Grand Rounds Recap 4.26.23

Ultrasound in early pregnancy - High and Lows - In-flight emergencies - high altitude illnesses

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Ultrasound in early Pregnancy w/ Dr. Frederick

• 1st trimester pregnancy accounts for 10% of all ED visits from women of reproductive age

• 28% present on weekends

• 37% present after hours

• Despite the fact that a lot of these patients present after hours, radiology is rarely available 24/7

• TVUS diagnoses nearly 50% of early pregnancies after an inconclusive transabdominal US

  • ED-performed TVUS has not been shown to increase ED length of stay

  • Patients have not been shown to refuse a second TVUS after ED-performed study

• Steps: 

  • Get set up

  • Scan transabdominally first (you do not have to wait for the b-hcg to result)

  • Do the TVUS at the same time as the pelvic exam 

• Anatomy:

  • Version: the relationship between the uterus and the vagina in the sagittal plane

  • Flexion: the relationship between the uterine body and the cervix in the sagittal plane

• Start by getting a true sagittal plane

• Identify the fundus, follow the endometrial stripe (trilaminar endometrium) along its entire course down to the cervix

• Include maternal bladder

• Scan through the adnexa bilaterally, best evaluated in the sagittal plane. You can use the iliac vessels as your landmark to locate the ovaries (which have been described to look like chocolate chip cookies)

• Scan through in two orthogonal planes

• Always perform a comprehensive exam, even if you see an IUP right away

• Identifying the IUP

  • Gestational sac

    • thick-walled anechoic structure

    • seen at about 5 weeks or b-hcg of 1000 

  • Yolk sac

    • thick, hyperechoic structure, round like a cheerio 

    • seen at about 6 weeks or b-hcg of 2500

  • Fetal pole

    • seen at about 6.5 weeks or b-hcg 5000

  • Amion

    • thin walled structure within the gestational sac (not always seen)

  • Fetal HR

    • seen at about 7 weeks or b-hcg of 7000

    • 120-160 bpm

    • Use M mode (never use doppler as this can harm the fetus)

• Positioning

  • IUP ideally positioned in the upper ⅔ of the uterus, adjacent to and touching the endometrial canal

  • Endomyometrial mantle (measured at the thinnest point from the inner border of the gestational sac to the outer border of the uterus, measured in two planes)

    • 8mm to be adequate

    • <5mm is very concerning for ectopic

    • 5-8mm requires OB/GYN consult

• Interstitial Pregnancy

  • Pregnancy that implants on the portion of the fallopian tube adjacent to the uterus

• Angular Pregnancies

  • Pregnancy that implants just medial to the utero-tubal junction on the lateral angle of the uterus 

Dating of Pregnancies

• most accurate in 1st trimester

• most accurate measure is crown rump length

• ED assessment is often earliest ultrasound 

• dating in the ED can assist with the scheduling of prenatal care and testing

• early dating is critical in establishing EDD for patients with indications for late preterm or early-term deliveries

  • Late preterm infants have 3-5x higher mortality when compared with term infants

Early Dating (1st trimester)

• Ultrasound machine will calculate for you (freeze a still image, hit the “calc” button, and these two are programmed in)

• Mean Sac Diameter

  • measure length, width, and height of gestational sac

  • average of these measurements + 30 = gestational age in days

  • used at 5-7 weeks gestation

• Crown Rump Length

  • can be used as soon as fetal pole is seen (6-13 weeks)

  • find the longest midsagittal embryo length in the horizontal plane (not flexed or extended)

  • measure from head to rump (excluding limbs or yolk sac)

  • measure 3 times and average

Ectopic Pregnancy

• 1-2% of all pregnancies

• #1 cause of first trimester maternal death

• 10% of total maternal mortality

• Concerning if: failure to diagnose an IUP, extrauterine mass, pelvic free fluid

Heterotopic Pregnancy

• simultaneous IUP and ectopic pregnancy

• 58-73% are missed on ultrasound

• expectant management or surgery 

Cervical Ectopic

• gestational sac implanted in the cervix

• often confused for miscarriage in process

Cesarean Scar Ectopic

• eccentrically located in the lower anterior myometrium

Corpus luteum cyst

• created from follicle after release of egg

• can be confused with ectopic pregnancy

• thick walled, cystic structure in the ovary

• look for characteristic “ring of fire” on color doppler

Free fluid

• most often posterior to the uterus

• quantify by dividing the posterior uterus into thirds

• the TIE Fighter sign can be seen and represents the uterus suspended in free fluid by the ovarian ligaments

• If a RUQ view is done in the ED, patients with diagnosis of ruptured ectopic were found to have their diagnosis made 2.2 hours earlier and went to OR 3.5 hours earlier

• Free fluid in the RUQ has been shown to have a LR of 112 of requiring operative management 

Risk Factors for Ectopic Pregnancy

• prior ectopic pregnancy

• surgery

• infection

• assisted reproductive technologies

• IUD

• However, 50% of patients with ectopic pregnancy have no risk factors

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High and Lows w/ Dr. Comiskey

Hyperammonemia

• 10% of of patient presenting with hepatic encephalopathy do not have elevated ammonias

• Most commonly seen in adults is secondary to liver dysfunction with cirrhosis or portal venous system shunting. Other causes include infections, certain drugs and hematologic disorders

• In the pediatric population, more commonly seen are the urea cycle disorders 

• Cerebral edema occurs due to edema of the astrocytes within the brain, which are the primary ammonia scavengers within the CNS

  • Significant edema can lead to herniation and brain death

• Treatment is aimed at reducing the production and absorption of ammonia, and common agents are lactulose and rifaximin, although these do not confer mortality benefit. Once ammonia levels are high enough, usually 2-3x the upper limit of normal, dialysis will be initiated.

• For cerebral edema, hypertonic saline is the preferred solution over mannitol

• Propofol is the preferred sedating agent due to its hyperosmolar state and anti-epileptic properties. Avoid Depakote in these patients if they begin seizing, as that will only worsen their disease process

Essential Thrombocytosis 

• most commonly seen in females, with average age of onset between 50-60 years

• differential diagnosis also includes clonal neoplasms, spurious lab values, and reactive thrombocytosis

• about half of patients diagnosed with essential thrombocytosis are found to have a JAK2 mutation

• patients are at risk for thrombosis, but also develop an acquired vWD because there are so many platelets that they become dysfunctional which increases risk for bleeding

• Treatment is aimed at preventing complications, mostly from thrombotic and hemorrhagic events

  • Low risk = <60 yrs old and no prior thrombotic events

    • aspirin, close monitoring

  • High risk = > 60 yrs old with prior history of thrombosis

    • antiplatelet, cytoreduction

• Hydroxyurea is the first line cytoreductive therapy, with one study demonstrating patients on hydroxyurea experiencing a 3.6% incidence of thrombosis compared to 24% of patient on placebo over a 6 month period 

Hyperviscosity syndrome

• most commonly seen with hypergammaglobulinemia due to their large structures, with 30% of patients with Waldenstrom macroglobulinemia developing HVS in their lifetime

• caused by increased thickness of the blood

• presents with visual disturbances, neurologic complications and bleeding

• treatment is aimed at reducing complications. Methods include hydration, emergency plasmapheresis if indicated, and treatment of the underlying pathology, usually with chemotherapy

Severe Iron Deficiency Anemia

• often related to poor nutrition in the pediatric population

• complication is high output cardiac failure

• feared and rare complication of chronic anemia is high output heart failure, the least common form of heart failure

• defined low SVR and oxygen a-v gradient with high cardiac output; which differs from low output heart failure since there is usually an associated increase in SVR with circulating vasoconstrictors

• activation of the RAAS system and increased ADH in attempt to increase intravascular volume, but eventually leads to cardiac remodeling and hypertrophy

• treatment is aimed at correcting the underlying cause of heart failure, in this case correction of the anemia with a blood transfusion, but must be a slow infusion over 3-4hr per unit and IV iron sucrose

• reduction of extravascular volume with diuretics, fluid and salt restriction

• vasopressors may be used to increase SVR 

HIV/AIDS

• Labs prior to initiation of HAART therapy

  • CMP, CBC, b-hcg, STI testing, and screening for AIDS-defining illness 

• HAART should be started on patients once the diagnosis is confirmed regardless of their CD4 count

• If patients are able to increase their CD4 >500, they are anticipated to have a normal life expectancy

• Left untreated, HIV patients are anticipated to live ~10yrs and if they are transition to AIDS, life expectancy falls to <2 yrs

• Undetectable = untransmittable

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R3 Small Groups: Commercial In-Flight Emergencies w/ Dr. Smith

Quick Facts regarding In-Flight Emergencies: 

• 2.75 billion passengers annually

• 1 medical emergency per 604 flights

• Most common complaints: 

  • Syncope/presyncope: 37.4%

  • Respiratory symptoms: 12.1%

  • Nausea and vomiting: 9.5%

• Diversion occurs 7.3% of in-flight emergencies 

• Deaths occurred 0.3% of in flight emergencies

• 31% EMS was not requested, of those where EMS was requests, only 37% were transported

• 60% of OB cases were miscarriages prior to 24 weeks gestation

• Most commonly used medications are: oxygen, IVF, and ASA

Your Team

• Flight attendants should have some basic medical training, can help you locate supplies, and can help with communication with the pilot

• Medical Ground Support:

  • Usually by radio or telephone in the cockpit

  • May be able to speak directly with them or all information may have to be relayed 

  • All conversations are recorded

  • Typically EMS fellowship trained EM physicians - two groups in the US. One through UPMC, one through Phoenix

  • Ground control has the ability to supercede decisions made by in flight responders

• If multiple people respond, introduce yourselves and assign roles

Special Circumstances:

• Diversion:

  • Decision made by pilot, +/- medical ground support 

  • Cost estimated 10,000 to 500,000 dollars

• Death on Board:

  • Can presume death and stop resuscitation 

  • Don’t declare deaths. Legal implications vary from country to country. 

  • Pilot will decide when/how/who to inform on the ground

• DNRs:

  • Airlines can refuse to honor DNR and can still request medical assistance

  • Individually decide whether or not to honor it versus resuscitate

  • Airline can ask for someone different (aka ignore you) 

• If there is concern for a communicable disease, make pilot and team aware if other passengers need to be evaluated or quarantined

Legal:

• US: the Aviation Medical Assistance Act passed April 24, 1998 which states individual not liable for damages in any action brought in Federal or State court from the acts or omissions in providing or attempting to provide assistance in the case of in-flight emergencies (unless the individual is guilty of gross negligence or willful misconduct)

• International: depends on the country, but most countries have something similar. 

• No known cases of an individual medical provider being successfully sued anywhere in the world for an in-flight emergency. Airline companies have been sued. Generally accepted (and some airlines spell it out) that they are assuming the liability even for you helping 

Documentation: 

• To protect yourself (and the airline), will/should make documentation of what happened. Each airline generally has their own protocol. 

• Recommend keeping a copy of the records for yourself 

FAA Regulation Medical Kit

• Sphygmomanometer

• Stethoscope

• Airways, oropharyngeal: 1 pediatric, 1 small adult, and 1 large adult or equivalent

• Self-inflating manual resuscitation device with 1 pediatric mask, 1 small adult mask, and 1 large adult or equivalent mask

• Cardiopulmonary resuscitation masks: 1 pediatric, 1 small adult, and 1 large adult or equivalent

• V. administration set: 1 tubing with 2 Y-site connectors, 2 alcohol-soaked sponges, 1 standard roll of 1-inch-wide adhesive tape, 1 pair of tape scissors, and 1 tourniquet

• Protective nonpermeable gloves or equivalent, 1 pair

• Needles: 2 18 gauge, 2 20 gauge, and 2 22 gauge; or 6 needles in sizes necessary to administer required medications

• Syringes: 1 5 cc and 2 10 cc; or 4 syringes in sizes necessary to administer required medications

• Analgesic, nonnarcotic, 325-mg tablets, 4

• Antihistamine, 25-mg tablets, 4

• Antihistamine injection, 50-mg single-dose ampule or equivalent, 2

• Atropine injection, 0.5-mg single-dose 5-mL ampule or equivalent, 2

• Aspirin, 325-mg tablets, 4

• Bronchodilator, metered-dose inhaler or equivalent

• 50% Dextrose injection, single-dose 50-mL ampule or equivalent

• Epinephrine injection, 1:1000 (1 mg/mL) single-dose 1-mL ampule or equivalent, 2

• Epinephrine injection, 1:10,000 (0.1 mg/mL) single-dose 2*-mL ampule or equivalent, 2

• Lidocaine injection, 20-mg/mL single-dose 5-mL ampule or equivalent, 2

• Nitroglycerin, 0.4-mg tablets, 10

• 9% Sodium chloride injection, 500 mL

• Basic instructions for use of the drugs in the kit

• AED

Of note, there is no requirement for airlines to carry a glucometer or some other common medical equipment. Some airlines may carry more than what is required. 

The AirRx app contains information regarding common medications and equipment available, top diagnoses, medicolegal information and more, and is available to download for free.

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High Altitude illnesses w/ Dr. Kletsel

Physiology

High-altitude environment leads to hypoxemia

o   Concentration of oxygen in inspired air (FiO2) stays constant at 21% regardless of altitude

o   However, as barometric pressure decreases with altitude, the partial pressure of oxygen decreases as well

o   This leads to reduced arterial partial pressure of oxygen (PaO2) in those residing at higher altitudes

·         Physiology of acclimatization

o   Body tries to adapt to the hypoxemia of a high-altitude environment if given time

o   Respiratory

• Will increase RR to compensate for low PaO2

• Yet, this is limited by respiratory alkalosis, which serves as a brake on the respiratory system

• Eventually kidneys will act to excrete bicarbonate, to lower the pH

• Now RR can increase further

• But, need 4-7 days for kidneys to begin to excrete bicarbonate

o   Cardiovascular

• Increase in HR to maintain adequate CO

• Global pulmonary vasoconstriction in response to hypoxemia

• Increase in cerebral blood flow to deliver more oxygen-deprived blood to the CNS

o   Circulatory

• Increase EPO production to increase RBC mass over days to weeks

• Increase 2-3 DPGA production to shift oxygen-dissociation curve to the right and allow easier oxygen unloading to tissues

High-Altitude Syndromes

o   Spectrum of disorders, that have the fundamental etiology of hypoxia and generally occur due to rapid ascent and not enough time of physiological acclimatization

o   Principles of management

• Do not ascend any higher if patient develops symptoms

• If safe, descend if initial treatment fails to improve symptoms

• If safe, descend immediately if HACE or HAPE occur

o   Acute Mountain Sickness

• Incidence varies according to

  • Rate of ascent, sleeping altitude, genetics

• Clinical features

  • Typically after ascent to altitude >2000m

  • Occurs rather quickly, usually first 1-6 hours

  • Headache, nausea, vomiting, weakness, sleep disturbances

• Treatment

  • No further ascent if mild symptoms or descent if moderate/severe symptoms

  • Oxygen administration (0.5-1 L/m of nocturnal O2 is most helpful)

  • Acetazolamide

    • 125-250 mg PO BID

    • Blocks carbonic anhydrase to reduce kidney bicarbonate reabsorption

    • Helps lower pH to allow respiratory system to further increase RR

  • Dexamethasone

    • 4 mg PO/IM/IV q6h

    • Reserved for severe symptoms

  • Symptom control

    • Acetaminophen/Ibuprofen PRN

    • Zofran PRN

  • Prevention

    • Graded ascent (avoid abrupt ascent >3000m

    • Prophylactic acetazolamide (started 24h prior to ascent and continued for first two days)

o   High-Altitude Cerebral Edema (HACE)

• Pathophysiology involves vasogenic edema in the CNS

  • Involves increase CBF and a leaky blood-brain barrier

  • Due to loss of auto-regulation and increased permeability due to inflammatory mediators

  • Expect T2 signaling on MR imaging

• Clinical features

  • Progressive neurological decline

    • AMS, ataxia, stupor

    • Focal neurological signs (usually CN3 or CN6 palsies)

    • Occasionally seizures and coma

• Treatment

  • If safe, descent is highest priority

    • If unable, can simulate descent with a hyperbaric bag (i.e. Gamow bag)

  • Supplemental oxygen

  • Dexamethasone

    • 8mg IV initially, then 4 mg PO/IM/IV q6h

  • No evidence for hypertonic saline or mannitol

o   High-Altitude Pulmonary Edema (HAPE)

• Risk factors

  • Rapid ascent and associated heavy exertion

  • Cold environment

  • Underlying pulmonary hypertension

• Pathophysiology involves non-cardiogenic pulmonary edema

  • Due to increased pulmonary vascular resistance in response to global hypoxemia

• Clinical features

  • Progression of dyspnea is hallmark of HAPE

  • Early in disease process

    • Dry cough, dyspnea on exertion, poor exercise tolerance, localized rales, reduced SpO2 readings

  • Later in disease process

    • Wet cough, dyspnea at rest, generalized rales, tachypnea, tachycardia

• Treatment

  • If safe, descent is highest priority

    • If unable, can simulate descent with a hyperbaric bag (Gamow bag)

  • Supplemental oxygen

  • Nifedipine

    • 20-30mg extended release PO q12h

    • Reduces pulmonary artery pressure

  • Tadalafil

    • 10mg PO q24h typically started for prevention of HAPE 24h prior to ascent

    • Generates nitric oxide to blunt pulmonary hypoxic vasoconstriction