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Medical Emergencies
.
Anuradha Perera (B.Sc.N)special
Respiratory failure
Definitions
• acute respiratory failure occurs when:
– pulmonary system is no longer able to meet
the metabolic demands of the body
• hypoxaemic respiratory failure:
– PaO2  50 mm Hg when breathing room air
• hypercapnic respiratory failure:
– PaCO2  50 mm Hg.
Oxygen in
• Depends on
–
–
–
–
PAO2
Diffusing capacity
Perfusion
Ventilation-perfusion matching
Oxygen
Carbon
dioxide
Water
vapour
Nitrogen
Alveolarpressure PAO2  PACO2  PAH2O  PAN2
Pathophysiology
Perfusion without
ventilation (Shunting)
• Intra-cardiac
– Any cause of right to left shunt
• eg Fallot’s, Eisenmenger
• Intra-pulmonary
–
–
–
–
–
Pneumonia
Pulmonary oedema
Atelectasis
Collapse
Pulmonary haemorrhage or contusion
Perfusion without
ventilation (shunting)
Intra-pulmonary
• Small airways occluded ( e.g asthma, chronic
bronchitis)
• Alveoli are filled with fluid ( e.g pulm edema,
pneumonia)
• Alveolar collapse ( e.g atelectasis)
Brainstem
Airway
Lung
Spinal cord
Nerve root
Nerve
Pleura
Chest wall
Neuromuscular
junction
Respiratory
muscle
Sites at which disease may cause ventilatory disturbance
Respiratory Failure
Symptoms
CNS:
Headache
Visual Disturbances
Anxiety
Confusion
Memory Loss
Weakness
Decreased Functional Performance
Respiratory Failure
Symptoms
Pulmonary:
Cough
Chest pains
Sputum production
Stridor
Dyspnea
Respiratory Failure
Symptoms
Cardiac:
Orthopnea
Peripheral edema
Chest pain
Other:
Fever, Abdominal pain, Anemia, Bleeding
Clinical
• Respiratory compensation
• Sympathetic stimulation
• Tissue hypoxia
• Haemoglobin desaturation
Clinical
• Respiratory compensation
–
–
–
–
Tachypnoea RR > 35 Breath /min
Accessory muscles
Recesssion
Nasal flaring
• Sympathetic stimulation
• Tissue hypoxia
• Haemoglobin desaturation
Clinical
• Respiratory compensation
• Sympathetic stimulation
– HR
– BP
– sweating
• Tissue hypoxia
• Haemoglobin desaturation
Clinical
• Respiratory compensation
• Sympathetic stimulation
• Tissue hypoxia
– Altered mental state
– HR and BP (late)
• Haemoglobin desaturation
Clinical
Altered mental state
⇓PaO2 +⇑PaCO2 ⇨ acidosis ⇨
dilatation of cerebral resistance
vesseles ⇨ ⇑ICP
Disorientation
Headache
coma
personality changes
Clinical
• Respiratory
compensation
• Sympathetic
stimulation
• Tissue hypoxia
• Haemoglobin
desaturation
– cyanosis
Respiratory Failure
Laboratory Testing
Arterial blood gas
PaO2
PaCO2
PH
Chest imaging
Chest x-ray
CT sacn
Ultrasound
Ventilation–perfusion scan
Respiratory Failure
Laboratory Testing
Respiratory mechanics
Spirometry (FVC, FEV1, Peak flow)
Respiratory muscle pressures
MIP ( maximum inspiratory pressure)
MEP ( maximum expiratory pressure)
Respiratory Failure
Laboratory Testing
Other tests
Hemoglobin
Electrolytes, blood urea nitrogen, creatinine
Creatinine phosphokinase, aldolase
EKG, echocardiogram
Electromyography (EMG)
Nerve conduction study
True or False
•Diffusion abnormality is
considered the most
common cause of
hypoxia.
True or False
•Dead space ventilation
decreases when blood
flow is reduced
True or False
•Shunt occurs when areas
of lung are perfused but
not ventilated
True or False
•In myasthenia gravis
mechanism of hypoxia
may be due to alveoli
being perfused but not
ventilated
True or False
•Arterial hypoxemia may
be caused by alveolar
hypoventilation alone
True or False
• The distinction between
ventilation/perfusion mismatch
and intrapulmonary shunting
can be made by measuring the
response to the administration
of 100% oxygen
True or False
• There is a good relationship
between dyspnea and arterial
hypoxemia but a poor
relationship between dyspnea
and arterial carbon dioxide
retention
Which of the following statements
regarding the physical examination
for patients with acute respiratory
failure are true or false?
• Central nervous examination is important
• Breath sounds are commonly diminished
• Supraclavicular and intercostal space
muscle retractions do not correlate with
increased work of breathing
QUESTIONS
?
?
?
?
Pulse oximetry
Hb saturation (%)
90
8
PaO2 (kPa)
Cardiac failure
Heart Attack
• Acute myocardial
infarction (AMI)
• Pain signals death
of cells.
• Opening the
coronary artery
within the first
hour can prevent
damage.
• Immediate
Signs and Symptoms
• Sudden onset of weakness, nausea,
sweating without obvious cause
• Chest pain/discomfort
– Often crushing or squeezing
– Does not change with each breath
• Pain in lower jaw, arms, back,
abdomen, or neck
• Sudden arrhythmia with syncope
• Shortness of breath or dyspnea
• Pulmonary edema
Pain of Heart Attack
• May or may not be caused by
exertion
• Does not resolve in a few minutes
• Can last from 30 minutes to several
hours
• May not be relieved by rest or
nitroglycerin
Sudden Death
• 40% of AMI patients do not reach
the hospital.
• Heart may be twitching.
Arrhythmias
Bradycardia
Ventricular Tachycardia
Cardiogenic Shock
• Heart lacks power to force blood
through the circulatory system.
• Onset may be immediate or not
apparent for 24 hours after AMI.
Congestive Heart Failure
• CHF occurs when ventricles are
damaged.
• Heart tries to compensate.
• Increased heart rate
• Enlarged left ventricle
• Fluid backs up into lungs or
body as heart fails to pump.
• You obtain a brief history while
taking the patient’s blood pressure.
• Your partner retrieves the
nitroglycerin and obtains
permission from medical control.
• Your partner administers the
nitroglycerin.
• What else can you do at this time?
You are the Provider
(continued)
Focused History and Physical Exam
• Medications are important!
• Medications often prescribed for
CHF:
– Furosemide
– Digoxin
– Amiodarone
Focused Physical Exam
• Cardiac and respiratory systems
• Look for skin changes.
• Lung sounds
• Baseline vital signs
– BOTH systolic and diastolic BP
readings
Communication
Relay history, vital signs, changes, medications,
and treatments.
Aspirin
• Administer according to local
protocol.
• Prevents clots from becoming
bigger
• Normal dosage is from 162 to 324
mg.
Nitroglycerin
• Forms
– Pill, spray, skin
patch
• Effects
– Relaxes blood vessel
walls
– Dilates coronary
arteries
– Reduces workload of
heart
Nitroglycerin
Contraindications
• Systolic blood pressure of
less than 100 mm Hg
• Head injury
• Maximum dose taken in
past hour
Nitroglycerin Potency
• Nitroglycerin loses potency over
time.
– Especially if exposed to light
• When nitroglycerin tablets lose
potency:
– May not feel the fizzing sensation
– May not experience the burning
sensation and headache
• Fizzing only occurs with a potent
Assisting With Nitroglycerin
• Obtain order from medical
direction.
• Take patient’s blood pressure.
(1 of 4)
Assisting With
Nitroglycerin (2 of 4)
• Check that you have right
medication, patient, and delivery
route.
• Check expiration date.
• Find out last dose taken and effects.
• Be prepared to lay the patient down.
Assisting With Nitroglycerin
4)
(3 of
• Administer tablet or spray under
tongue.
• Have patient keep mouth closed
until tablet dissolves or is
absorbed.
Assisting With
Nitroglycerin (4 of 4)
• Recheck blood pressure.
• Record each activity and time of
application.
• Reevaluate and note response.
• May repeat dose in 3 to 5 minutes.
Ongoing Assessment
• Repeat initial assessment.
• Reassess vital signs every 5
minutes.
• Monitor closely.
• If cardiac arrest occurs, begin
defibrillation or CPR immediately.
• Record interventions, instructions
from medical control, patient’s
response.
Heart Surgeries and
Pacemakers
• Coronary artery bypass graft
(CABG)
• Angioplasty
• Cardiac pacemaker
Automatic Implantable
Cardiac Defibrillators (1 of 2)
• Maintains a
regular heart
rhythm and rate
• Do not place AED
patches over
pacemaker.
Automatic Implantable
Cardiac Defibrillators (2 of 2)
• Monitor heart rhythm
and deliver shocks as
needed.
• Low electricity will not
affect rescuers.
Cardiac Arrest
• The complete cessation of cardiac
activity, either electrical,
mechanical, or both.
Automated External
Defibrillator (AED)
• AEDs come in various
models.
• Some operator
interaction required.
• A specialized
computer recognizes
heart rhythms that
require defibrillation.
Potential AED Problems
• Battery is dead.
• Patient is moving.
• Patient is
responsive and has
a rapid pulse.
AED Advantages
• ALS providers do not
need to be on scene.
• Remote, adhesive
defibrillator pads are
used.
• Efficient transmission of
electricity
Non-Shockable Rhythms
• Asystole
• Pulseless electrical
activity
Rationale for Early Defibrillation
• Early defibrillation is
the third link in the
chain of survival.
• A patient in ventricular
fibrillation needs to be
defibrillated within 2
minutes.
AED Maintenance
• Read operator’s manual.
• Check AED and battery at beginning
of each shift.
• Get a checklist from the
manufacturer.
• Report any failures to the
manufacturer and the FDA.
Medical Direction
• Should approve protocols
• Should review AED usage
• Should review speed of defibrillation
• Should provide review of skills every
3 to 6 months
Preparation
• Make sure the electricity injures no
one.
• Do not defibrillate a patient lying in
pooled water.
• Dry a soaking wet patient’s chest
first.
• Do not defibrillate a patient who is
touching metal.
• Remove nitroglycerin patches.
Using an AED
(1 of 8)
• Assess
responsiveness.
• Stop CPR if in
progress.
• Check breathing
and pulse.
• If patient is
unresponsive and
not breathing
adequately, give
Using an AED
(2 of 8)
• If there is a
delay in
obtaining an
AED, have your
partner start or
resume CPR.
• If an AED is
close at hand,
prepare the AED
pads.
Using an AED
(3 of 8)
• Remove clothing
from the
patient’s chest
area. Apply pads
to the chest.
• Stop CPR.
• State aloud,
“Clear the
patient.”
Using an AED
(4 of 8)
• Push the analyze
button, if there
is one.
• Wait for the
computer.
• If shock is not
needed, start
CPR.
• If shock is
advised, make
sure that no one
Using an AED
(5 of 8)
• After the shock is delivered, begin 5
cycles of CPR, beginning with chest
compressions.
• After 5 cycles, reanalyze patient’s
rhythm.
• If the machine advises a shock, clear
the patient and push shock button.
• If no shock advised, check for pulse.
Using an AED
(6 of 8)
• If the patient has
a pulse, check
breathing.
• If the patient is
breathing
adequately,
provide oxygen
via
nonrebreathing
mask and
Using an AED
(7 of 8)
• If the patient is
not breathing
adequately, use
necessary airway
adjuncts and
proper
positioning to
open airway.
• Provide artificial
ventilations with
Using an AED
(8 of 8)
• If the patient has no pulse, perform 2
minutes of CPR.
• Gather additional information on the
arrest event.
• After 2 minutes of CPR, make sure no
one is touching the patient.
• Push the analyze button again (as
applicable).
• If necessary, repeat alternating
CPR/Analyze/Shock until ALS arrives.
• Transport and check with medical
After AED Shocks
• Check pulse.
• No pulse, no shock advised
• No pulse, shock advised
• If a patient is breathing
independently:
– Administer oxygen.
– Check pulse.
• If a patient has a pulse but
breathing is inadequate,
assist ventilations.
Transport
Considerations
• Transport:
– When patient regains pulse
– After delivering six to nine
shocks
– After receiving three consecutive
“no shock advised” messages
• Keep AED attached.
• Check pulse frequently.
• Stop ambulance to use an AED.
Cardiac Arrest During Transport
(1 of 2)
• Check unconscious patient’s pulse
every 30 seconds.
• If pulse is not present:
–
–
–
–
–
Stop the vehicle.
Perform CPR until AED is available.
Analyze rhythm.
Deliver shock(s).
Continue resuscitation according to local
protocol.
Cardiac Arrest During Transport
(2 of 2)
• If patient becomes unconscious during
transport:
–
–
–
–
–
–
Check pulse.
Stop the vehicle.
Perform CPR until AED is available.
Analyze rhythm.
Deliver up to three shocks.
Continue resuscitation according to local
protocol.