Postoperative pain and delirium is a common concern and currently approached by different interventions. There is some evidence suggesting that ketamine given intra-operatively might have an influence on postoperative pain and delirium. Some anaesthetists commonly give a single dose of ketamine intra-operatively for exactly this reason.
Thumbs up for Ket
Ketamine has kept its fascination in various settings, from retrieval medicine onto the the care of critically ill patients in the ICU. Ketamine reduces postoperative markers of inflammation, is a rapid-acting antidepressant drug with an effect lasting for several days and might have neuroprotective properties.
Ketamine also has become increasingly popular as an adjunct to other sedatives in the ICU. There is evidence showing that ketamine used in the ICU has the potential to reduce cumulative opioid consumption after surgery (Asad E. et al. J Intensive Care Med December 8 2015 ).
Even better: It does not cause any kidney injuries, preserves laryngeal protective reflexes, lower airway resistance and much more...
And: Ketamine is cheap and has been used safely for over 50 years by anaesthetists!
The Dark Side of Ket
But there's the other side of ketamine making all of this a little more complicated. After all, Ketamine is a psychoactive drug and has well known hallucinogenic properties. Developed in the 1960s as a dissociative anaesthetic agent it started to appear on the street in the early 1970s and made its way to the 1980s as Special K, Acid and Super C (Dotson JW et al. J of Drug Abuse, Vol 25, Issue 4, 1995).
From a medical point of view there are some worries that these psychotomimetic effects, which are of concern in the critically ill patient, might predispose to delirium (Erstad BL, J Crit Care, Oct 2016, Vol 35, p 145-149).
The PODCAST Trial
On the background of all this facts this trial revealed some interesting findings. Avidan et al. performed a
multicentre, international randomised trial
in which they randomly assigned
672 patients undergoing major cardiac and non-cardiac surgery under general anaethesia
into three groups to either receive a bolus of
placebo (normal saline), low-dose ketamine (0·5 mg/kg), or high dose ketamine (1·0 mg/kg) after induction of anaesthesia, before surgical incision.
Participants, clinicians, and investigators were blinded to group assignment. They found
NO difference in in the incidence of postoperative delirium among these groups
significantly more postoperative hallucinations and nightmares with increasing ketamine doses compared to placebo
This trial seems well performed with an acceptable sample size. The application of a single dose of ketamine before surgery neither prevented delirium nor induced it. With this sample size it seems safe to say that even if ketamine does prevent delirium, its effect would be rather small.
Furthermore, postoperative pain was not influenced by giving a single dose of ketamine and this is in contrast to previous findings and current guidelines. Importantly, most of the previous studies are smaller than this trial, making these findings remarkable.
But what really drew my attention was the fact that the appearance of hallucinations and night-mares was increased for at least 3 days after surgery.
So if ketamine has no influence on postoperative delirium or pain but does induce hallucinations and nightmares, even 3 days after surgery, current guidelines might have to be revised.
The Bottom Line
- The application of a subanaesthetic dose of ketamine during surgery to tackle postoperative pain and delirium does not seem to be as effective as previously assumed
- The usage of ketamine in this setting even seems to have undesirable side-effects like hallucinations and nightmare - and this effect might even last for up to 3 days!
- This trial provides good reasons to look for other options to prevent postoperative delirium!
(Like dexmedetomidine? The answer to this question has just been answered: READ HERE!)
Sometimes there's this moment you read about medical research in the news... sometimes you read lots of rubbish on medical issues in the news... but sometimes you stop and read, and you don't know what to think. This happened to quite some of us a couple of days ago when reading the headlines in the British Independent:
Well, it's not very often you read the term sepsis in the news but the word 'cure' causes estonishment or rather misbelief. Further reading certainly catches your attention: 'A doctor in the US state of Virginia claims to have found his own cure for sepsis' and 'Since then, he has used it to treat 150 sepsis patients. Just one has died of the condition, claims Dr Marik'. And it's not an article from some remote pseude magazine... no, it has been published in 'Chest'! And all this is not due to some novel molecule... it's all about Vitamin C!
Thanks to #FOAMed quite some smart brains have looked into this topic already...
So here's the most important facts you need to know - in short:
What's the Story?
Paul Marik et al. have published a
single-centre retrospective cohort study
in which they have treated
47 consecutive septic patients over a periode of 7 months with intravenous vitamin C (1.5g 6-hourly), hydrocortisone (50mg 6-hourly) and thiamine (200mg 12-hourly)
and then compared these patients to
47 septic patients treated in their unit during the preceding 7 months
Propensity score matching
An overall hospital mortality of 40.4% in the control group compared to 8.5% in the intervention group
An absolute risk reduction of 31.9% and also according to the authors none of the patients in the intervention arm died of sepsis!
What Does This Mean?
These results are quite amazing on the first look, but there's more behind these numbers. Paul Marik has first of all published an observational study: unblinded, uncontrolled, retrospective and low in patient numbers.
There are several limitations that go hand in hand with studies as such and unblinded before-and-after studies have a lot. A major challenge in conducting observational studies is to draw inferences that are acceptably free from influences by overt biases, as well as to assess the influence of potential hidden biases. One of the biggest drawbacks in this current study is the timely/ seasonal difference when patients have been selected.
If you are interested to have a closer look on this you should read Dan's blog entry on stemlynsblog.org HERE.
Studies like this one are an important part of science, but observational studies are observational... not proof!
Why Vitamin C in Sepsis?
There is a scientific rationale behind all of this. As mentioned by Paul in his paper vitamin C levels do fall low in sepsis and the most efficient way to administer it is intravenously. The same is true for thiamin which also goes low in up to one third of all septic patients.
There are two rather small randomised control trials suggesting that vitamin C is safe in septic patients and might actually be of some degree of benefit for the patient.
- Neutralizes free radicals and has therefore antioxydative properties
- Is an important conenzyme for the procollagen-proline dioxygenase, which itself is necessary for the biosynthesis of stable collagen in our body. Vitamin C deficiency leeds to unstable collagen and therefore scurvy
- Is an important cofactor in the synthesis of steroids like cortisol and catecholamines like dopamine and noradrenalin as well
- and it has many more functions that go beyond the scope of this blog entry!
However, the importance of vitamin C in the treatment and prevention of diseases like e.g. the common cold or influenza remains highly contrversial. The observation of some moderate positive influence on the course of disease in some studies could not be reproduced in other trials.
Under normal circumstances vitamin C deficiency is practically non-existent in Europe, but becomes a fact during sepsis. If this is clinically relevant in septic patients seems plausible but remains to be elucidated.
Shailja Chambial, Shailendra Dwivedi, Kamla Kant Shukla, Placheril J. John, and Praveen Sharma. Vitamin C in Disease Prevention and Cure: An Overview. Indian Journal of Clinical Biochemistry. Oktober 2013; 28(4): S. 314–328
H. Hemilä, E. Chalker: Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2013
R. M. Douglas, E. B. Chalker, B. Treacy: Vitamin C for preventing and treating the common cold. In: Cochrane Database of Systematic Reviews. 2000; 2:CD000980.
Another great read into the details: Josh Farkas from pulmcrit
More Ifs and Buts
Sepsis is not a disease, its a clinical syndrome that has physiologic, biologic and biochemical abnormalities caused by a dysregulated inflammatory response to infection. The fact that different definitions have evolved since the early 1990s shows that we still struggle to definde sepsis as a single entity. This is one reason why a single therapy might not always be the best for each diesease causing sepsis.
Paul Marik’s publication is interesting and deserves respect. It’s an observational study but provides no evidence by far. Vitamin C might be an interesting novel approach to sepsis but the term ‘cure’ used in the media is inappropriate and misleading.
The term ‘cure for sepsis’ also implicates that vitamin C is a cure for all infections causing sepsis and is therefore problematic.
The Current Bottom Line
- The study published by Marik et al. is purely observational and provides no proof at all.
- Just because vitamine C might be safe in Sepsis does not mean this has to be given. At this stage no recommendation can be made for the use of vitamin C in sepsis.
- Studies like these are an part of research itself - However, the use of the term 'cure' seem problematic and inappropriate in this context.
Marik et. al, J Chest 2017
When filling out the form for a CT scan in you hospital you will not only have to provide clinical information about the patient but almost certainly also the latest creatinine levels. This information is required as many clinicians are worried that IV contrast media might cause iatrogenic acute kidney injury and therefore increased rates of dialysis, renal failure, and death. Despite several reports of contrast-induced nephropathies in the past, the causal relationship between IV contrast media and the development of acute kidney injury has been challenged recently (Read our previous summary HERE).
The major problem is that performing a randomized controlled trial to elucidate the true incidence of contrast-induced nephropathy is considered unethical because of the presumption that contrast media administration is a direct cause of acute kidney injury.
While the discussion goes on Hinson et al. have come up with another nice piece of evidence that in emergency situations there is no reason to withhold the application of IV contrast for CT scans when required.
In this single-center retrospective cohort study researchers have included a total of 17'934 patient visits to their emergency department over a period of 5 years. They analysed three patient groups that where demographically similar: contrast-enhanced CT, unenhanced CT and no CT scan performed. Patients were included when their initial serum creatinine level was between 35 umol/L and 352 umol/L. Of all CT scans, 57.2 percent were contrast-enhanced. The probability of developing acute kidney injury was 6.8 percent for patients undergoing contrast-enhanced CT, 8.9 percent for patients receiving unenhanced CT and 8.1 percent for patients not receiving CT at all. This proofs to be the largest controlled study of its kind in the emergency department and shows that:
In current clinical context, contrast media administration for CT scans is NOT associated with an increased incidence of acute kidney injury. And even though a large randomised controlled trial is still missing it seems safe...
There is no reason to withhold the use of IV contrast media in cases where contrast-enhanced CT is indicated to avoid delayed or missed diagnosis of critical disease.
Hinson J et al. Annals of Emergency Medicine, 2017; DOI: 10.1016/j.annemergmed.2016.11.021 OPEN ACCESS
Crit Cloud Review from 18/01/2015
For the resuscitation out-of-hospital one of the mainstays besides compression and defibrillation ist the application of adrenalin and amiodarone. According to the new ACLS guidelines 2015 these are the only drugs remaining in the treatment for shockable rhythms.
While adrenaline is given for maximum vasoconstriction in order to promote coronary perfusion pressure CPP, amiodarone and sometimes lidocaine are used to promote successful defibrillation of shock-refractory ventricular fibrillation VF or pulseless ventricular tachycardia VT. While the usage of these drugs is undoubtedly very effective in patients with existing circulation the effectiveness during resuscitation remains a matter of debate.
The Effect of Adrenaline
As a matter of fact it has never been proven that adrenalin actually improves long-term outcome. In 2014 Steve Lin and colleagues published a systemativ review on the efficacy of adrenaline in adult out-of-hospital cardiac arrest (OHCA). They were able to show that according to current evidence standard dose adrenaline (1mg) improved rates of survival to hospital admission and return of spontaneous circulation (ROSC) but had no benefit in means of survival to discharge or neurologic outcomes.
What about Amiodarone and Lidocaine?
Kudenchuck et al. now made the effort to look into the efficacy of amiodarone and lidocaine in the setting of OHCA. Used according to the ACLS guidelines 2016 amidarone is given after the third shock applied when treating a shockable rhythm. Two rather small controlled trials have shown so far that using amidarone actually does increase the likelihood of ROSC and the chance to arrive at a hospital alive. It's impact on survival to hospital discharge and neurologic outcome though remains uncertain.
In this randomized, double-blind trial, the investigators compared parenteral amiodarone, lidocaine and saline placebo in adult, non-traumatic, OHCA. They ended up with 3026 patients meeting inclusion criteria and which were randomly assigned to receive amiodarone, lidocaine or saline placebo for treatment. They finally found that neither amiodarone nor lidocaine improved rate of survival to discharge or neurologic outcome significantly. There were also no differences in these outcomes between amiodarone and lidocaine. Across these trial groups also in-hospital care like frequency of coronary catheterisation, therapeutic hypothermia and withdrawal of life-sustaining treatments did not really differ, making a bias due to treatments after admission unlikely.
- This study was not able to show any benefit of amiodarone or lidocaine in the the setting of OHCA in terms of survival to hospital discharge and neurologic outcome
- Amiodarone seems to improve the likelihood of ROSC and survival to hospital admission (similar to adrenaline)
- As there are no other options, I believe amiodarone should remain part of the standard treatment for shockable rhythms in OHCA
- Lidocaine can be safely removed from CPR sets as there is no benefit of over amiodarone
N Engl J Med 2016;374:1711-22
Resuscitation, June 2014, Vol 85, Issue 6, p 732-740
New ACLS Guidelines 2015, The Changes
As posted on BIJC before, Asad et al. had performed a systematic review on the usage of ketamine as a continuous infusion (>24h) in intensive care patients. The same authors have now published a narrative review providing a more depth discussion about the pharmacological and pharmacokinetic properties of ketamine. Also they present recommendations for dosing and monitoring in an ICU setting.
The Goodies of Ket
Current evidence shows that Ketamine...
- Has no adverse effects on the gastrointestinal tract (bleeding) and does not cause acute kidney injury (compared to nonsteroidal anti-inflammatory drungs, NSAID's)
- Does not negatively influence bowel motility (in contrast to opioids)
- Preserves laryngeal protective reflexes
- Lowers airway resistance
- Increases lung compliance
- Is less likely to cause respiratory depression
- Is sympathomimetic, facilitates adrenergic transmission and inhibits synaptic catecholamine reuptake, therefore increasing heart rate and blood pressure
The Concerns of Ket
- Might increase pulmonary airway pressure and therefore aggravate pulmonary hypertension
- Might cause well known psychotomimetic effects which are of concern in the critically ill patient as this might predispose to delirium
- Interacts with benzodiazepines via the P450 pathway which could result in drug accumulation and prolonged recovery
Concerns Proven Wrong
- Ketamine need not to be avoided in patients at risk for seizures, particularly when used for analgosedation for short periods in the ICU setting
- Current evidence shows no increased intracranial pressure or associated adverse neurologic outcomes associated with ketamine administration in critically ill patients
The use of ketamine for analgosedation in the ICU continues to lack high-level evidence.However, it is effectively used around the globe and remains an attractive alternative agent for appropriately selected patients. Taking current knowledge and evidence into account this is especially true for patients with severe pain unresponsive to conventional therapies.
Taking precautions and contraindications into account ketamine is considerably safe and even avoids potentially adverse side effects of other agents used.
Erstad BL, J Crit Care, Oct 2016, Vol 35, p 145-149
Continuous Etomidate Suppresses the Adrenal Gland in a Dose-Dependent Manner - A Potentially Life-Saving Intervention
An endogenous Cushing's syndrome, mostly caused by an adenoma of the pituitary gland, is associated with significant morbidity and mortality when left untreated. The condition is closely associated to life-threatening infections, diabetes mellitus, hypertension and increased risk associated with surgery.
For Cushing's disease the first line therapy is surgical removal of the pituitary tumor. Sometimes though urgent medical therapy is needed first. It has been shown, that surgical risk may be significantly reduced if cortisol concentrations are normalised preoperatively. Conditions requiring urgent cortisol-lowering measures are severe biochemical disturbances (e.g. hypokalaemia), immunosuppression or mental instability.
Medical Treatment Options
Ketokonazole (yes, the antifungal agent) and metyrapone are used to suppress adrenal steroidogenesis at enzymatic sites. Both agents carry the risk of postential side effects. Mifepristone, a glucocorticoid receptor antagonist, and pasireotide, a new targeted pituitary therapy, are alternative agents. However, they also have their limits and side effects.
Now that's where etomidate joins the game. Interestingly, etomidate and ketokonazole are chemically closely related... they are both members of the imidazole family. Etomidate is used as an anaesthetic agent since 1972 and became popular for hemodynamic stability and the lack if histamine release. In 1983 a Lancet article noted an increased mortality when etomidate was used in critically unwell patients. In 1984 an article in Anaesthesia first showed a link to low serum cortisol levels caused by etomidate. Until now the discussion continues, whether a single induction dose actually negatively influences patient outcome. A meta-analysis in 2010 was unable confirm this apprehension and the debate continues.
Etomidate suppresses the production of cortisol by inhibiting the mitochondrial cytochrome p450-dependent adrenal enzyme 11-beta-hydroxylase and therefore lower serum cortisol levels within 12 hours. In higher doses it also blocks side chain cleavage enzymes and also aldosterone synthase. It might even have anti-proliferative effects on adrenal cortical cells.
On this basis the idea arose, that etomidate might be a useful therapy for severe hypercortisolaemia.
Continuous Etomidate - What's the Evidence
A review article by Preda et al. in 2012 identified 18 publications about the primary therapeutic usage of etomidate in Cushing's syndrome, most of which were case reports. Review of current literature reveals that etomidate indeed suppresses hypercortisolaemia safely and efficiently in patients requiring parenteral therapy. Moreover, etomidate shows a dose-dependent suppression and allows adjustment of the medication to target cortisol levels. At recommended dosages etomidate is considered safe with almost no serious side effects.
The authors conclude, that etomidate is a useful therapeutic option in a hospital setting when oral therapy is not tolerated or inappropriate.
- Continuous etomidate (in non-hypnotic doses) reduces cortisol concentrations in a dose-dependent manner in both hyper- and eucortisolaemic subjects
- The application of continuous etomidate in Cushing's disease is safe and efficient
- After termination of infusion adrenocortical suppression persists for about 3 hours
- The suspicion, that a single dose of etomidate for rapid sequence inductions might negatively influence patient outcome in the critically ill remains a matter of debate
J Clin Endocrinol Metab. 1990 May;70(5):1426-30.
Preda et al. European Journal of Endocrinology (2012) 167 137-143 OPEN ACCESS
Soh et al. Letter to the Editor, European Journal of Endocrinology (2012) 167 727–728
Ge et al. Critical Care201317:R20 OPEN ACCESS
Dexmedetomidine has shaken up the usual sedatives in ICU but remains a matter of debate among intensivists. One question is whether the higher costs compared to midazolam are justified by clinical advantages. There is research available suggesting that dexmedetomidine might be an attractive alternative to standard sedatives especially in regards of time to extubation and costs (Turinen et al., Jacob et al.). This seems to hold true for moderate to light sedation of intubated patients.
I've stepped over this prospective, double-blind, randomised trial by Riker et al. in which 68 centres in 5 countries recruited intubated 366 patients to received moderate to light sedation with either dexmedetomidine or midazolam. All patients received daily arousal assessment.
Their primary end point was the percentage of time within the target sedation range (RASS score −2 to +1) and this did not differ between the two groups.
Looking at the secondary endpoints though make things a lot more interesting. Just before the beginning of the sedation period both groups had a similar prevalence of delirium. During study drug administration though, the effect of dexmedetomidine treatment on delirium was significant. A reduction of 24.9% with dexmedetomidine is rather impressive (see figure below). This effect was even greater in patients who were CAM-ICU-positive at baseline.
Finally patients on dexmedetomidine had shorter time to extubation (1.9 days in average) while their length of stay on ICU did not differ.
From a safety point of view the most common adverse effect of dexmedetomidine was bradycardia. It's noteworthy that patients on midazolam had more episodes of hypotension and tachycardia.
THE BOTTOM LINE
- This is another study indicating that dexmedetomidine seems to be beneficial in regards of delirium in mechanically ventilated patients and might speed up time to extubation
- Dexmedetomidine is safe in patients where moderate to light sedation is the aim
Riker et al. JAMA. 2009;301(5):489-499. doi:10.1001/jama.2009.56 OPEN ACCESS
Read more HERE on BIJC
Ketamine's success seems unstoppable:
+++ Anaesthesiologists are opening private clinics for off-label infusions of ketamine for depression http://bit.ly/1IGYTcI +++ Dr. Jim Roberts says #ketamine is an ideal treatment for excited #delirium: http://emn.online/Dec15InFocus +++ Major #ketamine treatment trial to start in 2016 http://m.huffpost.com/au/entry/8501942 +++ More impressed every day with low dose ketamine for pain management! https://www.youtube.com/watch?v=DgckjVVBb48 ...
Intravenous ketamine is also used in critical care units and to my knowledge most clinicians use ketamine as an adjunct to other sedatives. This might be for patients on mechanical ventilation, intubation procedures or simply as an additive to a patient-controlled analgesia pump. I personally think ketamine is one of the essentials in ICU's, but what does the evidence say.
Asad et al. have performed a systematic review on the usage of ketamine as a continuous infusion (>24h) in intensive care patients. The aim was to find evidence in favour for the utilisation of ketamine in the ICU.
As a result of this review - current evidence suggests that:
- In critically ill postoperative patients ketamine has the potential to reduce the cumulative morphine consumption at 48h compared to morphine only
- Several trials show the potential safety of ketamine in regards of cerebral haemodynamics in patients with traumatic brain injury, improved gastrointestinal motility and decreased vasopressor requirements
- One observational study and case reports suggest that ketamine is safe, effective and may have a role in patients who are refractory to other therapies
Our conclusion: THUMBS UP for ketamine in the ICU
Asad E. et al. J Intensive Care Med December 8, 2015
Many patients admitted to the emergency department (ED) suffer of nausea and vomiting - and many doctors treat this with antiemetics like metoclopramide or ondansetron. Treating nausea is tricky and of course we all try to do our best to comfort patients as good as possible. But are you really sure giving an antiemetic in the ED actually improves symptoms?
Unfortunately results coming in on this topic do not look very promising. 3 publications looked at exactly this setting and although their number of patients isn't overwhelming the results are rather discouraging.
Egerton-Warburton and colleagues performed a RCDT and looked a total 258 patients who got either metoclopramide, ondansetron or normal saline as a treatment for nausea in the ED. They basically found no differences in reduction of nausea severity.
Back in 2006 Braude et al. already stated in a RCDT including 97 patients that metoclopramide and prochlorperazine were not more effective than saline placebo as an antiemetics in the ED. Only droperidol was found to be more effective than metoclopramide or prochlorperazine but caused more extrapyramidal symptoms.
And in 2011 Barrett and colleagues published a study with 163 patients where they compared metoclopramide, ondansetron, promethazine and saline placebo in the ED. Same again: no evidence was found that ondansetron is superior to metoclopramide and promethazine in reducing nausea in ED adults.
Even if the number of patients is not that big... it's three trials so far and they all don't really support the use of antiemetics in the emergency department.
It is interesting to note that these drugs have been proven to be effective in the setting of chemotherapy and in anaesthetics, but the setting in the ED seems to differ. At least most patients experienced some relief over time... most probably to treatment of the cause itself!
Egerton-Warburton et al. Ann Emerg Med. 2014;64:526-532 OPEN ACCESS
Braude, D et al. Am J Emerg Med. 2006; 24: 177–182
Barrett et al. Am J Emerg Med. 2011; 29: 247–255
Developed in the early 70'ies tramadol has become a very popular drug for pain relief for various reasons. Among others it is often said that tramadol is safe to use and has non-addictive properties, making this an ideal opioid to use for in and out of hospital. The facts though point in the opposite direction.
In JAMA Internal Medicine Fournier et al. have just published a case control analysis to look at the fact that tramadol before has been associated with the occurrence of significant hypoglycemia. Their cohort included a total of 334'034 patients whereas each case of hospitalization for hypoglycemia was matched with up to 10 controls on age, sex, and duration of follow-up. Basically they compared similar patients which were either started on tramadol or codeine for pain treatment. They were able to show that compared with codeine, tramadol use was associated with an increased risk of hospitalization for hypoglycemia, particularly in the first 30 days of use. It has to be noted though, that the overall incidence is low with 7 per 10'000 per annum.
In the same issue's commentary Nelson and Juurlink take the opportunity to point out some other remarkable problems associated with Tramadol, again showing us that things are not a simple as we think they are.
- Tramadol itself has only a low affinity to opioid receptors and mainly works over one of its metabolites: O-Desmethyltramadol (M1), which then binds to µ opioid receptors
- The expression of the enzyme that metabolites tramadol to M1 is extremely variable, thus: giving a certain dose of tramadol leaves you with an unknown dose of acting opioid!
- Despite suggestions to the contrary, tramadol does pose a risk for addiction
- And there are increasing reports of deaths involving this drug
- Other documented adverse effects are: serotonin syndrome and seizures
Conclusion: Tramadol remains a non-ideal drug in the setting of an ICU.
Fournier et al. JAMA Intern Med. 2015;175(2):186-193.
Nelson and Juurlink JAMA Intern Med. 2015;175(2):194-195.