October 2024

Via EMCRIT

• Andy Neill
• Dave McCreary

• Can you give hypertonic saline through a peripheral cannula

• Khasiyev, F., Hakoun, A., Christopher, K., Braun, J. & Wang, F. Safety and Effect on Intracranial Pressure of 3% Hypertonic Saline Bolus Via Peripheral Intravenous Catheter for Neurological Emergencies. Neurocritical Care 1–6 (2024) doi:10.1007/s12028-024-01941-3.

• Some medications come with provisos that they can only be safely given through a central line. The classic medication being vasopressor infusions and we have seen several papers in the past decade all suggesting that this can be done safely with lots of caveats. This paper follows the trend looking particularly at hypertonic saline.

• This is one of those papers where i like the conclusion but can't say I like the methods. This is a retrospective chart review of what they considered their normal practice of giving hypertonic saline via peripreral lines for acute ICP crises.
• It's not very clear where these patients were at the time. Were they in the ICU, the ED, the ward etc.... All we know is they were in a single centre over a 3 year period.
• It's not very clear how they identified these patients though it seems likely they've done a database search for hypertonic saline use and worked backwards from there.
• They only looked at 3%
• They collected lots of data but they don't seem to offer the details we like to see in chart review papers. There's a classic paper (Gilbert and Steiner 1996 in Annals) that outlines what constitutes good chart review methodology. Involves things like blinding your chart review abstractors from the primary outcome and having lots of explicit definitions and plans for what to do with missing data. They do very little of that I must say.
• For example it is unclear what the primary outcome is.

• 124 patients with 200 boluses between them, mix of ICH, stroke and TBI
• There were 8 reported infusion incidents all of which appear very benign and inconsequential in the context

• As noted i like the result but i don't think they've justified it and if nothing else go and read that Gilbert paper from 1996.
• At my hospital we're very enlightened and we already permit hypertonic saline via peripheral line though there is a line it would be "preferably" be a CVC. That being said we only use 3%. I have in other units used 8% and the weirdly dosed 23.4% stuff and the risk is bound to be higher with that.
• Of note 3% has an osmolality of 1000 or so compared with a bag of saline around 300, 50% dex is aorund 2700.

Clinical Question

Is two better than one when it comes to defibs?

Title of Paper

Defibrillation Strategies for Refractory Ventricular Fibrillation

Journal and Year

NEJM. Nov 2022.

Lead Author

Sheldon Cheskes

Background

• Defibrillation is good for VF/VT - no arguments there
• Sometimes it doesn’t work and we get refractory VF
• When defibrillation fails to terminate, fibrillation resumes in the region of lowest voltage and current gradient in the myocardium
• This could be because of pad positioning (along with body habitus etc) or it could just be a lack of energy getting to the troublesome myocardium
• So how about changing the pad positioning during resuscitation, or adding an additional defib?

Study Design

• Three-group, cluster-randomised, controlled trial with crossover
• 6 paramedic services in Canada

Patients Studied

• Adult patients with out-of-hospital ventricular arrest of presumed cardiac cause
• Refractory to 3 standard defibrillation attempts

Intervention

Vector Change (VC) Defibrillation: all subsequent defibrillations were performed via Antero-Posterior pad placement OR Double Sequential External Defibrillation (DSED): A second defibrillator with pads placed Antero-Posterior in addition to the initial defibrillator. Single operator presses shock on Antero-Lateral defib immediately followed by Antero-Posterior defib with <1sec interval.

Comparison

• Standard defibrillation: all attempts in the standard Antero-Lateral position

Outcomes

• Primary: Survival to hospital discharge
• Secondary:
  • termination of VF
  • ROSC
  • Good neurological outcome (MRS ≤2)

Summary of Results

• They had calculated a sample size of 930 patients for an 8% improvement in survival with DSED or VC. Safety monitoring board stopped trial at 405 patients.
• 87.7% of patients got their assigned defibrillation
• 67.9% witnessed and 58% with bystander CPR

Primary Outcome: Survival to hospital discharge was significantly increased in both the DSED and the VC groups, more so in the DSED group

• DSED vs Standard Care: 30.4% vs 13.3% (RR 2.21 [95%CI 1.33-3.67])
• VC vs Standard Care: 21.7% vs 13.3% (RR 1.71 [95%CI 1.01-2.88])

Secondary Outcomes favoured DSED and VC (to a lesser degree) across the board:

• Termination of VF:
  • DSED vs Standard: RR 1.25 (1.09-1.44)
  • VC vs Standard: RR 1.18 (1.03-1.36)
• ROSC:
  • DSED vs Standard: RR 1.72 (1.22-2.42)
  • VC vs Standard: RR 1.39 (0.97-1.99)
• MRS ≤2:
  • DSED vs Standard: RR 2.21 (1.26-3.88)
  • VC vs Standard: RR 1.48 (0.81-2.71)

Of note, no reports of defibrillator damage or malfunction when DSED performed.

Authors Conclusion

Survival to hospital discharge appeared to be higher with DSED and VC defibrillation that with standard defibrillation among patients with refractory ventricular fibrillation during out-of-hospital cardiac arrest.

Clinical Bottom Line

This should be a game changer for the management of refractory VF/VT. Albeit a rare presentation in the ED, we should be prepared to perform DSED if needed, and if you don’t have access to a second defibrillator, then VC is likely worth a try (though the evidence for it isn’t as strong here, with a fragility index of 1 for primary outcome).

The important thing to note though is that you can’t just whip out DSED the next time you have a refractory VF if you haven’t prepared for the choreography of the whole thing. For that I recommend watching the videos on the NEJM website.

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