Related Experiment Video

Updated: Aug 14, 2026

Combining Volumetric Capnography And Barometric Plethysmography To Measure The Lung Structure-function Relationship
08:25

Combining Volumetric Capnography And Barometric Plethysmography To Measure The Lung Structure-function Relationship

Published on: January 8, 2019

Anatomic dead space in infants and children

A H Numa1, C J Newth

  • 1Division of Pediatric Critical Care, Children's Hospital Los Angeles, University of Southern California 90027, USA.

Journal of Applied Physiology (Bethesda, Md. : 1985)
|May 1, 1996
PubMed

Insights

Pediatric anatomic dead space is significantly larger in infants compared to adults, decreasing with age. This study quantifies this age-dependent relationship in children.

Area of Science:

  • Pediatric physiology
  • Respiratory mechanics

Background:

  • Adult anatomic dead space is approximately 2.2 ml/kg.
  • Infants and children have a proportionally larger head size, suggesting greater extrathoracic dead space.

Purpose of the Study:

  • To investigate the hypothesis that pediatric subjects have relatively larger extrathoracic and total dead space compared to adults.
  • To quantify the age-dependent relationship of anatomic dead space in pediatric patients.

Main Methods:

  • Extrathoracic dead space was measured using a water displacement technique in 40 intubated pediatric patients (7 days to 14.2 years).
  • Intrathoracic dead space was measured via continuous analysis of PCO2 and ventilation in 10 pediatric patients (18 days to 14.7 years).

Main Results:

  • Extrathoracic dead space per kilogram decreased exponentially with age, from 2.3 ml/kg in infancy to 0.8 ml/kg in children over 6 years.
  • Mean intrathoracic dead space was 1.03 ml/kg and showed no age dependency.
  • A derived formula showed total anatomic dead space (ml/kg) = 3.28 - 0.56 [ln(1 + Age)], with high correlation (r=0.95, P=0.0001).

Conclusions:

  • Anatomic dead space in pediatric patients is age-dependent.
  • Total anatomic dead space is greater than 3 ml/kg in early infancy.

More Related Videos

Laryngeal Mask Airway (LMA) Placement in a Neonatal Patient Simulator Using a Non-Inflatable Supraglottic Airway (SGA)04:56

Laryngeal Mask Airway (LMA) Placement in a Neonatal Patient Simulator Using a Non-Inflatable Supraglottic Airway (SGA)

Published on: July 14, 2023

Continuous Telemetric In Utero Tracheal Pressure Measurements in Fetal Lambs05:40

Continuous Telemetric In Utero Tracheal Pressure Measurements in Fetal Lambs

Published on: December 22, 2023

Related Concept Videos

Breathing01:05

Breathing

The process of breathing, inhaling and exhaling, involves the coordinated movement of the chest wall, the lungs, and the muscles that move them. Two muscle groups with important roles in breathing are the diaphragm, located directly below the lungs, and the intercostal muscles, which lie between the ribs. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity and creating more room for the lungs to expand. When the intercostal muscles contract, the ribs...
Pulmonary Cycle: Exhalation01:17

Pulmonary Cycle: Exhalation

In terms of human respiration, the act of expelling air, known as exhalation (or expiration), operates on the principle of pressure gradients. During expiration, the pressure within the lungs exceeds that of the surrounding atmosphere. Under normal conditions, quiet breathing involves passive exhalation and is free of muscular contractions. This is because the exhalation process is driven by the natural elastic recoil of the lungs and chest wall, both of which have an inherent tendency to...
Respiratory Volumes and Capacities01:22

Respiratory Volumes and Capacities

The respiratory system is responsible for the intake of oxygen and the expulsion of carbon dioxide from the body. Respiratory volumes describe the volume of air in the lungs at different phases of the respiratory cycle. Tidal volume is the air breathed in and out during normal, quiet breathing. Inspiratory reserve volume is the air that can be forcefully inspired beyond the tidal volume. In contrast, expiratory reserve volume refers to the air that can be expelled from the lungs after a normal...
External and Internal Respiration01:24

External and Internal Respiration

External respiration occurs in the lungs, and it is the first step in the journey of oxygen inside the body. When we inhale, oxygen enters our lungs and diffuses across the thin alveolar membrane. The alveoli are tiny, air-filled sacs that provide a vast surface area for gas exchange. Oxygen in the alveoli has a higher partial pressure (105 mmHg) than in the adjacent pulmonary capillaries (40 mmHg), establishing a pressure gradient. As a result, oxygen molecules move from the alveoli into the...
Physical Assessment of the Respiratory Tract II: Inspection01:27

Physical Assessment of the Respiratory Tract II: Inspection

Physical assessment of the respiratory tract through inspection is a crucial step in understanding the patient's respiratory health. It provides insights into the functioning of the respiratory system, the musculoskeletal structure, and even the patient's nutritional status. This comprehensive approach involves observing several vital aspects: chest configuration, breathing patterns, respiratory rates, skin color, and use of accessory muscles.
Chest Configuration
The chest configuration can...
Atelectasis II: Pathophysiology01:10

Atelectasis II: Pathophysiology

Atelectasis develops when alveoli lose their air and collapse inward. Because lung tissue is naturally elastic, these air sacs shrink rather than remaining open. Collapsed alveoli are no longer ventilated, reducing their role in gas exchange. Blood flow may continue in these regions, creating a ventilation–perfusion mismatch. Clinical findings include decreased breath sounds, dullness to percussion, reduced chest expansion, and decreased tactile fremitus as sound transmission through collapsed...