Ellen de Kort

158 Chapter 9 Controversy exists regarding the definition of hypotension in neonates as well as the importance of hypotensive episodes in general for the patient. Hypotension in preterm infants has been associated with mortality and serious morbidities. 65-70 Blood pressure, however, is not always the best indicator of circulation and organ perfusion. In this light it has been thought that hypotension in the absence of signs of inadequate tissue perfusion does not yield any long-term negative effects and should not be treated. This phenomenon is referred to as permissive hypotension. 71-73 To date, there are different opinions as to the importance of propofol-induced hypotension for the neonate. The study of Welzing et al. was terminated prematurely because of the high incidence of hypotension, but the necessity of this termination has been questioned by others. 57,74 Smits et al. found an overall hypotension incidence of 64% but, in the absence of clinical signs of shock, the majority of hypotension episodes were designated as being permissive. 60 Several small studies investigated the relationship between cerebral oxygenation and systemic hypotension after treatment with propofol. An important correlation between blood pressure and cerebral oxygenation was not found in all three studies. 75-77 Although these findings seem to be reassuring, it concerned only small sample sizes and focused on near infrared spectroscopy (NIRS) data only. Clinical short-term and long-term consequences of propofol-induced hypotension have never been investigated. Therefore, the importance of propofol-induced hypotension on the short and long term is yet to be elucidated and might not be as permissive as is thought. In conclusion, both remifentanil andpropofol as single drugpremedication strategies possess significant difficulties in providing adequate sedation for the procedure. In addition, both drugs are accompanied by a high risk of side effects. The use of remifentanil as well as propofol as premedication for endotracheal intubation, therefore, should be seriously reconsidered. Based on the current available evidence, in general, the combination of an opioid with a muscle relaxant is the most effective and safe strategy. Fentanyl seems the most suitable opioid candidate. Chest wall rigidity, being a known side effect of fentanyl as well, can be prevented by slower infusion times and can also be overcome by the subsequent use of a muscle relaxant. To prevent patients frombeing paralyzedwhile not being sedated, sufficient time should be taken to reach the effect of fentanyl before the muscle relaxant is being administered. Morphine, although one of the drugs most used as premedication, 28-30 should not be used any longer because of its delayed onset and prolonged duration of action. Remifentanil as a single bolus also does not seem a suitable candidate in combination with a muscle relaxant, because its ultrashort period of action that is shorter than that of most muscle relaxants brings the risk of leaving patients paralyzed while the sedative effect has alreadyceased. Continuous infusion of remifentanil could be considered in combinationwith a muscle relaxant, but this strategy needs further investigation first.