UMEM Educational Pearls - Critical Care

Do Sepsis Alert Systems Work?

Researchers in Korea completed a high quality systematic review and meta-analysis of sepsis alert systems for adult ED patients

Using high quality methods, they identified over 3000 studies with 22 meeting criteria. 

They found these systems were associated with:

• reduced mortality risk (risk ratio [RR], 0.81; 95% CI, 0.71 to 0.91)
• length of hospital stay (standardized mean difference, ?0.15; 95% CI, ?0.20 to ?0.11)
• Better adherence to sepsis bundle elements:
  • shorter time to fluid administration (SMD, ?0.42; 95% CI, ?0.52 to ?0.32), 
  • blood culture (SMD, ?0.31; 95% CI, ?0.40 to ?0.21)
  • antibiotic administration (SMD, ?0.34; 95% CI, ?0.39 to ?0.29)
  • lactate measurement (SMD, ?0.15; 95% CI, ?0.22 to ?0.08)

Electronic alerts were further associated with:

• reduced mortality (RR, 0.78; 95% CI, 0.67 to 0.92)
• adherence with blood culture guidelines (RR, 1.14; 95% CI, 1.03 to 1.27).

Summary (+ a little editorialization)

As annoying as we may find these systems in our daily practice, there is growing evidence that they do provide some benefit with impacts on task saturation and decreasing cognitive load in addition to real patient benefit. While there is also recent evidence that physician gestalt performs well against these systems, there is a suggested benefit in their inclusion in clinical decision making as a safety net or as an “assist”.

The incorporation of rule-based algorithms like these in more advance machine learning methods are covered quite well in a recent opinion piece on “The AI Future of Emergency Medicine”. However, it is important to always know the source of any “algorithm” that you are using, whether rule or mathematically based, given real concerns for bias and error.

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The CLOVERS trial (NEJM 2023) examined one of the eternal questions of critical care, liberal vs restrictive fluid management in sepsis… and found no difference.  But there are criticism of CLOVERS, and while some other trials agreed with this result, there are also signals in the literature that restrictive fluid strategies are beneficial.  Furthermore, we know that these trials suffer from issues of  heterogeneity, and often lump together very different patients.

Jorda et al recently published in Critical Care a posthoc re-analysis of CLOVERS looking specifically at patients with advanced CKD (eGFR < 30).  This is a challenging group of patients to manage.  On the one hand their renal function is already marginal, so the last thing we want to do is potentially deprive starved kidneys of necessary intravascular volume, but on the flip side their septic shock puts them at high risk of full blown renal failure (transient or permanent) and they're thus at very high risk of fluid overload with aggressive resuscitative fluids and potentially limited ability to clear those fluids renally in the next few days.  So how did these patients do in CLOVERS?

They did significantly better with the restrictive fluid strategy (mortality 22% vs 39%, HR CI 0.29-0.85).  They also had more pressor free days and vent free days.  

Bottom Line (my opinion): While a restrictive vs liberal fluid strategy in septic shock remains a bit up for debate, the evidence continues to slowly tip towards restrictive fluids (i.e. earlier pressors) as the preferred approach.  In patients with advanced CKD (eGFR < 30), there is probably now sufficient evidence to favor vasopressors over IV fluid administration when resuscitating septic shock.

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This May, the Society of Critical Care Medicine (SCCM) published new recommendations [1] for the use of corticosteroids in critical illness (separate from patients with known adrenal insufficiency or on chronic steroids), namely:

1. “Suggesting” for all septic shock with continued vasopressor requirement not just “refractory” (requiring 2+ pressors) 
   • Matches the 2021 Surviving Sepsis Campaign Guidelines suggestion [2]
2. “Suggesting” for ARDS (acute onset, bilateral infiltrates not due to cardiac dysfunction or volume overload, PaO2: FiO2 </= 300)
   • Matches the 2024 American Thoracic Society Clinical Practice Guidelines suggestion [3]
   • Does not explicitly exclude influenza+ ARDS, in which steroids have previously been associated with worsened outcomes [4]
3. “Recommending” for patients with bacterial community acquired pneumonia and new O2 requirement
   • New guidelines from ATS/IDSA not yet updated from 2019; support primarily from 2023 CAPE COD trial [5]

Bottom Line:

For severe bacterial pneumonia and septic shock, ED physicians should feel comfortable administering a dose of hydrocortisone 50mg IV as hydrocortisone 200mg/day is an accepted regimen for these disease processes. 

For patients with ARDS who remain boarding in the ED, EM docs should discuss initiation of steroids with their intensivists, whether the institutional preference is for dexamethasone 20mg IV (per DEXA-ARDS) [6] or methylprednisolone 1mg/kg/day (per Meduri)[7].

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Noninvasive Ventilation for Preoxygenation

• Over 1 million critically ill patients are intubated each year in the United States.
• Hypoxemia can occur in up to 20% of intubations and may lead to adverse outcomes such as peri-intubation cardiovascular collapse or cardiac arrest.
• Appropriate preoxygenation is critical to increase the safe apnea time and decrease the risk of hypoxemia during rapid sequence intubation (RSI).
• At present, the majority of critically ill patients undergoing RSI are preoxygenated with an oxygen mask.
• In a randomized, pragmatic, parallel-group trial conducted in 7 EDs and 15 ICUs in the United States, Gibbs et al compared the use of noninvasive ventilation for preoxygenation to an oxygen mask on the incidence of hypoxemia during intubation.
• In over 1,300 patients, the incidence of hypoxemia during the interval between induction and 2 minutes after intubation was markedly lower in patients preoxygenated with noninvasive ventilation compared to those preoxygenation with an oxygen mask.
• Importantly, the greatest benefit to noninvasive ventilation for preoxygenation was seen in patients with acute hypoxemic respiratory failure, those requiring > 70% FiO2 prior to intubation, and those with a BMI > 30.
• Lastly, the trial did not enroll patients who needed emergent intubation without time for at least 3 minutes of preoxygenation.

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Background: Sepsis remains a common entity associated with a relatively high rate of inpatient mortality, with timely recognition and treatment being key to improving patient outcomes. Various screening and warning scores have been created to attempt to identify sepsis and those patients at high risk of mortality earlier, but have limited performance because of suboptimal sensitivity and specificity.

A prospective observational study compared the performance of a variety of these scores (SIRS, qSOFA, SOFA, MEWS) as well as a machine learning model (MLM) against ED physician gestalt in diagnosing sepsis within the first 15 minutes of ED arrival. 

• 2550 patients deemed by EMS or triage nurse as potentially critically-ill
  • Excluded trauma, cardiac arrest, acute MI, stroke activation, patients in labor
• Seen by ED attendings (94%) / senior residents (6%) at a single urban academic center
  • Visual analog scale assessment, 0-100% likelihood that patient has sepsis
  • VAS >50% treated as ED physician gestalt in favor of sepsis
• 275 patients ultimately with discharge diagnosis of sepsis present on arrival to hospital
• Initial VAS outperformed all scores (AUC 0.90; 95% CI 0.88 to 0.92) both at 15 minutes and 1 hour

Although not without its limitations, this study highlights the importance and relative accuracy of physician gestalt in recognizing sepsis, with implications for how to develop future screening tools and limit unnecessary exposure to unnecessary fluids and empiric broad spectrum antibiotics.

Bottom Line: In the era of machine learning models and AI, ED physicians are not obsolete. Even at 15 minutes, without lab results and diagnostics, our assessments lead to appropriate diagnoses and care. In this new normal of prolonged wait times and ED boarding, ED triage and evaluation models that optimize early physician assessment are of the utmost importance.

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Magnesium is known to relax smooth muscles.  Interestingly, there is also some literature using it as part of Rapid Sequence Intubation (RSI) pre-treatment in general, in hopes that this or other mechanisms might allow it to improve intubating conditions.  Zouche et al recently published an RCT looking at giving IV magnesium as part of RSI pretreatment in cases where neuromuscular blockade (NMB) is not going to be given (e.g. scenarios where it is contraindicated).  IV Magnesium Sulfate, 50 mg/kg in 100 mL of saline given 15 minutes before induction, significantly improved intubating conditions in those getting sedation but not NMB (95% vs 39%).  

In 2013, Park et al did an RCT giving magnesium to all RSIs, even with the use of rocuronium in those patients, arguing that magnesium is also known to potentiate the effects of non-depolarizing NMB agents.  They also found better intubating conditions in the magnesium patients.

In both trials, magnesium was associated with lower heart rates and less hypertension in the peri-intubation and immediate post-intubation periods (of note: high dose magnesium is known to be associated with lower blood pressures, and can induce overt hypotension).  Neither study was really powered for more important measures like first pass success, mortality, or important side effects like peri-intubation hypotension.

Bottom Line: These are two small trials, and while more abundant literature should probably be obtained before we change our practice, one could consider giving magnesium sulfate, 50 mg/kg in 100 mL saline, prior to intubation in an attempt to improve intubating conditions.  In my opinion, this is probably worth considering in the rare circumstance that your patient has a true contraindication to neuromuscular blockade, but I probably wouldn't start doing this in standard RSI where you're going to be giving NMB until more literature confirms the safety of this approach.  Also, I would avoid this in situations where the patient is already hypotensive or at high risk of peri-intubation hypotension.  This may be worth considering in the very rare patient you're not necessarily going to give NMB to right away (maybe awake fiberoptic intubations?) who are also very low risk for hypotension.

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Title: Antipsychotics in the Treatment of Delirium in Critically Ill Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

We all do it. When our patients in the ICU develop delirium, we would give them an antipsychotic, commonly quetiapine (Brand name Seroquel), and all is good. However, results from this most recent meta-analysis may suggest otherwise. 

Settings: This is a meta-analysis from 5 Randomized Control Trials. Intervention was antipsychotic vs. placebo or just standard of care.

Participants: The 5 trials included A total of 1750 participants. All trials used Confusion Assessment Method for the ICU or Intensive Care Delirium Screening Checklist to measure delirium.

Outcome measurement: Delirium – and Coma-Free days

Study Results:

The use of any antipsychotic (typical or atypical) did not result in a statistically significant difference in delirium- and coma-free days among patients with ICU delirium (Mean Difference of 0.9 day; 95% CI -0.32 to 2.12).

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Similarly, atypical antipsychotic medication also did not result in difference of delirium- and coma-free days: Mean difference of 0.56 day; 95% CI -0.85 to 1.97).

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ICU length of stay was also not different in the group receiving antipsychotic: Mean difference -0.47 day, 95% CI -1.89 to 0.95).

![A close-up of a graph

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Discussion:

The authors used both delirium -free and coma-free days as a composite outcome because they reasoned that delirium cannot be evaluated in unresponsive patients. This composite outcome might have affected the true incidence of delirium and the outcome of delirium-free days. 

This meta-analysis would be different from previous ones that aimed to answer the same question. Previous studies compared either haloperidol vs a broader range of other medication (atypical antipsychotic, benzodiazepines) (Reference 2) or included all ICU patients  with or without delirium who received haloperidol vs. placebo (Reference 3). Overall, those previous studies also reported that the use of haloperidol has not resulted in improvement of delirium-free days.

Conclusion: 

There is evidence that the use of anti-psychotic medication does not result in difference of delirium- or coma-free days among critically ill patients with delirium.

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Many patients present to the ED with hypercarbic respiratory failure (i.e. COPD exacerbation, obesity hypoventilation syndrome etc.). Typically, our first line of treatment is the use of BiPAP, where we set an inspiratory pressure (IPAP) and an expiratory pressure (EPAP). The difference between these two pressures (as well as patient effort) determines the tidal volumes (and consequently minute ventilation) a patient receives in our attempts to help the patient “blow off CO2.” 

If you are having trouble with continued hypercarbia despite the use of BiPAP, another NIPPV mode that can be trialed is Average Volume-Assured Pressure Support (AVAPS). With BiPAP the patient receives the same fixed IPAP no matter what, even if their tidal volumes are lower than what is needed. With AVAPS, the ventilator will self-titrate the IPAP and increase (or decrease) the IPAP to reach the tidal volumes that you set, increasing the odds the patient will achieve the minute ventilation you are trying to achieve.

(AVAPS is essentially a non-invasive version of PRVC)

Initial settings (ask your RTs for help!):

• The target tidal volume is set to 8 ml/kg of ideal weight 
• The maximal IPAP value is generally fixed at 20-25 cm H2O
• The minimal IPAP value equals to EPAP + 4 cm H2O
• The value of the minimal inspiratory pressure is no less than 8 cmH2O and commonly higher
• The respiratory rate is set at 2-3 BPM below the resting respiratory rate

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This really interesting study suggests that the classic site of CPR “in the middle of the chest” may actually not be the ideal place to perform CPR. Previous imaging studies demonstrate that the ventricles are primarily beneath the lower third of the sternum and that standard placement of CPR compressions may deform the aortic valve, blocking the LVOT, and theoretically limiting perfusion of the coronaries and brain.

This study compared a standard CPR group with those undergoing TEE-guided chest compressions to avoid aortic valve compression. Those in the non-AV compression group had significantly increased likelihood of ROSC, survival to ICU, and higher femoral arterial diastolic pressures. However, there was no difference in long-term outcomes or end-tidal CO2.

Summary: Avoiding AV compression during CPR significantly improved the chance at ROSC in adult OHCA, but this small observational study did not show any difference in long term outcomes when compared to standard practice. Lowering the point of chest compressions in CPR to the lower third of the sternum may be beneficial.

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Historically, guideline recommendations have been to use a transfusion threshold of hemoglobin < 7 g/dL for patients unless they are a) undergoing orthopedic surgery or b) have cardiovascular disease (CVD).  

Applefeld et al conducted a meta-analysis in 2018 which suggested that restrictive (i.e. lower hemoglobin trigger, typically 7-8) transfusion targets lead to worse outcomes in CVD patients than liberal (i.e. higher hemoglobin trigger, typically 9-10) targets, and those authors have updated this analysis to include data from newer trials.  Interestingly, the conclusion remains similar: that when you look at the larger studies on restrictive vs liberal transfusion targets, CVD plays an important role, as patients with CVD tend to do better with liberal targets, and patients without CVD tend to do better with restrictive targets.  Of note, CVD is variably defined in these studies, and sometimes limited only to active Acute Coronary Syndromes, and other times refers to all patients with acute or chronic CVD.  However, according to their analysis, the aggregated data suggests that we should continue having higher transfusion targets in patients with CVD, and perhaps even more in the 9-10 range, as opposed to the goals of 7 or 8 which are common.

Bottom Line: We will likely continue to see different transfusion targets recommended for patients with cardiovascular disease (CVD), and may even see guideline and blood bank recommendations raise the target for these patients more into the 9-10 range, or expand this group to include chronic CVD.  This would mean a substantial increase in recommended RBC transfusions, and as emergency physicians it is important for us to monitor these recommendations, especially since transfusions are not harmless and raising hemoglobin thresholds could lead to complications that are difficult to measure in the literature.

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Title: Safety and Efficacy of Reduced-Dose Versus Full-Dose Alteplase for Acute Pulmonary Embolism: A Multicenter Observational Comparative Effectiveness Study

Settings: Retrospective observational study from a combination of Abbott Northwestern Hospital and 15 others as part of the Mayo Health system.

Participants: Patients between 2012 – 2020 who were treated for PE. Patients were propensity-matched according to the probability of a patient receiving a reduced- dose of alteplase.

Outcome measurement: 

• Primary outcome: all-cause and PE-related mortality or hemorrhage within 7 days of alteplase administration.
• Secondary outcomes: shock index at 8 hours after alteplase administration, LOS.

Study Results:

• A total of 284 patients were included in the retrospective analysis; 98 were treated with the full-dose and 186 with the reduced-dose alteplase regimen.
• Primary outcome was similar in both groups:
  • 7-day all-cause (5.6% in full- dose vs. 8% in reduced-dose, p = 0.45) 
  • PE-related (4% in full-dose vs. 4.2% in reduced-dose, p = 0.93)
• All other secondary outcomes were similar between both groups
• overall rates of hemorrhagic complications were significantly lower in the reduced-dose group than in the full-dose group (13% vs. 24.5%, respectively, p = 0.014).
• Major intracranial hemorrhage was higher, but not statistically significant, for full-dose group: 1.3% in reduced-dose vs. 7.1% in full-dose for major, (p = 0.067)

Discussion:

• Overall, there was more risk for full-dose. However, this is a retrospective study so whether it will be factored into clinical practice remains to be seen.
• The PERT team at UMMC still recommends full dose for hemodynamic unstable patients. Perhaps for those with somewhat instability, a half dose should be considered?
• There is still not enough data regarding the newer ones, as UMMS hospitals are starting to use TNK more frequently nowadays.

Conclusion: 

In this retrospective, Propensity-score matching study, the full-dose regimen but is associated with a lower risk of bleeding.

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Background:

           -Muscle rigidity has been described as a side-effect of fentanyl, specifically activation of expiratory muscles 

           -Excessive expiratory muscle use acts as “anti-PEEP,” causing lung derecruitment and hypoxemia

           -End-expiratory lung volume (EELV) has been used as a surrogate for lung recruitment

Study:

          -Small, two center, observational study (46 patients with ARDS)

          -50% of  patients had a significant increase in EELV after administration of neuromuscular blockade (NMB)

          -Statistically significant correlation between a higher dosage of fentanyl and a greater increase in EELV after NMB

Takeaways:

          -NMB can improve lung recruitment for a subset of patients with ARDS, particularly in patients with significant expiratory muscle use (this can be seen on your physical exam of your intubated ED boarding patient)

          -Although this was not the main point of this study, consider fentanyl-associated “anti-PEEP,” particularly in patients receiving fentanyl whose hypoxemia and/or ventilator mechanics are disproportionate to their imaging

                    -This can be assessed with NMB (but ensure the patient will have adequate minute ventilation first)

                    -Naloxone has also been shown to reverse fentanyl-associated rigidity, but obviously would induce patient discomfort/withdrawal

*Of note, because this was an observational trial, it is possible that the patients with increased work of breathing were simply given more fentanyl. Regardless, these findings are consistent with previously documented physiologic side effects of fentanyl.

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Moderate to High-Risk Pulmonary Embolism

In stable patients, call your local PE Response Team (PERT) for advice. The UMMC PERT team is available for any patient in the region and can be contacted through Maryland Access Center.

UMMC PERT stratifies by BOVA (with lactate criteria), CTA imaging, and patient physiology/history. For the consult, we will use the patients most recent vitals, their ROOM AIR sat if available, presence of RV dysfunction on echo/CTA, recent lactate, troponin, BNP, bedside/formal echo, and HPI.

Broad management recommendations for moderate or high-risk patients

• Presence of signs and symptoms of RV failure are usually the most concerning findings (cor pulmonale, RV:LV ratio > 1, hypoxia, etc)
• Fluid should only be given to optimize preload, usually guided by bedside echo. Start with aliquots of 250mL or 500mL. Fluid-restrictive strategy is usually preferred.
• First line pressor is norepinephrine. Epinephrine should be used for evidence of ventricular dysfunction
• We recommend inhaled vasodilators should be used in persistent hypoxemia or evidence of RV dysfunction. (This can be done via high-flow nasal cannula. Author editorial: every ED in America with HFNC should have the ability to do this. This alone can save a life.)
• Recommended SPO2 goal is >90% in absence of other lung pathology. AVOID positive pressure ventilation if at all possible.
• If intubation is necessary, optimize pressors, inotropes, and bronchodilation beforehand and have code drugs ready!
• Anticoagulation with unfractionated heparin in high risk patients. Our typical recommendation is 48-72 hours of unfractionated heparin in moderate risk patients as well, but DOACs are also an option. DOACs are not recommended in high risk patients currently.
• In hemodynamically unstable or coding patients without rapid access to VA-ECMO, we usually recommend thrombolytics in all patients with high suspicion for PE and without absolute contraindications (see below - PERT team can help guide this decision if there is time).
• See Pearl from 8/23/2023 for excellent summary of fibrinolytics and CPR in PE.
• IMPORTANT: While a patient may not be a candidate for therapy at the moment, it is important to clarify with PERT if they WOULD BE if they experience a degradation in circulating biomarkers or physiology (most patients would). Please pass this along to your admitting teams as well!
• Typical recommendations are for anticoagulation and repeat echocardiography in 48-72 hours to detect any worsening in RV function. 
• When in doubt, call your local PERT team!

PERT Acceptance for Transfer to UMMC/CCRU

• The primary decision will be whether this patient is a candidate for mechanical therapy (catheter-based or VA-ECMO). We are also evaluating for enrollment in the HI-PEITHO trial (see below). For patients who are candidates for mechanical therapy, the CCRU attending may bring on the entire PERT team: Cardiac Surgery, MICU, and Interventional Radiology (day 1-7 each month) or Vascular Surgery (day 8 or after each month).

See below for more information.

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Definitions of RV dysfunction

• TTE - RV/LV ratio >0.9, sPAP >30, RV end diastolic diameter >30mm, RV dilation, or free wall hypokinesis
• CTA - RV/LV ratio > 1

Absolute Contraindications to Fibrinolytic Therapy in Pulmonary Embolism

UMMC Relative Exclusion Criteria for VA ECMO for PE

• Age > 75
• Known metastatic cancer
• Cirrhosis
• O2 dependent COPD/ lung disease
• Severe dementia/ nursing home dependence

HI-PEITHO (NCT04790370) “is a prospective, multicenter RCT comparing Ultrasound-facilitated catheter-directed therapy (USCDT) and best medical therapy (BMT; systemic anticoagulation) with BMT alone in patients with acute intermediate–high-risk PE.”

Inclusion Criteria

• Two or more of: 
  • HR >100
  • SBP<110
  • RR>20 or SPO2<90% RA
• RV:LV > 1.0 on CTA
• Troponin elevated

In cardiac arrest, avoidance of excessive ventilation is key to achieving HQ-CPR and minimizing decreases in venous return to the heart. The controversy regarding BVM vs definitive airway and OHCA outcomes continues, but data indicates that mechanical ventilation during CPR carries no more variability in airway peak pressures and tidal volume delivery than BVM ventilation [1], with the AHA suggestion to keep in-hospital cardiac arrest patients with COVID-19 on the ventilator during the pandemic [2]. 

So, can we automate this part of CPR?

Two recent studies looked at mechanical ventilation (MV) compared to bagged ventilation (BV) in intubated patients with out-of-hospital-cardiac arrest (OHCA).  

Shin et al.'s pilot RCT evaluated 60 intubated patients, randomizing half to MV and half to BV, finding no difference in the primary outcome of ROSC or sustained ROSC, or ABG values, despite significantly lower tidal volumes and minute ventilation in the MV group [3]. 

Malinverni et al. retrospectively compared MV and BV OHCA patients from the Belgian Cardiac Arrest Registry, finding that MV was associated with increased ROSC although not with improved neurologic outcomes. Of note, patients across the airway spectrum were included (mask, supraglottic, intubated), and the mechanical ventilation was a bilevel pressure mode called Cardiopulmonary Ventilation (CPV) specific to their ventilators, specifically for use during cardiac arrest [4]. 

Bottom Line: Larger randomized trials will be necessary to get a definitive answer as to how mechanical ventilation affects outcomes in OHCA, but in instances where the cause of arrest is not primarily pulmonary (severe asthma, pneumothorax) and the ED is short-staffed or prolonged resuscitations are likely (such as in accidental hypothermic arrests), it is probably reasonable to keep patients on the ventilator:

• in a control mode
• with a target tidal volume of 6ml/kg,
• a PEEP of 5-8cmH2O (depending on habitus)
• and an FiO2 of 100% while still in arrest.
• Set the trigger to “off” to avoid additional breaths triggered by chest compressions
• Pressure alarms may need adjustment to allow asynchronous breath delivery during chest compressions

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Multiple studies have suggested differences in patient outcomes with balanced solutions (e.g. plasmalyte) vs unbalanced solutions (e.g. normal saline) when large volumes are administered.  But what about when giving smaller volumes of fluid?  Does it matter which one you choose?

A recent study by Raes et al in the Journal of Nephrology looked at urine and serum effects of administering 1L of normal saline, vs 1L of plasmalyte, to ICU patients needing a fluid bolus.  Chloride levels, strong ion difference (SID), and base excess were all significantly different between the two groups.  There was no difference in blood pressure or need for vasopressors.  As best I can tell, other clinically significant differences such as kidney injury were unfortunately not reported.

Bottom Line: When giving small (e.g. 1L) volumes of IVF, there ARE real physiologic differences seen between balanced and unbalanced solutions.  Whether these differences translate to patient-oriented or clinically significant outcomes remains unclear.

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Bag-Valve-Mask Ventilation During OHCA

• Current OHCA resuscitation guidelines recommend a 30:2 strategy of CPR with BVM ventilations.
• Idris and colleagues performed a secondary analysis of the Resuscitation Outcomes Consortium CCC clinical trial to determine the incidence of BVM ventilation during a 30:2 CPR strategy and assess the association of detectable ventilations with patient outcomes.
• In 1,976 patients, the authors found that only 40% of patients had detectable ventilations (> 250 ml) in more than half of CPR pauses.
• For those patients with detectable ventilations in more than 50% of pauses, there was an association with increased survival to hospital admission, increased survival to hospital discharge, and increased survival with favorable neurologic outcome.
• The current study highlights the importance of proper BVM ventilation during OHCA resuscitation and the opportunity to improve performance of this vital skill.

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Post-arrest shock is a common entity after ROSC. There is support for the use of continuous norepinephrine infusion over epinephrine to treat shock after ROSC, due to concerns about increased myocardial oxygen demand and associations with higher rates of rearrest [1,2] and mortality [2,3] with the use of epinephrine compared to norepinephrine, and increased refractory shock with use of epinephrine infusion after acute MI [4].

An article in this month’s AJEM compared norepinephrine and epinephrine infusions to treat shock in the first 6 hours post-ROSC in OHCA [5].  With a study population of 221 patients, they found no difference in the primary outcome of incidence of tachyarrhythmias, but did find that in-hospital mortality and rearrest rates were higher in the epinephrine group. 

Bottom Line: Absent definitive evidence, norepinephrine should probably be the first pressor you reach for to manage post-arrest shock, especially if there is strong suspicion for acute myocardial infarction.

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Background: There is no clear guidelines regarding whether norepinephrine or epinephrine would be the preferred agent to maintain hemodynamic stability after cardiac arrest. In recent years, there has been more opinions about the use of norepinephrine in this situation.

Settings: retrospective multi-site cohort study of adult patients who presented to emergency departments at Mayo Clinic hospitals in Minnesota, Florida, Arizona with out-of-hospital-cardiac arrest (OHCA). Study period was May 5th, 2018, to January 31st, 2022

Participants: 18 years of age and older

Outcome measurement: tachycardia, rate of re-arrest during hospitalization, in-hospital mortality.

Multivariate logistic regressions were performed.

Study Results:

• The study included 221 patients, 151 patients received norepinephrine infusion vs. 70 patients received epinephrine infusion.
• The maximum dose of epinephrine = 0.28 mcg/kg/min vs. 0.15 mcg/kg/min for norepinephrine.
• The Odds for clinically significant tachyarrhythmia was the same between both groups (OR 1.34, 95% CI 0.6802.62, P=0.40).
• Epinephrine infusion was associated with higher odds of in-hospital mortality (OR 6.21, 95% CI 2.37–16.25, P <0.001)
• Epinephrine infusion was associated with higher odds of re-arrest ( OR 5.77, 95% CI 2.74–12.18, P < 0.001)

Discussion:

It was retrospective study that uses electronic health records. Thus, other important factors from the pre-hospital settings might not be accurate.

On the other hand, the patient population came from multiple hospitals with varying practices so the patient population is more generalizable.

Conclusion: 

Although the rate of tachyarrhythmia was not different between patients receiving norepinephrine vs. epinephrine after ROSC. This study would add more data to the current literature that norepinephrine might be more beneficial for patients with post-cardiac arrest shock.

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Background: Acutely intoxicated / poisoned patients are commonly encountered in the ED, with the classic teaching that a GCS < 9 is an indication to intubate for airway protection. But we’ve probably all had a patient who was borderline, or who we thought was still protecting their airway pretty well despite a lower GCS. Are we risking our patient’s health and our careers by holding off on intubation? Maybe not. 

The NICO trial, a multicenter, randomized controlled trial, looked at patients presenting by EMS with GCS <9 due to suspected poisoning, without immediate indication for intubation (defined by signs of respiratory distress with hypoxia, clinical suspicion of any brain injury, seizure, or shock with systolic BP <90 mmHg). They found that withholding intubation with close monitoring, compared to the standard practice of intubating at the EMS or ED physician’s discretion, resulted in: 

• No deaths in either group
• Fewer intubations (18.1% vs 59.6%; AR difference 41.5%, 95% CI -54.1 to -30.9)
• Fewer intubation-associated adverse events (6% vs. 14.7%; 95% CI -16.6 to -0.7)
• Decreased incidence of pneumonia (6.9% vs 14.7%; 95% CI -15.9 to 0.3)
• Fewer ICU admissions (39.7% vs. 66.1%) and decreased hospital and ICU LOS

Comparing the patients who were intubated in each group, there was no significant difference between groups in:

• Rate of intubation-associated adverse events or first-pass failure
• Median ICU or hospital length of stay

Notes: 

• French study – EMS setup there is different from ours in the US
• Median GCS = 6, study population skewed young and male (mean age 33yo, 62% male) 
• Mostly alcohol or benzodiazepine intoxication
• Unblinded study

Bottom Line: Without clear indication for intubation such as respiratory distress or accompanying head bleed, etcetera, intubation for mental status alone shouldn't be dogma in acute intoxication. Close monitoring will identify need for intubation, without apparent worsened outcomes due to a watchful waiting approach.

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PEEP in the Ventilated COPD Patient?

• Patients with acute respiratory failure secondary to COPD often have dynamic hyperinflation and intrinsic PEEP (PEEPi).
• Both dynamic hyperinflation and PEEPi adversely effect pulmonary mechanics, markedly increase the work of breathing, impair respiratory muscle function, and can result in hemodynamic compromise.
• It has traditionally been felt that the application of external PEEP in the intubated COPD patient may worsen hyperinflation.
• Importantly, external PEEP has been shown to improve ventilator synchrony and decrease the work of breathing.
• PEEPi is measured using an end-expiratory hold maneuver in a passive, relaxed patient.
• External PEEP can then be set to approximately 70% of PEEPi, followed by frequent monitoring of plateau pressures in a volume-cycled ventilation mode.

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