Direction of shunt in CHD affects uptake of anesthesia

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Takeaway

  • In patients with congenital heart disease (CHD) with right-to-left shunt, the time to inhalational induction of anesthesia is significantly extended compared with patients without CHD or those with left-to-right shunt, in whom it is similar.
  • Sevoflurane is safe and maintains stable hemodynamics in the presence of CHD.

Study design

  • A prospective, single‑center clinical study.
  • 93 pediatric patients undergoing elective surgery were segregated into 3 equal groups: group 1 (no CHD), group 2 (acyanotic CHD) and group 3 (cyanotic CHD).
  • General anesthesia was induced with 8% sevoflurane in 6 L/min air‑oxygen.
  • Time to induction was noted at loss of eyelash reflex and decrease in bispectral index (BIS) value below 60.
  • End-tidal sevoflurane concentration, minimum alveolar concentration, and BIS were recorded at 15 s intervals for the first min, followed by 30 s interval for another 1 min during induction.
  • Hemodynamic data were recorded before and after induction.

Key results

  • Patients in group 3 had significantly prolonged induction time (99±12.3 s; P<.001), almost double that of the patients in other 2 groups (51±11.3 s in group 1 and 53±12.0 s in group 2).
  • Hypotension occurred after induction in group 1.
  • No other adverse hemodynamic perturbations were observed.

Limitations

  • Children without CHD were older than those in the other 2 groups.
  • Patients were oxygenated at different levels.
  • Data derived from central venous pressure, including systemic vascular resistance, could not be obtained.

Why this matters

  • Intracardiac shunts can change induction times in patients with CHD and overdosing and undesirable myocardial depression may result if the delivery of anesthetic agent is not carefully titrated.