Related Experiment Video
Updated: Aug 9, 2026

A Novel Rescue Technique for Difficult Intubation and Difficult Ventilation
Published on: January 17, 2011
Factors affecting leak around tracheal tubes in children
Abstract:
This study determined which variables affected endotracheal tube "leak" pressures in 80 surgical patients, two weeks to 11 years of age, intubated with uncuffed tracheal tubes. We defined "leak" pressure as the inspiratory pressure needed to cause an audible escape of gas around the endotracheal tube. "Leak" pressure was measured after varying either head position, tracheal tube depth within the trachea, fresh gas flow rate, or degree of neuromuscular block. "Leak" pressure increased progressively from 16.9 +/- 1.3 cmH2O with complete patient paralysis to 30.6 +/- 1.4 cmH2O following 100 per cent recovery of neuromuscular function. Turning the head from a neutral position to one side increased "leak" pressure from 14.7 +/- 1.7 cmH2O to 24.4 +/- 2.5 cmH2O. Varying tracheal tube depth or fresh gas flow rate produced no significant change in "leak" pressure. Thus, there may be marked variability in "leak" pressure, depending on head position and degree of neuromuscular blockade. Keeping the patient fully paralyzed with the head in a neutral position provides a reliable and consistent method for measuring "leak" pressures.
Related Concept Videos
Trachea
Anatomical Features:
Location: About half of the trachea is situated in the neck, anterior to the esophagus, and extends from the larynx (at the level of the...
Pressure Relationships in Thoracic Cavity
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
Oxygen Delivering System II: Venturi Mask and Transtracheal Oxygen
Venturi Mask
The Venturi mask, named after the Venturi effect, is designed to deliver precise oxygen concentrations. It consists of a large tube with an oxygen inlet that narrows down, causing a pressure drop that pulls air in through adjustable side ports. The mask is a lightweight,...
Oxygen Delivering System III: Tracheostomy and T-piece
Tracheostomy
A tracheostomy is a surgically created opening (stoma) in the anterior part of the trachea. It is used to establish a patient airway, bypass an upper airway obstruction, simplify the removal of secretions, permit long-term...
Tracheostomy: Procedure and Tubes
Tracheostomy tubes can be made of semiflexible plastic (polyurethane or silicone), rigid plastic, or metal, and they come in...

