GAS EXCHANGE PATHOPHYSIOLOGY DURING ANESTHESIA

Pre-oxygenation enhances induction with sevoflurane as assessed using bispectral index monitoring

BACKGROUND

Several methods may enhance the inhalational induction of anesthesia. In this randomized double-blind study, we evaluated the speed of induction of anesthesia with sevoflurane with or without pre-oxygenation.

METHODS

Fifty-four patients scheduled for hysteroscopy received for 10 min air or 100% oxygen via a facemask followed by > or = 7% sevoflurane in 100% oxygen. During the first 300 s of sevoflurane administration, bispectral index (BIS) values were recorded every 30 s in all patients. In 14 patients, seven in each group, BIS, endtidal CO(2), tidal volume, respiratory rate, SpO(2), and heart rate were recorded every minute during the pre-induction period and every 30 s during the first 5 min of sevoflurane administration.

RESULTS

The BIS, endtidal CO(2), tidal volume and respiratory rate did not differ between the oxygen or air breathing groups (P = 0.696, P = 0.999, P = 0.388, and P = 0.875, respectively), though the oxygen group exhibited lower tidal volumes by 16-20%. The SpO(2) and heart rates were higher in the oxygen breathing group (P < 0.001 and P = 0.042, respectively). During sevoflurane administration, BIS values were lower in the oxygen group vs. the group breathing air, in particular at 90, 120, 150, 180 and 210 s (P = 0.001, P = 0.001, P = 0.001, P = 0.001 and P = 0.030, respectively). The endtidal CO(2) and the tidal volumes between the groups did not differ. The two groups differed in the SpO(2) and the heart rates during induction (P = 0.004 and 0.003, respectively).

CONCLUSIONS

Before sevoflurane administration, breathing 100% oxygen for 10 min enhances induction of anesthesia with sevoflurane.

Rapid sequence intubation of the pediatric patient. Fundamentals of practice

Rapid-sequence intubation and rapid sequence induction of general anesthesia are synonyms and refer to the technique of choice for tracheal intubation in many pediatric patients in the emergency department. The principles of safe practice and basic standards of care uniformly apply to all clinical situations in which the technique is performed. RSI has two basic technical components: induction of general anesthesia and direct laryngoscopy with tracheal intubation. The technique is a prescribed protocol that can be modified slightly by the clinical circumstances. RSI is designed to rapidly create ideal intubating conditions, attenuate pathophysiologic reflex responses to direct laryngoscopy and tracheal intubation, and reduce the risk for pulmonary aspiration. Optimal performance requires appropriate training and knowledge, technical skill, and sound medical judgment. Medical and airway evaluation, careful patient selection, recognition of the need for consultation or safer alternatives, thorough familiarity with appropriate drug management, and attention to detail are essential for minimizing the risk for adverse complications. RSI with a rapid injection of preselected dosages of an anesthetic induction agent and muscle relaxant is the pharmacologic technique of choice. Premedication should not be routinely used. Anticipation, recognition, and management of complications are inherent to the competent delivery of all medical care. The unanticipated difficult airway is arguably the most severe complication of RSI, and all individuals performing the technique must prepare in advance a specific plan for this scenario. As with all such skills or procedures, a quality assurance program is important to monitor care, and individuals practicing RSI need to take appropriate steps to maintain competence.