The introduction of Advanced Pediatric Life support (APLS) has importantly improved emergency care critically ill children. Early intubation and mechanical ventilation (MV) in children with respiratory insufficiency is an undisputed principle in APLS. Mechanical ventilation of especially young children requires both specific knowledge and equipment. A lot of seriously ill children do not present in a hospital with a pediatric intensive care unit (PICU). The time between the initial resuscitation phase and transfer to a PICU needs to be bridged. In daily practice we are frequently confronted with problems during MV in young children caused by a too large additional dead space. A large dead space can have dramatic consequences. The solution is often simple and effective as is illustrated by the following case.

A 3-month-old boy with a body weight of 2.7 kg was admitted to the emergency department because of apneas. Capillary blood-gas analysis showed acute respiratory acidosis and transcutaneous measured O₂ saturation was 85%. Because of frequent apneas he was intubated and mechanically ventilated. Shortly after respiratory acidosis however aggravated. His condition was systematically evaluated. A tube dislocation seemed unlikely, capnography was positive but showed and immeasurably high. The chest excursions were normal and also normal breath sounds were audible. When the PICU team arrived for transport of the patient it was noticed that the reason for his decline was due to a large additional dead space. This was caused by a ventilator circuit, swivel connector, mainstream capnograph and a heat moisture exchanger with sizes normally used in adults. He was switched to ventilation equipment appropriate for his age. He showed a rapid and full recovery.

The airways of the respiratory system, that do not take part in gas exchange, constitute the anatomical dead space. Anatomical dead space in adults and children differs considerably and is 2.2 and 3 ml/kg body weight respectively. Dead space is expanded when a patient is connected to a ventilator and may cause rebreathing of expired air. The ventilator circuit and additional devices placed between the endotracheal tube and the Y-piece all increase dead space. The different devices used in this patient each had an unacceptable large dead space on itself. An additional dead space 1.5-2 ml/kg body weight at maximum is considered save. With the use of specific equipment the additional dead space was in this case reduced from 90 ml to 3 ml.

As a rule of thumb an additional dead space of 1.5-2 ml/kg body weight is acceptable in young children. We recommend that wards where young children are resuscitated do have specific equipment to mechanically ventilate young children and have a protocol with explicit attention to dead space.

This supplementary information is presented as submitted by the corresponding author. It has not been copy-edited by NTvG.