End tidal CO2 and procedural sedation

One hundred and thirty-two adults underwent propofol sedation in the emergency department and were randomised into a group in which treating physicians had access to the capnography and a blinded group in which they did not. All patients received supplemental oxygen (3 L/minute) and opioids greater than 30 minutes before. Propofol was dosed at 1.0 mg/kg, followed by 0.5 mg/kg as needed.

Hypoxia (defined as SpO2 less than 93%) was observed in 17 of 68 (25%) subjects with capnography and 27 of 64 (42%) with blinded capnography (p=.035; difference 17%; 95% confidence interval 1.3% to 33%). Capnography identified all cases of hypoxia before onset (sensitivity 100%; specificity 64%), with the median time from capnographic evidence of respiratory depression to hypoxia 60 seconds (range 5 to 240 seconds).

The journal comments: ‘this study provides compelling evidence that capnography can aid in the detection of respiratory depression and reduce hypoxia during procedural sedation.’

However in an accompanying article outlining a pro-con debate for introducing capnography as standard practice in ED procedural sedation, the point is made that the safety benefit purported in this and similar studies is decreased hypoxemia, according to thresholds ranging from 90% to 95%, lasting from 5 to 15 seconds. In the clinical context, many of these events are self-limiting or resolve with minimal interventions such as airway repositioning or supplemental oxygen, and other more clinically relevant outcomes are rarely examined (perhaps due to the rarity of genuinely adverse events in ED procedural sedation by emergency physicians).

Does end tidal CO2 monitoring during emergency department procedural sedation and analgesia with propofol decrease the incidence of hypoxic events? A randomized, controlled trial
Ann Emerg Med. 2010 Mar;55(3):258-64

Prone Ventilation for ARDS

A multicentre randomised controlled trial of 342 adult patients with moderate to severe ARDS assessed the effect of prone ventilation on mortality, and showed no benefit (6-month mortality was 52.7% and 63.2%, respectively (RR, 0.78; 95% CI, 0.53-1.14; P = .19).

Complications were higher in the prone group.

Prone positioning in patients with moderate and severe acute respiratory distress syndrome: a randomized controlled trial
JAMA. 2009 Nov 11;302(18):1977-84

Nonvariceal Upper Gl Bleeding – international guidelines

International Consensus Recommendations on the Management of Patients With Nonvariceal Upper Gastrointestinal Bleeding have been published. Here is a summary of the recommendations; a link to the full text document is at the bottom of this page.

  1. Prognostic scales are recommended for early stratification of patients into low- and high-risk categories for rebleeding and mortality.
  2. Blood transfusions should be administered to a patient with a hemoglobin level of 70 g/L or less.
  3. In patients receiving anticoagulants, correction of coagulopathy is recommended but should not delay endoscopy.
  4. Promotility agents should not be used routinely before endoscopy to increase the diagnostic yield.
  5. Selected patients with acute ulcer bleeding who are at low risk for rebleeding on the basis of clinical and endoscopic criteria may be discharged promptly after endoscopy.
  6. Preendoscopic PPI therapy may be considered to downstage the endoscopic lesion and decrease the need for endoscopic intervention but should not delay endoscopy (the observed lesion downstaging attributable to PPI therapy before endoscopy may be even more beneficial in situations in which early endoscopy may be delayed or when available endoscopic expertise may be suboptimal).
  7. Early endoscopy (within 24 hours of presentation) is recommended for most patients with acute upper gastrointestinal bleeding.
  8. A finding of a clot in an ulcer bed warrants targeted irrigation in an attempt at dislodgement, with appropriate treatment of the underlying lesion.
  9. The role of endoscopic therapy for ulcers with adherent clots is controversial. Endoscopic therapy may be considered, although intensive PPI therapy alone may be sufficient.
  10. Epinephrine injection alone provides suboptimal efficacy and should be used in combination with another method.
  11. Clips, thermocoagulation, or sclerosant injection should be used in patients with high-risk lesions, alone or in combination with epinephrine injection
  12. Routine second-look endoscopy is not recommended.
  13. An intravenous bolus followed by continuous-infusion PPI therapy should be used to decrease rebleeding and mortality in patients with high-risk stigmata who have undergone successful endoscopic therapy.
  14. Patients should be discharged with a prescription for a single daily-dose oral PPI for a duration as dictated by the underlying etiology.
  15. Most patients who have undergone endoscopic hemostasis for high-risk stigmata should be hospitalized for at least 72 hours thereafter.
  16. Where available, percutaneous embolization can be considered as an alternative to surgery for patients for whom endoscopic therapy has failed.
  17. Patients with bleeding peptic ulcers should be tested for H. pylori and receive eradication therapy if it is present, with confirmation of eradication.
  18. Negative H. pylori diagnostic tests obtained in the acute setting should be repeated
  19. In patients with previous ulcer bleeding who require an NSAID, it should be recognized that treatment with a traditional NSAID plus PPI or a cyclooxygenase-2 (COX-2) inhibitor alone is still associated with a clinically important risk for recurrent ulcer bleeding.
  20. In patients with previous ulcer bleeding who require an NSAID, the combination of a PPI and a COX-2 inhibitor is recommended to reduce the risk for recurrent bleeding from that of COX-2 inhibitors alone.
  21. In patients who receive low-dose ASA and develop acute ulcer bleeding, ASA therapy should be restarted as soon as the risk for cardiovascular complication is thought to outweigh the risk for bleeding.
  22. In patients with previous ulcer bleeding who require cardiovascular prophylaxis, it should be recognized that clopidogrel alone has a higher risk for rebleeding than ASA combined with a PPI.

International Consensus Recommendations on the Management of Patients With Nonvariceal Upper Gastrointestinal Bleeding
Ann Intern Med. 2010 Jan 19;152(2):101-13 (Full Text)

Higher PEEP in ARDS

The current mortality of 35% associated with acute lung injury (ALI) is roughly three times higher than that associated with ST-segment elevation myocardial infarction. Protective ventilation strategies limiting tidal volumes and plateau pressures improve outcome, but the optimial level of PEEP is debated. In patients with ALI and its more severe form acute respiratory distress syndrome (ARDS), higher levels of PEEP may prevent atelectasis, recruit already collapsed alveolar units, and reduce pulmonary damage by avoiding the cyclical opening and collapse of alveoli.

In a systematic review and meta-analysis of individual-patient data, researchers investigated the association between higher vs lower PEEP levels and patient-important outcomes among adults with acute lung injury or ARDS who receive ventilation with low tidal volumes.

Randomized trials eligible for this review compared higher with lower levels of PEEP (mean difference of at least 3 cm H2O between groups) in critically ill adults with ALI or ARDS. Eligible trials incorporated a target tidal volume of less than 8 mL/kg of predicted body weight in both the experimental and the control ventilation strategies and provided patient follow-up to death or for at least 20 days.

Three trials, including 2299 patients, met the eligibility criteria: the Assessment of Low Tidal Volume and Elevated End-Expiratory Pressure to Obviate Lung Injury (ALVEOLI) trial, the Lung Open Ventilation to Decrease Mortality in the Acute Respiratory Distress Syndrome (LOVS) study, and the Expiratory Pressure Study (EXPRESS).

There were 374 hospital deaths in 1136 patients (32.9%) assigned to treatment with higher PEEP and 409 hospital deaths in 1163 patients (35.2%) assigned to lower PEEP (adjusted relative risk [RR], 0.94; 95% confidence interval [CI], 0.86-1.04; P = .25). Treatment effects varied with the presence or absence of ARDS (as opposed to ALI). In patients with ARDS (n = 1892), there were 324 hospital deaths (34.1%) in the higher PEEP group and 368 (39.1%) in the lower PEEP group (adjusted RR, 0.90; 95% CI, 0.81-1.00; P = .049). Rates of pneumothorax and vasopressor use were similar.

The authors conclude that treatment with higher vs lower levels of PEEP was not associated with improved hospital survival overall when ALI/ARDS were considered together, but higher levels were associated with improved survival among the pre-defined subgroup of patients with ARDS.

Higher vs lower positive end-expiratory pressure in patients with acute lung injury and acute respiratory distress syndrome: systematic review and meta-analysis
JAMA. 2010 Mar 3;303(9):865-73

Difficult mask ventilation

A comprehensive review of difficult mask ventilation (DMV) reports that the incidence of DMV varies widely (from 0.08% to 15%) depending on the criteria used for its definition. It reminds us that the independent predictors of DMV are:

  • Obesity
  • Age older than 55 yr
  • History of snoring
  • Lack of teeth
  • The presence of a beard
  • Mallampati Class III or IV
  • Abnormal mandibular protrusion test

The review also points out that DMV does not automatically mean difficult laryngoscopy, although it does increase its likelihood.

In addition to positioning, oral and nasal adjuncts, two person technique, and jaw thrust, the application of 10 cmH20 CPAP may help splint open the airway and reduce the difficulty of mask ventilation in some patients.

Difficult mask ventilation
Anesth Analg. 2009 Dec;109(6):1870-80

Causes of DMV:

1) Technique-related

1. Operator: Lack of experience

2. Equipment

a. Improper mask size
b. Difficult mask fit: e.g., beard, facial anomalies, retrognathia
c. Leakage from the circuit
d. Faulty valve
e. Improper oral/nasal airway size
3. Position: Suboptimal head and neck position
4. Incorrectly applied cricoid pressure
5. Drug related
a. Opioid-induced vocal cord closure
b. Succinylcholine-induced masseter rigidity
c. Inadequate depth of anesthesia
d. Lack of relaxation?

2) Airway-related

1. Upper airway obstruction

a. Tongue or epiglottis
b. Redundant soft tissue in morbid obesity and sleep
apnea patients
c. Tonsillar hyperplasia
d. Oral, maxillary, pharyngeal, or laryngeal tumor
e. Airway edema e.g., repeated intubation attempts,
trauma, angioedema
f. Laryngeal spasm
g. External compression e.g., large neck masses and
neck hematoma

2. Lower airway obstruction

a. Severe bronchospasm
b. Tracheal or bronchial tumor
c. Anterior mediastinal mass
d. Stiff lung
e. Foreign body
f. Pneumothorax
g. Bronchopleural fistula

3) Severe chest wall deformity or kyphoscoliosis restricting chest expansion

Lactate clearance goal in sepsis

Previous work in severe sepsis/septic shock patients has shown that a decrease in lactate concentration by at least 10% during emergency department resuscitation predicts survival. Since this is a potential alternative resuscitation goal to a central venous oxygen saturation (ScvO2) of 70% (as per surviving sepsis campaign guidelines), lactate clearance was compared with ScvO2 in a randomised non-inferiority trial of 300 patients.

All patients were managed in the ED and received fluids, antibiotics, and vasopressors as needed. Then lactate clearance or ScvO2 were measured, and if the respective goals of 10% or 70% were not met, packed cells or dobutamine were given depending on haematocrit. Lactate clearance was the percentage decrease in lactate between two venous specimens taken two hours apart.

Interestingly only 29 patients received either packed cells or dobutamine. Each group was similar in terms of time to antibiotic therapy and amount of fluid given. Patients in the group resuscitated to a lactate clearance of 10% or higher had 6% lower in-hospital mortality than those resuscitated to an ScvO2 of at least 70% (95% CI for this difference, –3% to 15%) exceeding the –10% predefined noninferiority threshold.

The authors conclude ‘these data support the substitution of lactate measurements in peripheral venous blood as a safe and efficacious alternative to a computerized spectrophotometric catheter in the resuscitation of sepsis.’

Lactate clearance vs central venous oxygen saturation as goals of early sepsis therapy: a randomized clinical trial
JAMA. 2010 Feb 24;303(8):739-46

Chlorhexidine-alcohol surgical site prep

In contrast to the situation with skin preparation for intravascular catheters, there have been no recommendations for surgical practice. A randomised controlled trial compared chlorhexidine–alcohol (2% chlorhexidine gluconate and 70% isopropyl alcohol or ‘ChloraPrep’) with povidone–iodine in 849 patients undergoing surgery. The overall rate of surgical-site infection was significantly lower in the chlorhexidine–alcohol group than in the povidone–iodine group (9.5% vs. 16.1%) and chlorhexidine–alcohol was significantly more protective than povidone–iodine against both superficial incisional infections (4.2% vs. 8.6%) and deep incisional infections (1% vs. 3%) but not against organ-space infections (4.4% vs. 4.5%)

Chlorhexidine-Alcohol versus Povidone-Iodine for Surgical-Site Antisepsis
N Engl J Med. 2010 Jan 7;362(1):18-26

Alternative to warfarin after VTE

In a randomised noninferiority trial the oral direct thrombin inhibitor dabigatran was compared with warfarin in patients with venous thromboembolic disease (VTE) after acute treatment with parenteral anticoagulation. Recurrent VTE and major bleeding rates were similar in the two groups. Dabigatran has the advantage of not requiring blood monitoring.

Dabigatran versus Warfarin in the Treatment of Acute Venous Thromboembolism
N Engl J Med. 2009 Dec 10;361(24):2342-52

Noradrenaline vs Dopamine in Shock

Another nail in dopamine’s coffin? In a blinded randomised controlled trial in shocked patients1, there was no difference in mortality when dopamine was compared with noradrenaline as the initial vasopressor. However the dopamine group had a significantly higher incidence of dysrythmia. In addition, mortality was higher in the predefined subgroup of 280 patients with cardiogenic shock. The results of this European study of 1679 patients are very similar to those of a similar but open-label American trial in 252 patients published recently2.

1. Comparison of Dopamine and Norepinephrine in the Treatment of Shock
NEJM 2010;362(9):779-89

2. Efficacy and Safety of Dopamine versus Norepinephrine in the Management of Septic Shock
Shock. 2009 Oct 21. [Epub ahead of print]

Cricoid pressure squashes kids’ airways

A bronchoscopic study of anaesthetised infants and children receiving cricoid pressure revealed the procedure to distort the airway or occlude it by more than 50% with as little as 5N of force in under 1s and between 15 and 25N in teenagers. Therefore forces well below the recommended value of 30 N will cause significant compression/distortion of the airway in a child

Effect of cricoid force on airway calibre in children: a bronchoscopic assessment
Br J Anaesth. 2010 Jan;104(1):71-4