Archive | April, 2013

random medical sizing: the French catheter system & needle gauges

30 Apr

FRENCH CATHETER SCALE

where you’ll see it:  chest tubes, foley catheters, etc.

bigger number =:  bigger tube size

quick reference:  external diameter is (French #)/3

example:  18 French catheter has a 6mm external diameter (18/3 = 6)

 

 

NEEDLE GAUGE SYSTEM

where you’ll see it:  hypodermic needles. duh.

bigger number =: smaller needle size

quick reference:  not simple. see the chart, if you want.

example(s): 

  • 14 gauge needle ~= 2mm outer diameter
  • 20 gauge needle ~= 1mm outer diameter
  • 30 gauge needle ~= 0.3mm outer diameter

 

Thanks, medicine, for keeping it easy and consistent.  But there you go.

 

References: dr. wikipedia french; dr. wikipedia gauges; picture

Advertisements

does (chest tube) size matter?

29 Apr

nice post from the Emergency Medicine Literature of Note blog, on the issue of chest tube size in trauma (click through for the original post)

 

HIGHLIGHTS:

“Traditionally…hemothorax is routinely treated by the largest chest tube possible.”

“Theoretically, smaller chest tubes will clog with debris or blood clot…”

 

“…authors note several simulations of chest tube drainage indicating tubes as small as 14 French may be adequate.  They also hypothesize these larger chest tubes are as painful as tragically possible, and the tradition of large chest tubes results in undue suffering.”

 

“There was no difference observed in their analysis of chest tubes of maximum size versus smaller-than-maxiumum size.  But, a 28-32 Fr chest tube is still a pretty darn large tube.

 

THE STUDY:

28-32 versus 36-40 French chest tube size in trauma. (not a huge difference)

a total of 353 chest tubes

no difference in the:

  • efficacy of drainage,
  • retained hemothorax,
  • need for additional tube drainage,
  • invasive procedures.
  • pain felt by patients at the site of insertion.

 

‘smaller’ study 

36 patients received 14-French pigtail catheters (prospective) vs. 191 chest tubes (retrospective database review).

the patients who got pigtails were all stable blunt-trauma patients (maybe not a perfect sampling of our patient population)

both groups had similar results for:

  • mean initial output
  • Tube duration,
  • rate of insertion-related complications,
  • failure rate

 

BOTTOM LINE:

dogma for traumatic hemothorax chest tube size: ‘bigger is better’

some studies starting to challenge that notion (of clot/debris issues with smaller tubes), but data is not slam-dunk just yet

 

References: emlitofnote post; original article; 14-french article; picture

Naloxone (a.k.a. Narcan, a.k.a. Vitamin N)

26 Apr

Naloxone

-Pure competitive antagonist at all opioid receptors

-Fully reverses all effects of opioids (respiratory depression, CNS depression, AND analgesia)

Onset is 1-2 minutes with duration of action 20-90 minutes

 

Dosing of Naloxone

For opioid dependent patients with mental status depression but only MINIMAL respiratory depression, initial starting dose of 0.05mg IV is recommended

            -High doses can make patients combative by causing withdrawal symptoms!

For opioid naïve patients also with CNS depression but minimal respiratory depression, starting dose of 0.4mg IV is recommended

-Repeat doses between 0.05 to 0.4mg IV can be given until you reach the desired mental status

– For patients with apnea and/or cyanosis, 2mg IV naloxone should be given REGARDLESS of their drug use history. 

-Repeated doses of 2mg IV can be given every 2-3 minutes until a maximum of 10mg IV is given

 

Naloxone Infusions

-Naloxone is a short acting medication so often it is of shorter duration than the opiate taken by the patient requiring re-doses

-Infusions should only be given if patients responded to repeated boluses

-Calculating dose

            –Determine “wake up dose” and given 2/3 of that dose per hour by IV infusion

 

Disposition:

Heroin exposure:  Discharge safely if meet following criteria 1-2 hours after naloxone

  • Independent mobility,
  • oxygen saturation >92% on room air,
  • RR >10,
  • HR >50,
  • GCS 15

Non-heroin overdose:  Generally require at least 4-6 hours of observation except for certain long acting opiates such as methadone

 

Submitted by J. Grover.

 

Sources: Tintinalli’s Emergency Medicine:  7th Edition.; picture

Hypothyroidism (QUICK HITS)

25 Apr

Diagnosis:

-TSH measurement is known to be the primary method of detecting thyroid disease

-After assessing TSH, Free T4 is the secondary test

 

Epidemiology

-The Framingham study showed a rate of 4.4% of hypothyroidism in women over 60

 

Manifestations of Hypothyroidism

-Vary greatly from subclinical hypothyroidism to severe hypothyroidism

-Generally follow one of two changes

Slowing of metabolic processes:  

    • weight gain,
    • fatigue,
    • cold intolerance,
    • constipation,
    • bradycardia
    • irregular menses,
    • depression,
    • muscle weakness

Accumulation of glycosaminoglycans in tissues:  

    • Coarse hair and skin,
    • tongue enlargement,
    • hoarseness.

Myxedema (nonpitting edema) only occurs in severe hypothyroidism.

-Other important manifestations include anemia

 

Cardiovascular Effects

-Causes decreased cardiac contractility and decreased heart rate

-Patients often complain of dyspnea with exertion

Hypercholesterolemia secondary to decrease in cholesterol metabolism

 

Reproductive Effects

-Women may present with amenorrhea, hypermenorrhea, or normal cycles

-Both women and men with hypothyroidism have been shown to have decreased fertility

-Common complaints with men include decreased libido, erectile dysfunction, and delayed ejaculation. 

 

Metabolic Effects

-Decreased cholesterol metabolism and decreased drug clearance

Hyponatremia may occur secondary to an overall reduction in a person’s free water clearance. 

 

Myxedema Coma

-Severe hypothyroidism who are then exposed to new stresses including trauma, infection.

-Commonly present with hypothermic, hyponatremic, hypercapnic in a comatose patient. 

 

Treatment:

T4 Supplementation

 

Submitted by J. Grover.

  

Sources: Bensenor IM et al.  “Hypothyroidism in the Elderly:  Diagnosis and Management.  Clinical Interventions in Aging 2012:7 97-111. Tintinallis Emergency Medicine:  7th Edition. Uptodate:  Clinical Manifestations of Hypothyroidism.; picture

Aspirin (Salicylate) Overdose

24 Apr

Absorption

Peak salicylate levels can occur within one hour when taken in standard forms at normal therapeutic doses

Enteric coated or delayed release tablets can take much longer to reach peak serum levels

-In an overdose, absorption can be delayed because of aspirin’s effect on gastric emptying, bezoar formation (coalescing of the aspirin into one large mass- Remember Harry Potter!) with peak levels taking up to 24 hours to be reached

-NOTE:  above normal therapeutic doses, protein binding decreases, the liver’s detoxification is saturated, and clearance becomes primarily dependent on renal excretion extending the half life of the drug

 

Effects of Aspirin

Cyclooxygenase inhibition leading to gastric irritation and platelet dysfunction

-Directly stimulates the medullary respiratory center in the CNS leading to increased respiratory rate

-Stimulation of the chemoreceptor trigger zone in the medulla causing nausea and vomiting

-Stimulates skeletal muscle metabolism leading to increased oxygen consumption and CO2 production

Oxidative phosphorylation uncoupling

-Increased lipolysis

-Reversible ototoxicity

-Mobilizes glycogen stores and inhibits gluconeogenesis

-Krebs Cycle inhibition

-Increased vascular permeability (Non-cardiogenic pulmonary edema)

 

Overdose

-Symptoms:  Nausea, vomiting, tinnitus/hearing loss, sweating, hyperventilation

Mixed acid base:  Respiratory alkalosis with metabolic acidosis

-Prognostic factors:  unconsciousness (can’t maintain hyperventilation!), fever, severe acidosis, seizures, dysrhythmias, older age. 

 

Testing:

-In moderate to severe poisonings, ASA level testing every 1-2 hours is recommending until concentrations begin to decline and the patient’s status improves

-Remember that depending on the type of pill taken (delayed absorption/enteric coated) and delayed gastric emptying, levels can continue to increase for up to 24 hours after ingestion

 

Treatment:

-The first goal is to minimize further absorption– charcoal, gastric lavage (less popular nowadays), and sorbitol can all be considered

-Replace fluid loss and electrolytes from vomiting/diarrhea with normal saline infusion

-Increasing systemic pH is the goal- Sodium Bicarbonate infusion is the primary treatment

Dialysis as last option:  intubated patients, clinical deteriorating patients, acute lung injury patients, altered mental status, renal failure/insufficiency, and severe acid/base disturbance

-NOTE:  If patient must be intubated/ventilated, hyperventilation MUST be continued

 

Submitted by J. Grover.

 

Sources: Tintinalli’s Emergency Medicine 7th Edition; Uptodate.  Salicylate poisoning in adults; picture 

 

Ludwig Angina (Floor of the Mouth Infections)

23 Apr

OVERVIEW

Bilateral infection of the submandibular space that involves both of the two main compartments in the floor of the mouth- the sublingual and the submylohyoid spaces

-Commonly caused from an infection of either the second or third mandibular molar tooth since their roots are located below the level where the mylohyloid muscle attaches to the mandible

Rapidly spreadingaggressive infection with SEVERE potential for airway compromise

-Abscess formation is not usually present

 

Microbiology:

-Typically polymicrobial involving normal oral flora

 

Signs/Symptoms:

-Fever, mouth pain, stiff neck, drooling, dysphagia, and may tripod in order to maximize airway size

-Voice changes and stridor are particularly late findings

 

Physical Exam:

-Tender symmetric induration/swelling in the submandibular area

Floor of the oropharynx is extremely tender, elevated (look under the tongue), and erythematous

 

Diagnosis:

-your eyes/hands/brain

CT is not necessary for diagnosis but can help demonstrate extent of infection 

 

Treatment:

Airway protection is the primary issue with these infections; definitive airway should be established prior to stridor/cyanosis

            -nasotrachial intubation, or cric, if the OP approach is toast

Antibiotics

Clindamycin, Unasyn, PCN G plus Metronidazole are all suitable choices.

-For immunocompromised patients, Cefepime plus metronidazole, a Carbapenam, or Zosyn

-If MRSA is a high risk factor, Vancomycin should be ADDED to the above regimen

Dexamethasone

            -Some studies have shown improved outcomes with dexamethasone administration

-When a tooth is suspected as the culprit for the infection, prompt tooth removal is ESSENTIAL

-PROMPT ENT consultation is recommended

Submitted by J. Grover.  

Sources: Saifeldeen K and Evans R. “Ludwig’s Angina.”  Emergency Medicine Journal.  2004;21:242-243.; Tintinalli’s Emergency Medicine.  7th Edition.; Uptodate.  Submandibular Space Infections; picture 1 from lifeinthefastlane.com; picture 2

Angioedema (of the face) – QUICK HITS

22 Apr

Self limited swelling of the lips/mouth/uvula/face (Another type of angioedema, bowel wall angioedema, will not be covered here.)

-can occur with or without other signs/symptoms of allergic reaction.   

-Causes can include Hereditary angioedema, Mast cell mediated angioedema (allergic ractions), or in bradykinin induced angioedema

 

Mast Cell Mediated Angioedema

-Symptoms begin with minutes of exposure and resolve in 24-48 hours

-Associated with other symptoms/signs of allergic reaction including

  • urticaria,
  • pruritis,
  • bronchospasm,
  • hypotension,
  • throat tightness

 

Bradykinin Induced Angioedema

Generally isolated to swelling with no other symptoms (no urticaria or other signs of systemic involvement)

-Usually develops slower, over 24-36 hours, and can last two to four days

-No clear association with when this may occur- for ACE inhibitor angioedema, can occur at onset of medication use, after a recent medication dose change, or after years of use

Immunosuppressed patients are more likely to experience this type of reaction even from medications they have been on for a long time

-Unilateral angioedema is more commonly related to ACE inhibitor induced angioedema

 

Hereditary Angioedema

-Caused from C1 inhibitor deficiency

-About 25% of patients have with Hereditary angioedema have a new mutation, so no family history does not rule out hereditary angioedema as a cause

 

Idiopathic Angioedema

-Recurrent episodes of angioedema without any systemic symptoms who have no drug exposure or complement pathway deficiency

 

Treatment

-Without a clear cause general treatment is the same for all three groups:

            –AIRWAY: Intubate if patient exhibits impending airway loss

            -If laryngeal or other respiratory involvement consider Epinephrine IM or SC and/or albuterol

 

            –Glucocorticoids

            –H1 and H2 antihistamines

-Note:  if Bradykinin induced angioedema, the main treatment is cessation of the medication causing the reaction           

 

Common Medication Causes for All Types of Angioedema

-ACE inhibitor or ARB

NSAID

-Calcium channel blockers

-Estrogens

-Antibiotics

 

Submitted by J. Grover. 

 

Sources:  Chan YF and Kalira D.  “Angiotensin-Converting Enzyme Inhibitors as a Cause of Unilateral Tongue Angioedema in a 68 Year old Woman.”  American Journal of Emergency Medicine 2005: 9:249-250.; Kuhlen JL and Forcucci J.  “Angiotensin-Converting Enzyme Inhibitor-induced Unilateral Tongue Angioedema.”  American Journal of the Medical Sciences 2012: 344:5;416-417.; Uptodate.  An Overview of Angioedema:  Clinical Features, Diagnosis, and Management; picture