Prematurity: Overview of complications
Premature babies born <37 weeks of pregnancy Author: Elizabeth de Klerk Simran Sandhu Reviewers: Yan Yu, Mao Ding Nick Baldwin* *MD at time of publication Immature immune system Prematurity Structurally immature lungs Immature retinal vessels are more sensitive to O2 Supplemental O2 makes retinal environment hyperoxic (excessive supply of O2) Hyperoxia vasoconstricts retinal blood vessels leading to retinal ischemia Ischemic retina produces vascular endothelial growth factor (VEGF) to generate new blood vessels + improve retinal perfusion Excess VEGF causes abnormal blood vessel proliferation Abnormal vessels are fragile + prone to hemorrhage which can lead to retinal distortion Retinopathy of Prematurity (ROP) (See relevant slide) Poor structural support to blood vessels of the germinal matrix (the tissue surrounding the lateral ventricles of the brain) Vessels are vulnerable to hemodynamic instability Abrupt changes to cerebral blood flow damage blood vessels Vessels bleed into germinal matrix and lateral ventricles Intraventricular Hemorrhage (IVH) (See relevant slide) Note: Pre-term complications not discussed here include hypothermia, hypoglycemia, apnea, patent ductus arteriosus Low quantity: ↓ surfactant production Low quality: ↓ surfactant activity (different lipid + protein composition compared to full-term infants) ↑ Infections ↓ Number of white blood cells and complement protein ↑ Bacterial colonization of GI tract + penetration of intestinal wall Abnormally high surface tension of alveoli Alveoli spontaneously collapse (diffuse alveolar atelectasis) Ineffective ventilation of alveoli (V)ànot supplying pulmonary blood (Q) with oxygen (V-Q mismatch) Respiratory Distress Syndrome (RDS) (See relevant slide) Positive pressure ventilation (PPV) used therapeutically PPV disrupts lung development & damages lung tissue Bronchopulmonary Dysplasia (BPD) (See relevant slide) Intestinal ischemia, or Formula Feeds (unclear mechanisms) Activation of inflammatory cascade releases cytokines (peptides that help activate immune response) Cytokines cause bowel necrosis (tissue death) Necrotizing Enterocolitis (NEC) (See relevant slide) Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published October 31, 2013, updated March 25, 2023 on www.thecalgaryguide.com