Malcolm Sim

The Effect of High-Flow Nasal Cannula Oxygen Therapy on Mortality and Intubation Rate in Acute Respiratory Failure: A Systematic Review and Meta-Analysis.

Objective: High-flow nasal cannulae are used in adults with or at risk of acute respiratory failure. We conducted a systematic review and meta-analysis to evaluate the evidence for their use in this setting. Data Sources: Ovid Medline, Embase, and Cochrane Database of Systematic Reviews. Study Selection: Databases were searched for randomized controlled trials comparing administration of high-flow nasal cannulae with usual care (i.e., conventional oxygen therapy or noninvasive ventilation) in adults with respiratory failure. The primary outcome was hospital mortality; the rate of intubation and assessment of delirium and comfort were secondary outcomes. Data Extraction: One hundred forty-seven nonduplicate citations were screened, 32 underwent full screening and data extraction, and 14 trials were eligible for inclusion in the review. Nine trials were used in the meta-analysis, including a total of 2,507 subjects. Data Synthesis: When high-flow nasal cannulae were compared with usual care, there was no difference in mortality (high-flow nasal cannulae, 60/1,006 [6%] vs usual care, 90/1,106 [8.1%]) (n = 2,112; p = 0.29; I 2, 25%; fixed effect model: odds ratio, 0.83; 95% CI, 0.58–1.17) or rate of intubation (high-flow nasal cannulae, 119/1,207 [9.9%] vs usual care, 204/1,300 [15.7%]) (n = 2,507; p = 0.08; I 2, 53%; random effect model: odds ratio, 0.63; 95% CI, 0.37–1.06). A qualitative analysis of 13 studies on tolerability and comfort suggested that high-flow nasal cannulae are associated with improved patient comfort and dyspnea scores. Trial sequential analyses on primary and secondary outcomes suggested that required information size was not reached. Conclusions: No difference in mortality or intubation was detected in patients with acute respiratory failure treated with high-flow nasal cannulae compared with usual care. High-flow nasal cannulae seem well tolerated by patients. Further large randomized controlled trials are required to evaluate their utility in this setting.

Confirmed Bacillus anthracis Infection among Persons Who Inject Drugs, Scotland, 2009–2010

Patients who died had an increased sequential organ failure assessment score and need for vasopressors.

ACHE: An Architecture for Clinical Hypothesis Examination

Physiological monitoring equipment can be found in many hospital settings. This allows a wide range of physiological parameters to be stored, which in turn allows clinicians and analysts to investigate a range of medical hypotheses. This paper introduces ACHE (architecture for clinical hypotheses examination), a framework specifically designed to support the preparation of such analyses. To evaluate the initial version of ACHE, a study to detect acute myocardial infarctions, was conducted with data from Glasgow Royal Infirmarys Intensive Care Unit (ICU). Initial results from the study are very encouraging and ACHE substantially reduced the time required to perform the study. A study of the same phenomena across a much larger patient dataset will be undertaken shortly.

Argumentation-logic for explaining anomalous patient responses to treatments

The EIRA system has proved to be successful in the detection of anomalous patient responses to treatments in the Intensive Care Unit (ICU). One weakness of EIRA is the lack of mechanisms to describe to the clinicians, rationales behind the anomalous detections. In this paper, we extend EIRA by providing it with an argumentation-based justification system that formalizes and communicates to the clinicians the reasons why a patient response is anomalous. The implemented justification system uses human-like argumentation techniques and is based on real dialogues between ICU clinicians.

A System to Detect Inconsistencies between a Domain Expert’s Different Perspectives on (Classification) Tasks

This paper discusses the range of knowledge acquisition, including machine learning, approaches used to develop knowledge bases for Intelligent Systems. Specifically, this paper focuses on developing techniques which enable an expert to detect inconsistencies in 2 (or more) perspectives that the expert might have on the same (classification) task. Further, the INSIGHT system has been developed to provide a tool which supports domain experts exploring, and removing, the inconsistencies in their conceptualization of a task. We report here a study of Intensive Care physicians reconciling 2 perspectives on their patients. The high level task which the physicians had set themselves was to classify, on a 5 point scale (A-E), the hourly reports produced by the Unit’s patient management system. The 2 perspectives provided to INSIGHT were an annotated set of patient records where the expert had selected the appropriate category to describe that snapshot of the patient, and a set of rules which are able to classify the various time points on the same 5-point scale.

Uptake of therapeutic hypothermia following out‐of‐hospital cardiac arrest in Scottish Intensive Care Units

hypothermia after cardiac arrestonce again. Critical Care and Resuscitation 2006; 8: 151–4. 7 Alderson P, Gadkary C, Signorini DF. Therapeutic hypothermia for head injury. Cochrane Database of Systematic Reviews 1999; 2: CD001048. DOI: 10.1002 ⁄ 14651858.CD001048.pub2 8 Frank SM, Fleisher LA, Breslow MJ, et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. Journal of the American Medical Association 1997; 277: 1127– 34.

Predicting adverse events: detecting myocardial damage in intensive care unit (ICU) patients

Myocardial damage is known to occur relatively frequently, and although it is not often fatal it results in the patient staying in the ICU for significantly longer. Thus it is important for clinicians to detect these events. Confirmation of myocardial damage is by a biomarker (troponin), but these tests are only done at fixed time-points. Consequently it is desirable for doctors, and support systems, to detect myocardial damage from the standard parameters collected for ICU patients. We have undertaken a study with several ICU consultants to determine the conditions which generally precede a myocardial-damaging event. In fact, these knowledge acquisition sessions produced a complex model which we have realized as 2 interacting modules. Subsequently, we compared this models predictions against the original datasets; the model when run against the test dataset resulted in a relatively high True Positive (TP) rate (75.8%). The implications of these analyses are discussed, as are a number of planned follow-up studies

Detecting and resolving inconsistencies between domain experts' different perspectives on (classification) tasks

OBJECTIVES The work reported here focuses on developing novel techniques which enable an expert to detect inconsistencies in 2 (or more) perspectives that the expert might have on the same (classification) task. The high level task which the experts (physicians) had set themselves was to classify, on a 5-point severity scale (A-E), the hourly reports produced by an intensive care units patient management system. METHOD The INSIGHT system has been developed to support domain experts exploring, and removing inconsistencies in their conceptualization of a task. We report here a study of intensive care physicians reconciling 2 perspectives on their patients. The 2 perspectives provided to INSIGHT were an annotated set of patient records where the expert had selected the appropriate category to describe that snapshot of the patient, and a set of rules which are able to classify the various time points on the same 5-point scale. Inconsistencies between these 2 perspectives are displayed as a confusion matrix; moreover INSIGHT then allows the expert to revise both the annotated datasets (correcting data errors, or changing the assigned categories) and the actual rule-set. RESULTS Each of the 3 experts achieved a very high degree of consensus (~97%) between his refined knowledge sources (i.e., annotated hourly patient records and the rule-set). We then had the experts produce a common rule-set and then refine their several sets of annotations against it; this again resulted in inter-expert agreements of ~97%. The resulting rule-set can then be used in applications with considerable confidence. CONCLUSION This study has shown that under some circumstances, it is possible for domain experts to achieve a high degree of correlation between 2 perspectives of the same task. The experts agreed that the immediate feedback provided by INSIGHT was a significant contribution to this successful outcome.

Propofol is not safe for sedation for hip relocation

We read with interest the clinically based study of Mathieu et al on the use of propofol to sedate patients for relocation of hip prostheses in the emergency department.1 The authors rightly point out that there are problems with the safety and efficacy of using midazolam, and conclude that the described technique is effective and safe. In another paper by the same authors, they demonstrate that this technique of ‘sedation’ has a better success than midazolam and reduces the delay in these patients going to theatre and therefore the discomfort the patients may experience (although there is no mention of pain scores of these patients).2 However, we disagree strongly with the conclusions that the adverse effects were acceptably uncommon and argue that the authors have not demonstrated the safety of this technique. First, we would like to comment on the sedation protocol. Disappointingly there is no attempt to describe the depth of sedation provided. The report of the Academy of Royal Colleges …

145: Development Of A Quantitative Clinical Instability Score Weighted For The Degree Of Support Required

Learning Objectives: Many currently available scoring systems characterizing physiological disturbance in critical illness ignore or only partially allow for the level of physiological support. For example, a patient may have a “normal” blood pressure while on inotropes or vasopressors. Hypothesis: A score of instability weighted for the degree of support could be developed from ranges used in current scoring systems and physiological principles. Methods: Five key consistently recorded physiological parameters were used to develop the score. These were mean arterial blood pressure, heart rate, oxygen saturation, urine output and body temperature. They were divided into 7 ranges of derangement. A literature review of other scores and accepted physiological limitations in adults informed decisions about the upper and lower limit each parameter was assigned within a particular range. A value for a parameter falling within the normal range scored zero points and up to 3 points for increasing derangement. Mean arterial pressure and oxygen saturation which can be substantially affected (positively or negatively) by pharmacological or physiological intervention were weighted accordingly. Mean arterial pressure was weighted for quantities of inotropes, vasopressors, fluids and sedation. Oxygen saturation was weighted for inspired oxygen fraction and positive end expiratory pressure. Up to 6 points could be added or subtracted according to the parameter and the weighting factor. An iterative and incremental development approach was used to repeatedly refine the scoring system against a series of virtual clinical scenarios to ensure that changes in individual parameters led to appropriate adjustment of the score. Results: Repeated iterations of the scenarios resulted in the final version of the 51 point score. This score was then calculated repeatedly using real datasets and graphical outputs displayed. Conclusions: This new quantitative score may have clinical utility because of the ability to reflect alterations in underlying physiology which may be masked by increasing levels of support.