We present a case of a massive pulmonary air embolism during permanent pacemaker lead implantation under mild sedation in a 73-year-old woman. We used a peel-away sheath that is devoid of a hemostatic valve. The air embolism occurred after deep inspiration associated with loud snoring sounds and resolved after short chest massage and administration of adrenaline. Temporary closure of the intravenous entrance route of the peel-away sheath before inserting the lead may prevent this potentially lethal complication.