per minute.
Beneficial for infants with RDS, but not so much for older kids or adults
When is diagnostic bronchoalveolar lavage indicated?
- Immunocompromised patient with pneumonia
- Pneumonias refractory to standard antibiotics that have remained sputum and blood culture negative
If the patient is relatively stable, but you suspected you may need to prophylactically intubate soon, it is best to get a ___ prior to intubation.
If the patient is relatively stable, but you suspected you may need to prophylactically intubate soon, it is best to get a CXR prior to intubation.
Particularly in the acute setting, this may help rule out pneumothorax, which is not an indication for mechanical ventilation.
“Negative pressure” ALI
ALI caused by forceful inhalation against an obstructed or narrowed airway
Often self-limiting, but requires mechanical ventilation and judicious fluid management
Important prognostic factors for a patient with acute subdural hematoma
- Size
- Time to care
- Blood pressure status (hypotension can greatly worsen brain injuries in this case)
For the purposes of primary survey, traumatic brain injury should be treated as. . .
. . . a ventilatory issue, as it can often affect ventilation
Physical exam of the abdomen in a patient with multiple blunt trauma may be limited by. . .
- Distracting injuries (rib fractures, long bone fractures)
- Altered sensorium (traumatic brain injury, intoxication)
Why do we intubate every patient who is unresponsive, even if their breathing seems okay?
Because the tongue may fall back and the pharyngeal muscles may collapse, causing airway obstruction
Hyperventilation and ICP
Hyperventilation blows off CO2, which lowers PaCO2 levels and results in arterial smooth muscle constriction.
Based on Poiseuille’s law, small decreases in the arterial radius from vasoconstriction can profoundly decrease cerebral blood flow. Since the cranial vault has a finite amount of space, decreasing cerebral blood flow allows more room for brain tissue and reductions in ICP.
When to perform tracheostomy over cricothyrotomy
- Cricothyrotomy is an emergency procedure done in those who are acutely at risk of airway loss or have lost their airway already
- Tracheostomy is an urgent procedure done in those who are at risk of losing their airway at some point in the next several hours to days and will need long-term ventilatory access. Most commonly it is done in those with neck cancer who are beginning to have dyspnea
Acute vs chronic compartment syndrome management
- Acute: Emergeny fasciotomy within 6 hours of symptom onset
- Chronic: Conservative measures
Therapy for barotrauma-associated pneumothorax (from a ventilator)
Chest tube
Widened mediastinum = ___.
Cardiomegaly = ___.
Widened mediastinum = aortic rupture.
Cardiomegaly = tamponade.
Standard chest tube placement for draining fluid
- 5th intercostal space, midaxillary line is the standard
- May be done in the 7th intercostal space and posteriorly to improve drainage, but the above is standard
Treatment of choice for third degree burns
Debridement within 5 days followed by split-thickness skin grafting
Permissive hypotension, also known as damage-control resuscitation
- Maintaining a systolic blood pressure of < 90 mm Hg
- Used in the setting of severe bleeding
- Goal is to avoid resuscitating in such a way that would prompt more bleeding by restoring normal vital signs with large fluid boluses
- This strategy minimizes crystalloid resuscitation to avoid dilutional coagulopathy and decrease in body temperature
- Contraindication is traumatic brain injury, as these patients would benefit from higher cerebral perfusion pressures
Tranexamic acid is most effective within ___ of an injury
Tranexamic acid is most effective within 3 hours of an injury
“Damage control” operations
- Surgeries performed in a critically ill patient using the strategy of limiting the operation to life-saving procedures only with the plan to return to the OR at a later date for definitive repair when the patient’s condition has improved
- Used primarily in the context of the “lethal triad”
- Usually used in conjunction with damage-control resuscitation
Lethal triad
- Hypothermia, acidosis, and coagulopathy
- Seen in cases of severe injury and large volume blood loss
When can’t you trust your abdominal exam to rule out peritonitis?
- When the patient has received analgesics or hallucinogens or is intoxicated with alcohol
Is abdominal fascial perforation an absolute indication for exploratory laporotomy?
Not necessarily
In someone who is stable and asymptomatic with a normal abdominal exam, you can observe for 24 hours to see if anything develops before pulling the trigger on whether or not to do a laporotomy.
Post-splenectomy vaccine schedule
- 2 weeks after splenectomy: Hib, meningococcal, PCV13
- 10 weeks after splenectomy: PPSV23
- No abx prophylaxis is required in adults.
Normal ICP
5-10 mmHg
“Secondary” brain injury
Caused by hypoxia, hypercarbia, and hypotension in the context of a primary brain injury (often from trauma)
Managing mannitol for ICP
In the acute setting, even when elevated ICP is suspected, you may not want to give mannitol immediately. Additionally, it should only be given if there is physical exam or imaging evidence of elevated ICP.
Avoiding hypotension is more important than reducing ICP acutely. If a patient with a TBI is not volume replete, do not give mannitol until they are fluid resuscitated.
Target PaCO2 for traumatic brain injury
~35-40 mmHg (slightly hyperventilated)
Epidural hematomas typically occur in __ due to rupture of __
Epidural hematomas typically occur in the temporal region due to rupture of the middle meningeal artery
“Lens shaped” hematoma on CT
Classic for epidural hematoma
“Crescent shaped” hematoma on CT
Classic for subdural hematoma
Epidural vs subdural hematomas on CT
Burr hole
- Hole drilled though the skull for decompression in traumatic brain injury with elevated ICP
- Typically in the setting of subdural hematoma
- Usually done on the side with the enlarged pupil
- Can be life-saving, but has its risks
A comatose patient (with GCS < 9) with abnormal pupillary responses often signifies. . .
. . . an ipsilateral mass lesion
This is due to uncal herniation (aka transtentorial herniation) of the temporal lobe which compresses the parasympathetic nerve fibers of CN3, leading to unopposed sympthetic activity of that pupil (dilation, “blown pupil”)
Common CNS herniations and syndromes
Balance disturbance following cranial trauma
Specific, but not sensitive, for concussion
CVP in assessment of etiology of shock
Low CVP indicates distributive or hypovolemic shock
High CVP indicates obstructive or cardiogenic shock.
Sudden onset respiratory distress after venous catheter removal
Venous air embolism
Immediately place the patient in left lateral decubitus position. This traps the air on the lateral wall of the right ventricle, preventing right ventricular outflow tract obstruction and further embolization.
Paroxysmal sympathetic hyperactivity syndrome
- Episodic severe hypertension, tachycardia, fever, and diaphoresis in a patient with traumatic brain injury
- Episodes last 20-30 minutes and are often triggered by an external stimulus, such as physical manipulation
- Opioids, GABA agonists, and alpha-2 agonists are effective in reducing central symathetic outflow as treatment
