Week 3: Respiratory physiology Flashcards
- Breathing efforts (respiratory rhythm) begin in _______.
- _________ lung development.
- Surfactants are produced after ____-____ weeks gestation by ________ _________.
- Utero
- Embryonic
- 26 to 28; type II pneumocytes
- As the neonate passes through the birth canal during vaginal delivery, much of the fluid is expelled via upper airways.
- Residual drains through _______ and ________ channels in the first day of life.
lymphatic and pulmonary
- The abrupt transition to extratuterine gas exchange at birth involves rapid ___________ of the lungs, increased ___________, and initiation of a ____________.
- This change results in: a functional closure of the _________.
- expansion; pulmonary blood flow, regular respiratory rhythm.
- foramen ovale
- Breathing is regulated by a complex system of ________ and _________ receptors.
- The infant has a very _________ chest wall which results in a tendency to ____________ with general anesthesia.
- peripheral; central
- compliant; atelectasis
- _________ stabilizes the alveoli and prevents their collapse on expiration. Reducing the surface tension also makes it easier to “________” the alveoli.
- _________ is a critical component of surfactant in the lung, and is produced by type II pneumocytes, beginning around _____ weeks gestation and continuing until ____-___weeks gestation.
- Surfactant; re-recruit
-Lecithin; 22; - 35 to 36
- Lecithin production is measured by determining the ____________ ratio in amniotic fluid.
- The L/S ratio measures lung maturity and predicts __________.
- Lecithin/sphingomyelin (L/S)
- ## Respiratory distress syndrome (RDS).
The L/S ration is generally
- <1 until ______ weeks gestation;
- 2 at ________ weeks gestation; and,
- _____ to _____ by full-term.
- 32
- 35
- 4 to 6
- Preterm infants with a lack of surfactant suffer from ______.
- Typically, the parturient receives ___________ in an effort to accelerate the biochemical processes in the lung responsible for maturation.
- Additionally, exogenous surfactant therapy is administered at delivery via an _______ at birth and repeated in ________ hours in the NICU.
- Respiratory distress syndrome
- corticosteroids
- ETT; 12
Periop assessment
Risk factors associated with increase risk of perioperative events
The small size of the peripheral airways may predispose the child to obstructive lung diseases such as ____________.
- History- Uri in previous 2 weeks,
- Wheezing,
- Cough,
- Eczema,
- Family history,
- Smoke exposure,
- Gestational age,
- Chronic disease (is the asthmatic child controlled with therapy, etc).
premie at higher risk up to 2y/o
bronchiolitis
Pulmonary function testing
- Highly dependent upon patient cooperation.
- __________ studies are often conducted on children to determine efficacy of treatment (i.e., asthma).
- Maximum expiratory and inspiratory flow-volume curves are useful for determining the site and nature of airway obstruction (i.e., fixed vs variable; extra vs intrathoracic).
- Spirometric
Perioperative triggers:
Children with a recent or current URI have an increased incidence of:
- Perioperative laryngospasm,
- Bronchospasm,
- Arterial hemoglobin desaturation,
- Severe coughing, and
- Breath holding,
- Atelectasis,
- Respiratory failure compared with uninfected children.
Upper respiratory tract infection
Elective surgery is usually postponed for children with more severe symptoms that include at least one of the following: (4)
- Mucopurulent secretions
- Lower respiratory tract signs (e.g., wheezing) that do not clear with a deep cough
- Pyrexia >100.4°F (38°C)
- Change in sensorium (e.g., not behaving or playing normally, not been eating properly)
Upper respiratory tract infection
- The optimal time when an anesthetic can be given to a child after a **URI ** without increasing the risk of adverse respiratory events remains contentious, but most clinicians wait _____ to _____ weeks after resolution of the URI before proceeding.
- A child with an _________ URI who is afebrile with ______ secretions and is otherwise healthy may proceed with surgery as planned.
- The decision becomes more complicated when the uri is between mild and severe in terms of severity.
- 2-4
- uncomplicated; clear
Lower airway disease
- In infants and children up to 18 months of age, ____________ is a very serious and common viral infection that infects the lower respiratory tract
- Other viruses include:
- respiratory syncytial virus (RSV)
- Parainfluenza virus,
- Adenovirus, and
- Human metapneumovirus
Croup or laryngotracheobronchitis, defined as acute inflammation of the airway (below the vocal cords), has been attributed primarily to ___________ as well as to _________.
- parainfluenza virus,
- adenovirus
- Asthma is one of the most common chronic diseases of childhood, affecting an estimated more than 6 million children in the United States
- Working definition of asthma is a common chronic disorder of the airways that is complex and characterized by variable and recurring symptoms, _________, _________, and __________ of the airways
- airway obstruction, inflammation, and hyperresponsiveness
Clinical expressions of asthma include:(4)
Severe respiratory distress can occur during acute exacerbations and may be characterized by: (7)
- Wheezing
- Chest tightness or discomfort
- Persistent dry cough (chronic cough is most common manifestation)
- Dyspnea on exertion
- Chronic inflammation
- Chest wall retraction
- Accessory muscles use
- Respiratory failure and death
- Prolonged expiration
- Pneumothorax
- Airway remodeling
Asthma
- Children should continue their regular medications before anesthesia
- ________ has been reported to be a safe premedication for asthmatics
- ________ is the traditional choice of intravenous (IV) induction agent in children with severe asthma
- _________ before or after induction are helpful.
- _________ is associated with an increased risk of bronchospasm compared with sevoflurane or isoflurane, and because it can increase airway resistance in children, should be avoided in asthmatics
- Midazolam
- Ketamine
- Inhaled b-agonists
- Desflurane
Bronchospasm
First-line treatment for bronchospasm involves removing the triggering stimulus (if possible)
Interventions:
All children who experience anything more than minor bronchospasm should also receive ____________.
- Deepening anesthesia,
- Increasing the fraction of inspired oxygen (FIO2) if appropriate,
- Decreasing the positive end-expiratory pressure (PEEP),
- Increasing the expiratory time to minimize alveolar air trapping.
- Inhaled b-agonists
Corticosteroids
Intraoperative Bronchospasm S/S: (7)
- Polyphonic expiratory wheeze
- Prolonged expiration
- Active expiration with increased respiratory effort
- Increased airway pressures
- Slow upslope of end-tidal CO2 monitor waveform
- Increased end-tidal CO2
- Hypoxemia
In severe status asthmaticus, ventilation strategy focuses primarily on achieving adequate __________, rather than attempting to normalize ________ at the potential cost of inducing pulmonary barotrauma.
oxygenation; PaCO2
Cystic fibrosis
- is an autosomal _________ disorderinvolving a dysregulation of __________ and other ion fluxes.
- Multisystem presentation: a disruption of electrolyte transport in the epithelial cells of the: (7)
The clinical outcomes are variable.
- recessive, chloride
- of the:
- Biliary tree
- Intestine
- Pancreatic ducts
- Airways
- Sweat ducts
- Vas deferens
Cystic Fibrosis
S/S (7)
causes:
- Increased sweat chloride concentrations,
- Viscous mucus production,
- Lung disease,
- Intestinal obstruction,
- Pancreatic insufficiency,
- Biliary cirrhosis,
- Congenital absence of the vas deferens.
Cystic Fibrosis
Recurrent exacerbations are associated with: (10)
- Airway obstruction,
- Bronchiectasis,
- Emphysema,
- v/q mismatch,
- Hypoxemia,
- Hemoptysis
- Pneumothorax secondary to bullae formation.
- End stage cor pulmonale.
- Malnutrition (pancreatic insufficiency)
- Hepatic dysfunction
- Hyperventilation is compensatory.
- Obstructive pattern
Cystic fibrosis
- _______ and ________ are good predictors of survival.
- Inquire about frequency of infections, hospitalizations, effectiveness of bronchodilators.
- Exercise tolerance and physical fitness
Sickle cell disease
- SCD is an inherited ________
- Point mutation on chromosome ________ which codes for production of hemoglobin _____ instead of hemoglobin ______.
- hemoglobinopathy
- 11
- s; a
Sickle cell disease
Clinical features of the disease include:
Mean life expectancy just over ______ decades.
- Splenic infarction
- Acute episodes of pain
- Renal insufficiency
- Acute and chronic pulmonary disease
- Hemorrhagic and occlusive stroke
3
Sickle Cell Disease
- Acute chest syndrome (ACS) is an _____________ caused by SCD.
- ACS is a risk factor for _______.
- Precipitated by:
- acute lung injury
- SCLD
- Infection,
- Fat embolism,
- Pulmonary infarction,
- Surgery.
Sickle Cell Disease
Diagnostic criteria include of acute chest syndrome (ACS):
- A new ___________ involving at least one lung segment on the radiograph (excluding atelectasis)
- combined with one or more symptoms or signs of: (5)
- pulmonary infiltrate;
- Chest pain
- Pyrexia greater than 101.3°F (38.5°C)
- Tachypnea
- Wheezing, or
- Cough.
Sickle cell disease
- Children with scd who have experienced a _______ are at a high risk for perioperative complications.
- Risk factors of SCD:
- stroke
Therapy is still evolving
- Male gender,
- Low hemoglobin,
- Hypertension and
- Genetic polymorphisms.
Sickle Cell Disease
- Children with SCD frequently develop postoperative ________.
- ______ management can be difficult in these children.
- Large doses of opioids can depress ventilation and cause atelectasis.
- Incentive spirometry can prevent the development of atelectasis and pulmonary infiltrates
- Atelectasis
- Pain
Regional analgesia, supplemental nonopioid analgesics, prophylactic incentive spirometry, early mobilization, and good pulmonary toilet may decrease the incidence of atelectasis and ACS
Sickle Cell Disease
- Treatment of ACS is focused on supporting gas exchange.
- Supplemental oxygen, noninvasive ventilatory support such as ________, or intubation and mechanical ventilation are indicated by the degree of dysfunction.
- _________, incentive spirometry, and chest physiotherapy may be useful in preventing disease progression
- Perioperative transfusion goal is hematocrit of _______%
- CPAP
- Bronchodilators
- 30
Respiratory Physiology
Neonates are historically considered “obligate _______ breathers”.
The ability to breathe through the _______ when the nares are obstructed is age dependent.
- nose
- mouth
This may present a challenge when attempting to mask ventilate infants.
Respiratory Physiology
Functionally, the airway is most narrow at the level of the ________, just below the vocal cords.
The cricoid is the only ________ ring of cartilage In the laryngotracheobronchial tree.
cricoid cartilage;
complete
Larynx is adjacent to
C3 in _________,
C4 in ________, and
C5 in ________.
The high cervical level of the larynx means the “___________” will not help you visualize the glottis as it does in the adult.
Consider a “________” to help align your view during direct laryngoscopy.
- premature neonates
- infants
- adults.
- sniffing position
- shoulder roll
Review
Airway management
Proper sizing of OPA
Miller/ Wis-hipple/Macintosh
Preterm
Neonate
Neonate - 2 yrs
2 - 6 years
6 - 10 years
> 10 years
Syndromes
Goldenhar syndrome
- Micrognathia (unilateral)
- Cervical dysfunction
Apert syndrome
- Micrognathia
- Macroglossia
- Limited cervical motion
- Midface hypoplasia
Hunter and hurler syndromes
- Cervical dysfunction
- Macroglossia
Beckwith-Wiedemann syndrome
- Macroglossia
Regresses with age
Freeman- Sheldon syndrome
AKA
- Circumoral fibrosis
- Microsotomia
- Limit cervical motion
“Whistling face”
Down syndrome
- Atlantooccipital abnormalities
- Small oral cavity
- Macroglossia
Klippel-Feil Syndrome
- Cervical fusion
Hallermann-Streiff syndrome
Microstomia
- Micrognathia
- Displacement of TMJ
Arthrogryposis
Cervical dysfunction
- Torticollis
- Hypoplastic mandible
Edwards syndrome
- Micrognathia
Cri-du-chat syndrome
- Micrognathia
- Laryngomalacia
Pediatric Leak Test for ETT
- A leak around the ETT is necessary to reduce the risk of edema and obstruction.
- The leak should be documented on anesthesia record (Example: write “+ leak at 22 cm H20”)
Two types:
- Minimal Leak Test (MLT)
- Minimal Occluding Volume (MOV), which requires a manometer.
Unexpected difficult Peds intubation
