Liberation of neurosurgical patients from mechanical ventilation and tracheostomy in neurocritical care

Journal of Critical Care (2012) 27, 417.e1–417.e8

Ventilation

Liberation of neurosurgical patients from mechanical ventilation and tracheostomy in neurocritical care☆,☆☆ Christos Lazaridis MDa,⁎, Stacia M. DeSantis PhDb , Marc McLawhorn MSc , Vibhor Krishna MDd a

Department of Neurosciences-Neurosciences Critical Care, Medical University of South Carolina, Charleston, SC 29425, USA b Department of Biostatistics, Medical University of South Carolina, Charleston, SC 29425, USA c Medical University of South Carolina, Charleston, SC 29425, USA d Department of Neurosurgery, Medical University of South Carolina, Charleston, SC 29425, USA

Keywords: Mechanical ventilation; Brain injury; Ventilator liberation; Extubation

Abstract Neurosurgical patients commonly require mechanical ventilation and monitoring in a neurocritical care unit. There are only few studies that specifically address the process of liberation from mechanical ventilation in this population. Patients who remain ventilator or artificial airway dependent receive a tracheostomy. The appropriate timing for the procedure is not well defined and may be different among an inhomogeneous population of critically ill patients. In this article, we review the general principles of liberation and the current literature as it pertains to neurosurgical patients with primary brain injury. The criteria for “readiness of extubation” include a combination of neurologic assessment, hemodynamic, and respiratory parameters. Future studies are required to better assess indicators for extubation readiness, evaluate the predictors of extubation failure in brain-injured patients, and define the most appropriate timing for a tracheostomy. © 2012 Elsevier Inc. All rights reserved.

1. Introduction Neurosurgical patients commonly require mechanical ventilation (MV) and monitoring in a neurocritical care unit (NCCU). The purpose of MV is to maintain ventilation, optimize oxygenation, and protect the airway.

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Financial disclosures: None. Funding disclosure: None. ⁎ Corresponding author. Division of Neurosciences Critical Care, Departments of Neurology and Neurosurgery, Medical University of South Carolina, Charleston, SC 29425, USA. Tel.: +1 843 792 3221; fax: +1 843 876 8626. E-mail address: [email protected] (C. Lazaridis). ☆☆

0883-9441/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.jcrc.2011.08.018

Most patients can be liberated from MV as soon as they recover from the acute physiologic derangement or postoperative state that brought them to the intensive care unit (ICU). Nevertheless, 5% to 20% of all ICU patients remain ventilator dependent for at least 7 days [1]. Prolonged MV is associated with significant complications that increase morbidity and mortality and generate significant financial and logistic burdens. Some common complications include ventilator-associated pneumonia, ventilator-induced lung injury, airway injury, ventilator-induced diaphragmatic dysfunction, and prolonged immobility. Here, we will discuss the principles of liberation from MV and review the current clinical literature, as it pertains to patients with primary brain injury in the NCCU.

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2. General principles of liberation from MV Liberation from MV involves 2 separate processes: (a) discontinuation from the ventilator and (b) removal of the artificial airway. These 2 steps should be examined independently because successful extubation requires the patient to fulfill both requirements independently. Consideration for MV discontinuation is given when the primary physiologic insult has stabilized, the main cause of respiratory and/or airway failure has been identified, and interventions to reverse it are successfully underway. The American College of Chest Physicians, the Society of Critical Care Medicine, and the American Association of Respiratory Care have created evidence-based guidelines according to the following principles [2]: a. Frequent assessment is required to determine whether ventilatory support andan artificial airwayare still needed; b. Factors that contribute to ventilator dependence must be continually reevaluated; and c. Nonphysician clinicians can effectively carry out ventilator discontinuation and weaning protocols. This multisociety-sponsored, evidence-based task force [3] has recommended that a patient be considered a candidate for MV withdrawal if: a. The lung injury is stable/resolving, the gas exchange is adequate with low positive end-expiratory pressure/fraction of inspired oxygen requirements (eg, positive end-expiratory pressure, 5-8 cm H2O; fraction of inspired oxygen, 0.4-0.5); b. Hemodynamic variables are stable (eg, without significant need for therapy with vasopressors); and c. The patient is capable of initiating spontaneous breaths. Recently, several randomized controlled trials (RCTs) demonstrated that outcomes of MV patients managed under protocols were better than those of control patients managed with nonprotocol or usual care. Discontinuation protocols have been investigated with success in medical, surgical, and multidisciplinary critical care populations [4,5]. It has become clear from these RCTs that integrated assessments performed during a carefully monitored spontaneous breathing trial (SBT) provide the most useful information to guide the discontinuation decision. An SBT consists of spontaneous breathing with little or no ventilator assistance (eg, T-piece trial or using 1-5 cm H2O continuous positive airway pressure, 5-7 cm H2O of pressure support from the ventilator). The task force further recommended that no single parameter be used to judge SBT success or failure. Rather, an integrated assessment of the respiratory pattern (especially the development of tachypnea), hemodynamic status (especially tachycardias, bradycardias, or blood pressure fluctuations), gas exchange (especially decreases in pulse oximetry), and patient work of breathing and

C. Lazaridis et al. comfort (especially the development of anxiety or diaphoresis) should be used [6]. An SBT must last at least 30 minutes but no longer than 120 minutes. Esteban et al [7] reported that successful extubation was achieved equally effectively with trials targeted to last 30 or 120 minutes. If it is unclear that the patient has successfully completed an SBT at the 30- or 120-minute time point, then the patient should be considered an “SBT failure” and placed on a comfortable, resting mode of MV. An SBT is a safe procedure and should not be delayed by screens incorporating complicated weaning parameters [8,9]. This process of screening and SBT should be repeated daily. In the MV weaning process, the mode of ventilation and the use of sedation warrant further consideration. The mode of ventilation used for weaning is important, and synchronized intermittent mandatory ventilation with gradual reductions of pressure support (PS) and mandatory respiratory rate should probably be avoided because it has been shown to be inferior to both PS ventilation (PSV) and T-tube trials [10,11]. Critically ill patients often require sedation and analgesia. Occasionally, neuromuscular blockers are used to improve synchrony with the ventilator and to reduce oxygen and metabolic demands in the face of hemodynamic instability and shock. These medications interfere with spontaneous breathing and have been suggested to contribute to muscular weakness acquired in the ICU. Protocols undertaking daily withdrawal of sedation have been shown to decrease the duration of MV, and its practice should be considered a standard of care for MV patients. Less sedation can be accomplished when delivered in the form of intermittent boluses instead of continuous infusions [12-14]. Sedation should be titrated to specific clinical targets appropriate to physiologic state and goals of care. The 2008 revision of the international guidelines for management of severe sepsis and septic shock put forth by the Surviving Sepsis Campaign endorses these practices [15].

3. Special considerations for patients with brain injury How can we apply this accumulated knowledge and evidence in MV, critically ill patients with primary brain injury? Most of the above-referenced RCTs do not include brain-injured patients, and very few studies address the specific and unique needs of patients with primary neurologic impairment. Brain-injured patients may “wean off” positive pressure ventilation without difficulty, but they may continue to require an artificial airway secondary to poor mental status or brain stem and/or lower cranial nerve deficits. The reasons for failed extubation in this population remain poorly understood [16,17]. Counterintuitively, a low score on Glasgow Coma scale (GCS) has not been consistently linked with extubation failure and the need for an artificial airway. It should be kept in mind that GCS is

Liberation of patients from MV and tracheostomy only a crude measure of neurologic function. As King et al [18] suggested in a comprehensive review of the literature, GCS, inability to follow commands, and airway reflexes maybe independent of each other. Prospective trials are needed where these individual variables are specifically investigated. This uncertainty leads to wide variation in the decision making for extubation readiness and timing when it comes to brain-injured patients [19]. According to the National Nosocomial Infections Surveillance System Report from January 1992 through June 2004, neurosurgical units have the third highest ventilator associated pneumonia (VAP) rate among 10 different ICU subspecialty types, falling behind only trauma and burn ICUs [20]. Recent literature suggests that 25% to 45% of patients mechanically ventilated due to primary neurologic injury develop VAP across different NCCU populations such as traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) [21,22]. We suspect that reluctance to attempt extubation in patients with brain injury and the absence of protocol-driven care are at least partially responsible for the high VAP rates reported. A landmark observational prospective study on the subject was conducted by Coplin et al [19] in which consecutive patients with acute brain injury and MV over a 7-month period in a level I trauma center were analyzed. Although TBI was the most common primary diagnosis, patients with SAH, ischemic stroke, status epilepticus, global cerebral ischemia, and encephalitis were also included. These authors used a combination of standard respiratory and hemodynamic criteria for liberation concurrently with neurologic criteria, which included a stable neurologic examination and intracranial pressure (ICP) less than 20, cerebral perfusion pressure (CPP) 60 or higher. Extubation delay was defined as the period between the day patients met the above criteria with an additional 48-hour “grace period” and the actual day of extubation. One hundred forty-six subjects met inclusion criteria, and 136 were analyzed; 99 (73%) of 136 were extubated without delay. The 37 patients who were delayed were extubated a median of 3 days after meeting the liberation criteria (range, 2-19 days) and had a total of 165 days of “delayed” MV. The first important finding of this study was the wide variability in liberation practices for this cohort of patients. Delayed patients differed in that they had been intubated for a longer period before meeting readiness criteria; they had lower GCS and, overall, they required more airway care. Of sixty patients with a GCS 8 or less, 29 (29/60; 48%) were delayed vs only 8 of 76 patients with a GCS greater than 8 (P b .001). Interestingly, at least half of the delayed patients showed no neurologic improvement from the day they met readiness criteria to the day of extubation. The overall reintubation rate in this study was 18%, similar to what reported for MV patients across different ICU populations with no neurologic impairment. However, this finding contradicted prior reports that braininjured patients experience higher reintubation rates [23]. No difference with regard to reintubation was observed between extubation delay patients and promptly extubated ones.

417.e3 Reintubation secondary to airway or pulmonary dysfunction was not related to presence of coma at the time of the extubation trial. Another important finding of this study, against common intuition, is the finding that a significant number of comatose patients and patients with an absent or weak gag and/or cough reflex were extubated successfully without difficulty. In fact, 39 (80%) of 49 of patients with a GCS 8 or less, 10 of 11 patients with a GCS 4 or less, 32 of 36 patients with absent or weak gag reflex, and 18 of 22 patients with an absent or weak cough reflex were successfully extubated. These findings challenge common notions about the ability to protect the airway based on measures such as the GCS and the presence of gag and/or cough reflexes. Salam et al [24] examined specifically medical-cardiac ICU patients after they passed an SBT and were ready to be extubated. These authors used 4 simple tasks (opened eyes, tracking eyes, hand grip, and sticking out tongue) to assess neurologic status, and they also reviewed cough peak flow and volume of endotracheal secretions. They found a synergistic interaction between failure to perform the 4 tasks, amount of secretions, and cough strength in predicting extubation failure. Patients with all 3 factors, unable to perform any of the 4 commands, weak cough reflex, and voluminous secretions had a 100% rate of extubation failure. The authors speculated that these 4 tasks may be more sensitive than GCS in predicting airway competency. In the cohort of Coplin et al [19], 35 (25.7%) of 136 patients developed pneumonia. Comatose subjects who had delayed extubation showed an increased incidence (3.7 times) of pneumonia compared with comatose patients who were extubated promptly. All delayed patients who had pneumonia did so while awaiting extubation after meeting readiness criteria. This last finding argues strongly for avoiding extubation delay in brain-injured patients who otherwise meet criteria. Extubation delay was additionally deleterious by increasing length of stay (LOS) in the ICU, increasing inhospital LOS, and increasing the overall cost. Namen et al [25] took the first step in applying a respiratory therapist-driven weaning protocol, incorporating daily screens with SBTs and prompts to caregivers, in a neurosurgical ICU. All decisions regarding patient care were made by attending neurosurgeons. Namen et al used a randomized controlled study design, performed in a similar fashion as a prior trial from the same group in a medicalcardiac ICU. The earlier trial revealed that daily screening (DS) followed by an SBT and extubation-readiness prompts to caregivers can reduce the duration of MV, reduce intensive care costs, and is associated with fewer complications than usual [5]. Primary outcomes were defined a priori as the overall duration of MV, LOS in ICU/hospital, and time to successful extubation. Secondary outcomes were the frequency of complications (reintubation, self-extubation, tracheostomy, and MV exceeding 21 days), cost, and mortality. One hundred patients consented to participate, and 49 patients were randomized to intervention, and 51

417.e4 patients were grouped as controls. Diagnoses of these patients included TBI (23%), SAH (19%), intracerebral hemorrage/arteriovenous malformation (34%), tumor (8%), and spinal trauma (4%). Most patients were intubated and mechanically ventilated due to their neurologic injury. No difference in any of the outcomes was found, and the median duration of ventilation (6 days) and time to first successful extubation (10 days) were similar for both groups. The overall mortality was 36%, 16 % were reintubated, and 29% had a tracheostomy performed. Interestingly, only 1 of 4 patients passing DS/SBT was actually offered an attempt to extubation. The overwhelming reason for not proceeding with extubation despite the prompt was poor mental status; the second important reason was the decision to perform a tracheostomy before any trial of extubation. The lack of any difference in outcomes should be seen as a failure of the protocol to alter caregiver behavior toward liberation, the main reason being that the protocol did not reflect the very special needs of a neurosurgical population by not incorporating neurologic criteria into the DS of these patients. In patients who were successfully extubated, GCS was the best predictor of successful extubation. In fact, the odds of being successfully extubated increased by 39% for every increment in the GCS and a GCS 8 or higher was most accurate for predicting successful extubation. The presence of a cough reflex was not associated with success on extubation. It should be noted that the reintubation rate in this study is quite high: only 61% of initial extubations were successful. The authors note that this contrasts with their experience in other ICUs at their institution in which as many as 85% first attempts are successful. No deaths or other complications of reintubation were observed, a finding attributed to close monitoring. Several studies have shown that delayed time to reintubation is a major cause of mortality from reintubation and that reintubation secondary to upper airway obstruction is associated with lower mortality when compared with nonairway etiologies [26]. Laxity of the airway is a common reason why extubation may fail in braininjured patients. In this sense, reintubation may be a reasonable risk to undertake in brain-injured patients who meet standard criteria and are closely monitored. Manno et al [27] attempted to assess the safety and feasibility of recruiting mechanically ventilated patients with brain injury, who are solely intubated for airway protection, into early or delayed extubation, and obtained estimates to refine sample size calculations for a larger study. This study randomized 16 brain-injured patients (GCS b8) into early (average, 3.8 days) or delayed extubation (7.4 days). Patients had to pass both hemodynamic/respiratory criteria and also a modified airway care score assessing their ability to handle secretions. The results suggested that between 64 and 110 patients are needed in each treatment arm to detect a treatment effect with 80% power. Recently, Navalesi et al [28] completed the first RCT comparing protocol-driven liberation from MV vs physiciandriven, nonprotocol discontinuation in neurocritically ill

C. Lazaridis et al. patients. These authors, within a dedicated NCCU, randomized 165 patients to the protocolized group and 153 to the control group. Their protocol was composed of standard cardiorespiratory screening criteria with the addition of a GCS 8 or higher and the presence of audible cough upon suctioning, followed by a 1-hour spontaneous breathing trial. Navalesi et al reported a decreased reintubation rate in the intervention group (5% vs 12%; P = .047). Mortality, rate of tracheostomy, duration of MV, and ICU LOS were not significantly different between the 2 groups. Patients on continuous sedation and/or controlled MV were excluded, potentially leading to the low observed mortality, reintubation rates, LOS, and tracheostomy rates. Tracheostomy was not part of the protocolized regimen [29]. A summary of MV discontinuation studies can be found in the Table 1.

4. Tracheostomy Tracheostomy is commonly performed in ICU patients and is increasingly done at the bedside as a percutaneous dilatational technique by intensivists not requiring specialized surgeons and operating room time [30-32]. It has many potential advantages over translaryngeal endotracheal intubation (ETT) including decreased danger of self-extubation and reduction of airway trauma; sinusitis; respiratory resistance; and, as a result, work of breathing [33]; it is better tolerated by patients leading to a potentially decreased need for sedation that by itself has been shown to accelerate liberation from MV [14]. Less sedation is of added value in neurocritical care patients, as it facilitates continuous neurologic assessments. The procedure, however, is not without risk, and potential complications include surgical site infection, hemorrhage, pneumomediastinum, pneumothorax, and death [34]. Tracheostomy should be deferred in patients with unstable ICP/CPP [35]. Furthermore, the appropriate timing for the most benefit is not well defined and may differ in different patient populations. The consensus conference on artificial airways in patients on MV published in 1989 suggested that, for anticipated need of the artificial airway for greater than 21 days, tracheostomy is preferred [36]. These recommendations remained in the more recent Evidence-Based Guidelines for Weaning and Discontinuing Ventilatory Support by McIntyre et al [3]. This task force did note that there are little quality data to guide clinicians on the optimal timing of tracheostomy in an inhomogeneous population of critically ill patients [3,6]. One of the first studies involving brain-injured patients is the report by D'Amelio et al [37], examining 43 multitrauma patients, including 31 patients with TBI, and the effects of early tracheostomy/percutaneous endoscopic gastrostomy placement (early b7 days) vs late. The authors found shorter ICU and hospital LOS and fewer days of MV postprocedures. The small number of subjects and the case series design are major limitations of these observations. Koh et al

Liberation of patients from MV and tracheostomy

Table 1

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Summary of Mechanical Ventilation Liberation Studies

Author-year

Study design

n

Brochard et al [10], 1994

RCT

109 Medical ICU; patients met standard weaning criteria but failed 2-h SBT

Esteban et al [11], 1995

RCT

130

Ely et al [5], 1996

RCT

300

Vallverdu et al [23], Prospective 1998 observational

217

Esteban et al [7], 1999

RCT

526

Brook et al [12], 1999

RCT

321

Kress et al [14], 2000

RCT

128

Coplin et al [19], 2000

Prospective observational

136

Namen et al [25], 2001

RCT

100

Salam et al [24], 2004

Prospective observational

88

Population

Intervention/predictors

Outcomes

Weaning with either Less failures (ventilation N21 d, T-piece (35), SIMV (43) reintubation, and tracheostomy) Or PSV (31) in PSV group (P b .05) Likelihood of remaining on ventilator, weaning duration, and length of ICU stay less in PSV group (P b .05). Duration of MV significantly less Medical ICU; neurologic Weaning with either IMV, PSV, intermittent in SBT group; risk ratio of illnesses and trauma successful weaning in once-daily multiple SBT, or included; patients met SBT group vs IMV (2.83, standard weaning criteria intermittent daily SBT 1.36-5.89) and PSV (2.05, but failed SBT 1.04-4.04). Medical ICU and DS with 2-h SBT vs DS Mean days of MV (4.5 vs 6), coronary CU complications (20% vs 41%), and ICU costs (15 740 vs 20 890) less in intervention group. Medical and surgical ICU; 3 categories of reasons Highest rate of reintubation in patients met standard for intubation: COPD, neurologic patients due to the weaning criteria and neurologic, and other inability to clear secretions; passed 2-h SBT causes of respiratory maximum expiratory pressure failure suggested as a predictor of success of extubation. Medical ICU; patients SBT trial for 30 vs No difference in rates of who met standard 120 min extubation, reintubation, weaning criteria successful extubation at 48 h, and mortality rates between 2 groups. Median duration of MV 55.9 vs Medical ICU; patients Protocol-directed 117 h (P b .05); significantly less who met standard sedation vs length of ICU stay (5.7 ± 5.9 vs weaning criteria non–protocol-directed 7.5 ± 6.5), hospital stay sedation (14 ± 17.3 vs 19.9 ± 24.2), and tracheostomy rates (6.4% vs 9.9%). Medical ICU Daily interruption of Lesser median duration of MV sedation vs sedation (4.9 vs 7.3; P b .05) and ICU interruption based on length of stay (6.4 vs 9.9; physician discretion P b .02); complications similar. Higher rates of pneumonia Brain-injured patients Delayed intubation (38% vs 21%; P b .05), hospital meeting readiness to beyond meeting the length of stay (19.9 vs 13.2 days; extubate criteria standard readiness P b .05) but similar reintubation criteria rates. No difference in median duration Patients in neurologic Respiratory-driven of MV and outcomes; GCS ICU screening with SBT predicts successful extubation. and prompts to care givers vs standard Medical ICU; patients CPF, secretions, and Risk ration of extubation failure met weaning parameters 4 simple tasks with CPF b60 L/min (4.8; 95% CI, and passed SBT 1.4-16.2), secretions N2.5 mL/h (3; 95% CI, 1-8.8), and failure to perform tasks (4.3; 95% CI, 1.8-10.4); 100% failure with presence of all 3 risk factors. (continued on next page)

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C. Lazaridis et al.

Table 1 (continued) Author-year

Study design

n

Tanios et al [9], 2006

RCT

Navalesi et al [28], 2008

RCT

Manno et al [27], 2008

Single-blinded RCT

Population

Intervention/predictors

Outcomes

304 Medical and general ICU; patients with primary neurologic events excluded

Respiratory rate/tidal volume ratio taken into decision vs standard

318 Neurologic patients

Systematic approach to weaning and extubation with daily screen and SBT vs physician directed approach Early or delayed extubation

Median duration of weaning (3 vs 2 days; P b .05) less for RSBI group; no difference in extubation failure, mortality, tracheostomy rates. Lesser reintubation rates (5% vs 12.5%; P b .05); no difference in rates of reintubation, duration of MV, length of stay, mortality, and tracheostomy. Small differences in modified Rankin score and functional independence measure.

16 Patients with severe brain injury (GCS b8) who passed respiratory criteria and airway care score

IMV indicates intermittent mandatory ventilation; CPF, cough peak flow; CI, confidence interval; RSBI, rapid shallow breathing rate; SIMV, synchronized intermittent mandatory ventilation.

[38] reported a retrospective review of 49 survivors from a neurosurgical ICU that were mechanically ventilated for more than 48 hours, 32 patients were successfully extubated, 9 underwent tracheostomy after one or more failed extubations, and 8 patients underwent elective tracheostomy. They found that elective early tracheostomy leads to shorter ICU stay when compared with tracheostomy performed after failed extubation attempts. In addition, the authors described a GCS less than 8 on day 7 as a good indicator of progression to tracheostomy. Of note, poorer GCS was not significantly associated with the need for reintubation. There was no description of the selection criteria used for elective tracheostomy. The author's recommendation is to proceed with tracheostomy at day 7, especially in patients with GCS less than 8 and presence of tenacious tracheal secretions. In a dedicated neurology/neurosurgery ICU, Qureshi et al [39] analyzed patients with infratentorial (cerebellum and brain stem) pathology secondary to hemorrhagic and ischemic strokes, brain tumors, and trauma. This retrospective chart review examined 69 patients, 23 were successfully extubated, 23 were tracheostomized, and 23 died before an attempt to extubation or tracheostomy. The decision to extubate was based on standard respiratory-related parameters in addition to GCS greater than 8, presence of strong cough, and tracheal suctioning not more frequent than every 2 hours. On multivariate logistic regression, GCS greater than 7 and absence of brain stem deficits (intact lower cranial nerve function and no long tract signs) were significantly and independently associated with successful extubation. The processes of liberation from positive pressure ventilation and discontinuation of the artificial airway constitute 2 separate events, and this becomes particularly evident in this select population of neurocritically ill patients with infratentorial lesions, most of which had minimal MV support requirements but needed a secure permanent airway. Despite the low potential for extubation, the authors argue that the

benefit of very early tracheostomy in such patients should be weighed against the high mortality rate during hospitalization observed in this group. They finally suggest tracheostomy after 8 days of MV to be a reasonable strategy. Bouderka at al [40] performed a prospective randomized trial in 62 patients with severe TBI (GCS ≤8 at time of enrollment). Patients were divided in 2 groups, one of an early tracheostomy after 5 days of ETT and another group of prolonged ETT. The early tracheostomy group had a reduced stay on MV, but there were no differences in mortality, ICU LOS, or rate of VAP. Weaning methods and sedation regimens were not described, making difficult to ascribe benefit to the strategy of earlier tracheostomy [41]. The largest RCT to investigate timing of tracheostomy in a mixed population of critically ill patients was recently published by Terragni et al [42]. This study was performed in Italian ICUs and randomized 419 patients of 600 studied, into an early tracheostomy group (after 6-8 days) and a late group (after 13-15 days). The primary end point, which was development of VAP, showed a trend toward reduction in the early group but did not reach statistical significance. There was no difference in the secondary outcomes of mortality (28-day and 1-year) and no difference in hospital LOS. Another important finding was that among both groups, a large number of patients did not eventually receive a tracheostomy (31% in the early group and 43% in the late group). The reasons for not receiving a tracheostomy were evenly divided between extubation and death [43]. This study does not support early tracheostomy in unselected ICU patients. Of particular interest to neurointensivists is the 102 of 419 patients who were randomized suffering of primary central nervous system failure. The trial investigators are currently looking at this subgroup of patients to determine if there is potentially difference among mechanically ventilated groups suffering by heterogeneous causes of primary organ failure (personal communication Marco Ranieri, MD).

Liberation of patients from MV and tracheostomy In summary, many patients with diverse acute insults to the brain require MV for either airway protection or management of secondary pulmonary and cardiac complications. Substantial literature exists to indicate a higher risk of VAP, prolonged ICU and hospital stays, and increased mortality in these patients. Cerebropulmonary interactions are not well defined, and optimizing the function of multiple organ systems can present clinicians with serious challenges especially when limited studies are available to guide management. This problem is evident with liberation of patients from MV and its parts, positive pressure, and the artificial airway. Our ability to predict “readiness” is poor, and commonly used measures are of questionable value and flawed by inconsistent reports regarding their accuracy. More and better studies are required to evaluate the pathophysiology of extubation failure in braininjured patients, to quantify the risks of reintubation, and to explore better predictors of extubation outcomes. Tracheostomy is a commonly performed procedure in the ICU for patients who require prolonged MV and/or need a stable airway. Patient selection and timing are intensely debated. Within general ICU populations, there seems not to be a major advantage from tracheostomy performed earlier than 2 weeks of ETT. There are not enough data to make firm recommendations for patients placed on a mechanical ventilator primarily due to brain injury. Based on limited direct evidence, populations of patients who could be considered earlier rather than later for a tracheostomy include patients with GCS less than 8 after a week of ICU admission, patients with brain stem pathology (provided a reasonable prospect of survival), and patients with neuromuscular syndromes, severely affected, with anticipation of prolonged MV.

Acknowledgment The authors thank Dr J Schnellmann, PhD, for her invaluable inputs during manuscript preparation.

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