Suction cannisters in series

Today during my TR shift, CY asked me for demonstration of how to connect suction canisters in series for large volume paracentesis.

Before we go into the actual technique, lets take a second to understand how the suction canister functions. This is not our exact model of suction canister lid, but is functionally the same. See my infographic below:

The goal: to connect 3 of the vacuum canisters together so that when one fills, the fluid then starts draining into the next. Once the second fills it will drain into third and automatically stop.

With this technique you can perform your paracentesis, start drainage, and then safely walk away. Please instruct your patient not to move whilst drainage is in action.

So connect one suction canister with vacuum tubes as you normally would: vacuum to wall suction; the next vacuum tube should go from either of the avalvulous ports to the next avalvulous port. Critical point: the only port that needs to be connected to the ballast valve port is the port that plugs into wall suction. All subsequent ports should be connected in series with the avalvulous ports.

The final attachment is the avalvulous port to christmas tree adapter, which is included in our thora/paracentesis kit.

During what I believe was my intern year, I had shown Strayer this technique, and much to my chagrin, he tweeted out a post about it. See below:

The benefits of utilizing this technique for large volume paracentesis are twofold: (1) increased safety and (2) utilization of resources (in this case physician time). Safety is increased because this method does not utilize sharp needles to transfer fluid to a vacuum flask; thereby, it reduces the risk of needle stick injury (especially important for the population of patients that need ED paracenteses). Utilization of resources is improved because a physician does not need to remain at bedside or repeatedly check the progress of evacuation, assessing for need to switch to the next vacuum flask.

For large volume paracentesis, I recommend only connecting a max of 4 of our suction canisters in series. I typically do 3, but 4 approaches that max of 5L that current thought suggests may cause hemodynamically significant fluid shifts.

Electrophysiology 101

One of my favorite topics that is as nerdy (if not more so) than toxicology is a subspecialty of cardiology called electrophysiology. While I am not an expert at any field at this point, I certainly enjoyed learning from our prestigious faculty in the CICU. This is the first of a 2 part pearl of the day. The next pearl of the day, we will get into the various modes of pacemaking and what they mean.

So let us review: pacemakers, AICD’s, the different varieties, why people have them, and what we as ED providers need to know.

Electrical Conduction system of the heart

I have attached an infographic showing the various points of heart block. Notice how the left posterior fascicle has many conducting fibers. This important, because in the setting of RBBB + LAFB, there are many conducting fibers left so the conducting system is more robust and unlikely to go into complete heartblock. However, in the setting of a RBBB + LPFB, there is only the tiny fibers of the LAF conducting to the rest of the heart; so these patients need a pacemaker.

Pacemakers

Complete heartblock or ecg findings that they will likely soon develop complete heart block (eg mobitz type 2 and combined RBBB with left posterior fascicular block) are indications for pacemaker placement. If they are unstable on presentation, they need an emergently placed transvenous pacer.

A single lead pacemaker tunnels through the venous system and delivers electrical impulses to the right ventricle. The wave of depolarization starts in the right ventricle; thus, the ECG finding of a paced rhythm is of a widened QRS seen in a LBBB.

For patients with reduced EF’s who need pacing, there is a current trend to place biventricular pacemakers. With these devices, a lead is placed into both the right and left chamber of the heart. This is termed cardiac resynchronization therapy (CRT). Because both the chambers of the heart are paced simultaneously, the QRS narrows and it is thought this improves EF.

Automatic implantable Cardiac Defibrillators (AICD’s)

There are various models of AICD’s and are capable of providing single chamber pacing and CRT in all of the various modes depending on model. There main function is to monitor the heart for dangerous arrhythmia and deliver electrify to abort the dangerous rhythm (usually tach or vfib).

Aside from there pacemaking and/or automatic defibrillator function, all of these devices are essentially continuous cardiac monitors. As such, any patient who has one of these devices who presents to our ED can have there device interrogated.

Mostly for the interns: any syncope, report of AICD discharge, palpitations, etc with an implantable device should have there device interrogated.

Special note: placing a magnet on an AICD will turn off the defibrillator mode. This should be performed after a failed resuscitation or in a DNR/DNI patient at the point of death.

Infiltration of IV contrast into SQ tissues

I think we all dread this: Just imagine this scenario: you are concerned that your patient has a pulmonary embolus. They are tachycardic, hypoxic on room air, but BP’s are stable (for now). They were a tough stick and 2 nurses tried for 5 minutes, so under real time ultrasound guidance you place what you think is an expert 20g x 48mm angiocath in their right cephalic vein.

You dial 6308 and ask the radiology technologist to scan the patient next, then you are off to see the next patient on a busy north side shift.

15 minutes later, you get a call: “Ummmm… Doc, patient x…. that line blew. They got the hole load in the right arm. Can you come take a look?”

This can happen about 0.24% of patients who receive IV contrast in the upper extremity (or about 1/400 studies).

UNDERSTANDING CONTRAST:

The Omnipaque™ we use for our IV contrast CT studies is Iohexol:

Here is its structure:

The concentration we use is 350 mg/mL, this results in a total osmolality of 844 mOsm/kg water. This is approximately 3 times the osmolality of serum. However, given the fact it is non-ionic, it does not cause a significant osmolar effect. Nonetheless, infiltration will lead to fluid shift of H2O down its gradient into the tissue compartment the infiltrated contrast material occupies, which is typically the interstitial space. This has been shown experimentally in a renal model: after contrast load urine output increases because the iohexol is renally excreted.

The most danger for infiltration occurs with high flow rates achieved during CT angiography studies. As per our technologist on our Siemens machine, the auto injector we use has a flow rate 4-5 mL/s achieved with a pressure gradient anywhere from 50-100 psi. If the IV has poor flow due high intracatheter or intravenous resistance, then the pressure can increase to upward of 400 PSI to achieve flow. When this high pressure occurs, the IV can become dislodged. Remember Newtonian mechanics: Pressure exerts a force, and for each force there is an equal and opposite reaction.

MANAGEMENT OF IV INFILTRATION OF A CONTRAST LOAD:

####first and foremost, you need to inform the patient what happened. Explain why this happened. Apologize for the complication. Address any pain issues. Tell them how you and the team will care for their likely painful upper extremity. Finally, you can reassure them for the reasons below.

*Gradually, the infiltrated contrast will diffuse out of the tissue compartment and back into the serum. This diffusion can be enhanced with gentle warm compresses.

**Plastic surgery recommendations for this complication are elevation of the extremity, local massage, and frequent neuromuscular checks.

***In a study of 102 cases of IV contrast extravasation in the upper extermity, surgical intervention was required in 0. The surgeons behind this study recommend surgical consultation if there obvious signs of skin compromise or compartment syndrome.

****compartment syndrome has been reported in the case literature, so please, please, please, watch for that. The incidence is on case report level, so it is likely very, very low.

SOME TIPS PREVENTION OF IV INFILTRATION OF US GUIDED PIV’s:

*Always use the 48 mm angiocath

**The more of the catheter that is in the lumen of the vein, the less likely it is to become dislodged. So a good rule of thumb is at least 1 cm of the catheter within the lumen of the vein. So any target >2cm deep to the skin will be difficult to properly position using a 45 degree angle of approach.

One fun final fact: non-ionic iodinate contrast materials are procoagulants and as per the FDA they should be avoided at all cost patients with homocystinuria.

AS ALWAYS FEEDBACK IS ENCOURAGED.IF YOU HAVE AN INTERESTING QUESTION, FACTOID, OR OPINION, PLEASE RESPOND ALL.

Best regards,

Wells

References:

https://www.accessdata.fda.gov/drugsatfda_docs/label/2015/018956s095,020608s031lbl.pdf

https://www.sigmaaldrich.com/catalog/substance/iohexol821146610895011?lang=en®ion=US

Jonas Pologe’s US PIV POD

Belzunegui T, Louis CJ, Torrededia L, Oteiza J. Extravasation of radiographic contrast material and compartment syndrome in the hand: a case report. Scand J Trauma Resusc Emerg Med. 2011;19:9.

Sbitany H, Koltz PF, Mays C, Girotto JA, Langstein HN. CT contrast extravasation in the upper extremity: strategies for management. Int J Surg. 2010;8(5):384-6.

Solomon R. Contrast media: are there differences in nephrotoxicity among contrast media?. Biomed Res Int. 2014;2014:934947.