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Search Results: 1 - 10 of 52928 matches for " David Zygun "
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Sodium and brain injury: do we know what we are doing?
David A Zygun
Critical Care , 2009, DOI: 10.1186/cc8014
Abstract: In the previous issue of Critical Care, Maggiore and colleagues [1] contributed significantly to our understanding of the incidence and associated consequences of hypernatremia in neurocritical care. This retrospective cohort study was performed in 130 consecutive patients with severe traumatic brain injury admitted to a tertiary academic referral institution. Hypernatremia was common, occurring in 51.5% of patients for 31% of the duration of their intensive care unit (ICU) stay. Hypernatremia was associated with a threefold increase in hazard of ICU death, even after adjustment for baseline risk. These results are consistent with the previous work of Aiyagari and colleagues [2], who found that hypernatremia was independently associated with increased mortality but only when severe (serum sodium >160 mEq/L) in a mixed neurocritical care sample that included patients with traumatic brain injury.It is important to note that these non-interventional studies employed rigorous analytic techniques to account for the etiology of sodium disturbance. Such complex analytic techniques are required as sodium concentration abnormalities may be due to consequences of the injury (for example, central diabetes insipidus or hyperglycemia induced osmotic diruesis) or may be related to treatment (for example, hypertonic saline or mannitol). Maggiore and colleagues [1] admirably performed a detailed analysis that included many relevant potential confounders in an attempt to describe the independent association of hypernatremia and mortality.Arguably, potentially important covariates have been excluded. Although adjusted for baseline risk using the impact prognostic model, the analysis did not include relevant ICU prognostic factors such as the development and degree of intracranial hypertension or systemic hypotension. This is significant when considering the indications for hypertonic saline and mannitol in neurotrauma. Both therapies are used as treatment of intracranial hypertension
Anemia and red blood cell transfusion in neurocritical care
Andreas H Kramer, David A Zygun
Critical Care , 2009, DOI: 10.1186/cc7916
Abstract: The first portion of this paper is a narrative review of the physiologic implications of anemia, hemodilution, and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations.There have been no randomized controlled trials that have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiologic studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiologic parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions.Although hemoglobin concentrations as low as 7 g/dl are well tolerated in most critical care patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurologic implications of transfusion also requires further investigation.A key paradigm in the management of neurocritical care patients is the avoidance of 'secondary' cerebral insults [1-3]. The acutely injured brain is vulnerable to systemic derangements, such as hypotension, hypoxemia, or fever, which may further exacerbate neuronal damage [4-7]. Thus, critical care practitioners attempt to maintain a physiologic milieu that minimizes secondary injury, thereby maximizing the chance of a favorable functional and neurocognitive recovery.Anemia is
Optimal glycemic control in neurocritical care patients: a systematic review and meta-analysis
Andreas H Kramer, Derek J Roberts, David A Zygun
Critical Care , 2012, DOI: 10.1186/cc11812
Abstract: We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing intensive insulin therapy with conventional glycemic control among patients with traumatic brain injury, ischemic or hemorrhagic stroke, anoxic encephalopathy, central nervous system infections or spinal cord injury.Sixteen RCTs, involving 1248 neurocritical care patients, were included. Glycemic targets with intensive insulin ranged from 70-140 mg/dl (3.9-7.8 mmol/L), while conventional protocols aimed to keep glucose levels below 144-300 mg/dl (8.0-16.7 mmol/L). Tight glycemic control had no impact on mortality (RR 0.99; 95% CI 0.83-1.17; p = 0.88), but did result in fewer unfavorable neurological outcomes (RR 0.91; 95% CI 0.84-1.00; p = 0.04). However, improved outcomes were only observed when glucose levels in the conventional glycemic control group were permitted to be relatively high [threshold for insulin administration > 200 mg/dl (> 11.1 mmol/L)], but not with more intermediate glycemic targets [threshold for insulin administration 140-180 mg/dl (7.8-10.0 mmol/L)]. Hypoglycemia was far more common with intensive therapy (RR 3.10; 95% CI 1.54-6.23; p = 0.002), but there was a large degree of heterogeneity in the results of individual trials (Q = 47.9; p<0.0001; I2 = 75%). Mortality was non-significantly higher with intensive insulin in studies where the proportion of patients developing hypoglycemia was large (> 33%) (RR 1.17; 95% CI 0.79-1.75; p = 0.44).Intensive insulin therapy significantly increases the risk of hypoglycemia and does not influence mortality among neurocritical care patients. Very loose glucose control is associated with worse neurological recovery and should be avoided. These results suggest that intermediate glycemic goals may be most appropriate.A key paradigm in the care of patients with acute brain and spinal cord injury is prevention of physiological abnormalities that may contribute to secondary neurological damage. Hyperglycemia is c
Pro/con debate: In patients who are potential candidates for organ donation after cardiac death, starting medications and/or interventions for the sole purpose of making the organs more viable is an acceptable practice
Jason Phua, Tow Lim, David A Zygun, Christopher J Doig
Critical Care , 2007, DOI: 10.1186/cc5711
Abstract: You are an intensivist in an institution that performs solid organ transplantations. In an effort to provide patients and families with increased opportunities to donate their organs, the institution has recently developed a policy for donation after cardiac death (DCD). With the new DCD policy, organ donation is offered to patients and their families in a controlled setting when death occurs immediately following the withdrawal of life-support. Based on your understanding of organ donation, you are aware there are certain medications (for example, inotropes to maintain tissue perfusion) and certain management practices that may allow the donated organs to have better outcome. You wonder about the ethics of starting interventions that will have no benefit to the dying patient but will benefit the organs that are about to be donated.Jason Phua and Tow Keang LimWhat medications and interventions are started in potential donors before death for the sole purpose of making the organs more viable in DCD, and how do they affect organ function?Firstly, inotropes and vasopressors are crucial for the preservation of organ perfusion in patients in shock. The majority of potential donors are hypotensive before cardiac death [1], and hypotension worsens graft function [2]. Secondly, anticoagulants such as heparin decrease the risk of thrombosis after the circulatory arrest and the negative consequences on organ function. To maximize effectiveness, heparin should ideally be administered before death into an intact circulation for systemic distribution [3]. Experimental data show preserved organ function with antemortem but not postmortem heparin administration [4,5]. Thirdly, vasodilators such as phentolamine may enhance organ blood flow and lower the incidence of delayed renal graft function [6]. More controversial practices are the administration of thrombolytics and antemortem cannulation in preparation for the administration of cold preservation solution.Although rarely perfo
SOFA is superior to MOD score for the determination of non-neurologic organ dysfunction in patients with severe traumatic brain injury: a cohort study
David Zygun, Luc Berthiaume, Kevin Laupland, John Kortbeek, Christopher Doig
Critical Care , 2006, DOI: 10.1186/cc5007
Abstract: We performed a prospective cohort study at Foothills Medical Centre, the sole adult tertiary care trauma center servicing southern Alberta (population about 1.3 million). All patients aged 16 years or older with severe traumatic brain injury and intensive care unit length of stay greater than 48 hours between 1 May 2000 and 31 April 2003 were included. Non-neurologic organ dysfunction was measured using the SOFA and MODS scoring systems. Determination of organ dysfunction for each non-neurologic organ system was compared between the two systems by calculating the proportion of patients with SOFA and MOD component score defined organ failure. Consistent with previous literature, organ system failure was defined as a component score of three or greater.The odds of death and unfavorable neurologic outcome in patients with SOFA defined cardiovascular failure were 14.7 times (95% confidence interval [CI] 5.9–36.3) and 7.6 times (95% CI 3.5–16.3) that of those without cardiovascular failure, respectively. The development of SOFA-defined cardiovascular failure was a reasonable discriminator of hospital mortality and unfavorable neurologic outcome (area under the receiver operating characteristic [ROC] curve 0.75 and 0.73, respectively). The odds of death and unfavorable neurologic outcome in patients with MOD-defined cardiovascular failure were 2.6 times (95% CI 1.24–5.26) and 4.1 times (95% CI 1.3–12.4) that of those without cardiovascular failure, respectively. The development of MOD-defined cardiovascular failure was a poor discriminator of hospital mortality and unfavorable neurologic outcome (area under the ROC curve 0.57 and 0.59, respectively). Neither SOFA-defined nor MOD-defined respiratory failure was significantly associated with hospital mortality.In patients with brain injury, the SOFA scoring system has superior discriminative ability and stronger association with outcome compared with the MOD scoring system with respect to hospital mortality and unfavorable
The epidemiology of intensive care unit-acquired hyponatraemia and hypernatraemia in medical-surgical intensive care units
Henry Stelfox, Sofia B Ahmed, Farah Khandwala, David Zygun, Reza Shahpori, Kevin Laupland
Critical Care , 2008, DOI: 10.1186/cc7162
Abstract: We identified 8142 consecutive adults (18 years of age or older) admitted to three medical-surgical ICUs between 1 January 2000 and 31 December 2006 who were documented to have normal serum sodium levels (133 to 145 mmol/L) during the first day of ICU admission. ICU acquired hyponatraemia and hypernatraemia were respectively defined as a change in serum sodium concentration to below 133 mmol/L or above 145 mmol/L following day one in the ICU.A first episode of ICU-acquired hyponatraemia developed in 917 (11%) patients and hypernatraemia in 2157 (26%) patients with an incidence density of 3.1 and 7.4 per 100 days of ICU admission, respectively, during 29,142 ICU admission days. The incidence of both ICU-acquired hyponatraemia (age, admission diagnosis, Acute Physiology and Chronic Health Evaluation (APACHE) II score, length of ICU stay, level of consciousness, serum glucose level, body temperature, serum potassium level) and ICU-acquired hypernatraemia (baseline creatinine, APACHE II score, mechanical ventilation, length of ICU stay, body temperature, serum potassium level, level of care) varied according to patients' characteristics. Compared with patients with normal serum sodium levels, hospital mortality was increased in patients with ICU-acquired hyponatraemia (16% versus 28%, p < 0.001) and ICU-acquired hypernatraemia (16% versus 34%, p < 0.001).ICU-acquired hyponatraemia and hypernatraemia are common in critically ill patients and are associated with increased risk of hospital mortality.Sodium disturbances, leading to hyponatraemia and hypernatraemia, are a common problem in adult patients admitted to hospital and are associated with hospital mortality rates ranging from 42% to 60% [1-7]. Because of their incapacitation, lack of free access to water and the usually serious nature of their underlying diseases, patients in the intensive care unit (ICU) are at high risk of developing sodium disturbances [8]. However, previous studies suggest that sodium disturban
Intensivists' base specialty of training is associated with variations in mortality and practice patterns
Emma O Billington, David A Zygun, H Tom Stelfox, Adam D Peets
Critical Care , 2009, DOI: 10.1186/cc8227
Abstract: The records of all patients who were admitted to one of three closed multi-system ICUs within tertiary care centers in the Calgary Health Region, Alberta, Canada, during a five year period were retrospectively reviewed. Outcomes for patients admitted by Intensivists with base training in General Internal Medicine, Pulmonary Medicine, or other eligible base specialties (Anesthesia, General Surgery, and Emergency Medicine combined) were compared.ICU mortality in the entire cohort (n = 9,808) was 17.2% and in-hospital mortality was 32.0%. After controlling for potential confounders, ICU mortality (odds ratio (OR): 0.69; 95% confidence interval (CI): 0.52 to 0.94) was significantly lower for patients admitted by Intensivists with Pulmonary Medicine as a base specialty of training, but not ICU length of stay (LOS) (coefficient: 0.11; -0.20 to 0.42) or hospital mortality (OR: 0.88; 0.68 to 1.13). There was no difference in ICU or hospital mortality or length of stay between the three base specialty groups for patients who were admitted and managed by a single Intensivist for their entire ICU admission (n = 4,612). However, we identified significant variation in practice patterns between the three specialty groups for the number of invasive procedures performed and decisions to limit life-sustaining therapies.Intensivists' base specialty of training is associated with practice pattern variations. This may contribute to differences in processes and outcomes of patient care.Over the past decade, the literature has suggested that Intensive Care Units (ICUs) staffed by physicians certified in critical care medicine led to improved patient outcomes [1]. However, a recent retrospective review of over 100,000 ICU admissions found the opposite: patients managed by critical care physicians were at increased risk of death compared to those managed by physicians without critical care training [2]. Potential explanations given for these discrepant results included inability to control
The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study
Ben J Wilson, Hamish J Cowan, Jason A Lord, Dan J Zuege, David A Zygun
BMC Emergency Medicine , 2010, DOI: 10.1186/1471-227x-10-9
Abstract: This analysis consisted of a retrospective cohort of 88 consecutive ED patients with severe sepsis who had a simultaneous arterial blood gas and an SpO2 value recorded. Adult ICU patients that were admitted from any Calgary Health Region adult ED with a pre-specified, sepsis-related admission diagnosis between October 1, 2005 and September 30, 2006, were identified. Accuracy (SpO2 - SaO2) was analyzed by the method of Bland and Altman. The effects of hypoxemia, acidosis, hyperlactatemia, anemia, and the use of vasoactive drugs on bias were determined.The cohort consisted of 88 subjects, with a mean age of 57 years (19 - 89). The mean difference (SpO2 - SaO2) was 2.75% and the standard deviation of the differences was 3.1%. Subgroup analysis demonstrated that hypoxemia (SaO2 < 90) significantly affected pulse oximeter accuracy. The mean difference was 4.9% in hypoxemic patients and 1.89% in non-hypoxemic patients (p < 0.004). In 50% (11/22) of cases in which SpO2 was in the 90-93% range the SaO2 was <90%. Though pulse oximeter accuracy was not affected by acidoisis, hyperlactatementa, anemia or vasoactive drugs, these factors worsened precision.Pulse oximetry overestimates ABG-determined SaO2 by a mean of 2.75% in emergency department patients with severe sepsis and septic shock. This overestimation is exacerbated by the presence of hypoxemia. When SaO2 needs to be determined with a high degree of accuracy arterial blood gases are recommended.Pulse oximetry is a routine part of the monitoring and management of critically ill patients [1]. Studies have proposed that specific pulse oximter oxygen saturations (SpO2) be targeted to decrease the likelihood of hypoxemia [1-4], to titrate fractional inspired oxygen [5], and to wean mechanical ventilation [6].The accuracy of pulse oximetry to estimate arterial oxygen saturation (SaO2) in critically ill patients has yielded mixed results. Both the degree of inaccuracy, or bias, and its direction has been inconsistent [1-3,5,7
Prolonged refractory status epilepticus following acute traumatic brain injury: a case report of excellent neurological recovery
Adam D Peets, Luc R Berthiaume, Sean M Bagshaw, Paolo Federico, Christopher J Doig, David A Zygun
Critical Care , 2005, DOI: 10.1186/cc3884
Abstract: This case report describes a 20 year old previously healthy woman who suffered a severe TBI as a result of a motor vehicle collision and subsequently developed RSE. Pharmacological coma, physiological support and continuous electroencephalography (cEEG) were undertaken.Following 25 days of pharmacological coma, electrographic and clinical seizures subsided and the patient has made an excellent cognitive recovery.With early identification, aggressive physiological support, appropriate monitoring, including cEEG, and an adequate length of treatment, young trauma patients with no previous seizure history and limited structural damage to the brain can have excellent neurological recovery from prolonged RSE.We describe a case of refractory status epilepticus (RSE) secondary to traumatic brain injury (TBI) requiring 25 days of pharmacological coma with subsequent excellent neurological recovery. A review of the relevant literature on RSE, including diagnostic and treatment issues as well as the difficult ethical questions surrounding appropriate length of treatment in this condition, is undertaken.A previously healthy right-handed 20 year old woman sustained multiple injuries following a rollover motor vehicle collision. Her initial Glasgow Coma Scale (GCS) was 6, but deteriorated to 3 on scene. Her vehicle was found overturned. She was belted into the driver's seat with the shoulder belt compressing her neck. Her face was cyanotic. She was intubated on scene and transferred to hospital.In the emergency department, her temperature was 35.7°C, blood pressure 112/66, heart rate 108 and oxygen saturation on 50% FiO2 was 98%. Pupils were 3 mm equal and reactive. Minimal withdrawal to pain in the lower extremities was noted. Reflexes were 1+ and symmetric with equivocal plantar responses.Initial laboratory investigations were normal. Injuries identified included a burst fracture of the 6th and 7th cervical vertebral bodies with canal narrowing of 50%, subluxation of the right
Critical care resource allocation: trying to PREEDICCT outcomes without a crystal ball
Michael D Christian, Robert Fowler, Matthew P Muller, Charles Gomersall, Charles L Sprung, Nathaniel Hupert, David Fisman, Andrew Tillyard, David Zygun, John C Marshal, PREEDICCT Study Group
Critical Care , 2013, DOI: 10.1186/cc11842
Abstract: The International Forum of Acute Care Trialists (InFACT) was formed in 2009 and provided a platform for international critical care research collaboration during the 2009/10 influenza A(H1N1) pandemic [12]. Over the past 2 years, a number of working groups have emerged from InFACT focused upon improving the investigation and care of patients with severe respiratory illness. Arising from these efforts, in June 2012 an inter-national group of clinicians convened the first meeting of the Providing Resources for Effective and Ethical Decisions In Critical Care Triage (PREEDICCT) Study Group. The study group's aim is to develop decision support tools appropriate for triaging critically ill adult patients during epidemics, mass-casualty scenarios or other resource-limited settings. This meeting identified a number of knowledge gaps and research priorities in this area, and suggested a revised framework for the requirements of an adequate triage decision support tool.While purpose-built triage protocols focus on specific events (for example, pandemics), resource allocation decisions are part of everyday practice for critical care physicians worldwide. Several PREEDICCT members work in settings where there are chronically insufficient critical care resources to meet the demand [13]. Critical care physicians also make resource allocation decisions every day in high-income countries, as they decide who might benefit from ICU care, when to accept outside transfers and when insufficient capacity dictates external transfer of patients. Yet intensivists lack objective tools to support these decision-making processes. Further, practices and specific decisions are likely to vary widely by country, by hospital and by individual provider.The first significant shift in direction advocated by our group is to move away from attempting to use a physiologic score alone to predict outcomes. The rationale for basing triage tools on a physiologic score is that all critically ill patients com
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