Sedation

Giovanni Mistraletti, Paolo Formenti, and Giovanni Sabbatini

Introduction

The severity of the acute respiratory failure, the necessity of lifesaving invasive procedures, and the harsh intensive care unit (ICU) environment make sedation necessary in ARDS patients [1]. Such patients may experience a dangerous condition, both physical and psychological, and need the most appropriate and individualized neurological treatment. Among many other vital organ failures, the early and longterm consequences of ARDS may lead to severe brain dysfunction [2].

Pain, agitation, delirium, anxiety, and alteration of consciousness are common conditions in ARDS patients [3]. They are frequently triggered by treatable causes, like hypoxemia, hypercarbia, acidosis, hypoglycemia, hypo- or hypernatremia, sepsis, hypovolemia, and alcohol or drug withdrawal, or by lifesaving medical treatments comprehending mechanical ventilation, invasive procedures, forced body postures, and uninterrupted noise and light stimulation, together with their consequences like sleep deprivation or the impossibility of communicating with the staff [4]. International guidelines recommend to face and treat first all organic and metabolic causes of distress and to minimize environment-linked stressors [5, 6]. As a second step, they suggest the administration of analgesic, sedative, and antipsychotic drugs to ensure comfort, at all stages of the illness. Adequate levels of sedation, therefore, represent a primary target for managing ARDS patients. However, since neuroactive therapy is related to several important side effects like hemodynamic instability and cardiac dysrhythmias [7], sepsis [8], ileus, delirium [9], and lengthening of respiratory weaning [10], it is important to titrate it to the lowest effective amount [11].

G. Mistraletti, MD (*) • P. Formenti, MD • G. Sabbatini, MD

Universita degli Studi di Milano, Dipartimento di Fisiopatologia medico-chirurgica e dei trapianti, A.S.S.T. dei Santi Paolo e Carlo, Ospedale San Paolo - Polo Universitario,

Via A. Di Rudinr, 8, 20142 Milan, Italy e-mail: This email address is being protected from spam bots, you need Javascript enabled to view it

Several authors have pointed out the need for light sedation [12, 13], due both to the detrimental effects of neuroactive therapy itself and to the clinical and economical costs associated with deeper-than-needed sedation levels [1, 14, 15]. Daily interruption of intravenous short-term sedative administration [16] in association with a spontaneous breathing trial [17] may decrease the mechanical ventilation length and reduce both complications and prevalence of delirium. Analgesia-based sedation could be another effective way to manage ARDS patients, relying on the opiates’ ability to maintain adaptation to mechanical ventilation while preserving patients’ consciousness [18]. However, the use of short-half-life analgesics (remifentanil) is only indicated for short-stay patients, while there is no difference among opiates for patients requiring mechanical ventilation longer than 3 days [19, 20]. In 2010, Strom et al. demonstrated that a protocol based only on morphine 5 mg boluses allows minimal sedation and provides better outcomes, rather than adding propofol to achieve deeper sedation levels [21].

The conscious sedation target is an innovation of the utmost relevance in the field of ICU care. Nonetheless, some intensivists tend to consider it unfeasible, considering the potential higher risk of ventilation-related lung damage, the risk of selfremoval of invasive devices [22], and the possible stress/discomfort for patients [23]. From an ICU staff perspective, it also raises the issue of an increased workload. These beliefs, however, are at least partially unfounded [24]. Intensivists have to face the side effects of both pharmacological and physical “restraint” methods, continuously pursuing the best approach for patient security and healing.

Despite guideline suggestions and the fact that between 60 and 80% of ICUs use a specific score to evaluate the level of sedation [25], many physicians routinely maintain [26] a deeper than desired level of sedation [27], probably causing avoidable side effects. Pragmatically, it is important to underline the concept that it does not exist in one-and- only sedative treatment which can be always adequate; at the same time, a disproportionate fear to use sedative drugs is inappropriate. Even if the clinical course of each ARDS patient is different from the others, it is useful to distinguish at least two different scenarios, leading to the neuroactive drug prescription (Fig. 18.1) in ARDS patients. In the acute phase, intubation and placing of vascular catheters and other maneuvers devoted to clinical stabilization require a deep sedation target, similar to general anesthesia. On the other hand, in the subsequent phase, it is important to change the target toward a lighter sedation, by using the lowest amount of neuroactive drugs in order to only obtain a patient adaptation to critical illness. This second phase has to begin as soon as possible, frequently after the second/third ICU day. Other practices such as adjustment of the mechanical ventilation settings, of the drug therapies, and of the environment to the specific necessities of each specific patient can help in reducing discomfort.