***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Introduction Endotracheal suctioning ( ETS ) is essential for patient care in an ICU but may represent a cause of cerebral secondary injury . Ketamine has been historically contraindicated for its use in head injury patients , since an increase of intracranial pressure ( ICP ) was reported ; nevertheless , its use was recently suggested in neurosurgical patients . In this prospect i ve observational study we investigated the effect of ETS on ICP , cerebral perfusion pressure ( CPP ) , jugular oxygen saturation ( SjO2 ) and cerebral blood flow velocity ( mVMCA ) before and after the administration of ketamine . Methods In the control phase , ETS was performed on patients se date d with propofol and remifentanil in continuous infusion . If a cough was present , patients were assigned to the intervention phase , and 100 γ/kg/min of racemic ketamine for 10 minutes was added before ETS . Results In the control group ETS stimulated the cough reflex , with a median cough score of 2 ( interquartile range ( IQR ) 1 to 2 ) . Furthermore , it caused an increase in mean arterial pressure ( MAP ) ( from 89.0 ± 11.6 to 96.4 ± 13.1 mmHg ; P < 0.001 ) , ICP ( from 11.0 ± 6.7 to 18.5 ± 8.9 mmHg ; P < 0.001 ) , SjO2 ( from 82.3 ± 7.5 to 89.1 ± 5.4 ; P = 0.01 ) and mVMCA ( from 76.8 ± 20.4 to 90.2 ± 30.2 cm/sec ; P = 0.04 ) . CPP did not vary with ETS . In the intervention group , no significant variation of MAP , CPP , mVMCA , and SjO2 were observed in any step ; after ETS , ICP increased if compared with baseline ( 15.1 ± 9.4 vs. 11.0 ± 6.4 mmHg ; P < 0.05 ) . Cough score was significantly reduced in comparison with controls ( P < 0.0001 ) . Conclusions Ketamine did not induce any significant variation in cerebral and systemic parameters . After ETS , it maintained cerebral hemodynamics without changes in CPP , mVMCA and SjO2 , and prevented cough reflex . Nevertheless , ketamine was not completely effective when used to control ICP increase after administration of 100 γ/kg/min for 10 minutes Objective : The manual injection of a bolus of opioid in patients with brain injury induces an increase in intracranial pressure related to a decrease in mean arterial pressure . Such an effect has not been observed with the use of ketamine . The use of target-controlled infusion would minimize or suppress this adverse effect of opioid . This study evaluated the effects of an increase in plasma concentrations of sufentanil or ketamine administered by target-controlled infusion on cerebral hemodynamics . Design : Prospect i ve , r and omized study . Setting : Intensive care unit in a trauma center . Patients : Thirty patients with severe traumatic brain injury . Interventions : Patients were assigned to receive sedation consisting of sufentanil-midazolam or ketamine-midazolam using target-controlled infusion . Twenty-four hours after the onset of sedation , the target concentrations of sufentanil or ketamine were doubled for 15 mins . Blood sample s were collected to determine the actual plasma concentration of sufentanil and ketamine , before and 15 mins after concentration change . Measurements and Main Results : The baseline values of intracranial pressure and cerebral perfusion pressure were similar in both groups . The two-fold increase in drug concentrations did not involve a significant change for intracranial pressure , cerebral perfusion pressure , and mean velocity of middle cerebral artery in both the ketamine and the sufentanil groups . The measured plasma concentrations of sufentanil and ketamine  were 0.4 ± 0.2 ng/mL and 2.6 ± 2.2 & mgr;g/mL , respectively , before the increase in concentrations and 0.7 ± 0.4 ng/mL and 5.5 ± 3.8 & mgr;g/mL after . Conclusions : The present study shows that the increase in sufentanil or ketamine plasma concentrations using a target-controlled infusion is not associated with adverse effects on cerebral hemodynamics in patients with severe brain injury . The use of target-controlled infusion could be of interest in the management of severely brain-injured patients . However , there is a need for specific pharmacokinetic models design ed for intensive care unit patients Summary Ketamine was supposed to be contra-indicated in head injured patients although it possesses numerous advantages over other commonly used analgosedative drugs . Referring to these potential advantages and the lack of definitive data about its effect upon ICP , CPP or neurological development , we conducted a prospect i ve study in which moderate or severely head injured patients ( n=35 ) were prospect ively allocated to receive treatment either with a combination of ketamine and midazolam or fentanyl and midazolam . The initial dose was 6.5 mg/kg/day midazolam , 65 mg/kg/day ketamine or 65 μg/kg/day fentanyl and was later adjusted due to clinical requirements for a period of 3 to 14 days . Comparably high dosages of detamine have been found necessary ( 104 mg/kg/day).Four patients from the ketamine group ( n=17 ) and 5 from the control group ( n=18 ) were withdrawn during treatment due to persistent ICP above 25 mm Hg , countermeasured by barbiturate coma . Two more patients were withdrawn due to development of cardiovascular arrest ( ketamine group ) and multi organ failure . A comparison of the remaining patients revealed a lower requirement of catecholamines ( significant on first day , p<0.05 ) , an on average 8 mm Hg higher cerebral perfusion pressure and a 2 mm Hg higher intracranial pressure in the fentanyl group . Enterai food intake was better in the study group . The outcome was comparable in both groups with or without inclusion of withdrawn patients Rationale Use of etomi date in the critically ill is controversial due to its links with an inadequate response to corticotropin and potential for excess mortality . In a septic shock population , we tested the hypotheses that etomi date administration induces more non-responders to corticotropin and increases mortality and that hydrocortisone treatment decreases mortality in patients receiving etomi date . Methods An a-priori sub- study of the CORTICUS multi-centre , r and omised , double-blind , placebo-controlled trial of hydrocortisone in septic shock . Use and timing of etomi date administration were collected . Endpoints were corticotropin response and all-cause 28-day mortality in patients receiving etomi date . Measurements and main results Five hundred patients were recruited , of whom 499 were analysable ; 96 ( 19.2 % ) were administered etomi date within the 72 h prior to inclusion . The proportion of non-responders to corticotropin  was significantly higher in patients who were given etomi date in the 72 h before trial inclusion than in other patients ( 61.0 vs. 44.6 % , P = 0.004 ) . Etomi date therapy was associated with a higher 28-day mortality in univariate analysis ( P = 0.02 ) and after correction for severity of illness ( 42.7 vs. 30.5 % ; P = 0.06 and P = 0.03 ) in our two multi-variant models . Hydrocortisone administration did not change the mortality of patients receiving etomi date ( 45 vs. 40 % ) . Conclusions The use of bolus dose etomi date in the 72 h before study inclusion is associated with an increased incidence of inadequate response to corticotropin , but is also likely to be associated with an increase in mortality . We recommend clinicians demonstrate extreme caution in the use of etomi date in critically ill patients with septic shock We compared the effect of S(+)-ketamine to remifentanil , both in combination with propofol , on the neurocognitive outcome after open-heart surgery in 106 patients . A battery of neurocognitive tests was administered before surgery and 1 and 10 wk after surgery . Fourteen patients ( 25 % ) in the control group and 10 patients ( 20 % ) in the S(+)-ketamine group had 2 or more tests with a cognitive deficit ( decline by at least one preoperative SD of that test in all patients ) 10 wk after surgery ( P = 0.54 ) . Z-scores were calculated for all tests . No significantly better performance could be detected in the S(+)-ketamine group , except for the Trailmaking B test 10 wk after surgery . We conclude that S(+)-ketamine offers no greater neuroprotection compared with remifentanil during open-heart surgery Background : The potential adverse effects of ketamine in neurosurgical anesthesia have been well established and involve increased intracranial pressure ( ICP ) and cerebral blood flow . However , reexamination of ketamine is warranted because data regarding the effects of ketamine on cerebral hemodynamics are conflicting . Methods : Eight patients with traumatic brain injury were studied . In all patients , ICP monitoring was instituted before the study . Control of ICP ( less than 25 mmHg ) , hemodynamic values , and blood gas tension ( partial pressure of carbon dioxide in arterial blood between 35–38 mmHg ) was obtained with propofol infusion ( 3 mg [ center dot ] kg sup ‐1 [ center dot ] h sup ‐1 ) and mechanical ventilation . The effects of three doses of ketamine , 1.5 , 3 , and 5 mg/ kg , respectively , on ICP , cerebral perfusion pressure , jugular vein bulb oxygen saturation , middle cerebral artery blood flow velocity , and electric activity of the brain ( EEG ) were measured . The three doses were administered intravenously at 6‐h intervals over 30 s through a central venous line . Systemic and cerebral hemodynamics and end‐tidal carbon dioxide were continuously monitored and recorded at 1‐min intervals throughout the 30‐min study periods . Results : Ketamine , in all three doses studied ( 1.5 , 3 , and 5 mg/kg ) was associated with a significant decrease in ICP ( mean + /‐ SD : 2 + /‐ 0.5 mmHg [ P < 0.05 ] , 4 + /‐ 1 mmHg [ P < 0.05 ] , and 5 + /‐ 2 mmHg [ P < 0.05 ] ) among the study patients regardless of the ketamine dose used . There were no significant differences in cerebral perfusion pressure , jugular vein bulb oxygen saturation , and middle cerebral artery blood flow velocity . Ketamine induced a low‐amplitude fast‐activity electroencephalogram , with marked depression , such as burst suppression . Conclusions : These results suggest that ketamine may not adversely alter cerebral hemodynamics of mechanically ventilated head‐trauma patients se date d with propofol . These encouraging results should be confirmed in larger groups of similar patients OBJECTIVES To ascertain whether the sedative agent administered during  neuromuscular-blocking agent-facilitated intubation ( rapid sequence intubation [ RSI ] )  influences the number of attempts and overall success at RSI . METHODS Records were drawn from an ongoing , prospect i ve multicenter registry of emergency department intubations . Conditional logistic regression stratified by institution was used to identify factors associated with multiple intubation attempts and unsuccessful RSI . RESULTS Of 3,407 intubations over 33 months in 22 institutions , 2,380 involved RSI . After correcting for the specialty and experience of the intubator and for the presence of airway aberrancy , the sedative agent was significantly associated with the number of attempts at intubation ( p = 0.002 ) . Specifically , the use of etomi date ( adjusted odds ratio [ OR ] 0.35 [ 95 % CI = 0.17 to 0.72 ] ) , ketamine ( OR 0.27 [ 95 % CI = 0.11 to 0.65 ] ) , a benzodiazepine ( OR 0.47 [ 95 % CI = 0.23 to 0.95 ] ) , or no sedative agent ( OR 0.51 [ 95 % CI = 0.23 to 1.13 ] ) prior to neuromuscular blockade was associated with a lower likelihood of successful intubation on the first attempt , as compared with thiopental , methohexital , or propofol . The adjusted odds ratios for the likelihood of overall success had similar point estimates , but did not reach statistical significance due to lack of power ( p = 0.2 , with 36 unsuccessful intubations ) . Among patients receiving etomi date , intubation was more likely to be successful on the first attempt with increasing doses of either etomi date or succinylcholine . CONCLUSIONS Thiopental , methohexital , and propofol appear to facilitate RSI in emergency department patients , independent of patient characteristics or intubator training . A deeper plane of anesthesia may improve intubating conditions in emergency patients undergoing RSI by complementing incomplete muscle paralysis Objective The aim of the study was to compare the safety concerning cerebral hemod 
    Output:
    
CONCLUSION According to the available literature , the use of ketamine in critically ill patients does not appear to adversely affect patient outcomes