Respiratory Distress Flashcards
Clinical features
Respiratory distress is diagnosed when two or more of the following signs are present:
Tachypnoea >60 breaths per minute
Intercostal and subcostal recessions
Grunting
Cyanosis
Apnoea
Other signs may include nasal flaring, lethargy, poor feeding, hypothermia, and hypoglycaemia
Aetiology
The most common causes:
Transient tachypnoea of the newborn (TTN)
Respiratory distress syndrome (RDS)
Meconium aspiration syndrome(MAS)
Pneumonia
Sepsis
Pneumothorax
Delayed transition
Diagnosis of respiratory distress
History
Clinical examination
Investigations
Arterial blood gas
Chest x-ray
Blood investigations
Respiratory distress syndrome
Hyaline membrane disease
Leading cause of all neonatal deaths
Primarily in premature infants
60% to 80% of infants < 28/40
15% to 30% of infants between 32 and 36 weeks
Various risk factors
Risk factors
prematurity
asphyxia
maternal diabetes
multiple births
previous infants affected
highest incidence in male infants of Caucasian decent
Protective features of respiratory distress
Chronic hypertension
Pregnancy induced hypertension
Maternal heroin use
Antenatal corticosteroid prophylaxis
Respiratory distress syndrome
clinical manifestation of lung immaturity.
lipoprotein called surfactant, which is necessary for normal alveolar expansion is deficient, either because of lack of production or failure of release from alveolar Type II cells
Pathophysiological effects of RDS
Reduced lung compliance, increased surface tension
Ventilation perfusion imbalance
Pulmonary vasoconstriction resulting in a large right-to-left shunt of blood
Reduced alveolar ventilation and functional residual capacity
Increased minute ventilation and work of breathing.
These changes result in hypoxaemia, hypercapnia and eventually metabolic acidosis
Clinical features
• Respiratory rate of > 60 bpm
• Expiratory grunting
• intercoastal and/or sternal recessions
• Central cyanosis
• Nasal flaring
• Signs usually appear within minutes of delivery
• Breath sounds may vary from normal to, diminished
Clinical features of respiratory distress
In most cases, clinical signs reach a peak within 3 days, after which improvement is gradual
Improvement is attributed to diuresis, surfactant production
Death can be due to severe impaired gas exchange, alveolar air leaks, interstitial emphysema, pneumothorax, pulmonary haemorrhage, IVH
Diagnosis
History and clinical findings
Arterial blood gas: hypoxaemia, hypercapnia, acidosis
Chest x-ray
Grading of HMD on X ray
Grade 1: usually x- ray not different from a normal radiograph. May have fine reticular infiltrates, ground glass appearance
Grade 2: air bronchograms
Grade 3: more infiltrates, blurring of cardiac border and diaphragm
Grade 4: complete white out, homogenic lung opacity
Prevention of respiratory distress syndrome
• Appropriate management of high risk pregnancies
• Antenatal corticosteroids
- Reduces incidence of RDS, IVH, NEC, sepsis
Management of respiratory distress
Supportive care
Treat hypoxia
Oxygen to maintain saturation of 88-92%
Careful monitoring of vital signs
Avoid hypothermia
Nurse in an incubator, maintain adequate temperature
Fluids and caloric intake
Surfactant replacement therapy
Respiratory support
Surfactant replacement therapy
major advance in the care of the preterm infant with respiratory distress syndrome
mortality has been significantly reduced
two preparations of natural surfactant are commercially available in South Africa
surfactant is administered via an endotracheal tube
released into the alveoli
reduces surface tension, improves lung compliance
helps to maintain stability of alveoli
prevents collapse of small air spaces at end expiration
Nasal continuous positive airwaybpressure
prevents the collapse of alveoli
• improves the functional residual volume and ventilation/perfusion
• early use reduces need for ventilation
• most infants will be weaned of in 72 hours
Complications of NCPAP
• Nasal obstruction as a result of secretions
• Nasal prong displacement
• Nasal irritation
• Septal and mucosal irritation/ erosion/ necrosis
• Water accumulation in the circuit/nose
• Pneumothorax
• Abdominal distension
Complications of RDS
• Complications of tracheal intubation
• Bradycardia during intubation
• Pneumothorax
• Dislodgement of the tube
• Bronchopulmonary dysplasia
Transient Tachypnoea of newborn
• Common cause of respiratory distress
• 5 to 6 per 1,000 births
Wet lung syndrome
Brief, self-limiting, relatively benign condition follows a normal full-term pregnancy
Some may require oxygen or ventilation
Pathophysiology if respiratory distress
Results from delayed reabsorption and clearance of alveolar fluid.
Postdelivery prostaglandin release distends lymphatic vessels, which
removes lung fluid as pulmonary circulation increases with the initial
foetal breath.
Caesarean delivery is a risk factor
Clinical features of respiratory distress
• Presents within two hours of birth.
• Breath sounds can be clear.
• Mild respiratory distress, which settles within a few hours
Diagnosis of respiratory distress
History and examination
Chest x-ray:
hyperinflation, perihilar densities, fluid in the lung fissure, pleural effusion
Management respiratory distress
Supportive
Oxygen
+- Respiratory support
Neonatal sepsis plus pneumonia
• Sepsis can occur in term and preterm infants.
• Incidence of 1-2 per 1,000 live births.
• Risk factors include prolonged ROM, PTL, maternal pyrexia, maternal sepsis(UIT, chorioamnionitis etc).
