Critical Care

It's Okay to Delay Your Sequence... a Little.

Case: A 68 year old man with a history of CVA, CAD, HTN, and COPD presents from his nursing home with several days cough and fever.  He is brought in by EMS on nonrebreather mask and appears to be in severe respiratory distress with oxygen saturations in the 80's.  After he is placed on BiPap, chest x-ray demonstrates infiltrates consistent with pneumonia.  The decision to intubate the patient is made after he fails BiPap due to intolerance of the mask (he repeatedly attempted removing the mask) and continued poor oxygen saturation.  Endotracheal intubation was successfully performed with RSI, though the patient briefly desaturated to 75% during the process. 

Clinical question: Would delayed sequence intubation have benefited this patient and avoided desaturation?

Rapid sequence intubation, or RSI, is the preferred means of emergency airway management, allowing for a definitive airway in a short period of time and avoiding prolonged bag-valve-mask ventilation with the goal of minimizing the risk of aspiration [1].  In RSI, both an induction agent and a neuromuscular blocking agent are administered in quick succession.  Etomidate and succinylcholine are two commonly used medications for induction and paralysis, respectively.  The major disadvantage of RSI is the potential for a "cannot intubate, cannot ventilate" situation [2].  In a patient similar to the one above, this could lead to a precipitous drop in oxygen saturation and increases the risk of cardiac arrest from hypoxemia. 

One alternative that could ameliorate pre-existing hypoxemia is delayed sequence intubation, or DSI.  During DSI, the induction agent is first given to facilitate preoxygenation either by nonrebreather mask or non-invasive positive pressure ventilation (NIPPV).  After a period of preoxygenation, the patient is then given a paralytic and intubated.  DSI can be especially useful in situations where the patient has altered mental status or agitation that precludes adequate preoxygenation with a nonrebreather or NPPV mask.  Successful preoxygenation by this method would theoretically provide the patient with a better oxygen reserve and buffer against desaturation during intubation attempts [2].  

A prospective, observational study done by Weingart, et al. published in the Annals of Emergency Medicine investigated the degree of improvement in preoxygenation after a brief period of sedation with ketamine prior to intubation.  Patient selection consisted of a convenience sample of 64 patients who were uncooperative with preoxygenation (e.g. not tolerating or removing the mask, inability to remain on the stretcher).  Patients were administered 1 mg/kg of ketamine IV and preoxygenated for 3 minutes with high-flow nonrebreather or NIPPV if the nonrebreather did not raise SpO2 to >95%.  The study found that saturations after increased from a mean of 89.9% to 98.8% immediately before intubation, a difference of 8.9% (95% confidence interval 6.4% to 10.9%).  Two patients, both asthmatics, did not require intubation after DSI and were able to tolerate and be admitted on NIPPV [3].  Although the major shortcoming in the study is the lack of randomization with a control arm, the study does demonstrate that DSI with ketamine can create a more favorable peri-intubation oxygen saturation, potentially providing a buffer against hypoxemic peri-intubation cardiac arrest.  

 

Submitted by Phil Chan (@PhilChanEM), PGY-4

Faculty reviewed by Brian Fuller, MD, MSCI

 

References

[1] Salhi BA, Ander DS. Chapter 122. Intubation and Airway Support. Principles and Practice of Hospital Medicine. New York, NY: McGraw-Hill; 2012.

[2] Vissers RJ, Danzl DF. Chapter 29. Intubation and Mechanical Ventilation. Tintinalli’s Emergency Medicine, 8e. New York, NY: McGraw-Hill; 2016.

[3] Ann Emerg Med. 2015;65:349-355.

For the Sake of the Trach: Tracheostomy Basics & Complications in the ED

Clinical scenario: You’re working in the ED when you receive a pre-arrival page: 62 y M with trach in respiratory distress, unable to obtain sats, ETA 5 min.  As you are setting up suction in the resuscitation bay, EMS arrives with a pale, elderly male gasping for air.  What's your next move?

Review: Although (hopefully) not something we see in the emergency department every day, this is absolutely something we need to be comfortable stabilizing, if not definitively managing, on our own. In order to have a better understanding of tracheostomy complications, it’s important to understand some terminology and anatomy first.  

Differentiating tracheostomies from laryngectomies 
A critical piece of information to obtain in patients with a tracheostomy is to determine whether or not they have had a laryngectomy as well. A tracheostomy is simply an opening in the trachea created with an incision through the anterior neck. Some reasons for needing a tracheostomy include chronic mechanical ventilation, maxillofacial trauma, or upper airway obstruction such as from a mass. A laryngectomy—usually performed on patients with laryngeal cancer—is a complete removal of the larynx with separation of the airway from the mouth, nose, and esophagus. Since there is no connection between the mouth and the patient’s airway, laryngectomy patients can NEVER be orally
intubated. Outwardly, a laryngectomy patient looks like any other patient who has had a tracheostomy, so it is impossible to tell if a patient has had a laryngectomy simply by looking at his or her neck. While occluding the stoma of a patient who has only had a tracheostomy may not cause complete loss of the ability to ventilate (assuming that have at least a somewhat patent upper airway), occlusion of the stoma in a larygectomy patient will absolutely in all cases make it impossible for the patient to breathe, since the stoma is the only possible connection to the lungs in a laryngectomy patient. Despite being a “never” event, attempts at oral ventilation on a laryngectomy patient have been reported in the past [1].   If a patient with a total laryngectomy requires bagging and the trach tube is displaced, the stoma is the only way to ventilate them.  As an initial measure, an laryngeal-mask airway or neonatal mask can be applied to the stoma and used for bagging.


Tracheostomy basics 
To better understand tracheostomies in general, some basics are worth reviewing. Tracheostomies can be performed percutaneously at the bedside in the intensive care unit or surgically in the operating room. Various methods for a tracheostomy exist, but the neck incision is usually made midway between the cricoid cartilage and the sternal notch, well below where a cricothroidotomy is usually performed, and the trachea itself may be opened with a vertical or horizontal incision. A few safety features are sometimes integrated into the tracheostomy: stay sutures and Bjork flaps. Stay sutures are temporary sutures placed through 2-3 tracheal rings that allow for the trachea to be pulled back up to the skin should decannulation occur. This allows for visualization and easier reinsertion of the tracheostomy tube, thereby decreasing the risk of creating a false passage if the tracheostomy tube needs to be reinserted before the tract fully matures in about 7 days. Stay sutures are usually removed after 7 days, so patients presenting to the ED are not likely to have these. A Bjork flap is an upside-down U-shaped section of trachea that not only creates the tracheostomy, but the free edge of the flap is sutured to the skin of the neck, essentially creating a path for tracheostomy tube reinsertion and reduces the risk of creating a false passage when reinserting a tracheostomy tube prior to tract maturation [2]. 

Tracheostomy Tube Features 
Tracheostomy tube designs vary widely but most tracheostomy tubes have a number of parts in common. A few important details to know about every tube include the size of the tube, the brand or type, and whether or not the tube has a cuff. For example, when speaking with a consultant, one might say, “this patient has a size 6 cuffed Shiley.” The cuff is an important feature of many
tracheostomies as it allows for the airway to be sealed off, allowing for positive pressure ventilation and reducing the risk of aspiration. Deflating the cuff will allow the patient to breath through his or her mouth to some degree (assuming a patent upper airway), which serves as a backup for ventilation should the tube become occluded. Having the cuff down also allows for the patient to phonate when they occlude their tracheostomy tube, since air will be able to pass around the deflated cuff and tube through the vocal cords. Some tracheostomy tubes will have both an outer cannula and inner cannula, which allows for the inner cannula to be removed and cleaned or replaced without changing the entire tracheostomy tube. The downside to having an inner cannula, however, is that the effective inner diameter of the tube is decreased, so the patient may experience increased resistance to airflow.


Tracheostomy tube complications 
Setting up for the patient
Patients with tracheostomy tubes will on occasion present to our emergency department, and as the initial responders to these emergencies, it is important to be aware of the common or potentially life threatening complications associated with tracheostomy tubes. In the patient who is not rapidly decompensating, eliciting a brief history focused on the tracheostomy tube should be performed. Necessary details such as when the tracheostomy was placed, what size tube the patient uses, and why the tracheostomy was needed may be management altering pieces of information. When the patient arrives to the ED, supplies and equipment should be assembled in anticipation of potential worsening of the patient's complication. Personal protective equipment (face shield, gloves, fluid-resistant gown), suction catheters, Yankauer suction, replacement tracheostomy tubes (of the same and also one size smaller), tracheostomy tube ties, and a supplemental oxygen source should all be at the bedside ready for immediate use. Endotracheal tubes with intubating equipment (if the patient has a patent upper airway) should be readily available as well, if not at the bedside. 


Tracheostomy tube obstruction
Secretion buildup will often result in a narrowing of the effective tube diameter, commonly leading to increased resistance to flow and manifesting as respiratory distress in the patient. Inadequate suctioning, poor hydration, and decreased mobility are all risk factors for obstruction from secretions. The initial step in patients with a possible tube obstruction is to attempt passing a suction catheter through the tracheostomy tube. Instilling a few milliliters of sterile saline may help loosen secretions. If the suction catheter cannot be passed easily beyond a few centimeters or the length of the tube, the tube may either be obstructed or dislodged. In tubes with an inner cannula, the inner cannula should be removed and inspected or replaced, but if there is still resistance to passing a suction catheter, the tracheostomy tube is likely dislodged with the distal tip in the soft tissues of the neck and will need to be removed immediately and replaced [2]. 


Accidental decannulation
Although most patients will have a mature tracheostomy tract when they present to the ED, it is prudent to ask when the tracheostomy was placed. Tracheostomies that are less than 7 days old presenting with a decannulation of the tube should never be replaced blindly because of the risk of creating a false passage upon reinsertion. In a patient with a mature tract, he or she should be optimally positioned for reinsertion, preferably laying supine with a shoulder roll to extend the neck, which will help align the tissue planes and mimic the position by which the tracheostomy was originally created (likely supine on a operating table). Preoxygenating the patient oronasally or via the stoma will reduce the risk of oxygen desaturation should any difficulties arise during the procedure. Always use an obturator or introducer if available to avoid injuring the soft tissues with the end of the tracheostomy tube. Water-soluble lubricant or a lidocaine containing jelly should be applied to the tube. Holding the tube and obturator as one unit, the tube should be inserted with the tip initially pointed perpendicular to the stoma and then gently curved downward into the trachea following the bend of the tube. If the tube has been out of the stoma for more than several hours, the stoma may have begun to stenose and require dilation by an otolaryngologist prior to reinserting a tube. A chest x-ray should be performed to confirm placement. Alternatively, if available, a nasopharyngoscope or bronchoscope can be used to directly visualize the carina via the tracheostomy tube, which would guarantee proper tracheal placement.  For a video demonstration, see this you tube video.


Bleeding from the tracheostomy
Tracheostomy bleeds can be from a number of possible sources. Superficially, the skin underlying the flange of the tracheostomy tube should be checked, as malpositioning of the tube or patient may result in pressure ulceration. The tracheostomy tube may need to be removed to fully inspect the stoma and surrounding skin, and local bleeding can be controlled with pressure or topical silver nitrate. Often, granulation tissue, which are new growths of connective tissue and small blood vessels, can arise from the stoma site, or even within the trachea itself. Minor bleeding from around the stoma can similarly be treated with pressure or silver nitrate. Granulation tissue within the trachea is diagnosed by direct visualization with a nasopharyngoscope or bronchoscope, and needs to be definitively treated by ENT, usually by cauterization. Other potential sources of tracheostomy bleeding may come from the tube eroding into the thyroid vessels, thyroid gland, or tracheal wall. A tracheoinnominate fistula is perhaps the most feared complication of a tracheostomy tube and occurs when the tip of the cannula erodes through the anterior tracheal wall and into the innominate artery. This rare condition occurs in less than 1% of all patients with a tracheostomy tube but carries a mortality rate approaching 100% given the catastrophic bleeding into the airway. Approximately 75% of patients with a tracheoinnominate fistula will present within 3 to 4 weeks of tracheostomy tube placement, and some of these patients will have an initial "sentinel bleed" that may be relatively minor before developing massive hemorrhage [2,4]. Hemorrhage in these cases can be temporized by hyperinflating the cuff of the tracheostomy tube or endotracheal tube placed through the stoma as an attempt to tamponade the bleeding. These patients will need emergent thoracic and ENT consultation. Endovascular embolization of the innominate artery may be another option in these patients and has been demonstrated to be successful in a few case reports [5]. 


Cardiac arrest
Suppose a patient with a tracheostomy is brought into the emergency department with CPR in progress. Provided that the patient's stoma remains patent, a small cuffed endotracheal tube (e.g. a 6.0 tube) can be inserted through the stoma to ventilate a tracheostomy patient in this code scenario. Intubation of the stoma is not only is much faster than attempting oral intubation, but also avoids the potential attempt at oral intubation on a laryngectomy patient (which, again, should never occur) if his or her medical history is unknown. A laryngeal mask airway (LMA) can be placed over the stoma to ventilate if an endotracheal tube is not readily available, but the patient's mouth and nose should be covered if upper airway patency is unknown. Alternatively, should the stoma be stenosed (for example, if the tracheostomy tube has been out for hours) and the patient is known to have a patent upper airway, the stoma can be occluded and the patient can be ventilated with bag-valve-mask via the mouth and nose. 


Take Home Points 
Tracheostomy complications can quickly become life-threatening, and knowing some basic concepts about tracheostomies can allow us to better respond to and take care of patients with these complications. As with any patient, getting an adequate history should be the first step, and in particular, knowing if the patient has had a laryngectomy can prevent the “never event” of an orotracheal intubation attempt. Before performing any interventions on a patient where there is time to set up (i.e. on a relatively stable patient), one should gather appropriate equipment such as personal protective gear, extra tubes, and suction. Finally, consider the potential for a tracheo-innominate fistula in a bleeding tracheostomy patient given the extremely high associated mortality. 

Submitted by Phil Chan, PGY-3
Faculty Reviewed by jason wagner  (@TheTechDoc)
Everyday EBM Editor: Maia Dorsett (PGY-4, @maiadorsett) 

References

[1] El-Sayed IH, et al. Identifying and Improving Knowledge Deficits of Emergency Airway Management of Tracheotomy and Laryngectomy Patients: A Pilot Patient Safety Initiative. Int J Otolaryngology. 2010;2010:1-7.
[2] Morris LL, et al. Tracheostomy Care and Complications in the Intensive Care Unit. Crit Care Nursing. 2013;33(5):18-30.
[3] D. Doyle J, Scales DC. Tracheostomy. In: Hall JB, Schmidt GA, Kress JP. eds. Principles of Critical Care, 4e. New York, NY: McGraw-Hill; 2015. http://accessmedicine.mhmedical.com/content.aspx?bookid=1340&Sectionid=80032214. Accessed September 24, 2015.
[4] Epstein SK. Late Complications of Tracheostomy. Respir Care 2005;50(4):542-549.
[5] Hamaguchi S, Nakajima Y. J Vasc Surg. 2012;55:545-547

A Balancing Act

It’s another busy day in the ED when an elderly female comes in from triage with fever, cough, and new oxygen requirement. Even before the patient comes back you are concerned for pneumonia with sepsis. The patient is tachycardic and hypotensive with a shock index greater than one. You institute early antibiotics and fluids and systematically begin to aggressively resuscitate her. The patient requires nearly four liters of normal saline before her blood pressure stabilizes. Your attending suggests that your liberal use of normal saline will induce a hyperchloremic metabolic acidosis, and perhaps you should have used lower chloride containing fluid, like lactated ringers. You perform a brief literature review on the topic of balanced resuscitation using lower chloride containing fluids.

Literature Review:
Strong Ion Difference (Kishen et al)
The main difference between normal saline and balanced fluids, such as lactated ringers, is the strong ions difference (SID), that is, the difference between cations (e.g. Na+) and anions (e.g. Cl-).  Normal saline has a SID of zero (equal parts Na+ and Cl-) where as Lactated ringers has a SID of 28, which is due to the additional cations such as Ca+, K+, and lower anion (Cl-) content.  Importantly, normal plasma SID content ranges from 38-44mmol/L, therefore balanced fluids more closely approximates physiologic SID.  As the SID becomes narrower, as is the case with significant normal saline administration, a non-gap metabolic acidosis develops. [1]

The use of normal saline in large volumes has been shown to produce a reliable drop in serum pH as demonstrated by Scheinraber et al, in a study among patients undergoing elective surgery. [2] However, the development of a hyperchloremic acidosis is of unclear clinical significance. Early animal models in dog kidneys demonstrated that compared to non-chloride fluids, chloride containing solution led to renal vasoconstriction and decline in glomerular filtration rate. Similarly a randomized, double blind crossover study in healthy humans demonstrated a significant reduction in renal blood flow and renal tissue perfusion, after the administration of two liters of normal saline compared to low chloride (98 mEq/L) Plasma-Lyte solution. [3] However, the effect of isotonic saline in acutely ill patients is still not as clear. A prospective cohort study among 175 ICU patients demonstrated that higher chloride levels (109.4 vs 115.1mEq) was an independent factor for increased mortality, although a limitation of this study was they could not distinguish the cause of hyperchloremia (iatrogenic, renal dysfunction, or endogenous hyperchloremia) [4]
Traditional and 'balanced' fluid content (crashingpatient.com)
A large retrospective cohort study of critically ill adults with vasopressor dependent sepsis showed lower in-hospital mortality in patients who received balanced (lower chloride) fluids versus isotonic saline, 19.6% versus 22.8% (RR 0.86; 95% CI,0.78-0.94). A limitation of this study was that patients receiving balanced solutions were younger, less likely to have chronic heart and renal failure, and more likely to receive steroids, colloids and invasive monitoring. [5] A 2014 retrospective study in 109,836 patients that met SIRS criteria and received crystalloid fluid resuscitation, showed that low-chloride loads were associated with lower in-hospital mortality. This mortality difference remained even after adjustment for severity of illness and total fluid volume administered. [6]

Similarly, a before and after study by Yunos et al involving 1644 ICU patients, reported the use of chloride-restricted fluids was associated with lower serum creatinine and decreased rates of renal replacement therapy (6 vs 10%) compared to controls. Like the study by Shaw et al, the difference was independent of severity of illness or total fluid volume administered. However, as mentioned by the authors, determining which component of lower-chloride fluid may have led to the observed effect is difficult, as there was simultaneous administration of lower sodium content, as well as increase in the administration of acetate, lactate, and gluconate. Importantly, this study showed no difference in mortality. [7][8]

Take home points: Administration of large volume of isotonic saline is associated with a metabolic acidosis. Animal models have demonstrated decreased renal perfusion with chloride containing fluids. Several retrospective studies indicate that chloride is an independent risk factor for mortality in acutely ill patients. More and more literature in humans seems to indicate that a ‘balanced resuscitation’ may decrease morbidity, and possibly mortality, in patients receiving large volumes of crystalloids as part of their resuscitation.  A single nonrandomized study demonstrated a correlation between low chloride fluids and decreased use of renal replacement therapy. Blinded, randomized, prospective studies are needed to further elucidate this observed effect.

Expert Commentary:

Dr. Schwarz, an Assistant Professor here at Wash U, and both an Emergency Physician and Toxicologist has provided some of his own thoughts on the topic. 

First, I’d like to thank Louis for picking a great topic and generating discussion about a very important subject.  I initially became interested in this topic a few years ago.  Originally, I was much more interested in the mechanism by which normal saline (NS) caused a non-anion gap metabolic acidosis, and that’s when I learned about the strong ion difference and a ‘balanced resuscitation.’  As a full disclosure while I found the pathophysiology really interesting, I initially didn’t think it had much clinical relevance.  However as more investigators have studied this, I’ve come to believe that my initial impressions were incorrect and changed my practice.

 The last time I reviewed the literature, I didn’t see a randomized, controlled trial comparing resuscitation with NS and lactated ringers in the ED.  However I do believe that there are studies out there that are applicable to the ED.  A retrospective study compared patients undergoing elective or emergent general surgery that received either NS or a ‘balanced fluid.’1  Unadjusted mortality and the number of patients developing major complications were higher in the group that received NS; after adjusting with propensity scoring, the mortality was no longer significantly different between the 2 groups.  However, patients that received NS were 4.8 times more likely to require dialysis. In a meta-analysis of patients with sepsis, patients that received a ‘balanced resuscitation’ had a lower mortality than patients receiving NS.2  The trend, however, was not significant.

In a promise to keep this short, I won’t review all the other literature that has been published on this topic and kept the discussion on the 2 articles that I did include short.  I’ll also concede that the literature is not perfect, and as I mentioned earlier, I’m also still waiting for that perfect ED-based study to be completed.  However the cost of NS or a ‘balanced solution’ such as lactated ringers is nearly equivalent.  I’m also not aware of significant complications from administering lactated ringers in most patients. So when the risks, costs, and benefits of implementing a ‘balanced resuscitation’ verses a standard resuscitation with NS are viewed together, I think there is enough evidence to consider changing your resuscitation strategy.

Now like many EDs, lactated ringers is not kept in our department.  It is on shortage but so is NS.  Neither of those are reasons not to use it.  So what do I do? Since I haven’t been able to convince pharmacy to keep lactated ringers in the ED yet, I do my best to guess early on which patients are going to need large-volume resuscitations.  If I think they are going to likely need more than 2-3 liters of fluid, I order additional lactated ringers from the pharmacy when I place their initial orders. In an hour after the patient has received the first few liters of NS, the lactated ringers should be there from the pharmacy.  If they need further resuscitation I can use it or return if they no longer need it.  For those that are interested to read more about this topic, I’d direct you to the upcoming May 2015 edition of Emergency Physicians Monthly. From my understanding, it’s brilliantly written! (Sorry for my shameless plug)


Jamtgaard References:
 [1] Kishen R, Honoré PM, Jacobs R, et al. Facing acid–base disorders in the third millennium – the Stewart approach revisited. International Journal of Nephrology and Renovascular Disease. 2014;7:209-217. doi:10.2147/IJNRD.S62126.
[2] Scheingraber et al. Rapid Saline infusions produces hyperchloremic acidosis in patients undergoing gynecologic surgery. Anesthesiology 1999;90;1265
[3] Chowdhury A et al. .  A randomized, controlled, double-blind crossover study on the effects of 2-L infusions of 0.9% saline and plasma-lyte® 148 on renal blood flow velocity and renal cortical tissue perfusion in healthy volunteers.  Ann Surg. 2012;256(1):18-24
 [4] Boniatti MM et al.  Is hyperchloremia associated with mortality in critically ill patients? A prospective cohort study. J Crit Care. 2011;26:175–179. doi: 10.1016/j.jcrc.2010.04.013
[5] Raghunathan K, Shaw A, Nathanson B et al. Association between the choice of IV crystalloid and in-hospital mortality among critically ill adults with sepsis*. Crit Care Med 2014; 42: 1585–91
[6] Shaw A et al.  Association between intravenous chloride load during resuscitation and in-hospital mortality among patients with SIRS. Intensive Care Medicine. 2014;40(12):1897-1905. doi:10.1007/s00134-014-3505-3.
[7] Waikar SS, Saving the Kidneys by Sparing Intravenous Chloride?.JAMA. 2012;308(15):1583-1585. doi:10.1001/jama.2012.14076.
[8] Yunos N et al. Association between a chloride-liberal vs chloride restrictive intravenous fluid administration strategy and kidney injury in critically ill adults. JAMA 2012; 308: 1566– 72.

Schwarz References
1. Shaw et al.  Major Complications, Mortality, and Resource Utilization after Open Abdominal Surgery: 0.9% saline compared to Plasma-Lyte. Ann Surg 2012;255:821-829.
2. Rochwerg et al. Fluid Resuscitation in Sepsis. A Systematic Review and Network Meta Analysis. Ann Intern Med 2014;161:347-355.


Submitted by Louis Jamtgaard +Louis Jamtgaard , PGY-3
Faculty Reviewed by Evan Schwarz @TheSchwarziee 

Does cardiac standstill on bedside echo equal 100% mortality?

You’re in the midst of catching up on notes during a hectic overnight shift when out of the corner of your eye you see a stretcher zoom into the trauma bay – with an EMT leaning over the side performing chest compressions. As the team gathers, the paramedics give report. The patient is a middle-aged male, no known past medical history, who was acting normally about half an hour ago when he suddenly collapsed in front of his family. They started CPR within a couple minutes of the patient collapsing, and called EMS. The paramedics continued CPR, placed a supraglottic airway, and placed the patient on the monitor. He has had a slow, organized rhythm without pulse throughout the arrest. He has received several doses of epinephrine without response. The patient has been pulseless for a little over half an hour by the time he arrives. The ED crew takes over CPR, IV access is obtained, and the patient switched over to the ER monitors, which show a slow, wide-complex, relatively disorganized rhythm. The patient shows no signs of life. Your attending physician calls for the ultrasound, and calls out to the team that if the bedside echo shows cardiac standstill, you will consider terminating further resuscitative efforts.

Clinical Question:

Does cardiac standstill on bedside echo universally predict mortality in OHCA?

Literature Review:

A systematic review of studies investigating the diagnostic accuracy of bedside echo in OHCA was published by a Canadian group in Annals in 2012 [1]. This was a well-done study, with a broad search strategy, rigid but logical inclusion & exclusion criteria, and quality assessment with a modified version of the QUADAS instrument.
Eight studies were included in the final analysis, with a total of 568 patients. Of the 378 patients with cardiac standstill on bedside echo, only 9 (2.4%, 95% CI 1.3% – 4.5%) achieved ROSC. The authors pooled results of the included studies to devise a 2x2 table and determine test characteristics of bedside echo. This revealed a sensitivity of 91.6% (95% CI 84.6% - 96.1%) and specificity of 80.0% (95% CI 76.1% - 83.6%). The positive likelihood ratio is 4.26 (95% CI 2.63 - 6.92) and the negative likelihood ratio is 0.18 (95% CI 0.10 - 0.31). Heterogeneity was minimal (0.0%) for the negative likelihood ratio, but was significant (82.1%) for the positive likelihood ratio. The authors conclude, “While there is insufficient evidence to support using echo in isolation to decide whether or not to continue with cardiopulmonary resuscitations, the presence or absence of VWM in the context of the pretest survival likelihood can provide emergency personnel with further information to assist making that difficult decision whether to stop cardiopulmonary resuscitation with more confidence.”

It is important to note that the outcome of interest in this systematic review was survival to admission, which is not necessarily a good predictor of neurologically-intact long-term survival past discharge, which is the ultimate patient-centered outcome of OHCA. Further limitations included variable inclusion/exclusion of traumatic arrest patients in the included studies, and variability in application of bedside ultrasound. Namely, there were significant differences in training level of examiners, degree of external review of OCHA studies, and definition of “cardiac standstill” between the included studies.
This paper was the focus of a “Systematic Review Snapshot,” authored by our very own Dr. Brian Cohn and published in Annals in 2013 [2].

I attempted a PubMed search using the same search strategy as the authors in the original systematic review (available in the online supplementary material), but I did not discover any further studies on this topic that have been published since that paper in 2012.

Take-home Points:

- Cardiac standstill does not universally lead to failure of resuscitation of OHCA.
- The best-available current evidence does not support the use of bedside echo alone to predict outcomes in OHCA patients.
- Other factors influencing likelihood of neurologically-intact survival (down time, underlying rhythm, patient age/comorbidities, etiology of arrest, etc.) should be taken into account when interpreting bedside echo results.
- More research is needed to determine true prognostic factors associated with survival from OHCA.

Submitted by C. Sam Smith, MD. @CSamSmithMD
Faculty review by Brian Cohn +EMJClub 

References:
[1] Acad Emerg Med. 2012 Oct;19(10):1119-26.
[2] Ann Emerg Med. 2013 Aug;62(2):180-1.

Needle that belly!

An infant female with no significant history presents to your trauma bay after reported accidental blunt trauma to the abdomen, the patient arrives from a referral hospital where plain films demonstrated free air. On arrival the patient show signs of hemodynamic instability and an elevated lactate. The patient was decompressed with "needle peritoneumostomy" prior to going to the OR for exploration. 

Clinical Question:

Can “tension pneumoperitoneum” cause hemodynamic instability?

Literature Review:

The presence of "free air" in the peritoneum is often diagnostically significant; however, the gas itself is rarely of clinical importance. An exception to this rule is in the case of a tension pneumoperitoneum. Tension pneumoperitoneum (TPP), also known as hyperacute abdominal
Example of pneumoperitoneum & football sign
compartment syndrome [1], or abdominal tamponade [2], is a rare, but potentially deadly event. Similar to tension pneumothorax, the underlying mechanism is a tissue flap that acts as a one-way valve for air release, resulting in a progressive increase in intra-abdominal pressure. The increasing peritoneal pressures may rapidly lead to respiratory compromise due to diaphragmatic elevation and a drop in cardiac output resulting from decreased venous return or aortic outflow due to occlusion. [3] This can progress to cardiovascular collapse and respiratory failure and eventually death. [2]

In one of the earliest reported cases in 1913, tension pneumoperitoneum was theorized to be a consequence of gas forming bacteria in the abdominal cavity. [4] Now it is known that tension pneumoperitoneum is usually a consequence of hollow viscus perforation, post-operative complications, positive pressure ventilation or other insulflation-dependent procedures (eg, colonoscopy, endoscopy, cystoscopy or air enema). There has even been reported cases from CPR. [9,10] However, there are few published case reports of TPP as a result of blunt force trauma. [3,6]


Signs and symptoms of TPP include abdominal distension and fullness. The additional presence of a tympanitic, rigid abdomen, hypotension, dyspnea, and jugular vein congestion can be considered as signs of TPP, requiring immediate management.

The diagnosis of tension pneumoperitneum should be based physical exam and supported by imaging of the abdomen. Plain films of the abdomen show large amounts of intraperitoneal air. Lateral supine and left lateral decubitus films show the air best. Elevation of the diaphragm or medial displacement of the liver, called the “saddlebag sign” is suggestive of tension physiology.[1] The viscera may appear more distinct as they are outlined by the air tissue interface as in the double-wall sign (the visualization of the outer wall of bowel loops caused by the presence of extraluminal and intraluminal gas). Another radiographic sign of a large pneumoperitoneum is football sign - the intraperitoneal air outlines the abdominal cavity and the falciform ligament appears like the laces of a football.

With this said, plain films of the abdomen are rarely obtained in the setting of trauma. If hemodynamically stable, the patient is imaged using computed tomography (CT scan) which will show posterior liver compression by superiorly located free air. However, because CT scanning is contraindicated in the hemodynamically unstable patient, the diagnosis may have to rest on the clinical presentation and/or portable plain films. It can be confirmed by needle decompression or paracentesis with a rush of air and improvement of hemodynamic stability. [7]
Treatment of tension pneumoperitoneum depends on the stability of the patient. If the patient is acutely unstable with labile blood pressures and signs of shock, treatment is emergent needle decompression using a 14g angiocatheter. There are no large trials that recommend a specific location based on success and/or safety rates. However, several small case series suggest using the same sites for decompression: two centimeters below the umbilicus in the midline (through the linea alba) or five centimetres superior and medial to the anterior superior iliac spines on either side. [8]. If the patient is stable, a paracentesis catheter/drain can be placed. The definitive treatment is to determine what initially caused the air accumulation, which may necessitate an exploratory laparotomy. It should be noted that a nasogastric tube turned to suction is unlikely to evacuate the pneumoperitoneum due to the ball and valve mechanism that created it initially. [3]


Take-home Points: 
-Pathophysiology and treatment is similarly to pneumothorax, it can lead to cardiovascular collapse, respiratory failure, and eventually death if untreated. Unstable patients should be recognized on exam, however x-ray and CT have utility based on stability. Decompression is the treatment and can be performed with an angiocath placed two centimeters below the umbilicus in the midline. 


References:
[1] Lin B, Tension Pneumoperitoneum. The Journal of Emergency Medicine, Vol. 38, No. 1, pp. 57–59, 2010.
[2] Khan ZA. Conservative management of tension pneumoperitoneum. Ann R Coll Surg Engl. 2002 May;84(3):164-5.
[3] Ogle JW Tension Pneumoperitoneum after Blunt Trauma. The Journal of Trauma: Injury, Infection, and Critical Care. 1996 Nove; 41(5): 909-911.
[4] Falkenburg C. Ein Fall von Gasansammlung in der freien Bauch-Hohle. Dtsch Z Chir 1913;124: 130-6.
[5] Olinde A, Carpenter D, Maher J. Tension pneumo-peritoneum. Arch Surg 1983;118:1347-50.

[6] Ferrera PCChan L. Tension pneumoperitoneum caused by blunt trauma. Am J Emerg Med. 1999 Jul;17(4):351-3.
[7] Yakobi-Shvili RCheng D. Tension pneumoperitoneum--a complication of colonoscopy: recognition and treatment in the emergency department. J Emerg Med. 2002 May;22(4):419-20.
[8] Fu KIshikawa TYamamoto TKaji Y. Paracentesis for successful treatment of tension pneumoperitoneum related to endoscopic submucosal dissection. Endoscopy. 2009;41 Suppl 2:E245.
[9] Williams DTManoochehri PKim HT. Tension pneumoperitoneum. Emerg Med J. 2014 Nov;31(11):943.
[10] Mills SAPaulson DScott SMSethi G. Tension pneumoperitoneum and gastric rupture following cardiopulmonary resuscitation. Ann Emerg Med. 1983 Feb;12(2):94-5.
Submitted by Decompression Danny Kolinsky, PGY-2
Edited by Louis Jamtgaard, PGY-3. @Lgaard
Faculty review by Rebecca Bavolek

Assess the pipes, Carotid VTI and fluid responsiveness


Clinical Scenario:

You are working in the ED when a 75 yo F hx of CHF, DM presents with fever, cough, and hypoxia and hypotension. You are concerned for sepsis with presumed pneumonia as the source. You initiate volume resuscitation and start broad spectrum antibiotics.  Your  patient's BP initially responds to fluids, but now after your 3L your patient is still hypotensive. You perform bedside US of the inferior vena cava (IVC) with equivocal findings. You wonder, is there another way to perform rapid bedside ultrasound for volume responsiveness?  You remember a recent paper about carotid velocity time integral (VTI) , and begin to investigate

Literature review:
It seems that predicting volume responsiveness is the never-ending tale in critical care medicine, as numerous methods have been proposed over the past several years with varying degrees of success. With the expansion of ultrasound, measuring IVC collapsibility has been one of the more popular methods utilized in the emergency department. However, measuring the IVC can often be limited by body habitus, excessive intra-abdominal gas, respiratory variation, and operator experience. (1) Measuring IVC collapsibility at greater than 50% has been shown to correlate with a CVP of less than 8mmhg, and a lower CVP has been associated with volume responsiveness, but a higher CVP does not exclude volume responsiveness. (1) A recent paper by Marik et al described the novel use of Carotid VTI and passive leg raise (PLR) as a marker of volume responsiveness in hemodynamically unstable patients.  The benefit of  PLR is that it produces a hemodynamic response similar to a 200-300ml bolus, is relatively easy to perform, and is rapidly reversible.
 Courtesy Ultrasound Podcast
 By combining PLR with dynamic ultrasound, Marik et al sought to create the ideal non-invasive method of determining volume responsiveness.  They demonstrated that a 20% increase in carotid VTI had a sensitivity and specificity of 94% and 86% respectively for predicting volume responsiveness (a patient with a stroke volume increase of greater than 10% was considered volume responsiveness). 
This study was limited in that it was nonrandomized, nor blinded, and complete data was available for only 34 patient. (2)  Mike and Matt from the Ultrasound podcast provide an excellent review and explanation on how perform VTI that you can find here @ Ultrasound podcast

Take home points:
Studies have shown that only 50% of hemodynamically unstable patients are volume responders. Appropriate fluid resuscitation in sepsis is associated with improved outcomes, while excessive fluid administration is associated with increased ICU LOS and mortality. Determining fluid responsiveness is difficult but VTI combined with PLR appears to have both a high specificity and sensitivity for predicting volume responsiveness.  More studies will be needed to demonstrate validity of this method. 

Submitted by Louis Jamtgaard, PGY-3 @Lgaard
Faculty Reviewed by Deb Kane 


References

1)Nagdev A et al . Emergency department bedside ultrasonographic measurement of the caval index for noninvasive determination of low central venous pressure. Ann Emerg Med. 2010 Mar;55(3):290-5. doi: 10.1016/j.annemergmed.2009.04.021. Epub 2009 Jun 25.

2) Marik P et al. The use of bioreactance and carotid Doppler to determine volume responsiveness and blood flow redistribution following passive leg raising in hemodynamically unstable patients.
Chest. 2013 Feb 1;143(2):364-70.


Why so blue? - Methylene blue in Distributive Shock

Clinical Scenario:
You are working in Trauma Critical Care when a middle aged male with end-stage liver disease presents with altered mental status.  He is hypotensive  and tachycardic.  You resuscitate him with IV fluids, start broad spectrum antibiotics and initiate vasopressors.  You confirm a source of infection with a paracentesis. Despite multiple and escalating doses of pressors, the patient's blood pressure continues to fall.  You perform a RUSH exam, run through your differential diagnosis again, and confirm that all lines and tubes are connected appropriately.  As you prepare his family for the worst and sign him out to the ICU, your colleague suggests - what about methylene blue?  Is it worth a shot?

Clinical Question:
Is there a role of methylene blue in management of septic shock?

Image source: webmd.com
Literature Review:
Methylene blue was initially developed as a dye for the textile industry, then used as a stain for TB, treatment for malaria, treatment of cyanide toxicity, and more recently methemoglobinemia.  Typical dosing for methemoglobinemia is 1-2mg/kg of 1% solution IV.

In a recent review performed by the Toxicology Department at UCSD published in the Journal of Emergency Medicine in 2013, the authors presented the evidence behind the utility of methylene blue in the septic patient [1].  

Methylene blue (MB) is useful in septic shock due to its ability to increase peripheral vascular resistance and its reversal of myocardial depression.  Its mechanism of action is thought to be due to inhibition of inducible nitric oxide synthase (up regulated by endotoxin and cytokines producing vasodilatory nitric oxide and guanylate cyclase (makes vasodilatory cGMP) [2,3].  There have only been two randomized controlled trials that studied MB in septic shock (n=20; n=30).  In these studies MB was found to increased mean arterial pressure (MAP) and decrease vasopressor requirements, but there was no statistically significant difference in survival rates.

Other studies reviewed for this publication were case series and case reports.  In these, varying doses of MB were used ranging from 1-3mg/kg over 10-20 minutes, which all increased MAP, systemic vascular resistance (SVR), and mean pulmonary arterial pressure.  However MAP and SVR returned to baseline 2-4 hours after MB administrations.

With doses greater than 4mg/kg or rapid or prolonged (greater than 6-10 hrs) infusion, potential side effects of MB use includes serotonin syndrome reaction (if already taking serotoninergic agents, MB inhibits monoamine oxidase), methemoglobinemia (if G6PD deficiency, or at high doses MB acts as oxidizer instead of reducer), platelet aggregation/reduction, and vasoconstrictive effects with possible decreases in splanchnic perfusion and arterial oxygenation (do not use in ARDS or pulmonary hypertension) [1,3,4].  The clinical effects of MB persist for 2-3 hours (half-life=102 minutes) and should be preferably administered centrally as peripheral administration can cause cutaneous necrosis [3,4].

Take home points:
-Methylene blue may prove a useful adjunct to vasopressors in cardiovascular collapse.  
-Remember additional shock management strategies include adequate volume resuscitation and source control, inotropy, respiratory support, correction of electrolytes (K, Ca, Mg, Phos) and glucose, consideration of endocrine dysfunction (thyroid, adrenal, vasopressin), and ruling out obstructive etiologies.

References:
1. Lo JC, Darracq MA, Clark RF. A review of methylene blue treatment for cardiovascular collapse. J Emerg Med. 2014 May;46(5):670-9.
2. Landry DW, Oliver JA. The pathogenesis of vasodilatory shock. N Engl J Med 2001; 345(8): 588-595.
3. Kirov MY, Evgenov OV, Evgenov NV, Egorina EM, Sovershaev MA, Sveinbjørnsson B, Nedashkovsky EV, Bjertnaes LJ. Infusion of methylene blue in human septic shock: a pilot, randomized, controlled study. Crit Care Med 2001; 29(10): 1860-1867.
4. Juffermans NP, Vervloet MG, Daemen-Gubbels CR, Binnekade JM, de Jong M, Groeneveld AB.. A dose-finding study of methylene blue to inhibit nitric oxide actions in the hemodynamics of human septic shock. Nitric Oxide 2010; 22(4): 275-280.

Submitted by Lydia Luangruangrong, PGY-3.
Edited by  Steven Hung (@DocHungER), PGY-2
Faculty reviewed by Chris Holthaus