The obtunded inpatient with normal vital signs




Common misconceptions and mistakes





  • All unarousable patients should be immediately intubated because “they are not protecting their airway”



  • Failing to realize that only a finite number of processes can cause obtundation with normal vital signs



  • Checking for a gag reflex in an unarousable patient



  • Placing a nasogastric tube in an unarousable patient





Obtundation with normal vital signs





  • The inability to arouse an individual is a medical emergency



  • Obtundation that is not obviously attributable to either brainstem (reticular activating system) hypoperfusion (ie, shock) or respiratory failure (hypercarbia or extreme hypoxemia) requires a rapid systematic approach



  • The approach to the unarousable patient involves simultaneously looking for rapidly reversible causes (eg, naloxone for opiate overdose) while looking for “good” reasons to immediately intubate (eg, acute hypercarbia)



  • In this clinical setting, failure to protect one’s airway means that oral and pharyngeal reflexes are suppressed to such a degree that an individual would freely aspirate any material that found its way to the pharynx (ie, emesis)




    • Therefore if an obtunded patient is not vomiting, he or she does not need to be immediately intubated; there is time to rapidly rule out reversible causes





  • Never forget to empty the stomach if possible (ie, if the patient already has a nasogastric or gastric tube, place it to suction)



  • Placing a nasogastric tube in an obtunded patient to empty his or her stomach is not safe, given the potential to trigger gagging and emesis



  • Do not check for a gag reflex; it is not reliable and may trigger emesis



  • In general, patients whose obtundation is not from hypoglycemia , narcotic overdose , or postictal state (ie, quickly reversible conditions) will require intubation and a head CT scan





God helps or dogs help





  • The typical scenario:




    • You are called to the bedside by nursing, who is visibly concerned because their patient is obtunded



    • Temperature, heart rate (HR), blood pressure (BP), and oxygen saturation (0 2 sat) are all normal



    • The nurse anxiously reports the patient was fine earlier, adding, “I don’t think he’s protecting his airway”



    • You approach the patient, do a sternal rub, get no response, and begin:




      • Call a rapid response if your institution has a rapid response team



      • Immediately check blood glucose and an arterial blood gas (ABG)



      • Neuroexamination is limited to the eyes and pupils



      • Small (pinpoint) pupils equals opiate effect



      • Disconjugate gaze, fixed deviation, and/or a unilaterally dilated (blown) pupil equals intracranial hemorrhage until proven otherwise (by a stat noncontrast head CT scan)






  • G—Glucose:




    • Immediately obtain a finger stick blood glucose measurement



    • Severe hypoglycemia is a common, reversible cause of obtundation




      • Blood glucose (BG) < 60 mg/dl required (typically < 40 mg/dl)




    • Patients should be placed on their side (rescue or recovery position) while waiting for glucose therapy to work




      • Note that oral glucose paste takes several minutes to work






  • O—Overdose:




    • Inpatient overdose implies oversedation from narcotics, benzodiazepines, antipsychotics, or a GABAergic drug NOS (ie, cyclobenzaprine)



    • Only narcotics can be safely and reliably reversed (with naloxone)




      • Very low threshold for empiric naloxone use (0.4 mg IV × 1) if there is any chance the patient has received an opiate



      • Naloxone response should be dramatic; equivocal response equals no response




    • Benzodiazepine reversal with flumazenil should be reserved for procedure-related oversedation




      • Flumazenil given to a regular benzodiazepine user (most inpatients on benzodiazepines) comes with the risk of seizure




    • The decision to intubate vs observe patients suffering profound sedative medication effects must be individualized (duration of medication, dose, baseline mental status), but in general it is safer to intubate




      • Oversedated patients being observed need to be continually screened for hypoventilation with pH/P co 2 measurements (end-tidal CO 2 is not validated for this use yet but likely has a role)






  • D—Depressed respirations (ie, check ABG for hypercarbia and, to a lesser extent, occult hypoxemia):




    • Obtain a stat ABG if the patient does not have severe hypoglycemia or naloxone-responsive opiate overdose




      • Obtundation with an acute respiratory acidosis mandates intubation






  • H—Hepatic encephalopathy:




    • In patients with known hepatic encephalopathy, it may be reasonable to attempt treatment with lactulose to prevent intubation



    • However, insertion of an nasogastric (NG) tube in the obtunded patient may cause vomiting; therefore it is safer to intubate if feeding tube access is not available





  • E—Electrolytes (mainly high and low Na + , but also high Ca 2 + ):




    • Obtundation from free water imbalance (ie, hyper and hyponatremia) needs to be corrected slowly such that patients should be intubated while the etiology is discovered and correction is made



    • Last chemistry panel may provide clues (Na + abnormal)



    • Check Na + (and possibly Ca 2 + in the right clinical scenario eg, metastatic squamous cell cancer)



    • Hyponatremia: Na + < 120 mEq/L is typically required to cause obtundation




      • When Na + drops quickly, it may cause seizure, with subsequent postictal state




        • Na + is most likely to drop quickly when patients with an inability to excrete free H 2 O (ie, syndrome of inappropriate antidiuretic hormone secretion [SIADH]) are given hypotonic intravenous fluid (IVF)





    • Hypernatremia: Na + > 150 mEq/L is typically required (but varies, given the baseline mental status)




      • Na + rises in inpatients who have excessive free H 2 O losses (as in osmotic diuresis, diarrhea, and persistent fevers) and impaired thirst or access to water




        • Because impaired thirst and/or the inability to access water occur in debilitated/demented patients, baseline mental status is often diminished




          • In this situation, intubation is usually not required and instead observation while rehydrating is the optimal approach








  • L—Look inside the central nervous system (CNS) (ie, get a stat noncontrast head computed tomography [CT]; consider lumbar puncture [LP]):




    • Having a nonneurosurgery inpatient develop bacterial meningitis is extremely rare; therefore LP has a very limited role in the general evaluation of the obtunded inpatient




      • In contrast, neurosurgery patients get nosocomial meningitis relatively frequently (often cerebrospinal fluid [CSF] is easy to obtain from preexisting drain)




    • Intracranial catastrophes are relatively common in hospitalized individuals; therefore a head CT without contrast looking for hemorrhage and/or signs of intracranial hypertension needs to be performed stat in all individuals with either:




      • No toxic metabolic reason for obtundation (ie, the GOD HE portion of the algorithm)



      • A neuroexamination demonstrating disconjugate gaze, fixed deviation, and/or unilateral pupil dilatation




    • Very low threshold to obtain a noncontrast head CT scan




      • Obtunded patients should be intubated for airway protection before going off the floor for CT scanning






  • P—Postictal state:




    • Obtundation is common in the immediate postictal state and in the absence of emesis, or status epilepticus; intubation should be deferred during observation in the rescue/recovery position



    • The postictal state may precipitate hypoventilation , especially in people with blunted respiratory drive and/or underlying lung disease, such that one must have a very low threshold to obtain an ABG



    • The postictal state can be confidently diagnosed in the setting of witnessed seizure and can be reasonably inferred in the right clinical scenarios:




      • Patient with a known seizure disorder who misses medications



      • Patient admitted for alcohol withdrawal



      • Patient undergoing benzodiazepine taper




    • The obtundation portion of the postictal state clears in 5–15 minutes such that protracted obtundation in an individual with a known or suspected seizure should prompt consideration of nonconvulsive status, followed by intubation, stat head CT, and possibly EEG





  • S—Sepsis (early infection in the setting of a poor baseline neurologic function):




    • Patients with significant baseline cognitive dysfunction may experience obtundation as an initial sign of systemic infection and early sepsis



    • In the absence of hypoventilation, one should attempt to avoid intubation because antibiotics and supportive care often lead to significant improvement in just 6–12 hours



    • Early intubation (or intubation at all) may not be appropriate given the degree of baseline cognitive impairment in this group




      • Instead, call the family to confirm wishes for aggressive care and consideration of full care and do not attempt resuscitation (DNAR)/do not intubate (DNI) with a plan to change to comfort if respiratory failure ensues




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Sep 14, 2018 | Posted by in RESPIRATORY | Comments Off on The obtunded inpatient with normal vital signs
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