Respiratory Flashcards
Normal Neonatal ABG: normal pO2
50-70 (term infant)
45-65 (preterm infant)
LEFT shift in the oxyhemoglobin dissociation curve
hypothermia, hypocapnia, alkalosis, and decreasing 2-3 DPG
(think frost bite - blue fingers and toes (no o2 or perfusion in those cold extremities) )
RIGHT shift in the oxyhemoglobin dissociation curve
hyperthermia, acidosis (think hot), hypercapnia, increased levels of 2-3, DPG (when skin is hot, it flushes with blood and oxygen, increased perfusion)
Embryology: Embryonic Phase
3-6 weeks; lung bud develops ; single lung buds divide into the right and left lung buds and into trachea
some airway branching; pulmonary vein, pulmonary artery formation occurs
abnormal development: Tracheal agenesis, tracheal stenosis, TEF, pulmonary sequestration
Embryology: Psuedoglandular phase
6-16 weeks
conducting airways are formed
abnormal development: congenital lobar emphysema, congenital diaphragmatic hernia
Embryology: cannicular phase
16-26 weeks
the acinar or respiratory units form; Cuboidal cells develop into Type 1 Cells (those responsible for gas exchange) and Type 2 cells (those capable of surfactant production)
embryology: terminal sac or saccular phase
weeks 26-36
saccules develop which will eventually turn into alveoli; Type 2 cells increase in production and release of surfactant
infants delivered in this stage may have RDS, pulmonary insufficiency, PIE, BPD
factors that facilitate alveolarization
vitamin A
thyroxin
Fetal lung fluid production
produced at 4-5 ml/kg/hr
is facilitated by active transport of chloride from the interstitium
L-S ratio
lecithin-sphyngomyelin ratio of 2:1 is indicative of fetal lung maturity
its use is not accurate in infants of diabetic mothers
PG ratio (phosphatidyglycerol levels)
used to assess fetal lung maturity; more useful in IDM; increases in production at around 35 weeks, its presence indicates lung maturity
Fetal breathing movements
can be seen as early as 11 weeks
Role of antenatal steroids
maximum benefit is at 48 hours after administration with a result in the increase in production of proteins that control the manufacture of surfactant by type 2 cells
pulmonary hypoplasia
pulmonary underdevelopment;
- primary - intrinsic failure of resp. development
- secondary - result of abnormal processes that interfere with lung development;
- oligo r/t renal anomalies
- IUGR
- space occupying lesions (CHD, Cardiomegaly, cystic lung disease)
Pulmonary Hypoplasia Diagnosis & Management
- Diagnosis:
- CXR shows decrease lung volume
- Management
- abnormal pulmonary vasculature may result in PPHN
- poor lung compliance requires higher pressures to ventilate
- minimize over expansion (consider HFOV)
- admin surfactant
- consider iNO if PPHN present
Congenital Diaphragmatic Hernia
diaphragm defect allows herniation of bowel contents into chest; creates a mass effect → impedes resp. development
posterolateral defects most common; anterior 2nd
left side more commonly affected
presentation: severe resp. distress, scaphoid abdomen, cyanosis
avoid bag-mask and CPAP; immediate intubation required
use of cuffed ETT tubes may reduce gaseous distention
Tracheoesophageal Fistula / esophageal fistula
EA - anatomic interruption of the esophagus
TEF - combined anomalies of esophagus and trachea due to abnormal development of the embryonic foregut
male predisposition
TE/ EA associations
association with Trisomy 13,18,21, pierre-robin, digeorge, fanconi, polysplenia
higher incidence of VACTERL Association and CHARGE
TEF/EA Types
- A - isolated EA no fistula
- B - Proximal TEF with Distal EA
- C - Ea with Distal TEF - most common
- D - Both proximal and distal TEF - least common
- E - Isolated TEF (aka H type)
Absence of air in the abdomen indicates a pure ___ or an _____ with isolated _____.
pure EA or EA with isolated upper pouch TEF
Presence of air in the abdomen indicates a ________.
TEF patent to the distal esophagus.
TEF / EA management
avoid intubation if possible - may cause abdominal distention; if necessary - HFOV
Repogle on continuous suction to minimize secretion and aspiration
elevate HOB to minimize reflux
RDS
surfactant deficiency;
pulmonary edema from serum proteins leaking into the alveoli contibutes to the loss of FRC, alters ventilation:perfusion ratio
increased fetal insulin production in response to maternal diabetes inhibits proteins critical for surfactant production
Early onset Pneumonia organisms (common)
GBS, E. Coli, Klebsiella
E Coli(most common bacterial isolate)
Late onset pneumonia organism
Staphylococcus, Coagulase negative Staphylococci, Staph Aureus
Pneumonia on CXR
unilateral or bilateral, alveolar infiltrates, areas of confluent opacities, diffuse interstitial pattern, and pleural effusions
ground glass and air bronchograms may also be present
Treatment of early onset pneumonia
ampicillin and gentamicin
treatment of late onset pneumonia
vanc and gent
TTN CXR
pulmonary marking with perihilar streaking
hyperaeration with widened intercostal spaces, mild cardiomegaly, mild pleural effusion; flat diaphragm
TTN management
CPAP with or without supplemental oxygen to improve lung recruitment;
withholding feedings if tachypnea >60-80 bpm. , restricting fluid intake may decrease duration of support
usually self limiting within 72 hours
Risk factors for MAS
post-term, SGA, fetal distress, placental insufficiency, oligo, cord compression, intrauterine hypoxia
MAS patho
meconium can inactivate surfactant, inhibit production, cause obstruction, resulting in resp. distress, impaired exchange
MAS presentation
barrel shaped chest s/t hyperinflation, resp. distress,
Diffuse, patchy, asymmetrical infiltrates, areas of consolidation, hyper-expanded lucent areas mixed with areas of atelectasis, flat diaphragm on CXR
Respiratory Support for MAS
mechanical ventilation is common, use of PPV may result in air-leak r/t ball-valve effect of MAS, low levels of PPV and PEEP splint open partially obstructed airways
When airway resistance is high and lung compliance is normal, use of a slow rate and moderate pressure or volume is indicated.
at risk of PPHN due to high airway resistancec
When airway resistance is high and lung compliance is normal, use of a _____ rate and ______ pressure or volume is indicated.
slow rate and moderate pressure
Pulmonary Hemorrhage
thought to result from hemorrhagic pulmonary edema → results in poor lung compliance, surfactant inactivation, and pulmonary edema
PH risk factors
- PDa
- surfactant administration
- sepsis
- extreme prematurity
- coagulopathy
- IVH
- heart disease
- perinatal asphyxia
- male gender
- hypothermia
- multiple gestation
PH CXR
fluffy infiltrates or opacification of one or both lungs with air bronchograms
PH Management
check HCT, echo to assess PDA, Vent support with high mean airway pressures, PEEP 6-8;
avoid aggressive airway suctioning
PRBCS may be indicated
Persistant Pulmonary Hypertension (PPHN)
syndrome of acute respiratory distress from sustained elevation in PVR and pulmonary artery pressure leading to right to left shunting across the persistent shunts, decreased pulmonary perfusion, severe systemic hypoxemic respiratory failure, acidemia, and lactic acidosis
maternal risk factors PPHN
MSAF, maternal fever, UTI, anemia, diabetes, pulmonary disease, as well as SSRI use, hypothermia, c-section delivery
PPHN presentation
- resp. distress
- cyanosis with gradient of 10% or more between pre and post ductal saturation
- hyperoxia test - ABG before and after 10 minutes of 100% FiO2; PaO2 does not increase - a right to left shunt is indicated
- a single or narrowly split and accentuated second heart sound can be heard as well as a systolic murmur
PPHN management
- intubation to avoid hypoxia yet avoid hyperoxia and hyperventilation
- high oxygen concentrations (oxygen is potent vasodilator)
- hemodynamic support to maintain systemic blood pressure
- this may include volume expanders (saline, PRBCs)
- Pharm: inotropic agents like dobutamine and milrinone, or admin of vasopressors like dopamine, correction of hypoglycemia
- correction of hypoglycemia and hypocalcemia promotes myocardial function and improves response to inotropes
- admin of iNO promotes smooth muscle relaxation and pulmonary vasodilation for term and near term infants w/ minimal to no impact on systemic arterial pressure
- nitric oxide can be also be given via ventilator
- vent support should be weaned slowly to avoid rebound PPHN
- ECMO indicated for failure of response to resp. support
PIE
airleak syndrome where high pressures damage airways and alveoli and allow air to enter the interstitium
management: Decrease pressures, PEEP, and inspiratory time, high frequency ventilation may help reduce tidal volume
PIE on CXR
alveolar overdistention with linear cyst-like lucencies
Ventilation Strategies: poor respiratory drive
SIMV with low pressures, lungs often compliant but potential for overdistention
Ventilation Strategies: post-surgery
SIMV or AC with medium - High pressures and tidal volume
PEEP needed to maintain EELV and recruitment, with high intra-abdominal pressure may have poor response to conventional vent, HFOV OR HFJV preferred
Ventilation Strategies: Preterm RDS
poor lung compliance, poor chest wall compliance
AC with HIGH pressures, tidal volume 4-5, short i Time and fast rate well tolerated
Ventilation Strategies: Preterm with Pulmonary Hemorrhage
r./t poor lung compliance
SIMV or AC with high PEEP, tidal volume 5-6; longer iTime may help recruitment
Ventilation Strategies: Preterm with Pneumonia or Term with MAS
SIMV or SIMV + PSV with medium PEEP and tidal volume of 5-6;
higher TV needed in meconium aspiration due to increased alveolar dead space
Relative Hypercapnia is permissable to avoid ________ and associated ______.
overventilation and lung injury
Vent Management: low oxygenation, low saturation
increase MAP (increase PIP or Tidal Volume (if VG))
increase PEEP if pulmonary hemorrhage or struggling with stiff lungs
increase FiO2
Increase Ti (as long as its shorter than Te)
Vent Management: High pH with low CO2
over ventilation
Decrease Tidal Volume or PIP (first if baby has good chest movement and high Tv or MV)
Decrease Rate (pointless if using PC or AC and baby is breathing above the set rate)
extubate ( if not ready for extubation, consider switching to PC-AC or SIMV)
Vent Management: low pH with High CO2
under-ventilation
increase tidal volume (PIP or Vt)
Increase rate (by 5)
Chronic Lung Disease Management (aka BPD)
may require higher caloric intake (150-180 ml/kg/day) + higher protein, vitamin, mineral intake
Fluid intake restriction with reduction in salt intake (help reduce pulmonary edema) and include lasix, spironolactone, chlorothiazide, HCTZ
bronchodilators assists in reduction of bronchospasm
Caffeine promotes airway bronchodilation
corticosteroid therapy reduces inflammation, improves lung functions, facilltates weaning
risks of long term lasix use
hypercalciuria, bone demineralization, nephrolithiasis, ototoxicity
Central Apnea
respiratory efforts cease without evidence of obstruction
obstructive apnea
breathing motions without effect due to a blocked airway (50-60 percent of episodes are obstructive in nature)
mixed apnea
upper airway obstruction combined with central cessation of respiratory efforts
Choanal atresia
bone abnormality obstructing flow
bilateral is most common
cyanosis improves with crying
Laryngomalacia
obstructive d/o caused by a flaccid larynx, common cause of neonatal stridor
tracheomalacia
airway obstruction caused by the collapse of the trachea during expiration
micrognathia affecting respiratory distress
mandibular hypoplasia (can be assoc. with pierre robin sequence)
prone positioning, use of oral airway
Polycythemia affecting respiratory distress
Hct >65% leading to hyperviscosity - can increase risk of PPHN
Cystic hygroma
supraclavicular mass or varying size that transilluminates; distress varys with degree of compression of airway
Vent management: In conventional ventilation strategies, Carbon dioxide removal is most affected by ________ and _________.
tidal volume and frequency
Expiratory Time: A shortened expiratory time can contribute to an increase in _____________. Increases in expiratory time may also facilitate _______________.
Mean airway pressure; CO2 removal.
PIE diagnosis, management
cyst-like lucencies on CXR w/i first 48 hrs of life. Management - decrease Mean Airway pressure, PEEP, and iTime
Pneumothorax
Transilluminates on affected side, hyperlucent hemithorax on cxr
mgmt: thoracentesis, chest tube, vent management to reduce Paw, PEEP, TV
HFOV may be better
Pneumomediastinum
central air collections and lifting of thymus from heart (sail sign) on CXR - in lateral view, reduce Pressures
Pneumopericardium
air surrounding heart on cxr, needle aspiration if cardiac tamponade is present
Timing for BPD assessment
<32 weeks - assessment at 6 weeks PMA or discharge home (whichever comes first)
>32 weeks - assessment btw 28-56 postnatal days or discharge home (whichever comes first)
In conventional ventilation strategies, CO2 removal is most affected by 1) and 2)
Tidal Volume and Frequency
In HFV, CO2 removal is a product of ________- and ____________(aka_______)
frequency and the square of the tidal volume (aka frequency)
As Inspiratory time increases __________ also increases. Increases in expiratory time may ______________.
Mean Airway Pressure
Facilitate CO2 removal.
Intermittent Mandatory Ventilation (IMV)
Scheduled ventilator breaths
SIMV (synchronized intermittent mandatory ventilation)
ventilator breaths are scheduled but are triggered by an infants own respiratory efforts. Breaths beyond the scheduled rate are not supported
Useful when weaning ventilation
Assist Control
Every breath the infant initiates triggers a ventilator breath w/ a preset number of assisted breaths. Tidal volume is set and assisted to meet that volume with every breath (and then some if set above the infant’s natural respiratory rate)
Volume Control
A Tidal volume is set and PIP varies to meet set Tidal Volume, changes depending on lung compliance
Pressure Control
PIP / PEEP set and the tidal volume varies to meet set PIP and PEEP
Volume Guarentee
A targeted Vt and PIP are predetermined are predetermined and automatically adjusted to lung compliance and patient’s breathing patterns
In HFOV, the ___________ of the oscillations within the airway determine the _______ delivered around a constant ________.
amplitude of the oscillations within the airway determine the Vt delivered around a constant mean airway pressure
