Respiratory problems
in the OB PACU
Tom Archer, MD, MBA
Director, OB Anesthesia
UCSD Hillcrest
August 16, 2012
Vast subject for one hour
Keep it practical and clinical.
• Keep it focused on OB and PACU.
• Enough anatomy and pathophysiology to
give background and depth.
What we like from nurses and OBs:
• Get us involved early!
– We should never be upset with your getting
us involved early in patient care!
•
•
•
•
Morbid obesity
Asthma
Anesthesia fears, Hx of problems
Any significant medical problem
Use simple observation
• Talk with and examine the patient.
• Don’t think too much about fancy tests.
Signs and symptoms
• What is the patient experiencing? Talk to
her! Is she cyanotic? Put her on O2!
• What is her voice like?
• Does sitting up make it better (diaphragm
descends, lung expands)?
• Can the patient move her arms and legs?
Signs and symptoms
• How much air is the patient moving? Put your
hand to her mouth.
• What do you hear when you ask her to take a
rapid, deep breath?
• Has she had breathing problems in the past
(asthma)?
• What does she usually use (rescue inhaler)?
Signs and symptoms
• What is the SpO2? Is the sensor applied
properly? Same side as BP cuff?
• What do you hear on auscultation?
• Listen in all lung fields. Anything? Rales,
wheezes, stridor?
Signs and symptoms
• Rales: too much fluid in the alveoli.
• Wheezes: (expiratory sound) narrowed
intra-thoracic (bronchial) tubes
• Stridor : (inspiratory sound): narrowed
extra-thoracic trachea or larynx.
Signs and symptoms
• What are the neck veins like?
• CXR– essential for any serious problem
ABG– nice if you can get it, but don’t
waste time and effort if you can’t. Think
arterial line for serial ABGs.
What is the patient experiencing?
Talk to her!
• Don’t forget to talk with the patient!
• When did the problem start?
• Has this ever happened before?
• Does she have chest pain?
Put her on O2! Is she cyanotic?
• Cyanosis means there is de-oxygenated
blood, blood is not “matched” with O2.
• Blood that passes through the lung without
getting exposed to oxygen.
• “Shunt” or “low V/Q”
www.argentou
r.com/tangoi.ht
ml
The dance of pulmonary physiology—
Blood and oxygen coming together.
Sometimes the match between blood and oxygen
isn’t perfect!
http://www.bookmakersltd.com/art/edwards_art/3PrincessFrog.jpg
Failures of gas exchange
Shunt
Low V/Q
Alveolar dead space
Diffusion barrier
alveolus
capillary
High V/Q
ABGs
• In respiratory distress, we expect both
PO2 and PCO2 to be decreased.
• If PO2 is decreased and PCO2 is
increased, this is a true emergency!
• Normally, hyperventilated parts of lung will
compensate for hypoventilated parts of
lung for CO2, but not for O2
Respiratory changes of pregnancy:
Mother-to-be is consuming more
O2, producing more CO2 and is
breathing harder!
Mom
4 ml O2 / kg / min
Feto-placental unit
12 ml O2 / kg / min
Mother is consuming and delivering
oxygen for two!
www.studentlife.villanova.edu
At term, mother has respiratory alkalosis with
metabolic compensation (less HCO3- buffer).
ABGs
Chestnut
At term
PaCO2
Nonpregnant
40
PaO2
100
103
pH
7.40
7.44
HCO3-
24
18
30
Functional residual capacity (FRC):
gas left in the lung after we breathe out.
Functional residual capacity (FRC) is our “air tank” for apnea.
www.picture-newsletter.com/scuba-diving/scuba... from Google images
Pregnant Mom has a smaller “air tank”.
Non-pregnant
woman
www.pyramydair.com
/blog/images/scubaweb.jpg
Pregnant patient has less
“margin of safety” for apnea.
• If pregnant patient stops breathing she will
desaturate faster than non-pregnant
patient.
• Apnea from: hypotension, seizure,
anesthesia induction, high spinal,
magnesium overdose, etc.)
“Ramping up”
the obese
patient to
facilitate
intubation.
Sitting up will
also help any
respiratory
problem in the
PACU.
www.airpal.com/ramp.htm
Specific respiratory problems
Asthma-- has she had breathing
problems in the past?
Wheezing
• Expiratory sound.
• Worse with low lung volumes.
• Smooth muscle contraction + airway
edema + secretions
• Sit patient up / beta agonist rescue inhaler
/ steroid?
Wheezing is not a
complete diagnosis
• Smooth muscle spasm (bronchospasm)
can cause wheezing.
• Airway edema can cause wheezing (fluid
overload, CHF)
All That
Wheezes Is Not
Asthma:
Diagnosing the
Mimics
www.mdchoice.com/emed/main.
asp?template=0&pag...
He3 MR
showing
ventilation
defects in a
normal subject
and in
increasingly
severe
asthmatics.
Author Samee, S ; Altes T ; Powers P ; de Lange EE ; Knight-Scott J ; Rakes G
Title Imaging the lungs in asthmatic patients by using hyperpolarized helium-3 magnetic resonance: assessment of response to methacholine and exercise challenge
Journal Title Journal of Allergy & Clinical Immunology
Volume 111 Issue 6 Date 2003 Pages: 1205-11
Pulmonary edema
www.learningradiology.com/.../cow267lg.jpg
Pulmonary edema is not a
complete diagnosis!
• Too much water in the lung.
• Hydrostatic pressure: heart failure or
simple fluid overload.
• Alveolar capillary damage and fluid leak:
aspiration, sepsis (both lead to ARDS).
Pulmonary edema
• Hydrostatic– too much pressure in the
alveolar capillaries (normal lung + too
much fluid pressure).
– Too much IV fluid (pre-eclampsia)
– Congestive heart failure (peripartum
cardiomyopathy? LV failure with preeclampsia?)
– Renal failure
www.learningradiology.com/.../cow267lg.jpg
Pulmonary edema
• Increased capillary permeability (lung
damage).
– Pre-eclampsia
– Aspiration (usually with GA)
– Sepsis (chorioamnionitis)
– Anaphylaxis (antibiotics)
– Pulmonary embolus
– Amniotic fluid embolus (very rare)
www.learningradiology.com/.../cow267lg.jpg
Atelectasis
• An area of lung is compressed.
– External compression (obesity, pregnancy,
supine posture)
– Gas absorption (mucus plug) or after right
mainstem bronchus intubation.
– Treatment is upright posture, deep breathing
and removal of mucus plugs.
Atelectasis in obesity– dependent regions
Atelectasis– left upper lobe
www.med.yale.edu/.../graphics/rad1.gif
Right mainstem
bronchus intubation
Has her voice changed? Does she
have stridor?
• Voice change– larynx change
– Edema from ETT trauma
– Edema from pre-eclampsia
– Allergic reaction (hereditary angioedema).
The AIRWAY can be closed off by swelling of tongue or larynx.
Normal larynx
http://www.dochazenfield.com/images/Larynx_side-by-side_Rotated_Labeled.gif
Laryngeal edema–
voice change or stridor
http://www.healthsystem.virginia.edu/Internet/AnesthesiologyElective/images/anesth0018.jpg
Stridor
• Inspiratory “crow”. Listen with stethoscope
over the neck as part of your exam.
• Stridor suggests obstruction in the
trachea, vocal cords or throat.
Neuromuscular paralysis: can the
patient move her arms and legs?
Did she recently get a dose of epidural local
anesthetic (for post-op pain relief)?
Does she have a “high spinal” or epidural?
Did she get a GA? Does she have residual
neuromuscular blockade?
Can the patient move
her arms and legs?
Magnesium will exacerbate neuromuscular
disease or neuromuscular blocking agents.
Does she have unrecognized neuromuscular
disease?
Myasthenia gravis?
Pulmonary embolus
Pulmonary embolus
• Can have normal chest x-ray.
• Can have pain, or not.
• Spiral CT is fancy test of choice.
• V/Q scan is not nearly as good a test.
Pulmonary embolus
• May be associated with hypotension.
• May be associated with distended neck
veins.
Pneumothorax
• After GA and intubation
• Feel for subcutaneous emphysema (air).
Rice crispies at base of neck.
• Tension pneumothorax would have
distended neck veins and hypotension.
Tension pneumothorax
Distended neck veins
www.meddean.luc.edu/.../phyabn/image15.jpg
General measures
• Put her on oxygen by mask, at least 6
L/min (but increasing rate beyond 6 makes
little difference).
• Sit her up in bed (but watch for
hypotension if neuraxial block is in place).
• Make sure SOB is not due to hypotension.
How much air is the patient moving?
Put your hand to her mouth.
• With chest wall numbness patient does not
feel herself breathing, but can be
breathing very well.
• If tidal volume really is decreased, this is a
true emergency!
Respiratory emergency
• Respiratory rate > 24-30
• Cyanosis or low sats
• Rising CO2 (arterial)
• Patient tiring out. Change in consciousness.
• Seizure (think hypoxia and / or aspiration)
Respiratory emergency
• Think: anesthesiologist, oxygen, intubation,
crash cart, Ambu bag, suction, getting to
head of bed, call for ventilator, CXR.
• But get patient well oxygenated before
intubation, if possible, because of delay in
intubation and rapid desaturation.
Summary
• Respiratory problems are infrequent in
OB– young, healthy patients.
• Take a good history.
• Make simple, systematic observations.
• Is the patient in bad trouble?
Summary
• Please get us anesthesiologists involved
early.
• Thank you!
The End