UMEM Educational Pearls - Critical Care

Category: Critical Care

Title: Hemodynamic monitoring - arterial pressure monitoring

Keywords: non-invasive arterial monitoring, radial artery (PubMed Search)

Posted: 11/6/2007 by Mike Winters, MD (Updated: 11/19/2019)
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  • It is traditionally taught that in hypotensive patients the presence of a carotid pulse corresponds to a SBP of 60-70 mmHg, a femoral pulse with a SBP of 70-80 mmHg, and a radial pulse with an SBP of at least 80 mmHg
  • These physical exam estimates of BP have been shown to poorly correlate with the patient's actual BP
  • Similarly, non-invasive measurements of BP (automated cuff) in patients with hypotension may either overestimate or underestimate SBP by as much as 20 mmHg
  • Since physical exam estimates and non-invasive measurements are inaccurate in low-flow states, utilize invasive arterial monitoring
  • Radial and femoral artery sites have been found to produce results that are clinically interchangeable

Category: Critical Care

Title: TBI - Critical Care

Keywords: traumatic brain injury, cerebral perfusion pressure, intracranial pressure, hypertonic saline (PubMed Search)

Posted: 10/30/2007 by Mike Winters, MD (Updated: 11/19/2019)
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Critical Care Pearls for Traumatic Brain Injury

  • Avoid hypotension and hypoxia - SBP < 90 and/or PaO2 < 60 are associated with significant increases in morbidity and mortality
  • Hypertonic saline remains controversial - a recent large, controlled trial did not show any early or long-term benefit
  • ICP monitoring routinely recommended in patients with GCS < 8 - they have a 60% chance of increased ICP
  • Maintain ICP < 20 mmHg and CPP > 60
  • Supportive care
    • Elevate the head of bed > 30 degrees, if possible
    • Control fever
    • Provide analgesia and sedation
  • Ventilator management - keep PaCO2 between 30-35 mmHg
  • Surgery - last resort to controlling increased ICP
    • Decompressive craniotomy
    • Decompressive laparotomy

Category: Critical Care

Title: Vasopressors and acidosis

Keywords: vasopressors, acidosis, bicarbonate (PubMed Search)

Posted: 10/23/2007 by Mike Winters, MD (Updated: 11/19/2019)
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  • Binding of vasopressor agents to their receptors is influenced by pH (and temperature and concentration)
  • Acidic conditions have been shown to alter receptor numbers on cell surfaces as well as alter binding affinity
  • Overall, pH values > 7.15 do not have an appreciable clinical effects on vasopressors
  • At pH values < 7.1 reductions in effectiveness become apparent
  • Routine administration of bicarbonate remains controversial
  • Aggressively search for and treat the underlying cause of the acidosis

 


Category: Critical Care

Title: Hyperammonemia in the Critically Ill

Keywords: hyperammonemia, hepatic failure, cerebral edema (PubMed Search)

Posted: 10/16/2007 by Mike Winters, MD (Updated: 11/19/2019)
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Hyperammonemia in the Critically Ill

  • Patients with acute hyperammonemia have significant morbidity and mortality 
  • Fulminant hepatic failure is the most common cause of acute hyperammonemia in adult ICUs
  • Other causes include TPN, GI hemorrhage, steroid use, trauma, multiple myeloma, infection with urease-splitting organisms, and drugs (salicylates, valproate) 
  • Cerebral edema, intracranial hypertension, seizures, and herniation are the most significant effects
  • Initial management should focus on treating intracranial hypertension - mannitol, hypothermia, N-acetylcysteine have been used
  • Lactulose has not been shown to reduce mortality in acute hyperammonemia but is unlikely to be harmful

Clay AS, Hainline BE. Hyperammonemia in the ICU. Chest 2007;132:1368-1378.


Category: Critical Care

Title: Abdominal Compartment Syndrome

Keywords: abdominal compartment syndrome, decompressive laparotomy, bladder pressure (PubMed Search)

Posted: 10/8/2007 by Mike Winters, MD (Emailed: 10/9/2007) (Updated: 11/19/2019)
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[RESENT - STILL FIXING CODE - THESE TEST EMAILS SHOULD CEASE SHORTLY... SORRY FOR THE INCONVENIENCE]

  • Abdominal compartment syndrome (ACS) is increasingly identified in the critically ill medical patient population
  • ACS is defined as a sustained intra-abdominal pressure > 20 mmHg associated with new organ dysfunction
  • Primary organs adversely affected by ACS include cardiac, pulmonary, GI, and renal
  • To date, associated mortality rates have ranged from 27% to 50%
  • Risk factors for ACS include:
    • massive fluid resuscitation ( >10 L crystalloid in 24 hours)
    • massive transfusion ( > 10 U PRBCs in 24 hours)
    • severe sepsis or septic shock from any cause
    • mechanical ventilation
    • PEEP > 10 cm H20
  • Intravesicular (bladder) pressures are currently the standard monitoring modality
  • Decompressive laparotomy is the current standard for management of ACS

Category: Critical Care

Title: Disseminated Intravascular Coagulation

Keywords: DIC, sepsis, heparin (PubMed Search)

Posted: 10/2/2007 by Mike Winters, MD (Updated: 11/19/2019)
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DIC is the simultaneous occurrence of widespread (micro) vascular thrombosis, leading to compromised blood supply to vital organs Although major bleeding can be seen in some, the more common complication of DIC is organ failure DIC is not a disease itself but secondary to an underlying disorder Sepsis, solid and hematologic malignancies, severe trauma, and obstetrical emergencies (amniotic fluid embolism, abruption) are the most common disorders associated with DIC A prospectively validated scoring system (Toh CH, et al. J Thromb Haemost 2007;5:604-6.) is used for diagnosis and is comprised of platelet count, fibrin split products, PT, and fibrinogen level The key to treating DIC is vigorous treatment of the underlying disorder Platelet transfusion is generally only given for patients with major bleeding (i.e. intracranial) with platelets counts < 50 k

Category: Critical Care

Title: Re-expansion pulmonary edema

Keywords: pulmonary edema, tube thoracostomy (PubMed Search)

Posted: 9/25/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Reexpansion pulmonary edema represents a potentially life-threatening complication of tube thoracostomy (mortality rate as high as 20 percent) -It usually occurs after rapid reexpansion of a collapsed lung in patients with a pneumothorax -It may also follow evacuation of large volumes of pleural fluid (>1.0 to 1.5 liters) or after removal of an obstructing tumor -The incidence of edema appears to be related to the rapidity of lung reexpansion and to the severity and duration of lung collapse -The clinical manifestations vary from isolated radiographic changes to complete cardiopulmonary collapse -Treatment is supportive, mainly consisting of supplemental oxygen and, if necessary, mechanical ventilation

Category: Critical Care

Title: Non-invasive ventilation

Keywords: non-invasive ventilation, acute respiratory failure, intubation prevention (PubMed Search)

Posted: 9/11/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Non-invasive ventilation (NIV) is a form of ventilatory support that avoids intubation. -NIV refers to the provision of inspiratory pressure support + PEEP via a nasal or face mask (BiPAP, CPAP). -Strong evidence from randomized trials supports NIV to avoid intubation in patients with acute respiratory failure secondary to COPD exacerbation, acute cardiogenic pulmonary edema, and in immunocompromised patients (AIDS, transplant). -NIV can be considered in asthma exacerbations, pneumonia, and ARDS however the supporting evidence for these conditions is fairly weak. -Contraindications for NIV include respiratory arrest, hemodynamically unstable, unable to protect the airway, excessive secretions, uncooperative/agitated, and recent UGI or airway surgery. -You should expect to see clinical improvement within 1 to 2 hours.

Category: Critical Care

Title: Life threatening hypophosphatemia

Keywords: hypophosphatemia, CHF, respiratory failure (PubMed Search)

Posted: 9/4/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Phosphate is predominantly an intracellular ion that is critical for an array of cellular processes -Hypophosphatemia is most commonly seen in alcoholics, DKA, and sepsis: frequency rates of 40%-80% -Severe hypophosphatemia ( < 1.0 mg/dL) in the critically ill can manifest as widespread organ dysfunction: respiratory failure (diaphragmatic weakness), CHF (decreased myocardial contractility), rhabdomyolysis, arrhythmias, seizures, hemolysis, impaired hepatic function, and depressed WBC function -Severe hypophosphatemia should be treated with intravenous replacement: 0.08 - 0.16 mmol/kg over 2-6 hours -Be aware of complications from too rapid intravenous replacement: hypocalcemia, tetany, hypotension, volume excess, and metabolic acidosis

Category: Critical Care

Title: A quick vasopressor review

Keywords: norepinephrine, dopamine, vasopressin, phenylephrine (PubMed Search)

Posted: 8/28/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Norepinephrine: has both alpha-1 and beta-1 activity; stronger alpha than beta receptor agonist; increases MAP primarily through increase in SVR; dose 2-20mcg/minute -Phenylephrine: all alpha-1 activity; increases MAP through increase in SVR; initial dose 100-180 mcg/minute and titrate 40-60 mcg/min; primarily a 3rd line vasopressor -Vasopressin: a non-adrenergic vasoconstricting agent; activates vasopressin receptors; dose 0.01-0.04 Units/min; currently used as a second-line agent in the setting of sepsis; should not be used as the sole vasopressor medication due to gut and cardiac ischemia -Dopamine: activates dopaminergic receptors; at doses of 10-20 mcg/kg/min it has both alpha-1 and beta-1 activity; increases MAP primarily through increases in CO; stronger chronotropic agent than norepinephrine - will worsen existing tachycardia -Epinephrine: has potent beta-1 activity with moderate alpha-1 and beta-2 activity; at lower doses increases MAP through increase in CO; at higher doses increases MAP by increase in SVR; primarily used in anaphylactic shock; dose 1-20 mcg/min

Category: Critical Care

Title: Anaphylaxis - Epinephrine use

Keywords: anaphylaxis, epinephrine (PubMed Search)

Posted: 8/21/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Epinephrine is the drug of choice for anaphylaxis -Several studies indicate that epi is underutilized in ED patients with anaphylaxis -Indications for epinephrine include bronchospasm, laryngeal edema (hoarseness, stridor, difficulty swallowing), hypotension, rapidly progressive reaction, and severe gastrointestinal symptoms (due to bowel edema) -The dose of epinephrine is 0.3 to 0.5 mL of 1:1000 IM -Pearl: IM injection into the lateral thigh (vastus lateralis) has been shown to produce considerably faster time to maximum drug concentration than subq injection or IM injection into the deltoid

Category: Critical Care

Title: Acalculous cholecystitis

Keywords: acalculous cholecystitis, HIDA, cholecystectomy (PubMed Search)

Posted: 8/14/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Think about acalculous cholecystitis in the critically ill patient with fever, abdominal pain, and elevation of LFTs and bilirubin -Pathophys thought to be due to SIRS, biliary stasis, and ischemia -Abdominal pain is not always in the right upper quadrant -Patients have a high rate of complications - gangrene or perforation (40% to 60%) -Diagnostic studies: ultrasound (sens. 70%), HIDA (sens. 80% to 90%), CT (sens. 90%) -Consult surgery early because treatment of choice is surgical cholecystectomy; some can be treated with percutaneous cholecystostomy but this is up to your consultant

Category: Critical Care

Title: Post-intubation hypotension

Keywords: hypotension, pneumothorax, dynamic hyperinflation (PubMed Search)

Posted: 8/7/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Post-intubation hypotension can occur in a substantial proportion of patients -Before attributing this to the effects of your sedative medications, you must think about pnemothorax, hyperinflation from overzealous bag-valve mask ventilation, and hypovolemia -Pneumothorax - auscultate the lungs and repeat the CXR -Hyperinflation - disconnect the patient from the ventilator and allow them to "deflate" -Hypovolemia - give a fluid bolus

Category: Critical Care

Title: Mechanical Ventilation "Knobology" - tidal volume

Keywords: mechanical ventilation, tidal volume, ideal body weight (PubMed Search)

Posted: 7/31/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-When setting the ventilator, many of us use an initial tidal volume of 6 ml/kg -This number comes from ARDSnet data that demonstrated improved mortality with low tidal volumes in patients with ARDS/ALI -It is important to note that your calculation of 6 ml/kg is based upon IDEAL BODY WEIGHT (not total body weight) -For males: IBW = 50 kg + 2.3 kg for each inch over 5 feet. -For females: IBW = 45.5 kg + 2.3 kg for each inch over 5 feet.

Category: Critical Care

Title: Mechanical Ventilation "Knobology" - ventilation

Keywords: mechanical ventilation, pCO2, tidal volume, pH (PubMed Search)

Posted: 7/24/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-Remember that oxgenation is affected by changes in PEEP and/or FiO2 -For changes needed in ventilation (pH and pCO2), you alter the respiratory rate (RR) and/or tidal volume (TV) -Changes in RR produce a greater effect on pH and pCO2 than changes in TV -Focus more on maintaining a pH between 7.3 - 7.4, rather than on returning pCO2 to normal

Category: Critical Care

Title: Mechanical Ventilation "Knobology" - respiratory failure

Keywords: mechanical ventilation, assist control, SIMV, pressure support (PubMed Search)

Posted: 7/17/2007 by Mike Winters, MD (Updated: 11/19/2019)
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-One of the most common reasons for intubation/mechanical ventilation in the ED is patient fatigue -Essentially, patients are unable to keep up with the work of breathing -Patient work of breathing can be significant in CPAP, SIMV, and Pressure Support modes of mechanical ventilation -Avoid these as initial modes if your patient has respiratory fatigue

Category: Critical Care

Title: Pearl of the Day - Critical Care

Keywords: PEEP, oxygenation, ventilator (PubMed Search)

Posted: 7/14/2007 by Mike Winters, MD (Emailed: 7/10/2007) (Updated: 11/19/2019)
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Mechanical Ventilation "Knobology" - Oxygenation -FiO2 and PEEP are used to improve oxygenation in the ventilated patient -Immediately following intubation, start with an FiO2 of 100% -Increase PEEP by 2-3 cm H2O every 10-15 minutes to achieve the desired saturation -As you titrate PEEP, have respiratory therapy provide you with plateau pressures (maintain Pplat < 30) Mike

Category: Critical Care

Title: Critical care of patients with HIV/AIDS - Lactic Acidosis

Keywords: HIV, Lactic, Acidosis (PubMed Search)

Posted: 7/14/2007 by Mike Winters, MD (Emailed: 7/8/2007) (Updated: 11/19/2019)
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Critical care of patients with HIV/AIDS - Lactic Acidosis * Lactic acidosis can be a life-threatening complication of HAART - mortality as high as 77% * It can occur with any of the nucleoside/nucleotide reverse transcriptase inhibitors (most common are didanosine and stavudine) * Common presenting symptoms include abdominal pain, nausea, vomiting, myalgias, and elevation of transaminases * In patients with these symptoms check a lactate -> a value > 5 mmol/L is considered life-threatening * Treatment is supportive care with removal of the offending medication * In anecdotal reports, L-carnitine, thiamine, and riboflavin may reverse toxicity Reference: Morris A, Masur H, Huang L. Current issues in the critical care of the human immunodeficiency virus-infected patient. Crit Care Med 2006;34:42-9.

Category: Critical Care

Title: Serial lactate Levels

Keywords: Lactate, Sepsis, Infection (PubMed Search)

Posted: 7/14/2007 by Mike Winters, MD (Emailed: 7/8/2007) (Updated: 11/19/2019)
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Obtain serial lactate levels in ED patients with infection * Elevated serum lactate is associated with an increased risk of death in critically ill patients with infection * An initial lactate level > 4.0 mmol/l is significant and, in some series, is associated with a mortality of approximately 40% * Obtain serial venous lactate measurements every 3-4 hours * If serial levels remain > 4 mmol/l, or rise, be more aggressive with resuscitation Reference: Trzeciak S, et al. Serum lactate as a predictor of mortality in patients with infection. Inten Care Med 2007;33:970-7.


Category: Critical Care

Title: Start antibiotics ASAP in patients with septic shock

Keywords: Antiobiotics, Sepsis (PubMed Search)

Posted: 7/14/2007 by Mike Winters, MD (Emailed: 7/8/2007) (Updated: 11/19/2019)
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Start antibiotics ASAP in patients with septic shock * For patients with septic shock, start antibiotics within the first hour * For each additional hour that antibiotics are delayed, survival decreases by 7%-8%! * Once you address the ABC's, obtain appropriate cultures, and hang the antimicrobials * Make sure you are providing effective antimicrobials (take a look at the patient's history to see if they have resistant bugs) Reference: Kumar A, et al. Duration of hypotension before initiation of effective antimicrobial therapy is the critical determinant of survival in septic shock. Crit Care Med 2006;34:1589-96.