Duration of apnoea in anaesthetized children required for desaturation of haemoglobin to 95%: comparison of three different breathing gases

Abstract

In this study, we compared three gas compositions to determine if the duration of apnoea for SpO2 to decrease is proportionate to the oxygen fraction of the gas prior to apnoea. Twenty-five patients ASA physical status 1-2 aged two months to 12 years were included in the study. Anaesthesia was induced via a mask with 5% sevoflurane and 66% N2O in oxygen. After paralysis with vecuronium (0.12 mg.kg-1, i.v.) the trachea was intubated and anaesthesia was maintained with sevoflurane and N2O in oxygen. When cardiovascular stability was obtained, the patient was randomly set to breathe one of three gas compositions: 1. oxygen (FiO2 1.0), 2. N2O/O2 (FiO2 0.4), and 3. air/O2 (FiO2 0.4). All three gas compositions included 2-4% of sevoflurane to maintain anaesthesia. After more than eight min of each gas breathing, apnoea was begun by disconnecting the breathing circuit from the tracheal tube. The time from the start of apnoea (SpO2 100%) to SpO2 of 95% (T95) was measured. T95 measured after breathing N2O/O2 and air/O2 were 34.6 +/- 5.7 and 28.8 +/- 4.7% of that measured after oxygen breathing (P < 0.001 vs oxygen breathing, P < 0.001 vs oxygen and N2O/O2 breathing), respectively. Preoxygenation before intubation was validated to delay the haemoglobin desaturation brought about by apnoea. An induction technique using a low FiO2 will allow rapid haemoglobin desaturation.

Use of modified rapid sequence tracheal intubation in pediatric patients

“…A reduced tolerance to apnea, which may result from different factors such as increased oxygen demand, reduced functional residual capacity and increased closing capacity and very limited cooperation during the preoxygenation are related to age. Neonates and infants may develop hypoxemia (SpO 2 < 90%) before full neuromuscular blockade is accomplished[567] and rapid desaturation may be more dramatic in severely ill-children.…”

Preoksigenasi pada Anestesi Umum

“…Dixon et al menunjukkan manfaat serupa pada 3 randomized controlled trial pada pasien dengan body mass index lebih besar dari 40 yang mana diposisikan pada posisi head up 30 derajat. 5,21,22,23,24 Sebaliknya posisi Trendelenburg (kepala 30 derajat lebih tinggi dari kaki) juga meningkatkan preoksigenasi dan mungkin berguna pada pasien yang tidak dapat terikat pada bahu, yang diimobilisasi karena kemungkinan spinal injury.…”

Pulse oximetric thresholds for tonsillectomy and adenotomy in children: significance of 1–2% decline in oxyhemoglobin saturation

“…But the thresholds set by those investigators have been found to have relatively low sensitivity/specificity in diagnosing mild SDB such as upper airway resistance syndrome (13,14), which is known to occur without a large decline in SpO 2 (14–16). As younger children are more likely to exhibit a SpO 2 decline over the same duration of apnea/hypopnea than older children and adults (16–18), we thought that slight SpO 2 decline during sleep might be detected more easily in young children with mild SDB.…”