There are 4 types of respiratory failure that all providers should be familiar with

Type 1: Hypoxemic, PaO2 <50; this can include shunt , V/Q mismatch, or high altitude. Pulmonary edema, ARDS, pneumonia are common causes of this type of failure.

Type 2: Hypercapnic respiratory failure; decreased RR or tidal volume. This includes neuromuscular disorders including GBS or Myasthenia Gravis, in addition to medication overdose. COPD and asthma can lead to this type of respiratory failure as well.

Type 3: Peri-operative; atelectasis; decreased FRC from being supine or obese during the operative period.

Type 4: Shock or hypoperfusion leading to increased work of breathing and respiratory failure.

American Thoracic Society (ATS) Conference Highlights

The ATS conference was last week in San Francisco and a few cool articles were presented. They are briefly summarized below:

1.     Using a helmet vs face mask for ARDS: Non-invasive ventilation is not ideal for ARDS for a variety of reasons. At the same time, endotracheal intubation and ventilation carries some risks as well. Could a new design of a "helmet" device make a difference? This one center study from the Univ of Chicago suggests that it would: decreased rate of intubation, increase in ventilator free days, and decrease in 90 day mortality. http://jama.jamanetwork.com/article.aspx?articleid=2522693

2.     Can aspirin prevent the development of ARDS in at risk patients in the emergency department? Unfortunately, it does not appear to help. http://jama.jamanetwork.com/article.aspx?articleid=2522739

3.     Should you start renal-replacement therapy (HD, CRRT etc) in critically ill patients with AKI sooner or later? Seems to have no difference and may actually lead to patients not needing any dialysis. Really a great read  if you have time.  http://www.nejm.org/doi/full/10.1056/NEJMoa1603017?query=OF&

4.    Should I extubate at night? Lastly, probably don’t extubate at night if you can avoid it. Or just be cautious. http://www.atsjournals.org/doi/abs/10.1164/ajrccmconference.2016.193.1_MeetingAbstracts.A6150

A recent survey looked at resuscitation practices that could help improve survival during in-hospital cardiac arrest

• Monitoring for interruptions in chest compressions
• Reviewing cardiac arrest cases monthly
• Adequate resuscitation training

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What is cardio-renal syndrome CRS?

• Covers disorders where acute or long-term dysfunction of one organ can cause acute or long-term dysfunction of the other
• Worsening renal failure, diuretic resistance in heart failure, and worsening kidney function during heart failure are all characteristic of the disease process

There are 5 types

1. Acute CRS: abrupt worsening of heart function leading to kidney injury

2. Chronic CRS: chronic heart failure leads to progressive kidney disease

3. Acute renocardiac syndrome: abrupt kidney dysfunction leading to acute cardiac disorder

4. Chronic renocardiac syndrome: chronic kidney disease leading to decreased cardiac function

5. Systemic CRS: Systemic condition leading to both heart and kidney disease

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• A recent observational study was published looking at the ICU incidence and outcome of ARDS
• This international prospective cohort study looked at 459 ICUs and over 29,000 patients
• Incidence: 10.4% met ARDS criteria
• Severe ARDS occurred in 23.4%
• Clinical recognition of mild ARDS was only 51%
• Less than 2/3rds of patients with ARDS received a TV of 8 mL/kg or less
• Prone positioning was used in 16% of patients with severe ARDS
• Recognition of ARDS was associated with higher PEEP, greater use of neuromuscular blockers, and prone positioning
• Mortality ranged from 35% to 46%
• Pneumonia was the biggest risk factor for ARDS

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• AKI can be seen in up to 40% of ICU patients
• Around 5-10% require treatment with renal replacement therapies
• The most common cause is acute tubular necrosis
• Definition by KDIGO:

1. Increase in Creatinine by 0.3 or more within 48 hours OR
2. Increase in Cr to >1.5 x baseline, presumed to have occured within the prior 7 days
3. Urine volume <0.5 mL/kg/hr x 6 hours

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Happy New Year!!!

My new year's resolution is to use less antibiotics (and eat more Cap'n Crunch Berries)

Will I be successful?

A multi-center, ICU, observational study looking at over 900 patients from 67 ICUs showed that half of all empiric antibiotics ordered in patients are continued for at least 72 hours in the abscence of adjudicated infection.

• We have been well trained to start antibiotics but stopping or limiting use can be difficult
• The greater the severity of illness, the longer the antibiotics were continued in this study

Things to consider:

The same way we try and limit central line use, we should try and decrease antibiotic usage on a daily basis

Tips to decrease use: daily clinical pharmacist input, ID specialist involvement, automated stop dates, 72 hour vancomycin cessation protocols, incentives for de-escalation, educational resources

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• What type of fluid we use in critical care resuscitation has been hotly debated for some time
• The most recent battles have been played out between NS and plasmalyte or buffered solutions
• There has been some evidence that high chloride solutions can lead to renal injury requiring renal replacement therapy (RRT)
• Does a buffered crystalloid reduce renal complications compared with normal saline in patients admitted to the ICU?
• The SPLIT Trial (Saline vs Plasma-Lyte) from New Zealand ICU's adds more to our knowledge about this topic while enrolling over 2,000 patients
• Summary:

1. Primary outcome was a rise in creatinine
2. There was no difference in the primary outcome or incidence of AKI
3. There was no difference in use of RRT or mortality
4. Suggesting that is doesnt make too much of a difference

• There were some limitations: 90% of patients were given fluid before enrollment that was buffered crystalloid and patients were only given around 2 liters on average of fluid in the ICU

The Bottom Line: This was a nicely designed study to evaluate the safety of both fluids. It does suggest that either fluid type is for the most part OK. But in patients requiring hefty fluid boluses, we should be cautious in what type of fluid we choose.

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• Invasive candidal infections can carry a high mortality (up to 40%) and can hard to diagnose
• In the ICU it is important to know which patients are at risk for developing invasive candidal infections

Risk factors for invasive candidal infections

• Critical illness (long ICU stays)
• Abdominal surgery (anastomotic leaks, repeat laporatomies)
• Necrotizing pancreatitis
• Hematologic malignencies
• Solid organ transplant
• Solid organ tumors
• Neonates (low birth wt, preterm)
• Use of broad spectrum antibiotics
• Central lines/PICC lines
• TPN
• Hemodialysis
• Steroid use
• Candidal colinization (urine, sputum)  

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• A recent trial looked at the three common sites for central venous catheters in 3471 catheter insertions
• The primary outcome was a composite of catheter-related bloodstream infection and DVT
• The femoral line group had a higher risk of DVT and infections although the risk from both is still very low
• Pneumothorax occurred in 1.5% of subclavian lines and 0.5% of jugular lines
• Subclavian lines are thought to have lower infection rates due to a longer subcutaneous courses before entry. They also have the lowest bacterial bioburden and tend to be protected against disruption

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SIMV (Synchronized intermittent mandatory ventilation)

• A common mode of ventilation that all pratitioners should be familiar with
• It provides a minimum number of fully assisted breaths synchronized with patient respiratory effort
• Patient or time triggered
• Flow limited
• Volume cycled
• Any additional breaths are unassisted and determined by patient effort
• SIMV=AC when heavily sedated
• The idea is exercise the patients lungs but this can lead to increased work of breathing and fatigue, and prolong extubation when used

Pressure Regulated Volume Control (PRVC)

Here are some basic pearls about PRVC Ventilation

• Form of Assist Control (AC) ventilation: patient initiated or ventilator intiated
• Constant pressure through inspiration
• Decelerating inspiratory flow pattern
• Ventilator adjusts pressure breath to breath based on patient’s airway resistance and compliance
• Not recommended for asthma or COPD
• Set: RR, tidal volume, upper pressure limit, oxygen level, I:E ratio (can start at 1:2), PEEP

Benefits: minimum PIP, guaranteed tidal volume, patient can trigger more breaths, improved oxygenation, breath by breath changes 

Care of Drowning Patients in the ED

• 500,000 worldwide deaths per year/10 per day in US on average
• Main goal of resuscitation is to reverse hypoxemia: endotracheal intubation, mouth-to-mouth, BVM depending on setting
• In water resuscitation can be considered (mouth-to-mouth only) while the patient is being actively rescued
• CPR with Airway emphasis- five rescue breaths, 30 compressions, then 2 breaths/30 compressions until the airway can be secured
• Turning the patient over and performing abdominal thrusts or back blows is not helpful
• ARDSnet protocol is generally used when intubated
• No steroids or prophylactic antibiotics are indicated
• Consider trauma (CT head and C-spine precautions based on history/exam)
• Warm up your patient as needed--assume hypothermia on presentation
• Can consider therapeutic hypothermia after ROSC and when rewarmed---no clear benefit here

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With a new academic year starting, it is important to review some details on central lines

Complications of central lines (TLC-Triple lumen catheter)

• Pneumothorax (more common with subclavian)
• Arterial puncture (more common with femoral)
• Catheter malposition
• Subcutaneous hematoma
• Hemothorax
• Catheter related infection (historically more with femoral)
• Catheter induced thrombosis
• Arrhythmia (usually from guidewire insertion)
• Venous air embolism (avoid with Trendelenburg position)
• Bleeding

Avoiding infections: hand hygiene, chlorhexidine skin antisepsis, maximal barrier precautions, remove unnecessary lines, full gown and glove w/ mask and sterile technique.

Catheter position: 16-18cm for Right sided and 18-20 cm for Left sided. But can vary based on height, neck length, and catheter insertion site. Approximate length based on these factors.

Flow rates: Remember that putting in a central line does not necessarily improve your flow rates in resuscitation

16 G IV: 220 ml/min

Cordis/introducer sheath: 126 ml/min

18 G IV: 105 ml/min

16G distal port TLC: 69 ml/min

Ports (Can vary with type of catheter)

1. Distal exit port (16G)

2. Middle port (18G)

3. Proximal port (18G)

Arterial puncture: hold pressure for 5 mins and evaluate for hematoma formation (harder for subclavian approach)

Arterial cannulation: Has decreased due to ultrasound use but if you do cannulate an arterial site, don’t panic. Don’t remove the line. You can check a blood gas or arterial pulse waveform to confirm placement.  Call vascular surgery for open removal and repair or endovascular repair. You could potentially remove a femoral arterial line and hold pressure but seek vascular advice regarding possible closure devices to use after removal.

High Flow Nasal Cannula (HFNC) in acute respiratory hypoxemia

• HFNC has been used for a variety of patients with respiratory distress (See previous pearl: https://umem.org/educational_pearls/2411/)
• The benefits include:

1. Low levels of positive pressure in the upper airways
2. High flow rates, titratable oxygen levels, humidied air, more comfort than NIV
3. Decreases physiological dead space by flushing out CO2 therefore improving oxygenation

• A recent trial published in NEJM looked at using HFNC in patients with respiratory failure

The Trial:

• Patients without hypercapnia and with acute hypoxemic respiratory failure (PaO2/FiO2 <300 or less) were randomized to HFNC, standard oxygen therapy via face mask, or non-invasive positive pressure ventilation (NIV).
• Primary outcome was proportion of patients intubated at day 28
• 310 patients in European ICUs

Results:

• Intubation rate (p=0.18): 38% in the HFNC; 47% in the standard group; 50% in the NIV
• Number of ventilator free days at day 28 was significantly higher in the HFNC
• Higher mortality at 90 days with NIV
• No difference in intubation rates but there were more ventilator free dates as well as a lower 90 day mortality

Bottom line:

Consider using HFNC prior to or while deciding on intubation in patients with hypoxemic respiratory failure usually due to pneumonia

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Safety of Thoracentesis

• Thoracentesis is routinely performed in both acute and non-acute patients while patients are admitted to the hospital for respiratory distress
• A recent 12 year cohort study of 9320 thoracenteses was published from Cedars-Sinai Hospital
• The clinicians that perform these procedures are well experienced
• The most common complications include pneumothorax, re-expansion pulmonary edema, and bleeding

Results after 24 hours of followup post-procedure

• 0.61% of iatrogenic pneumothoraces
• 0.01% rate of re-expansion pulmonary edema
• 0.18% of bleeding episodes

Other interesting points:

• Pneumothorax was associated with removing >1500 mL of fluid and more than one needle pass
• Ultrasound was routinely used
• A safety-tipped needle/catheter was used
• Fluid was removed by manual hand pumping (not vacuum bottles)
• CXR only done post-procedure if patients were symptomatic
• No blood products were given for low platelets or thrombocytopenia

Bottom line: Use your ultrasound to direct your tap and dont take out more than 1500 mL routinely

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• A recent meta-analysis found that non-invasive ventilation can improve survival in acute care settings.
• Consider using NIPPV in:
  • COPD exacerbation
  • Obesity hypoventilation syndrome
  • Asthma
  • Hypoxemic respiratory failure
  • Cardiogenic pulmonary edema
  • ARDS
• Make sure to reassess your patients for improvement within one hour of applying NIPPV. If gas exchange has not significantly improved then endotracheal intubation and mechanical ventilation should be considered.
• Adverse effects:
  • Gastric distension
  • Pressure ulcers on the face
  • Can be uncomfortable
• In cardiogenic pulmonary edema there are cardiac performance benefits:
  • Decreases preload
  • Decreases left ventricular afterload
  • Improved cardiac ouput

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Transfusion in Major Trauma: The PROPPR Trial

What should we be transfusing in major trauma?

• Should we aim towards 1:1:1 ratios or is that unnecessary? Most trauma centers have gone towards a 1:1:1 ratio or a 1:1:2 ratio with a greater percentage of RBCs transfused in the latter
• Our strategy should be to avoid coagulopathy, acidosis, and hypothermia
• This trial looks at transfusion of Plasma, Platelets, and RBCs in a 1:1:1 vs a 1:1:2 ratio
• Is it safe to give 1:1:1 ratios?

The Trial

• RCT, Non-blinded
• 12 Trauma Centers in North America
• 15 years or older; highest level trauma activation
• Predicted to receive massive transfusion
• Transfusions stopped when clinically indicated

Results

• 24 hour or 30 day mortality no significant difference
• Post-hoc analysis: death by exsanguination (9% vs 15%) in the 1^st 24hrs was significantly decreased in the 1:1:1 group
• Achieved hemostatis (86% vs 78%; p = 0.006) greater in the 1:1:1 group

Conclusions

• Was not powered to detect a difference of less than 10% in mortality
• There was less mortality from exsanguination in the 1:1:1 ratio.
• Worth noting that platelets given first in 1:1:1 group (in control group 6 U and 3 FFP given prior to platelets)
• There was some "catch up" in the 1:1:2 group (after the initial transfusions, these patients got more than expected plasma and platelets based on INR/Plt counts)
• TEG was used in the majority of the patients and TXA was used in a majority of patients (but similar in both groups)

How does this affect my practice?

A 1:1:1 transfusion practice is safe and can decrease mortality from hemorrhage in major trauma

Other points: control bleeding, permissive hypotension, avoid crystalloids, use TEG to guide therapy (TXA etc)

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Updates in preventative strategies in the ICU

Preventing Ventilator Associated Pneumonia (VAP)

• Traditionally ICUs use techniques such as head of bed elevation> 30 degrees, chlorhexidine mouth rinses, reduced sedation, and controlling cuff pressure between 20-30 cm H2O to reduce VAP
• A new trial confirms that subglottic suctioning also reduces VAP
• Endotracheal tubes are made with a suction line along the edge with fenestrations below the vocal cords and above the cuff
• This is hooked to wall suction removing secretions before they are aspirated
• VAP rates are very low in the US (most likely due to under-reporting)
• It is reported at around 15 VAPs/ 1000 ventilator days in Europe

The trial

• 5 ICUs in Belgium; 352 total patients with suctioning vs control were randomized
• Reduced incidence of confirmed VAP 9% vs 18%, decrease ventilator days 10 vs 20 and antibiotic use 7% absolute reduction

Bottom Line

• More expensive around $20 or more vs $1 for a regular ETT
• NNT around 11 to prevent one VAP: it is cost efficient
• Use them in patients who will remain intubated for > 48hrs (not elective surgical patients)

Daily bathing with chlorhexidine does not reduce health care associated infections

• It is believed that daily bathing with chlorhexidine antibiotic washes decrease rates of infection in the ICU; this is debatable

The trial

• One center, 5 ICUs, 9340 patients
• 10 week cleaning period followed by a two week washout then crossover to the alternate treatment (non-antibiotic washes)
• Looking for CLABSIs, CAUTIs, VAP and C. diff infections
• 55 infections occurred in the chlorhexidine group; 60 in the control goup.
• 2.86 per 1000 patient days (chlorhexidine group) vs 2.9 per 1000 patient days (control)

Bottom Line

• Does not appear to be helpful (perhaps specific patient groups such as bone marrow units may benefit)
• More expensive to use these washes and can lead to resistance
• Very well designed study with a variety of ICUs used (although one center)

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Diaphragm weakness and its significance

• Acute respiratory failure is partially due to respiratory muscles inability to meet the demands of respiration that is strained by a medical condition
• Ventilation can have an adverse effect on respiratory muscles even after just 5-6 days (atrophy)

There are several ways to monitor diaphragm strength and function

• Airway pressure and flow waveforms
• Occlusion pressure
• Esophageal pressure waveforms
• Sniff maneuvers
• Ultrasound
• Diaphragm EMG
• Chest xray

Clinical Relevance

• Goal is to use these devices to limit the development of respiratory muscle atrophy because of disuse
• Prevent "overassist" from the ventilator
• Potential use in weaning trials to evaluate for respiratory muscle performance
• This is a new area of intensive care research that could lead to improvements in outcomes

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