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Mother And Child Medical Services |
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should not be used as a substitute for the medical care and advice of your physician. Information
provided here pertains to Medicine in general. There may be variations in treatment recommended by your physician based on
individual facts and circumstances. |
Oxygen
Therapy In The New Born
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GOAL
ü
The goal of oxygen therapy is to provide adequate tissue
oxygenation without undue risk of oxygen toxicity.
ü
An arterial partial pressure of oxygen (Pa02) of 45 torr
results in a saturation of fetal hemoglobin
(HbF) of approximately 90%
ü
Maintaining the Pa02 above 50 torr should be sufficient for
tissue oxygen needs
ü
An arbitrary ceiling of 80 torr is set to minimize the risk
of retinopathy of prematurity (ROP) in infants weighing
less than 1500 g at birth
DEFINITION/DESCRIPTION
Oxygen therapy is the administration of oxygen at
concentrations greater than that in ambient air with the intent of treating or
preventing the symptoms, and manifestations of hypoxia.
INDICATIONS
§
Documented hypoxemia
§
In neonates, PaO2 < 50 torr and/or SaO2 < 88% or
capillary oxygen tension (PcO2) < 40 torr
§
In adults, children, and infants older than 28 days,
arterial oxygen tension (PaO2) of < 60 torr or arterial oxygen saturation
(SaO2) of < 90% in subjects breathing room air or with PaO2 and/or SaO2 below
desirable range for specific clinical situation
§
An acute care situation in which hypoxemia is suspected,
substantiation of hypoxemia is required within an appropriate period of time
following initiation of therapy
§
Severe trauma
§
Acute myocardial infarction
§
Short-term therapy (eg, post-anesthesia recovery)
CONTRAINDICATIONS
No specific contraindications to oxygen therapy exist
when indications are judged to be present.
PRECAUTIONS AND / OR POSSIBLE COMPLICATIONS
With
PaO2 > or = 60 torr, ventilatory depression may occur in spontaneously
breathing patients with elevated PaCO2
With
FIO2 > or = 0.5, absorption atelectasis, oxygen toxicity, and or depression
of ciliary and / or leukocytic function may occur
§
In premature infants PaO2 of > 80 torr should be avoided
because of the possibility of retinopathy of prematurity
§
Increased PaO2 can contribute to closure or constriction of
the ductus arteriosus a possible concern in infants with ductus dependent heart
lesions
§
Supplemental oxygen should be administered with caution to
patients suffering from paraquat poisoning and to patients receiving bleomycin
§
During laser bronchoscopy, minimal levels of supplemental
oxygen should be used to avoid intratracheal ignition
§
Fire hazard is increased in the presence of increased oxygen
concentrations
§
Bacterial contamination associated with certain nebulization
and humidifications systems is a possible hazard
RESOURCES
Low-flow
systems
ü
deliver 100% (ie, FDO2 = 1.0) oxygen at flows that are
less than the patient's inspiratory flowrate (ie, the delivered oxygen is
diluted with room air) are classified as variable-performance
oxygen delivery systems
ü
the oxygen concentration inhaled (FIO2) may be low or
high, depending on the specific device and the patient's inspiratory flowrate
Nasal
cannulas
Nasal
cannulas consist of two soft prongs that arise from oxygen supply tubing. The
prongs are inserted into the patient's nares, and the tubing is secured to the
patient's face.
§
Can provide 24-40% oxygen with flowrates up to 6 L/min in
adults (depending on ventilatory pattern)
§
In newborns and infants flows should be limited to a maximum
of 2 L/min
§
Unlike in newborns oxygen supplied to adults via nasal
cannula at flowrates less than or equal to 4 L/min need not be humidified
Problems
o
Nasal cannulas and nasopharyngeal
catheters are contraindicated in patients with nasal obstruction (eg, nasal
polyps, choanal atresia)
o
Skin irritation can result from
material used to secure the cannula or from local allergic reaction to polyvinyl
chloride
o
Inadvertent CPAP may be
administered depending upon the size of the nasal cannula, the gas flow, and the
infant's anatomy
o
Irritation can result if flows are
excessive.
Nasopharyngeal
catheters
§
Are soft tubes with several distal holes. The catheter should
be inserted into the patient's nose to a depth equal to the distance from the
ala nasi to the tragus
§
Or be gently advanced and then withdrawn until it rests
slightly above the uvula
§
Oxygen flows from the catheter into the patient's oropharynx,
which acts as an anatomic reservoir
§
The FIO2 varies with the patient's inspiratory flow at about
20-40%
Problems
o
Nasopharyngeal catheters are
contraindicated in the presence of maxillofacial trauma and in patients in whom
a basal skull fracture is present or suspected.
o
Excessive flow can produce pain in
the frontal sinuses
o
Pneumocephalus is a rare but
possible complication
o
Excessive secretions and/or
mucosal inflammation can result
o
Skin irritation may result from
material used to secure the cannula and / or from local allergic reaction to
polyvinyl chloride
o
Excessive flow may cause gastric
distention
Tracheostomy
oxygen adapters
Are
devices that attach either directly to a tracheostomy tube or to a heat-moisture
exchanger (HME), which is then attached to the tube. (HMEs recycle the heat and
moisture of respired air). Work on 'blow on force technique'
Simple
oxygen masks
§
A reservoir effect is produced by the internal capacity of
the mask
§
Can provide 35-50% oxygen at flowrates from 5-10 L/min
§
Flowrates should be maintained at 5 L/min or more in order to
avoid rebreathing exhaled CO2 that can be retained in the mask
Partial-rebreathing
masks are similar to simple oxygen masks but contain a reservoir at the base of
the mask. The reservoir receives fresh gas plus exhaled gas approximately equal
to the volume of the patient's anatomic dead space. The oxygen concentration of
the exhaled gases combined with the supply of fresh oxygen, permits the use of
flows lower than those necessary for other devices (eg, non-rebreathing masks),
and potentially conserves oxygen use.
Non-rebreathing
masks are similar to partial-rebreathing masks but do not permit the mixing of
exhaled gases with the fresh gas supply. A series of one-way valves placed at
the reservoir opening and on the side ports, ensures a fresh oxygen supply with
minimal dilution from the entrainment of room air. This design provides a higher
FIO2 than the simple and partial-rebreathing masks and the nasal devices.
§
Masks with reservoir bags (partial rebreathers and non-rebreathers)
are designed to provide FIO2s of 0.5 or greater
§
In practice, both partial and non-rebreathers function in a
similar manner and provide FIO2 of about 0.6 (depending on mask fit and
ventilatory variables) provided the flowrate is sufficient to keep the reservoir
bag inflated during inspiration
Problems
o
Are confining and may not be well
tolerated
o
Interfere with feeding
o
May not be available in sizes
appropriate for all patients
o
Require a minimum flow to avoid
possible rebreathing of CO2
High-flow
systems
ü
deliver a prescribed gas mixture-either high or low
FiO2 at flowrates that exceed patient demand and are classified as fixed-performance
oxygen delivery systems
Jet-mixing
masks
§
Can accurately deliver predetermined oxygen concentration to
the trachea up to 40%
Aerosol
masks, tracheostomy collars, T-tube adapters, and face tents
§
Can be used with high-flow supplemental oxygen systems. The
gas flow can be humidified by a continuous aerosol generator or large-reservoir
humidifier
Mist
tents
§
May also be used to provide supplemental oxygen to pediatric
patients (and occasionally to adults), although FIO2 control and infection
control are difficult in such tents
Problems
o
Potential exists for electric
shock or fire from electrical or battery-operated devices inside the tent
o
Large-volume nebulizers used to
supply oxygen to tents are susceptible to contamination
o
Loss of the air circulation system
may result in failure to cool the tent
o
Potential exists for asphyxiation
if the patient becomes lodged between the mattress and the tent
Oygen
Hood
§
Supplemental oxygen may be administered to newborns and
infants by hood, with the high-flow oxygen
at FiO2 close to 1.0
Problems
o
Prolonged exposure to humidfied
oxygen may increase risk for cutaneous fungal infection
o
Inadequate or loss of gas flow may
result in hypoxia or hypercapnia.
o
Temperature within enclosures
should be closely monitored to reduce the potential for cold stress or apnea
from overheating in neonates
o
Use of an improperly sized hood
can result in irritation of the infant's skin
ASSESSMENT OF NEED
Need is determined by measurement of inadequate oxygen
tensions and / or saturations, by invasive or noninvasive methods, and / or the
presence of clinical indicators as previously described. Supplemental oxygen
flow should be titrated to maintain adequate oxygen saturation as indicated by
pulse oximetry (SpO2).
Nasal
cannulas and nasopharyngeal catheters
§
Are used when the need exists to provide low-level
supplemental oxygen to the infant or child
§
feed the infant without interrupting oxygen
delivery;(5,63,64)
§
increase mobility
Simple
oxygen masks
§
Are used to provide supplemental O2 in the moderate range
(0.35-0.50, depending on size and minute ventilation) for short periods of time
(eg, during procedures, for transport, in emergency situations)
§
Partial rebreathing masks are used to conserve the oxygen
supply when higher concentrations (FIO2 > 0.4, < 0.6) are warranted (eg,
during transport)
§
Non-rebreathing masks are used to deliver concentrations >
or = 0.60 or specific concentrations (as from a blender)
Hoods
are used to provide
§
controlled FIO2 and / or increased heated humidity to
patients who cannot tolerate other devices
§
controlled FIO2 when the chest, abdomen, and extremities must
be accessible to caregivers
§
the oxygen concentrations necessary for oxygen challenge (hyperoxia)
tests in the spontaneously breathing neonate
Tents
§
are appropriate to deliver supplemental oxygen and / or cool,
high-humidity gas mixtures to pediatric patients:
§
with laryngotracheobronchitis
§
with artificial airways in whom direct attachment of a device
to the airway is contraindicated
§
who are too big for hoods
§
with the need for comfort, without compromising therapy
Tracheostomy
oxygen adapters, which may or may not be coupled with HMEs, are used
to deliver oxygen to a tracheostomy
MONITORING
Patient
ü
Clinical assessment including but not limited to cardiac,
pulmonary, and neurologic status
ü
Assessment of physiologic para-meters: measurement of oxygen
tensions or saturation in any patient treated with oxygen
ü
In conjunction with the initiation of therapy; or
§
within 12 hours of initiation with FIO2 < 0.40
§
within 8 hours, with FIO2 > or = 0.40
§
within 1 hour for the neonate
extracorporeal Membrane Oxygenation (ECMO) is a new,
highly invasive therapy that is being investigated and utilized in newborn and
infants with cardiorespiratory
failure.
ü
Certain patients with a high risk of morbidity and mortality
are appropriate candidates for ECMO when pulmonary function and other studies
suggest that mechanical ventilation will be unsuccessful or cause undue harm
ü
ECMO should no longer be considered an extraordinary or
rescue therapy for moribund infants over 2 kilograms.
§
Infants born at greater than 35 weeks gestation with the
following disease states should be considered candidates:
§
Mechanical ventilation, general physiologic support, and
early surgical repair remain the current standard of care for CDH.
§
ECMO may improve survival in infants with CDH who have
continued respiratory failure after repair.
§
Given the increased vulnerability of the congenitally
hypoplastic lung to mechanical ventilation, institution of ECMO should be
considered earlier in these infants.
§
ECMO is appropriate for a limited number of infants with
respiratory failure due to sepsis who do not respond to other therapy.
§
Apparent RDS in infants of greater than 2 kilograms
birthweight appears in a small number of infants and may include other entitles
as yet poorly defined. ECMO is appropriate when optimal ventilatory management
fails.
§
ECMO is not appropriate for infants under 2 kilograms
and 36 weeks gestation except under carefully controlled research protocols.
§
ECMO is currently being used as rescue therapy for severe
respiratory failure in pediatric patients (1 month to 16 years) in a small
number of centers
§
ECMO is also being used as an adjunct to cardiac surgery in a
small number of centers.
§
ECMO is a temporizing and not a corrective intervention.
Repair and recovery is necessary for patients to benefit. There may be some
infants with irreversible organ dysfunction or damage with no hope of correction
who may be appropriately excluded from ECMO treatment. Each institution should
establish a mechanism of review for such infants.
ROP: Retinopathy Of
Prematurity
§
Excess oxygen produccs a vasoconstriction of immature retinal
vessels.
§
This vasoconstriction, which
is reversible in its early stages, occurs first in the termirlal artrioles and
in the arteriolar side of the capillary tree.
§
lt is followed by an irreversible vasoobliteration, at which
stage the vessel walls are adherent and show degenerative changes.
§
Cytopathic effects are noted first in the endothelium of
immature retinal capillaries.
§
Vaso proliferation typically occurs after normalization of
oxygen tension.
§
The severity of the vasoobliteration is directly proportional
to the duration and concentration of excess oxygen and to the degree of
immaturity of the retinal vascular system.
§
The toxic effects of oxygen can be prevented by intermittent
breathing.
§
Thus, kittens alternately receiving 1-hour periods of
80% to 90% ambient oxygen and
normal air showed no evidence of vasoobliteration.
§
Completely vascularized retinas of animals and humans are
imnmune to the toxic effects of oxgen.
§
The disorder makes its appearance between 10 days and 1 month
after birth.
§
Bilateral involvement is nearly invariable.
§
Myopia is present in a great majority to ROPs as a long term
sequlae.
Hyperbaric Oxygen Therapy
What difference does extra pressure create?
ü
Hemoglobin
(in red blood cells) holds 97% of its maximum amount of oxygen from normal air
or holds 100% when breathing pure oxygen.
ü
One
gram of hemoglobin can only combine with 1.34 ml of oxygen.
ü
Therefore,
red blood cells can only deliver a limited level of oxygen to tissue cells. This
is called oxygen tension (or oxygen partial pressure, "pO2").
ü
Injuries,
infections and diseases can drop this vital tissue oxygen level down to very low
levels.
ü
Ischemia,
drops the pO2 gravely low, destroys tissue, and slows healing. Research has
shown optimal tissue healing occurs if pO2 rises to between 50 and 80 mmHg.
ü
Oxygen
given in a normal room is not sufficient to raise tissue oxygen levels to that
level because red blood cells cannot carry the extra oxygen. The answer is to
deliver the oxygen in a pressurized chamber to raise oxygen tension beyond red
blood cell saturation
Condition In Which HBO Is Helpful
Severe Intestinal Ischemia and Necrotizing
Enterocolitis
§
Intestinal pathologies, such as,
ü
radiation necrosis,
ü
intestinal pneumatosis,
ü
intestinal ischemia,
ü
intestinal ischemia/reperfusion injury,
ü
intestinal obstruction,
ü
Crohn's disease,
ü
necrotizirig enterocolitis.
§
Hyperbaric oxygen therapy is also helpful in disseminated intravascular coagulation (DIC)
and shock.
§
Normally, neonates who are treated in the first 6 hours,
respond in the first one or two treatments.
§
It is rare for these patients to need more than 2 treatment,
and it is only in those cases where there are surgical complications that
further treatments may be required.
§
The effects of HBOT in neonates are visible within the first
minutes post-treatment.
§
In infants with severe intestinal ischemia and necrotizing
enterocolitis there is a significant reduction of abdominal circumference, gut
edema and pneumatosis.
§
They also have stabilization of the systemic responses (DIC
and shock).
§
Oral feeding is usually restored in the first 24-h post-HBOT.
Ischemic / Anoxic Encephalopathy
§
The rationale for the use of HBOT for this condition is to
prevent the development of the primary ischemic/anoxic lesion and secondary
ischemic / reperfusion injury.
§
It is recommended to treat these patients in the first 6
hours post-delivery
Oxygen Toxicity
§
Retinopathy: Presently, the retinopathy of the premature is
considered to be like an ischemia/reperfusion injury.
§
HBOT has been used to manage, and to prevent ischemia/reperfusion
injury.
§
Also, short exposures to low pressures (2.0 atmosphere
absolute or 202kPa for 45 minutes once or twice a day) will be unlikely to cause
this lesion and may even prevent it.
§
Toxicity to the CNS is very unlikely to occur at 2.0 atm abs
or less, as it usually occurs in compromised patients treated at much higher
pressures (3.0 atm abs).
§
Pulmonary oxygen toxicity in general, is not seen in HBOT
protocols. It is sometimes seen in the treatment of divers when long periods are
spent at high pressure -typically 2.8 atm abs on military therapeutic tables.
Probably this type of oxygen toxicity is related to
the action of reactive species of oxygen (free radicals) on the lipid part of
surfactant.
Fortunately, it responds well to inhaled steroids
and/or surfactants.
Thank You
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