According to Lippmann et al,4 there was an early progressive increase in heart rate, cardiac index, arterial and venous pressure, stroke work and oxygen delivery, oxygen consumption, and oxygen extraction. In critically ill patients, however, ketamine did not produce uniform responses and was not without some adverse effects. There were a diversity of responses in mean arterial pressure, heart rate, cardiac index, oxygen consumption, oxygen extraction, and venous admixture. In some cases, ketamine may even cause maldistribution of systemic blood flow resulting in inadequate tissue oxygenation. Patients in this series were severely stressed and critically ill with depleted catecholamine and adrenocortical stores. Moreover, prolonged severe stress blunts sympathetic and/or adrenocortical stimulation by ketamine.