1
Q
What are 4 physiology to the fetus (vs healthy neonate)?
A
- p02 is 17-19mmHg
- Right to left shunting
- high PVR and low systemic vascular resistance
- blood shunted to heart and brain
2
Q
What are 4 physiology to the healthy neonate (vs fetus)?
A
- p02 is 50-70mmHg
- Left to right shunting
- Low PVR and High systemic vascular resistance
- blood perfuses all organs
3
Q
What does it mean by “The fetus exists in a state of hypoxemia”
A
- fetus exists in a state of hypoxemia because the fetal pO2 is low (approximately 17–19 mmHg).
- This means that while the blood oxygen levels are low, tissue oxygen levels are sufficient to meet the fetus’s low oxygen needs
4
Q
What is Right-to-left shunting, through the foramen ovale and ductus arteriosus, is a feature of fetal circulation?
A
- Right-to-left shunting means that blood normally headed for the lungs via the pulmonary artery is shunted through the ductus arteriosus to the aorta, thereby bypassing the lungs.
- Further, blood in the right atrium normally headed for the right ventricle is shunted through the foramen ovale to the left atrium, thereby bypassing the lungs.
- Right-to-left shunting occurs because of patent shunts (foramen ovale and ductus arteriosus) and pressure gradients.
- Fetal pressure gradients are such that the pressure in the right heart is higher than the pressure in the left; blood follows the path of least resistance, flowing away from high-pressure areas toward low-pressure areas.
5
Q
What is high pressure in fetal lungs a result of (3)?
A
High pressure in fetal lungs is a result of
- pulmonary vasoconstriction,
- low blood oxygen and the
- collapsed and fluid-filled nature of fetal lungs.
6
Q
What does it mean by “Fetal circulation functions to provide vital organs with sufficient oxygen” (predictable blood)?
A
- Vital organs—heart and brain—receive blood that is preductal.
- Preductal blood is well oxygenated because it is the blood that has been shunted through the foramen ovale rather than the ductus arteriosus.
- Preductal blood is better oxygenated.
- The heart and the brain, due to their anatomic location, receive blood that arises from the coronary and carotid arteries, which are both preductal arteries (that is, they are located on the aorta prior to the location of the ductus arteriosus).
7
Q
Arrange neonatal transition events immediately following delivery in the correct order from first to last:
- cutting the umbilical cord
- p02 rising
- decreased systematic vasculature and increased pulmonary vasculature
- first breath
- ductus arteriosus begins to close
A
- first breath
- p02 rising
- ductus arteriosus begins to close
- cutting of the umbilical cord
- decreased systemic vasculature and increased pulmonary vasculature
8
Q
What effect does rising newborn pO2 have on transition?
A
- Closure of the DA:
- A rising pO2 begins to close the ductus arteriosus, which also increases pulmonary perfusion
9
Q
An increase in ______and a decrease in ________causes the closure of ductus arteriosus
A
- increase in pO2
- decrease in prostaglandin
**this occurs during labour and delivery.
10
Q
What can impede transition (4)?
A
Any event that interferes with the key events mentioned in the previous question can impede successful transition.
- Lung diseases such as diaphragmatic hernia and pulmonary hypoplasia can prevent gas exchange from adequately occurring in the lungs immediately after birth.
- Central nervous system depression can interfere with breathing at birth and can be due to drugs, intrauterine hypoxia, and congenital defects.
- Meconium aspiration can block airways and interfere with gas exchange at birth.
- Hypothermia can lead to high oxygen utilization and, while hypothermia does not cause asphyxia, it certainly worsens it
**For Transition Time and, if not remedied, will lead to asphyxia and PPHN.
11
Q
What can meconium aspiration lead to?
A
- MAS —> which leads to hypoxia and respiratory distress —> increase risk of PPHN
12
Q
What is meconium? Composed of (5)?
A
- a viscous, dark-green substance
- composed of water, intestinal epithelial cells, lanugo, mucus, and intestinal secretions.
13
Q
What can cause passage meconium to into amniotic fluid?
A
- Intrauterine distress
14
Q
Explain the meconium passage in utero?
A
- In utero, meconium passage results from neural stimulation of a mature GI tract and usually results from fetal hypoxic stress
- As the fetus approaches term, the GI tract matures, and vagal stimulation from head or cord compression may cause peristalsis and relaxation of the rectal sphincter leading to meconium passage.
15
Q
Is it true that meconium- stained amniotic fluid can be aspirated before or during labour and delivery?
A
True
16
Q
Is meconium found in amniotic fluid prior to 34 weeks gestation?
A
-meconium is rarely found in the amniotic fluid prior to 34 weeks’ gestation,
- meconium aspiration chiefly affects term and post-term infants.
17
Q
What are 4 effects of meconium in utero?
A
- Meconium directly alters the amniotic fluid,
- reducing antibacterial activity and
- subsequently increasing the risk of perinatal bacterial infection.
- Meconium is irritating to fetal skin.
18
Q
What are the 3 ways meconium aspiration affects pulmonary function?
A
- airway obstruction
- surfactant dysfunction
- chemical pneumonitis
19
Q
What is the result of airway obstructions by meconium?
A
- Complete obstruction of the airways by meconium results in atelectasis.
- Partial obstruction causes air trapping and hyperdistention of the alveoli, commonly termed the ball-valve effect.
- Hyperdistention of the alveoli occurs from airway expansion during inhalation and airway collapse around meconium in the airway, causing increased resistance during exhalation.
- The gas that is trapped (hyperinflating the lung) may rupture into the pleura (pneumothorax), mediastinum (pneumomediastinum), or pericardium (pneumopericardium).
20
Q
What does meconium do to surfactant?
A
- Meconium deactivates surfactant and results in diffuse atelectasis.
21
Q
What is the result chemical pneumonitis caused by meconium?
A
- Enzymes, bile salts, and fats in meconium irritate the airways and parenchyma, causing a release of cytokines and resulting in a diffuse pneumonitis.
22
Q
Does airway obstruction, surfactant dysfunction and chemical pneumonitis caused by meconium produce gross ventilation-perfusion (V/Q) mismatching?
A
Yes
- All of these pulmonary effects can produce gross ventilation-perfusion (V/Q) mismatching.
23
Q
What is the order of events?
-Hypoxia and hypercapnia
-Meconium aspiration syndrome (MAS)
-Persistent pulmonary hypertension of the newborn (PPHN)
-Airway obstruction, infection, and inflammation
-Atelectasis, right-to-left shunt, decreased pa02, lung injury, airway edema, surfactant deactivation
-Aspiration of meconium-stained fluid at delivery
-Meconium in utero
A
- meconium in utero
- aspiration of meconium-stained fluid at delivery
- MAS
- airway obstruction, infection, inflammation
- Atelectasis, right-to-left shunt, decreased pa02, lung injury, airway edema, surfactant deactivation
- Hypoxia and hypercapnia
- Persistent pulmonary hypertension of the newborn (PPHN)
24
Q
What can intrauterine hypoxia lead to (in utero to fetus)?
A
- Intrauterine hypoxia can lead to meconium passage, which may result in meconium aspiration.
- The ensuing respiratory distress, hypoxia, hypercapnia, and acidosis all put Caitlyn (who is trying to transition from fetal to extrauterine circulation) at risk for PPHN.
***Although MAS does not always lead to PPHN and PPHN is not always caused by MAS, the two often occur together, with MAS either causing or contributing to the development of PPHN.
25
What is Persistent pulmonary hypertension of the newborn PPHN?
- PPHN is failure of the normal circulatory transition resulting in right to left shunting (blood is bypassing the lungs) through the DA/FO and pulmonary vasoconstriction resulting in severe and often prolonged hypoxia, which can be very difficult to correct
26
What is PPHN defined as?
- defined as the failure of the normal circulatory transition that occurs after birth.
- It is a syndrome characterized by marked pulmonary hypertension that causes hypoxemia and right-to-left shunting of blood through the ductus arteriosus and foramen ovale
27
Is true that all asphyxiated infants are high risk for developing PPHN?
Yes
28
What are 3 common causes of PPHN?
- acute pulmonary vasoconstriction
- hypoplasia of pulmonary vascular bed
- pulmonary hypertension
29
What are 3 common causes of PPHN of acute pulmonary vasoconstriction?
Most common cause of PPHN
- hypoxia alveolar secondary to parenchymal lung disease:
= meconium aspiration syndrome
= respiratory distress syndrome
= pneumonia
- Hypoventilation resulting from asphyxia or other neurological conditions
- Hypothermia
30
What are 2 causes of PPHN produce hypoplasia of pulmonary vascular bed?
- Congenital diaphragmatic hernia CDH: degree of pulmonary hypoplasia
- Oligohydramnios (amniotic fluid disorder): utero may produce pulmonary hypoplasia and associated PPHN.
31
What is Congenital diaphragmatic hernia CDH?
- characterized by a variable degree of pulmonary hypoplasia associated with a decrease in cross-sectional area of the pulmonary vasculature and alterations of the surfactant system.
32
What are the three basic types of congenital diaphragmatic hernia?
There are three basic types of congenital diaphragmatic hernia:
- the posterolateral Bochdalek hernia (occurring at approximately 6 weeks' gestation),
- the anterior Morgagni hernia, and
- the hiatus hernia.
33
What 3 ways can pulmonary hypertension be a cause of PPHN?
- Constriction of the fetal ductus arteriosus in utero, which can occur after exposure to nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen during the third trimester
- Selective serotonin reuptake inhibitors (SSRIs) during late gestation is associated with PPHN
- Parenchymal and vascular disease: An abnormally remodeled vasculature may develop in utero in response to prolonged fetal stress, hypoxia, and/or pulmonary hypertension.
34
Why is that PPHN rarely occurs in premature babies?
- PPHN rarely occurs in premature babies, owing to their relative lack of musculature in pulmonary arterioles and capillaries.
- This lack of musculature means that premature infants do not respond to perinatal asphyxia with the same degree of pulmonary vasoconstriction.
- Preterm infants who have suffered from oligohydramnios, premature prolonged rupture of members (PPROM), pulmonary hypoplasia and sepsis are at increased risk for developing PPHN
35
What is PPHN characterized by (4)?
1. Increased pulmonary vascular resistance
- The normally high pulmonary vascular resistance, which was necessary for fetal circulation, persists into the newborn period.
2. Patent DA and FO
- Increased pulmonary vascular resistance leads to right-to-left-shunting of blood through the ductus arteriosus and possibly the foramen ovale. The foramen ovale will remain open as long as high right/low left pressure gradients exist.
3. Vasoconstriction of pulmonary vessels
- Vasoconstriction leads to minimal amounts of pulmonary blood flow and this, in turn, leads to more hypoxia, acidosis, and eventually lactic acidosis.
4. Hypoxia
- As the hypoxia continues, so does the pulmonary vasoconstriction. This state is considered the “vicious cycle” of PPHN.
36
What does perinatal asphyxia result in?
Perinatal asphyxia results in --> hypoxia, which leads to --> pulmonary vasoconstriction.
- Pulmonary vasoconstriction creates high pulmonary vascular resistance.
- High pulmonary vascular resistance causes right-to-left shunting and pulmonary hypoperfusion.
- Pulmonary hypoperfusion results in further hypoxia.
The hypoxia that occurs because of right-to-left shunting and pulmonary hypoperfusion is often quite profound and difficult to correct. This is why PPHN carries a high mortality rate.
37
What are the 2 primary goals of care for an infant with MAS and PPHN (to decrease)?
- minimizing hypoxia
- decreasing pulmonary vasoconstriction
38
How does cold stress could further compromise an infant experiencing MAS and PPHN?
- Cold stress further compromises an infant with MAS and PPHN by worsening the hypoxia and acidosis that already exist.
- Increased metabolic activity results in increased consumption of oxygen, which leads to anaerobic metabolism and eventually acidosis.
- As a result, infants experiencing cold stress have the vicious cycle of MAS and PPHN further perpetuated, adding to the hypoxia, acidosis, and pulmonary vasoconstriction already in existence.
39
How many veins/arteries does umbilical cord have?
- The umbilical cord has three umbilical vessels: one vein and two arteries.
- The vein is oval and thin walled and the arteries are round and thick walled.
40
What does umbilical venous catheters (UVC) offer and how long does it last for?
- The umbilical vein offers vascular access in the immediate period following birth and up to approximately one week of age
- Can be single, double or triple lumens
41
What are the indications for UVC (5)?
- LBW or critically ill infants requiring long-term vascular access
- Venous administration of hyperosmolar fluids or irritating medications is required
- Exchange transfusion
- Resuscitation
- Central venous pressure monitoring
42
What are 4 contraindications for UVC?
- Peritonitis
- Necrotizing enterocolitis
- Omphalitis
- Omphalocele
43
What are the two positioning for UVC?
- Low-lying position: 2–4 cm (used for drug administration during resuscitation)
- Central position: catheter tip in the interior vena cava at the junction of the right atrium
44
What are umbilical arterial catheters UAC used for?
- UACs are used for painless blood sampling and continuous blood pressure monitoring.
- For these reasons, UACs are often used in neonates with significant respiratory disease, with unstable hemodynamic status, and for those unstable on admission or likely to require significant blood sampling over the first few days of life
45
What are 3 indications for UAC?
- Blood pressure monitoring
- Arterial blood sampling
- Exchange transfusion
46
What are 4 contraindications for UAC?
- Vascular compromise of lower extremities
- Peritonitis
- Necrotizing enterocolitis
- Omphalitis
- Omphalocele
- Acute abdomen etiology
47
What are the two positionings for UAC?
- Low-lying position: between L3 and L4, catheter tip above the aortic bifurcation
- High-lying (preferred): between T6 to T9, catheter tip above the diaphragm
48
Can UAC be used for administration of drugs/fluids?
- Umbilical arterial catheters can be used for administration of drugs, fluids, parenteral nutrition and blood products;
- however, as a general rule they are only used for blood pressure monitoring and blood sampling unless a doctor orders otherwise.
49
What are 4 potential complications that can occur for infant with UAC/UVC?
- infection
- catheter migration/dislodgement
- vascular compromise of lower extremities
- malposition of catheter (most often into the heart or portal venous system)
- thrombosis, embolism
- necrotizing enterocolitis NEC
- hemorrhage
- occlusion
50
List assessment during maintenance of UAV/UVC?
- Check routine vital signs.
- Note line placement as a part of “bag-pump-baby” safety check at the beginning of the shift and compare to documented insertion measurement.
- Perform a Q1H assessment and documentation of UVC/UAC insertion site, securement, and lower limb/buttocks perfusion, colour, and warmth.
- Check peripheral pulses with every hands-on handling and when clinically indicated.
- Watch for an increase in pressure readings and occlusion alarms on infusion pumps.
- UAC: Document blood loss and cumulative blood loss from blood sampling.
- Ensure the presence and availability of safety equipment.
- Position infant to allow for continuous visualization of lines and insertion site.
51
What are two factors that causing hypoxia?
- Right-to-left shunting due to pulmonary vasoconstriction
- Hypoventilation due to meconium aspiration
52
What are 2 aim of PPHN treatment (improving)?
treatment is aimed at IMPROVING:
- pulmonary blood flow and
- alveolar ventilation.
53
What are 3 treatment of PPHN consists of?
- Optimizing lung expansion
- Inhaled nitric oxide therapy (iNO)
- Medications:
= Sedatives
= Muscle relaxants
= Cardiostimulatory therapy
54
What should be included for ventilation treatment modalities to improve respiratory function (3)?
- improving ventilation/perfusion matching
- recruitment of atelectatic alveoli while avoiding overdistention
- surfactant therapy to facilitate alveolar expansion
55
How does air trapping exists with MAS?
- For those infants experiencing MAS without associated PPHN, ventilatory management is aimed at cautious use of positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP).
- Air trapping usually exists with MAS and cautious use of PEEP and CPAP will decrease the risk of further air trapping, which can lead to air leaks such as pneumothorax.
56
When MAS is complicated by PPHN, what are the 2 ventilatory management aimed at (improving)?
- ventilation/perfusion matching and
- oxygenation.
57
What does high frequency ventilation HFV do?
- High frequency ventilation (HFV) attempts to minimize ventilator-induced injury by using volumes that are smaller than the lung’s physiological dead space (1–2 mL/kg), at very fast breathing rates.
- It is defined as “mechanical ventilation using tidal volumes less than or equal to the dead space volume and delivered at supraphysiologic rates.
- HFV devices are those that provide breathing rates greater than 150 breaths per minute
58
What are the two main types in acute care setting that can provide HFV?
1. High frequency oscillatory ventilation (HFOV )
- Rate is set in hertz (1 Hz = 60 cycles or breaths)
- Average hertz set at 10–15
- Example: Sensormedics 3100A
2. High frequency jet ventilation (HFJV)
- Rate 100–600 bpm
- Example: Bunnell Life Pulse Jet Ventilator
59
What is high frequency oscillatory ventilation HFOV?
- HFOV is a type of mechanical ventilation that uses a constant distending pressure (mean airway pressure [MAP or Paw, terms used interchangeably]) with pressure variations (amplitude/delta P) oscillating around the MAP at very high rates (up to 900 cycles per minute).
- This is accomplished by a piston that vibrates back and forth, resulting in an active inspiration and expiration at a very fast rate.
- It is the active exhalation phase that differentiates this mode of HFV from other modes such as HFJV.
60
What are 5 benefits of High Frequency Oscillatory Ventilation (HFOV)?
- smaller tidal volumes
- higher respiratory rates
- lower distal airway pressures
- preservation of lung tissue
- minimization of barotrauma
61
What are 2 ways MAP used in High Frequency Oscillatory Ventilation (HFOV)?
MAP is used
- to inflate the lung and
- optimize the alveolar surface area for gas exchange.
62
What does MAP/Paw equal to?
MAP/Paw = Lung volume
- The amplitude (delta P) is the size of the oscillation from the Paw. It displaces a small volume on top of the volume already obtained from the setting of the Paw. The total volume oscillated is directly proportional to the distance from the Paw to the peak of the oscillation, that is, the peak to trough pressure difference. The greater the distance, the greater the volume displaced. The starting amplitude, delta P, is chosen by looking at the shake of the infant’s chest movement. The greater the amplitude, the greater the shake, the greater the volume displaced.
- Frequency (Hz) controls the time allowed (distance) for the piston to move back and forth, which causes the exhalation valve to open and close for CO2 removal. The lower the frequency, the greater the volume displaced, and the higher the frequency, the smaller the volume displaced. 1Hz = 60 breaths/minute; therefore, a Hz of 10 is equal to 600 breaths/minute (respiratory rate).
63
Whats one examples to explain High Frequency Oscillatory Ventilation (HFOV)?
Think of the action of pumping up a bicycle tire.
- If you take long, slow pumps on the tire pump, you will move more air and therefore pump the tire up more quickly than if you take small, quick pumps, which will result in smaller volumes of air movement and a longer time to fill the bicycle tube.
- In HFOV, a very high hertz can result in less time for exhalation and therefore increased risk of air trapping.
64
What is the formula for the total amount of gas exchange, alveolar ventilation, that can occur?
Minute volume (MV) = tidal volume squared (vt2) × respiratory rate (RR)
65
In HFOV, why does tidal volume have greater effect in CO2 removal than RR?
- Tidal volume will have a greater effect in gas exchange than RR.
- Therefore, in HFOV, changes in tidal volume will have a greater effect in CO2 removal than RR.
66
How does oxygenation occur in high flow jet ventilator HFJV?
- Oxygenation occurs via the recruitment and maintenance of an optimal lung volume.
- This is achieved through the setting of the MAP/Paw and the FiO2.
67
What are 6 settings for High Frequency Oscillatory Ventilation (HFOV)?
- MAP/Paw
- Amplitude (delta P)
- Hertz (Hz)
- I:E ratio (always 1:2)
- Ti (always 33%)
- Flow commonly 20 LPM, smaller for extreme premature infants
68
In what situation would High Frequency Oscillatory Ventilation (HFOV) be used (5)?
1. Air leak
- Pulmonary interstitial emphysema (PIE)
- Pneumothorax
2. Pneumonia
- Focal pneumonia (non-homogeneous)
- Infants that present with a patchy or lobar pneumonia on CXR may not respond as well as those with diffuse lung involvement. If they present with hyperinflation, they may be at risk for air leak.
3. Meconium aspiration
- The lung is affected by the meconium liquid and produces a chemical pneumonitis/ RDS picture.
- Because of possible air trapping (in some cases), over aggressive use of the airway pressure can further aggravate the problem and result in PIE or pneumothoraces. PPHN may also complicate this picture.
4. When Conventional mechanical ventilation (CMV) causes excessive distention of airways.
- Air leak syndromes:
= Pulmonary interstitial emphysema (PIE)
= Pneumothorax
- Chronic lung disease (bronchopulmonary dysplasia)
5. When settings on conventional mechanical ventilation are maxed out
- Carbon dioxide retention and oxygenation failure
- HFOV is being used more and more frequently as a first-line mode of ventilation for any infants requiring mechanical ventilation because it is gentle and effective.
69
Alveolar ventilation during HFOV is defined as RR x Vt2; therefore, changes in volume delivery (as a function of delta P, frequency, amplitude) have the most significant effect on CO2 elimination
True or False?
True
70
To increase the removal of CO2 in HFOV you would:
a. Decrease the hertz
b. Increase the delta P
c. Increase the amplitude
d. All of the above
All of the above
71
The indications for the use of HFOV include:
a. Infants less than 1500 gms
b. Ventilation pressures are >30 cm H20
c. Sepsis
d. MEC
e. All of the above
All of the above
72
The main purpose of setting a MAP in HFOV is for:
a. Improving oxygenation
b. Improving ventilation
c. None of the above
Improving oxygenation
73
To decrease the removal of CO2 in HFOV you would:
a. Increase the hertz
b. Decrease the delta P
c. Decrease the amplitude
d. All of the above
All of the above
74
What is high frequency jet ventilation HFJV used in conjunction with?
High frequency jet ventilation (HFJV) is used in conjunction with a conventional ventilator.
75
What is conventional ventilator primarily used for?
- The conventional ventilator is primarily used for oxygenation.
- The conventional ventilator will deliver the peep, a continuous flow of gas from which the infant can breathe spontaneously, and allow the setting of intermittent sighs in order to help with lung recruitment.
- The conventional ventilator will either be set in the CPAP mode or CMV mode depending on the need for recruitment.
76
What is the jet ventilator primarily responsible for?
The jet ventilator is primarily responsible for CO2 removal.
77
What is LifePort Adaptor?
- A specifically designed adaptor connects onto the “Y” of the conventional ventilator (CV) circuit to allow the two ventilators to work in tandem (see the following image).
- This adapter, called the LifePort Adaptor, sends tiny pulses of gas directly into the trachea, creating an area of negative pressure entraining additional gas further into the lower airways
- The tiny volumes (less than 1 mL/kg) are sent into the lungs in very short inspiratory times and very high respiratory rates.
- The smaller tidal volumes reduce the risk of lung injury, and
- the short inspiratory times allow for more exhalation time, which decreases the risk of air trapping and adds to the removal of CO2.
78
What is one examples to explain high frequency jet ventilation HFJV?
- The tiny jet of gas is similar to that of water expelled from a fire hose through a narrowing of the nozzle on the end of the hose.
- The narrowing of the nozzle increases the water pressure, allowing the spray to cover a greater distance.
- Similarly, the jet adapter sends the short squirt of gas under pressure through the narrowing LifePort Adaptor, causing it to travel further into the airways.
- As the gas travels quickly through the middle of the airways, it bypasses a lot of dead space and creates gas exchange over a greater area and therefore better alveolar ventilation.
79
What is the sweeping bidirectional gas flow in HFJV?
- Unlike the HFOV, expiration on the HFJV is passive.
- This sweeping bidirectional gas flow is very effective in aiding secretion removal.
- Therefore, HFJV is very successful in the treatment of meconium aspiration or pneumonia.
80
What are some indications for the use of high flow jet ventilator HFJV (3)?
- Premature infants with RDS
- PIE (pulmonary interstitial emphysema)
- Meconium aspiration
- Pneumonias
- CDH (Congenital diaphragmatic hernia)
- PPHN
81
What are the 3 parameters set on the jet ventilator HFJV?
PIP
Ti
RR
82
What are the measured values of the jet ventilator (5)?
PIP
PEEP
MAP/Paw
Delta P
Servo pressure
83
What is the servo pressure feedback system on HFJV?
- The servo pressure is a feedback system on the jet ventilator that tells you whether the ventilator has had to increase or decrease its flow of gas in order to maintain the set PIP.
- The servo pressure changes as perceived lung volume changes, automatically adjusting the flows or driving pressure to maintain the PIP.
84
What does an increase or decrease in servo pressure indicate?
- increase in the servo pressure indicates an increase in the achieved lung volumes;
- decrease in the servo pressure indicates decreased lung volumes.
- This measured value is used to facilitate patient management.
85
What can a decrease in servo pressure be due to (4)?
A decrease in servo pressure can be due to
- worsening compliance and resistance,
- obstruction of the ETT,
- an increase in secretions, or
- maybe even a tension pneumothorax.
86
Why is an increase in servo pressure be a positive or negative outcome?
For example, an increase in lung volume may mean
- improved lung compliance and resistance are establishing better alveolar ventilation,
- or it could also indicate an air leak or disconnected tubing.
87
Select all that apply. Which occurrences can cause an increase in servo pressure (remember that servo pressure reflects perceived lung volume pressures)?
a. Increased response to pain
b. Disconnected tubing
c. An air leak (patient or circuit)
d. Increased secretions
e. Improved compliance and resistance
f. Atelectasis
B) Disconnected tubing
C) An air leak (patient or circuit)
E) Improved compliance and resistance
88
Select all that apply. Which occurrences can cause a decrease in servo pressure:
a. Obstruction of the ETT
b. ETT displacement
c. Worsening compliance and resistance of the lungs
d. Need for suctioning
e. Decreased pain and agitation
f. Tension pneumothorax
Obstruction of the ETT
Worsening compliance and resistance of the lungs
Need for suctioning
Tension pneumothorax
89
Monitoring of the jet ventilator should include:
a. PIP
b. Rate
c. MAP
d. FiO2, and the addition of a sigh breath or not
e. Servo pressure
f. All of the above
All of the above
90
Moving neonates on HFOV/HFJV: Imagine you are caring for an infant on HFOV or HFJV and this infant requires re-positioning. What do you anticipate what you might need in order to provide this care safely? What factors should you consider?
Consult with Respiratory therapist
When was infant last handled?
How stable is the infant (i.e. apneas, desatuations, bradycardias)?
How has the infant tolerated past turning and handling?
When was the infant last fed?
Has all the safety equipment been checked and is it ready to be used if necessary?
When was the infant last suctioned and what were the results of the last suction?
What were the findings of the last cardiovascular and respiratory assessment?
What was the last blood gas?
Based on the last chest x-ray, where is the ETT tip sitting?
Is the ETT secured and at what measurement is it sitting at.
If on HFOV, assess the infant’s ‘shake’ or ‘vibes’ or ‘wiggle’.
91
What is oxygen index (OI)?
- The oxygenation index (OI) provides a ratio between the level of oxygen being delivered to the lungs and the amount diffusing into the blood.
- It is a calculation used to reflect the current oxygenation, PaO2, reflected by the arterial blood gas achieved using the set mean airway pressure (MAP/Paw) and FiO2.
92
What is the formula for oxygen index OI
OI = (Paw x FiO2 x 100) / PaO2
93
What is Oxygen index OI normal range?
A normal OI ranges from 1–3; therefore the higher the OI, the sicker the infant.
94
Why is inhaled nitric oxide used in conjunction with ventilation?
- inhaled nitric oxide therapy (iNO) is often used in conjunction with ventilation to facilitate pulmonary vasodilation
95
Why is sedative and muscle relaxants used for infants suffering from PPHN?
- In infants who are suffering from PPHN, it is often necessary to minimize fluctuations in oxygenation and to optimize ventilation
- This is often done with sedation and paralysis.
96
What are 4 sedative drugs that's used in neonates?
- morphine (opiods)
- midazolam (benzodiazepines)
- fentanyl (opiods)
- precedex
97
What are the indications and side effects of morphine?
Indication
- Analgesic
- Sedation
- Opiate withdrawal
Side effects
- Respiratory depression, apnea, bronchospasm
- Bradycardia
- Hypotension
- Urinary retention
- Physical dependence
98
What are the indications and side effects of midazolam?
Indication
Sedative
Anticonvulsant
(3rd or 4th in line)
Side effects
- Hypotension and reduced cardiac output (when used in combination with fentanyl)
- Respiratory depression and apnea
- Tolerance may develop (>5 days)
99
What are the indications and side effects of fentanyl?
Indication
- Analgesic
- Sedation
- Anesthesia
Side effects
- Respiratory depression
- Chest wall rigidity
- Urinary retention
- Rapid tolerance with prolonged use (>2 days)
100
What are the indication (1) and side effects (2) of precedex?
Indication
- Sedation
Side effects
- hypotension
- bradycardia
101
What muscle relaxant is used?
Rocuronium is the most widely used muscle relaxant that produces muscle paralysis.
** It does not have sedative or analgesic effects.
102
Why would pharmacological paralysis be indicated?
- Pharmacological paralysis may be indicated when an infant is difficult to ventilate (breathing out of synchrony, agitated, or an uncompliant chest and/or lungs).
- In these situations, pharmacologically induced muscle paralysis may enhance mechanical ventilation, thereby improving blood gases.
103
How is rocuronium administered?
- Rocuronium is administered by intermittent IV boluses on a PRN basis.
- Frequent assessment of an infant receiving rocuronium is important to determine when additional doses are needed.
104
What 4 behavours by infant by indicate another dose of rocuronium is needed?
- twitching of extremities (often fingers and/or toes)
- eyelid movement
- spontaneous breathing
- increase or decrease in heart rate, saturations or blood pressure
***An infant is generally flaccid with absent muscle tone when receiving rocuronium.
105
Why is pain medications given in conjunction with rocuronium?
It is important to remember that these infants cannot move, but are able to experience pain.
- Since they are unable to move and therefore unable to communicate pain and discomfort through their behaviours, pain medication is consistently used in conjunction with rocuronium.
106
What are 4 some clinical problems associated with paralysis?
- dependent edema secondary to third spacing of fluids
- excessive salivating due to the inability to swallow
- skin breakdown due to the inability to change position
- dry eyes due to lack of a blink response
107
What are 3 reasons that Cardiostimulatory Therapy is used?
These drugs are used to
- optimize cardiac function,
- stabilize systemic blood pressure and
- reduce right-to-left shunting.
108
Infants who are critically ill often experience decreased perfusion to body organs. The decreased perfusion is secondary to (4)?
This decreased perfusion is often secondary to
- hypoxia,
- blood flow redistribution,
- hypotension, and/or
- decreased cardiac output.
109
What are 3 physiological events can right-to-left shunting lead to (in infants with PPHN)?
right-to-left shunting can lead to
- right-sided heart failure,
- decreased cardiac output, and
- metabolic acidosis,
which are all physiological events that result in hypotension and decreased perfusion to body organs.
110
What does inotropes improve?
- The administration of inotropes is one way to improve cardiac contractility, thereby raising blood pressure and improving the perfusion of organs.
- In addition, some inotropes will increase systemic arterial pressure to the point where it is greater than pulmonary pressure.
- This can help to decrease right-to-left shunting associated with PPHN.
111
What is dopamine?
- A sympathomimetic catecholamine that exhibits alpha adrenergic, beta adrenergic, and dopaminergic agonism.
- It increases heart rate, cardiac contractility and at higher doses increases peripheral vascular resistance.
112
What is dobutamine?
A synthetic catecholamine with primarily beta 1 adrenergic activity.
- It is an inotropic vasopressor.
- It increases myocardial contractility, cardiac index, oxygen delivery and oxygen consumption
113
What is epinephrine?
A catecholamine that stimulates alpha and beta receptors.
- It increases heart rate, myocardial contractility, automaticity and conduction velocity.
- Epinephrine also increases systemic vascular resistance (via constriction of arterioles) and increases blood flow to skeletal muscle, brain, liver and myocardium.
- It decreases renal blood flow by 40%.
- The major effect of adrenaline is to redistribute blood from the systemic to pulmonary circulation and thereby increase pulmonary pressure.
114
What is vasopressin?
- An antidiuretic hormone formed in the hypothalamus and secreted from the posterior pituitary gland.
- It exerts its effects through vascular V1 receptors (that increase arterial vasoconstriction) and renal tubular V2 receptors (that increase water reabsorption).
- Exogenous vasopressin is used in the treatment of catecholamine-resistant hypotension in vasodilatory shock.
115
What are the indications and side effects of dopamine?
Indications
To improve cardiac output, blood pressure and urine output in critically ill infants with hypotension
Side effects
- Extravasation can cause tissue ischemia and necrosis
- Tachycardia and arrhythmias (at doses >20 mcg/kg/min)
- Gastrointestinal upset
- Vasoconstriction, hypertension
116
What are the indications and side effects of dobutamine?
Indications
- Blood pressure support related to myocardial dysfunction
Side effects
- Extravasation can cause tissue ischemia and necrosis
- May cause hypotension if patient is hypovolemic
- Tachycardia at high dosage
117
What are the indications and side effects of epinephrine?
Indications
- Acute cardiovascular collapse (bradycardia, asystole)
- Can be used as a second or third line inotrope
- Short-term use for cardiac failure resistant to other drug management
Side effects
- Extravasation can cause tissue ischemia and necrosis
- Cardiac arrhythmias (PVCs and ventricular tachycardia)
- Renal vascular ischemia with decreased urine formation
- Severe hypertension with intracranial hemorrhage
- Pulmonary oedema
- Hyperglycaemia related to the inhibition of insulin secretion and conversion of glycogen reserves
- Hypokalemia
118
What are the indications and side effects of vasopressin?
Indications
- Hypotension associated with circulatory shock.
- Contraction of smooth muscles in the vascular bed without inotropic effects.
Side effects
- Arrhythmia,
- decreased cardiac output,
- asystole,
- venous thrombosis,
- hyponatraemia,
- tremors,
- bronchial constriction,
- nausea and vomiting.
119
Why is it prefer to run inotropes through central line?
It is preferential to run inotropes through a central line and
- to have continuous arterial blood pressure monitoring during infusions to closely monitor for blood pressure fluctuations.
120
What is Extracorporeal Membrane Oxygenation (ECMO)?
Extracorporeal membrane oxygenation (ECMO) provides life support to infants with cardiac and/or respiratory dysfunction,
- allowing the heart and lungs to rest and recover.
NS7920
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