Central Venous Access: Arterial Complications

Central lines are something we routinely do but can and do lead to complications. Complications include pneumothorax, dysrhythmias, guidewire loss, and of course arterial cannulation. We will focus mostly on talking about arterial cannulation and arterial dilation/insertion of a catheter. Arterial injury occurs in less than 1% of catheter placements, but arterial puncture occurs in 4.2–9.3% of line placements. Most of the time it is often easily recognized secondary to pulsatile flow, the artery is not dilated, and pressure is held with no complications. Hematoma formation has been reported in up to 4.7% of all catheter placements. Hematoma formation is often not life-threatening.

Complications from arterial puncture, and especially arterial dilation & catheter insertion include AV fistula, arterial thrombosis & subsequent stroke, arterial pseudoaneurysm, & arterial dissection. Immediate removal of an accidental arterial catheter can result in uncontrolled hemorrhage so the catheter should be left in place for removal by interventional radiology or vascular surgery (direct suture repair, percutaneous closure device, stent-graft insertion). Studies have demonstrated that leaving the arterial catheter in place with prompt repair carries less morbidity and mortality than catheter removal with pressure. 

Discerning if you are in the artery or vein 

1. Ultrasound can be used to confirm appropriate guidewire placement in the venous system prior to dilation

2. Venous pressure waveform on CVP monitor (applies more for ICU)

3. Watch for pulsatile flow, but recognition may be difficult in a hypotensive patient, which are a significant portion of patients who are getting central access

4. Send off blood gas and decide if it is a VBG or ABG (but VBG may resemble ABG in a hyperoxic patient on high FiO2) 

5. Confirmation using angiocath in the central line kit in conjunction with the extension tubing and evaluating the column of blood in the extension tube. Dr. Strayer has a complete description here. https://emupdates.com/catheter-in-artery-vs-vein/

6. CxR showing catheter going towards RA (venous) vs LV (arterial). However, with this method, confirmation is achieved only after dilation. 

If inadvertent arterial insertion fails to be recognized, further complications can arise from infusion of vasopressors into arterial circulation, such as ischemic stroke. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613416/

https://www.reliasmedia.com/articles/131944-complications-of-tubes-and-lines-part-i

https://emupdates.com/catheter-in-artery-vs-vein/

Cognitive Errors

I have definitely committed my fair share of cognitive errors resulting in missed diagnoses. The first step is to be aware of these cognitive biases so we can avoid them. I have listed some of the most common ones below and broken them down into sections. 

Over-attachment to a specific diagnosis

Anchoring- Fixating on specific features of a presentation too early in the diagnostic process and subsequent failure to adjust

Confirmation bias- The tendency to look for confirming evidence to support the hypothesis while overlooking and evidence that refutes it

Premature closure- Accepting a diagnosis before it has been fully verified

Failure to consider alternative diagnoses

Sutton’s slip- Fixation on the most obvious answer

Search satisfaction- The tendency to stop searching once something is found and not considering additional diagnoses (i.e. the first positive finding was a red herring).

Representativeness restraint- Not considering a particular diagnosis for a patient because the presentation is not representative enough, i.e. it is not a “classic” presentation 

Error due to inheriting someone else’s thought process

Triage cueing- A predisposition toward a diagnosis as a result of a judgment made by the triage physician, whose care may have been brief and early in the care process

Diagnosis momentum- The tendency for a particular diagnosis to become established in spite of other evidence

Framing effect- A decision being influenced by the way in which the scenario is presented or ‘‘framed’

Ascertainment effect- When thinking is preshaped by expectations. The alcoholic is just drunk (but may actually be herniating from ICH)

Errors in prevalence estimation

Availability bias- The tendency for things to be thought of and placed on the differential more frequently if they come to the mind more easily

Base-rate neglect-  Failing to accurately take into account the prevalence of a particular disease

Gambler’s fallacy- Belief the same thing won’t happen again

Playing the odds- Deciding a patient doesn’t have a disease based on low likelihood and prevalence

Posterior probability error- Having a decision unduly influenced by a previous case

Errors involving patient characteristics

Gender bias- When the decision made is influenced unduly by the patient’s gender or the gender of the decision maker

Psych out error- A variety of biases associated with the health care provider’s perception of the psychiatric patient and blaming new organic disease on chronic psychiatric illness

Yin-yang out- Presumption that extensive prior investigation has ruled out any serious diagnosis on the current presentation. Beware of dismissing high utilizers. 

Errors associated with physician affect or personality

Order effects- Focusing on information given at the beginning or end of a history and missing key information in the middle

Commission bias- Tendency toward action rather than inaction (over investigation, over intervention etc…)

Omission bias- Tendency toward inaction rather than action (under investigation etc…)

Outcome bias- Choosing a course of action according to a desired outcome and avoiding diagnoses that could lead to an undesirable outcome. 

Visceral bias- Making decisions influenced by personal (positive or negative) feelings toward patients

Overconfidence/under-confidence- Being overconfident in or under-confident in the efficacy of decisions

Sunk costs- Unwillingness to give up a diagnosis in which considerable time and effort has been invested

Zebra retreat- Not willing to pursue rare diagnoses for a variety of reasons (delay in departmental flow, time intensive workup etc…)

Intubation Modalities

Which intubation modality should I choose?

There are more options to intubate a patient besides our standard RSI techniques. I’ll be giving a brief overview of some other options below & an excellent flowchart from WJEM. Since this is a POTD, I will not be going in depth into each modality. However, I’ll try and include major indications & pitfalls when going through them.

Delayed Sequence Intubation (DSI): Primarily used in patients who are preventing you from oxygenating them (i.e. pulling off their bipap, agitated etc…). This is basically procedural sedation where the “procedure” is preoxygenation. 

Begin by giving a dissociative dose of IV Ketamine (1-2 mg/kg) and once the patient is properly sedated, preoxygenate them as you wish. Ketamine usually preserves their respiratory drive, but you may need to step in and intubate earlier than you anticipate if the patient were to experience respiratory depression. When the patient is adequately preoxygenated, you can give the paralytic and intubate the patient as you normally would. 

Sometimes, just forcing the patient to tolerate Bipap without interruption may result in the patient’s respiratory status improving and avoiding intubation. 

Ketamine Only Breathing Intubation (KOBI): KOBI is a great choice in physiologically challenging intubations where patients cannot tolerate a moment of apnea such severe acidosis. 

Begin by giving a dissociative dose of IV Ketamine. The patient will then be sedated, but still breathing. Then proceed with your intubation modality of choice. Beware, the patient may be a little rigid, have a higher risk of vomiting, and the vocal cords will still be moving. Either the vocal cords can be “timed” or a paralytic given shortly before passing the endotracheal tube. Even if a paralytic is not used, it should be readily available incase of complications such as jaw rigidity. 

Awake Intubation: Awake intubations are the ideal choice for cooperative patients that may be difficult intubations, but the intubation is less urgent. The advantage lies in that it is incredibly safe (the patient is breathing the whole time) and the procedure can be aborted if the intubation cannot be completed. An example could be a patient with Ludwig’s angina, where the loss of airway reflexes in RSI could lead to dire consequences if the patient is unable to be intubated. It would likely be difficult to oxygenate & ventilate a patient with Ludwig's angina, especially with all the soft tissue collapse after induction & paralysis in RSI, leading to disastrous consequences. 

Begin by drying out the oropharynx (gauze, glyopyrrolate). Then, the goal will be to topicalize extensively. 4% Nebulized lidocaine should be used. Atomized lidocaine should also be given via the nose and mouth (usually in awake intubations, nasotracheal intubation via fiberoptic bronchoscope is better tolerated than orotracheal intubation). Lastly, the patient can also gargle viscous lidocaine. The patient can also be given anxiolysis (such as versed) and may need soft restraints depending on the clinical scenario. Proceed with either orotracheal or nasotracheal intubation. Once you have passed the cords, the patient can be fully sedated since the airway is then secured. 

https://emcrit.org/dsi/

https://emupdates.com/kobi/

Merelman, A. H, Perlmutter, M. C, & Strayer, R. J. (2019). Alternatives to Rapid Sequence Intubation: Contemporary Airway Management with Ketamine. Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health, 20(3). http://dx.doi.org/10.5811/westjem.2019.4.42753 Retrieved from https://escholarship.org/uc/item/4b27s3ks

https://www.emdocs.net/awake-endotracheal-intubation/