Tag Archives: drugs

Adjacent haemofiltration catheters can remove CVC drugs

An important consideration when siting your lines in your critical care patients who require renal replacement therapy…


Dual-lumen haemodiafiltration catheters enable continuous renal replacement therapy in the critically ill and are often co-located with central venous catheters used to infuse drugs. The extent to which infusions are immediately aspirated by an adjacent haemodiafiltration catheter remains unknown. A bench model was constructed to evaluate this effect. A central venous catheter and a haemodiafiltration catheter were inserted into a simulated central vein and flow generated using centrifugal pumps within the simulated vein and haemodiafiltration circuit. Ink was used as a visual tracer and creatinine solution as a quantifiable tracer. Tracers were completely aspirated by the haemodiafiltration catheter unless the infusion was at least 1 cm downstream to the arterial port. No tracer was aspirated from catheters infusing at least 2 cm downstream. Orientation of side ports did not affect tracer elimination. Co-location of central venous and haemodiafiltration catheters may lead to complete aspiration of infusions into the haemodiafilter with resultant drug under-dosing.

Adjacent central venous catheters can result in immediate aspiration of infused drugs during renal replacement therapy
Anaesthesia. 2012 Feb;67(2):115-121

Caution with intraosseous adenosine

Two cases of failed cardioversion of SVT after tibial intraosseous administration of adenosine in infants are described in this month’s Pediatric Emergency Care. Both cases were subsequently cardioverted by intravenous adenosine. The maximum intraosseous dose given was 0.25 mg/kg. The successful IV doses were not higher than the IO doses.
It has been noted before that infants may require relatively higher doses of adenosine than children and that 0.2 mg/kg might even be considered a starting dose in infancy. I wonder if a bigger IO dose would have been effective, or whether a proximal humeral insertion site would make a difference. IO adenosine has been successfully used in infants and piglets.
This interesting case series provides a helpful caution in the management of paediatric SVT.

ABSTRACT: Supraventricular tachycardia (SVT) is a common tachyarrhythmia in the pediatric population that can necessitate immediate treatment. Adenosine has been well studied as a mainstay treatment, but the methods of adenosine administration have not been very well delineated. The intraosseous technique has presented itself as a possible method of administration. We describe 2 cases in which adenosine was administered through bone marrow infusion to convert SVT without success. The cases we describe show that intraosseous is not a reliable method of administering adenosine to stop SVT. Both patients presented with SVT refractory to vagal maneuvers and difficult intravenous placement. Intraosseous access was achieved, but administration of adenosine at increasing doses was unable to successfully convert the arrhythmia.

Intraosseous Infusion Is Unreliable for Adenosine Delivery in the Treatment of Supraventricular Tachycardia
Pediatr Emerg Care. 2012 Jan;28(1):47-8

Steroid replacement after etomidate: no benefit

More fuel for the etomidate debate…
In essence:

  • Etomidate has been a useful induction agent for RSI for many years due to its greater haemodynamic stability compared with thiopentone or propofol
  • It is widely used in the USA
  • It inhibits the 11β-hydroxylase enzyme that converts 11β-deoxycortisol into cortisol in the adrenal gland
  • A single dose of etomidate has been demonstrated to inhibit cortisol production for up to 48 hrs
  • This has led to concerns about its use in the critically ill, particular in patients with severe sepsis / septic shock
  • This small study randomised patients receiving etomidate to hydrocortisone or placebo, with no significant difference in these patient-oriented outcomes: duration of mechanical ventilation, intensive care unit length of stay, or 28-day mortality
  • This study suggests that replacement doses of hydrocortisone are not required after a single dose of etomidate
  • No randomised study has conclusively demonstrated increased mortality due to etomidate; however while controversy and the possibility of harm remain, I personally see no reason not to use ketamine for RSI in haemodynamically compromised patients.
  • Ketamine was compared with etomidate in a previous controlled trial


OBJECTIVE: To investigate the effects of moderate-dose hydrocortisone on hemodynamic status in critically ill patients throughout the period of etomidate-related adrenal insufficiency.

DESIGN: Randomized, controlled, double-blind trial (NCT00862381).

SETTING: University hospital emergency department and three intensive care units.

INTERVENTIONS: After single-dose etomidate (H0) for facilitating endotracheal intubation, patients without septic shock were randomly allocated at H6 to receive a 42-hr continuous infusion of either hydrocortisone at 200 mg/day (HC group; n = 49) or saline serum (control group; n = 50).

MEASUREMENTS AND MAIN RESULTS: After completion of a corticotrophin stimulation test, serum cortisol and 11β-deoxycortisol concentrations were subsequently assayed at H6, H12, H24, and H48. Forty-eight patients were analyzed in the HC group and 49 patients in the control group. Before treatment, the diagnostic criteria for etomidate-related adrenal insufficiency were fulfilled in 41 of 45 (91%) and 38 of 45 (84%) patients in the HC and control groups, respectively. The proportion of patients with a cardiovascular Sequential Organ Failure Assessment score of 3 or 4 declined comparably over time in both HC and control groups: 65% vs. 67% at H6, 65% vs. 69% at H12, 44% vs. 54% at H24, and 34% vs. 45% at H48, respectively. Required doses of norepinephrine decreased at a significantly higher rate in the HC group compared with the control group in patients treated with norepinephrine at H6. No intergroup differences were found regarding the duration of mechanical ventilation, intensive care unit length of stay, or 28-day mortality.

CONCLUSION: These findings suggest that critically ill patients without septic shock do not benefit from moderate-dose hydrocortisone administered to overcome etomidate-related adrenal insufficiency.

Corticosteroid after etomidate in critically ill patients: A randomized controlled trial
Crit Care Med. 2012 Jan;40(1):29-35

Enoxaparin in acute medical patients

A large multinational study challenges the practice of routine thromboprophylaxis for hospitalised acutely ill medical patients. Enoxaparin plus graduated compression stockings did not reduce 30 day mortality compared with stockings alone. There was no significant difference in the rates of major bleeding.


Background Although thromboprophylaxis reduces the incidence of venous thromboembolism in acutely ill medical patients, an associated reduction in the rate of death from any cause has not been shown.

Methods We conducted a double-blind, placebo-controlled, randomized trial to assess the effect of subcutaneous enoxaparin (40 mg daily) as compared with placebo — both administered for 10±4 days in patients who were wearing elastic stockings with graduated compression — on the rate of death from any cause among hospitalized, acutely ill medical patients at participating sites in China, India, Korea, Malaysia, Mexico, the Philippines, and Tunisia. Inclusion criteria were an age of at least 40 years and hospitalization for acute decompensated heart failure, severe systemic infection with at least one risk factor for venous thromboembolism, or active cancer. The primary efficacy outcome was the rate of death from any cause at 30 days after randomization. The primary safety outcome was the rate of major bleeding during and up to 48 hours after the treatment period.

Results A total of 8307 patients were randomly assigned to receive enoxaparin plus elastic stockings with graduated compression (4171 patients) or placebo plus elastic stockings with graduated compression (4136 patients) and were included in the intention-to-treat population. The rate of death from any cause at day 30 was 4.9% in the enoxaparin group as compared with 4.8% in the placebo group (risk ratio, 1.0; 95% confidence interval [CI], 0.8 to 1.2; P=0.83). The rate of major bleeding was 0.4% in the enoxaparin group and 0.3% in the placebo group (risk ratio, 1.4; 95% CI, 0.7 to 3.1; P=0.35).

Conclusions The use of enoxaparin plus elastic stockings with graduated compression, as compared with elastic stockings with graduated compression alone, was not associated with a reduction in the rate of death from any cause among hospitalized, acutely ill medical patients. (Funded by Sanofi; LIFENOX ClinicalTrials.gov number, NCT00622648.)

Low-Molecular-Weight Heparin and Mortality in Acutely Ill Medical Patients
N Engl J Med 2011; 365:2463-2472

Xigris withdrawn


Pharmaceutical company Eli Lilly has announced the withdrawal of its severe sepsis drug activated protein C, or drotrecogin alfa (proprietary name Xigris). This is because the PROWESS-SHOCK study, now complete, showed no benefit in its primary endpoint of 28 day mortality when compared with placebo in septic shock patients. There was also no benefit in a subgroup of patients with protein C deficiency, and no significant increased risk of severe bleeding.
The European Medicines Agency’s Instructions are:


At this stage physicians should not initiate treatment with Xigris in new patients and should stop ongoing treatment

The US Food and Drug Administration’s Instructions are:


Xigris treatment should not be started in new patients. Xigris treatment should be stopped in patients being treated with Xigris.

All remaining Xigris product should be returned to the supplier from whom it was purchased.

The UK Intensive Care Society’s Announcement contains a link to Eli Lilly’s press release.

The Xigris website looks like this at the time of posting

Pre-hospital hypertonic saline during ACLS

A newly published study examines pre-hospital hypertonic saline during CPR. A randomised trial compared 7.2% hypertonic saline / hydroxyethyl starch with hydroxyethyl starch alone in over 200 adult patients with non-traumatic out-of-hospital cardiac arrest. The volume infused was 2 ml /kg over 10 mins. All patients were resuscitated by the physicians of the Emergency Medical System (EMS) in Bonn, Germany.
There were no differences in survival to admission or discharge. There was a barely statistically significant increase in those survivors with higher cerebral performance categories (1 or 2) in the hypertonic saline group, inviting further study. The study was conducted from 2001 to 2004 (according to the 2000 CPR-Guidelines), so took an interestingly long time to see print.
Randomised study of hypertonic saline infusion during resuscitation from out-of-hospital cardiac arrest
Resuscitation. 2011 Sep 19. [Epub ahead of print]
[EXPAND Click to read abstract]


Aim of the study Animal models of hypertonic saline infusion during cardiopulmonary resuscitation (CPR) improve survival, as well as myocardial and cerebral perfusion during CPR. We studied the effect of hypertonic saline infusion during CPR (Guidelines 2000) on survival to hospital admission and hospital discharge, and neurological outcome on hospital discharge.

Methods The study was performed by the EMS of Bonn, Germany, with ethical committee approval. Study inclusion criteria were non-traumatic out-of-hospital cardiac arrest, aged 18–80 years, and given of adrenaline (epinephrine) during CPR. Patients were randomly infused 2 ml kg−1 HHS (7.2% NaCl with 6% hydroxyethyl starch 200,000/0.5 [HES]) or HES over 10 min.

Results 203 patients were randomised between May 2001 and June 2004. After HHS infusion, plasma sodium concentration increased significantly to 162 ± 36 mmol l−1 at 10 min after infusion and decreased to near normal (144 ± 6 mmol l−1) at hospital admission. Survival to hospital admission and hospital discharge was similar in both groups (50/100 HHS vs. 49/103 HES for hospital admission, 23/100 HHS vs. 22/103 HES for hospital discharge). There was a small improvement in neurological outcome in survivors on discharge (cerebral performance category 1 or 2) in the HHS group compared to the HES group (13/100 HHS vs. 5/100 HES, p < 0.05, odds-ratio 2.9, 95% confidence interval 1.004–8.5).
Conclusion Hypertonic saline infusion during CPR using Guidelines 2000 did not improve survival to hospital admission or hospital discharge. There was a small improvement with hypertonic saline in the secondary endpoint of neurological outcome on discharge in survivors. Further adequately powered studies using current guidelines are needed.

[/EXPAND]

Reversing new oral anticoagulants

A small study on normal volunteers examined reversal of the new oral anticoagulants, Rivaroxaban and Dabigatran.
Rivaroxaban is a Factor Xa inhibitor and Dabigatran is a direct thrombin inhibitor.

Image from "Australian Prescriber" website. Click for Original

We should note that this was a study on the reversal of effects on various coagulation tests, not on reversal of bleeding, which is what we would be interested in for our ED/critical care patients.
Nevertheless, it’s helpful to note that prothrombin complex concentrate appeared to reverse the effects of Rivaroxaban, but not of Dabigatran.


Background Rivaroxaban and dabigatran are new oral anticoagulants that specifically inhibit factor Xa and thrombin, respectively. Clinical studies on the prevention and treatment of venous and arterial thromboembolism show promising results. A major disadvantage of these anticoagulants is the absence of an antidote in case of serious bleeding or when an emergency intervention needs immediate correction of coagulation. This study evaluated the potential of prothrombin complex concentrate (PCC) to reverse the anticoagulant effect of these drugs.

Methods and Results In a randomized, double-blind, placebo-controlled study, 12 healthy male volunteers received rivaroxaban 20 mg twice daily (n=6) or dabigatran 150 mg twice daily (n=6) for 2½ days, followed by either a single bolus of 50 IU/kg PCC (Cofact) or a similar volume of saline. After a washout period, this procedure was repeated with the other anticoagulant treatment. Rivaroxaban induced a significant prolongation of the prothrombin time (15.8±1.3 versus 12.3±0.7 seconds at baseline; P<0.001) that was immediately and completely reversed by PCC (12.8±1.0; P<0.001). The endogenous thrombin potential was inhibited by rivaroxaban (51±22%; baseline, 92±22%; P=0.002) and normalized with PCC (114±26%; P<0.001), whereas saline had no effect. Dabigatran increased the activated partial thromboplastin time, ecarin clotting time (ECT), and thrombin time. Administration of PCC did not restore these coagulation tests.
Conclusion Prothrombin complex concentrate immediately and completely reverses the anticoagulant effect of rivaroxaban in healthy subjects but has no influence on the anticoagulant action of dabigatran at the PCC dose used in this study.

Reversal of Rivaroxaban and Dabigatran by Prothrombin Complex Concentrate
Circulation. 2011 Oct 4;124(14):1573-9

So what do we do about bleeding patients who are taking Dabigatran? If you haven’t seen it already, take a look at this video from HQMEDED.com made by my heroes at Hennepin County Medical Centre:

Bleeding in the Patient on Dabigatran from hqmeded.com on Vimeo.

They have an algorithm for the patient who is bleeding on dabigatran therapy that you can download a PDF of here

Is there nothing ketamine can't do?

As well as the benefits of cardiovascular stability, maintenance of cerebral perfusion pressure, possibly lowering ICP and providing other neuroprotective benefits, ketamine may have other advantages. These are reviewed in a British Journal of Anaesthesia article from which I’ve selected those benefits of interest to practitioners of emergency medicine and critical care.
 

 
Additional Beneficial Effects of Ketamine

  • the dysphoric, or ’emergence’ reactions associated with ketamine may be reduced by pre-administration or co-administration of sedatives, such as benzodiazepines, propofol, dexmedetomidine, or droperidol.
  • ketamine potentiates opioid analgesia in multiple settings, reducing opioid total dose and in some groups of patients reducing postoperative desaturation
  • ketamine has possible anti-inflammatory effects demonstrated in some types of surgical patients
  • ketamine may prevent awareness, recall, or both during general anaesthesia

Ketamine: new uses for an old drug?
Br J Anaesth. 2011 Aug;107(2):123-6

Why I don't give vasopressors in sepsis

It’s become popular to use the term ‘vasopressors’ or just ‘pressors’ when noradrenaline/norepinephrine or even (in some places still) dopamine are given. I have resisted this trend and continue to use the term ‘vasoactive’ drugs, on the basis that the effects they produce (and that we may desire) are not limited to a pure alpha adrenergic effect on vascular tone, but they have effects on heart rate and contractility too (as well as preload through venous effects). If you don’t believe me about noradrenaline/norepinephrine, then check out one of my favourite critical care papers of all time: the CAT study.
There are of course real pressors out there – phenylephrine acts on alpha receptors, as does methoxamine. Metaraminol predominantly acts on alpha receptors but does also cause some release of noradrenaline/norepinephrine.
Why is this important? All these drugs will fix hypotension, right? Yes, they should. However should blood pressure be our main treatment goal? What we’re really interested in is organ perfusion, which depends on regional blood flow to vital organs. It’s possible that a drug could fix the measured blood pressure and give a nice ‘macroscopic’ number, while at the same time reducing cardiac output and adversely affecting regional blood flow to organs through local vasoconstrictive effects. My view is that this is more likely with pure ‘pressors’ (like phenylephrine), which is why I avoid them in septic shock and opt for catecholamine infusions (noradrenaline/norepinephrine).
This is important in my practice setting of retrieval medicine, where, prior to interfacility transport, physicians might sometimes be tempted to ‘push pressors’ peripherally rather than insert a central venous catheter and commence a catecholamine infusion. While the former approach might be more expeditious and make the vital signs chart look pretty, one wonders about what effect this is having on tissue oxygen delivery.
A fascinating review of papers on pressor physiology1 suggests these agents have the following effects:

  • conflicting data on changes in myocardial perfusion
  • increase both left and right heart afterload
  • decrease venous compliance with the potential to increase venous return although the impact of this on cardiac output is controversial
  • controversial effect on cerebral bloodflow
  • decrease bloodflow to the kidneys
  • adverse affects on gastrointestinal tract bloodflow


abstract1
Phenylephrine and methoxamine are direct-acting, predominantly α(1) adrenergic receptor (AR) agonists. To better understand their physiologic effects, we screened 463 articles on the basis of PubMed searches of “methoxamine” and “phenylephrine” (limited to human, randomized studies published in English), as well as citations found therein. Relevant articles, as well as those discovered in the peer-review process, were incorporated into this review. Both methoxamine and phenylephrine increase cardiac afterload via several mechanisms, including increased vascular resistance, decreased vascular compliance, and disadvantageous alterations in the pressure waveforms produced by the pulsatile heart. Although pure α(1) agonists increase arterial blood pressure, neither animal nor human studies have ever shown pure α(1)-agonism to produce a favorable change in myocardial energetics because of the resultant increase in myocardial workload. Furthermore, the cost of increased blood pressure after pure α(1)-agonism is almost invariably decreased cardiac output, likely due to increases in venous resistance. The venous system contains α(1) ARs, and though stimulation of α(1) ARs decreases capacitance and may transiently increase venous return, this gain may be offset by changes in afterload, venous compliance, and venous resistance. Data on the effects of α(1) stimulation in the central nervous system show conflicting changes, while experimental animal data suggest that renal blood flow is reduced by α(1)-agonists, and both animal and human data suggest that gastrointestinal perfusion may be reduced by α(1) tone.

A review of clinical articles2 reveals few evidence-based indications for true pressors. Possible situations where they may be of benefit include intraoperative hypotension, aortic stenosis, during cyanotic episodes in Tetralogy of Fallot, and some obstetric situations. In the setting of sepis, phenylephrine has been compared with noradrenaline in which an initial pilot study found a statistically significant reduction in creatinine clearance and increase in arterial lactate after initiating the phenylephrine infusion. However a subsequent randomised controlled comparison of phenylephrine with noradrenaline/norepinephrine did not show differences in cardiopulmonary performance, global oxygen transport, or regional hemodynamics, although there were only 16 patients in each group3.


abstract2
Phenylephrine is a direct-acting, predominantly α(1) adrenergic receptor agonist used by anesthesiologists and intensivists to treat hypotension. A variety of physiologic studies suggest that α-agonists increase cardiac afterload, reduce venous compliance, and reduce renal bloodflow. The effects on gastrointestinal and cerebral perfusion are controversial. To better understand the effects of phenylephrine in a variety of clinical settings, we screened 463 articles on the basis of PubMed searches of “methoxamine,” a long-acting α agonist, and “phenylephrine” (limited to human, randomized studies published in English), as well as citations found therein. Relevant articles, as well as those discovered in the peer-review process, were incorporated into this review. Phenylephrine has been studied as an antihypotensive drug in patients with severe aortic stenosis, as a treatment for decompensated tetralogy of Fallot and hypoxemia during 1-lung ventilation, as well as for the treatment of septic shock, traumatic brain injury, vasospasm status-postsubarachnoid hemorrhage, and hypotension during cesarean delivery. In specific instances (critical aortic stenosis, tetralogy of Fallot, hypotension during cesarean delivery) in which the regional effects of phenylephrine (e.g., decreased heart rate, favorable alterations in Q(p):Q(s) ratio, improved fetal oxygen supply:demand ratio) outweigh its global effects (e.g., decreased cardiac output), phenylephrine may be a rational pharmacologic choice. In pathophysiologic states in which no regional advantages are gained by using an α(1) agonist, alternative vasopressors should be sought.

These review articles reinforce my own bias against the use of pure pressors in septic shock, although clearly more clinical research is needed. I am inclined to agree with the reviewers’ concluding statement:
…in all clinical settings, phenylephrine reduces cardiac output, and in most clinical settings has been shown to significantly increase LV afterload. Thus, only in instances in which its regional effects are thought to outweigh its global effects should phenylephrine be used for the treatment of hypotension.
1. The physiologic implications of isolated alpha(1) adrenergic stimulation
Anesth Analg. 2011 Aug;113(2):284-96
2. The clinical implications of isolated alpha(1) adrenergic stimulation
Anesth Analg. 2011 Aug;113(2):297-304
3. Phenylephrine versus norepinephrine for initial hemodynamic support of patients with septic shock: a randomized, controlled trial
Crit Care. 2008;12(6):R143
Full Text available here

Still no cardiac arrest survival benefit from epinephrine?

A double blind randomised controlled trial showed significantly better rates of return of spontaneous circulation and hospital admission with the use of adrenaline (epinephrine) compared with placebo. This effect was observed with both shockable and non-shockable initial cardiac arrest rhythms. There was no statistically significant difference in the primary outcome of survival to hospital discharge.
Interesting but unfortunate political factors appear to have prevented recruitment to the required numbers of patients for this study so it is underpowered for its primary outcome of survival to hospital discharge, which in the adrenaline group was double that in the placebo group, although this did not reach statistical significance. What was supposed to be a multi-centre study became a single centre one and it was not possible to continue as the study drugs reached their expiry date and no additional funding was available.
So do ROSC and survival to admission matter? The authors make the following point:


While not the primary outcome of our study, ROSC is an increasingly important clinical endpoint as the influence of post resuscitation care interventions (i.e.: therapeutic hypothermia, managing underlying cause, organ perfusion and oxygenation) on survival to hospital discharge are recognised.

Optimum dose and timing of adrenaline remain unknown, along with whether it impacts on long-term outcomes.


BACKGROUND: There is little evidence from clinical trials that the use of adrenaline (epinephrine) in treating cardiac arrest improves survival, despite adrenaline being considered standard of care for many decades. The aim of our study was to determine the effect of adrenaline on patient survival to hospital discharge in out of hospital cardiac arrest.

METHODS: We conducted a double blind randomised placebo-controlled trial of adrenaline in out-of-hospital cardiac arrest. Identical study vials containing either adrenaline 1:1000 or placebo (sodium chloride 0.9%) were prepared. Patients were randomly allocated to receive 1ml aliquots of the trial drug according to current advanced life support guidelines. Outcomes assessed included survival to hospital discharge (primary outcome), pre-hospital return of spontaneous circulation (ROSC) and neurological outcome (Cerebral Performance Category Score – CPC).

RESULTS: A total of 4103 cardiac arrests were screened during the study period of which 601 underwent randomisation. Documentation was available for a total of 534 patients: 262 in the placebo group and 272 in the adrenaline group. Groups were well matched for baseline characteristics including age, gender and receiving bystander CPR. ROSC occurred in 22 (8.4%) of patients receiving placebo and 64 (23.5%) who received adrenaline (OR=3.4; 95% CI 2.0-5.6). Survival to hospital discharge occurred in 5 (1.9%) and 11 (4.0%) patients receiving placebo or adrenaline respectively (OR=2.2; 95% CI 0.7-6.3). All but two patients (both in the adrenaline group) had a CPC score of 1-2.

CONCLUSION: Patients receiving adrenaline during cardiac arrest had no statistically significant improvement in the primary outcome of survival to hospital discharge although there was a significantly improved likelihood of achieving ROSC.

Effect of adrenaline on survival in out-of-hospital cardiac arrest: A randomised double-blind placebo-controlled trial
Resuscitation. 2011 Sep;82(9):1138-43