Oxygen is harmful - you just didn't know it

Changing practice is plain hard. Many of us cling to what we've been taught in medical school - what the professors said and what the textbooks teach must be true. Just like fluid therapy, which we all learnt somewhere, all ill patients should get a drip - right? According to Professor John Myburgh at SMACC 2013, fluids are given by junior staff with brownian motion like randomness, and they have all the potential to cause morbidity and mortality downstream. Similarly, supplemental oxygen, which is slapped onto almost all patients in the resus room , has the potential to cause harm, and we don't even think twice about it.
Now, hypoxia is bad, so oxygen therapy is a given in that situation. But, HYPERoxia may just be as harmful. The article below gives a great review of the historical evidence on oxygen therapy in critically ill patients:

The evidence is rather overwhelming against hyperoxia. Did you know, giving too much oxygen may be detrimental in:
  • AMI patients
  • acute stroke patients
  • septic patients
  • cardiac arrest patients
  • COPD patients
Which is pretty much the majority of the resus cases we see day to day, of whom all would get some form of supplemental oxygen. Do NOTE that while the totality of evidence suggests harm, there is no high quality evidence (i.e. RCTs) to prove that hyperoxia is really harmful. Conversely, there is also no high quality evidence to suggest the opposite; that hyperoxia will result in improved outcomes. The reviewers in the above article note this, and point out that guidelines advocating oxygen use acknowledge the paucity of data to guide oxygen recommendations, and most of it is based on expert opinion.
How do we then rationalise oxygen use? IMO, titrate oxygen use to SpO2, targeting 88-92% for patients with COPD, 94-98% for everyone else, and not letting the SpO2 reach 100% (which may mean PaO2 in the hundreds). The BTS guidelines (see below) lays it out pretty nicely:

In summary, next time, when you're on shift looking after that critical patient, remember to check the oxygen requirements for each patient, and use supplemental O2 wisely.

ZDogg tells it like it is.

The irrepressible and hilarious Dr Zubin Damania (aka ZDOGG MD) arrives at the big time. He tells of his evolution through medicine and the toll on his psyche. Also watch out for the all too rare paediatrician slam!
Check out his Youtube channel when you have the time. Well worth it.



Webucation 27/6

This week's web finds brings a host of ECG topics to demystifying papers to surviving the ED night shift.
As always, credit to the original posters.


Here at Emergence Phenomena we're a bunch of minimalists. So the last link was something of an absolution. Looking for occult markers of bleeding is all well and good. Having your artery punctured for it didn't make sense then and now. Have your own look, make up your minds and let us know if your experiences differ.

Paralytic Agents for RSI: Fun Facts

Posting on behalf of Prof Tiru who found this:

Emergency Physicians regularly use neuromuscular blocking agents for rapid sequence intubation. It is not uncommon to wonder why a specific patient seems to respond with inadequate paralysis or an extended duration of neuromuscular blockade. Some pearls regarding the use of nondepolarizing agents:
  • Hypercalcemia decreases duration of blockade.
  • Hypermagnesemia prolongs the duration of action.
  • Hypothermia can prolong the duration of action.
  • Hypokalemia may augment the blockade.
  • Acidosis enhances the blockade effect.
  • Aminoglycosides are known to prolong the duration of action.
  • Patients chronically on phenytoin/carbamazepine exhibit resistance to rocuronium.
  • Severe hepatic dysfunction prolongs rocuronium's effect. However, renal failure does not affect the duration of single doses.
References:
(1) Greenberg SB, et al. Crit Care Med 2013;41:1332-44.
(2) Warr J, et al. Ann Pharmacother 2011;45:1116-1126.

Nail in the coffin for CVP?

Does the Central Venous Pressure Predict Fluid Responsiveness? An Updated Meta-Analysis and a Plea for Some Common Sense*

Marik, Paul E. MD, FCCM1; Cavallazzi, Rodrigo MD2

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Abstract

Background: Despite a previous meta-analysis that concluded that central venous pressure should not be used to make clinical decisions regarding fluid management, central venous pressure continues to be recommended for this purpose.
Aim: To perform an updated meta-analysis incorporating recent studies that investigated indices predictive of fluid responsiveness. A priori subgroup analysis was planned according to the location where the study was performed (ICU or operating room).
Data Sources: MEDLINE, EMBASE, Cochrane Register of Controlled Trials, and citation review of relevant primary and review articles.
Study Selection: Clinical trials that reported the correlation coefficient or area under the receiver operating characteristic curve (AUC) between the central venous pressure and change in cardiac performance following an intervention that altered cardiac preload. From 191 articles screened, 43 studies met our inclusion criteria and were included for data extraction. The studies included human adult subjects, and included healthy controls (n = 1) and ICU (n = 22) and operating room (n = 20) patients.
Data Extraction: Data were abstracted on study characteristics, patient population, baseline central venous pressure, the correlation coefficient, and/or the AUC between central venous pressure and change in stroke volume index/cardiac index and the percentage of fluid responders. Meta-analytic techniques were used to summarize the data.
Data Synthesis: Overall 57% ± 13% of patients were fluid responders. The summary AUC was 0.56 (95% CI, 0.54–0.58) with no heterogenicity between studies. The summary AUC was 0.56 (95% CI, 0.52–0.60) for those studies done in the ICU and 0.56 (95% CI, 0.54–0.58) for those done in the operating room. The summary correlation coefficient between the baseline central venous pressure and change in stroke volume index/cardiac index was 0.18 (95% CI, 0.1–0.25), being 0.28 (95% CI, 0.16–0.40) in the ICU patients, and 0.11 (95% CI, 0.02–0.21) in the operating room patients.
Conclusions: There are no data to support the widespread practice of using central venous pressure to guide fluid therapy. This approach to fluid resuscitation should be abandoned

Original website here

Webucation 14/6/13

A slew of paediatrics around the web giving great advice. Also in the mix is some trauma imaging and tox for good measure. As always credit to the original authors and do visit their site.


The last link to Ryan Radecki's site is a must read and we fully appreciate the sentiment. It is something shared all over the world. Over investigation with no real change of management resulting from it. We understand that surveillance is warranted in some diseases by the pathologists but surely it is time to call a simple ceulluitis or chest infection (not from the middle east of course!) just that. 




    Adrenaline is the nectar of God, Dobutamine is the semen of the devil

    If you've ever wondered about the sepsis patient you're treating, whose BP starts dropping after IV fluids, this is the talk for you. John Myburgh gave this fantastic lecture during SMACC 2013, and when such a comment is uttered on stage, you've got to sit up and listen.

    The talk's about resuscitation and catecholamines, and it challenges what we think is dogma in resuscitation. We used to give tons of fluids to hypotensive septic patients, and then give dopamine to boost the blood pressure. We may not give much thought to the fluid therapy as well as the vasopressor/inotrope of choice, as the endpoint we're familiar with is a normal blood pressure. Now, more and more critical care physicians are turning to smaller volume resuscitation in sepsis, and there are good reasons for that. (As a side note, the FEAST trial appear to be just the right fuel for this debate. Though this is a trial involving paediatric patients in resource poor Africa, its implications are far reaching! In an editorial, John had called for the use of fluids as if they were drugs... think twice before hanging up the next bag!)

     What about the vasopressors then? John is both an intensivist and a professor in catecholamines research. He will give you a fascinating history on catecholamines and vasopressor use. Also, he will introduce some concepts (will be new to some but is known since Guyton's time) regarding the venous circulation, MSVP, and how catecholamine physiology works to improve cardiac output . This talk is bound to challenge and broaden your views on the use of vasopressors and inotropes.

     Here is the talk...

    We're all guilty!

    We've all done it in our careers. To be fair most of  us correct our mistakes. Some learn through good mentors, some learn through reading the papers, some even learn it off TV.
    The truth is that we should be wary of the greater picture of antibiotic resistance and ineffectual remedies which do not target the pathology.
    Here's a great article and the links below are for people who have access.
    Do the right thing folks.

    Medscape link
    NIH link


    Over-prescribing of Antibiotics and Imaging in the Management of Uncomplicated URIs in Emergency Departments

    K Tom Xu, Daniel Roberts, Irvin Sulapas, Omar Martinez, Justin Berk, John Baldwin

    Abstract

    Background Unnecessary use of resources for common illnesses has substantial effect on patient care and costs. Evidence-based guidelines do not recommend antibiotics or imaging for uncomplicated upper respiratory infections (URIs). The objective of the current study was to examine medical care providers' compliance with guidelines in treating uncomplicated URIs in emergency departments (EDs) in the US.
    Methods Nationally representative data from the NHAMCS 2007 and 2008 were used. Uncomplicated URIs were identified through ICD-9 codes of nasopharyngitis, laryngitis, bronchitis, URI not otherwise specified and influenza involving upper respiratory tract. Exclusion criteria were concurrent comorbidities, follow-up visits, and age < 18 or >64 years. Most frequently prescribed classes of antibiotics were identified. Multivariate analyses were conducted to identify the factors associated with the prescribing of antibiotics and use of imaging studies.
    Results In 2007 and 2008, there were 2.2 million adult uncomplicated URI visits without any other concurrent diagnoses in EDs in the US. Approximately 52% were given antibiotic prescriptions, over one-third of which were macrolides, and nearly half of the visits performed imaging studies. About 51% had a diagnosis of bronchitis, 35% URI NOS, 9% nasopharyngitis, laryngitis or influenza, and 4% multiple URI diagnoses. The diagnosis of bronchitis, fever at presentation, older ages, male gender, longer waiting time, and metropolitan areas were associated with a greater likelihood of prescribing antibiotics or imaging studies, controlling for confounding factors.
    Conclusion Despite the recommendations and campaign efforts by the CDC and many medical associations, the prescribing of antibiotics in treating uncomplicated URIs in the EDs remains prevalent. Furthermore, overutilization of imaging studies is prevalent. Changes at levels of health care system and hospitals are needed to avoid unnecessary resource utilization. In addition, further patient education about antibiotic use in the community may greatly facilitate the transition out of an antibiotic-dependent consumer culture.

    Webucation 1/6/13


    Here's a list of ED goodness from all sides of the planet. These intercontinental gems include investigations which yield lots and some with no yield whatsoever! Read on...

    • Needless tests - Last but not least, the ER Mentor relates his frustration at pointless labwork. This waste of cost and effort is universal and we are in total agreement. we try to change things in our institution with "culture-changing" tactics like online guides and pre attachment education. The results will only show up in the long term but we beseech the younger readers to consider the cost, effort and even blood cells when they decide to randomly "vampire" the well looking patient!