Tag Archives: ventilation

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

Prehospital Hypocapnia and Poor Outcome After Severe Traumatic Brain Injury

Patients admitted to a level 1 trauma centre with traumatic brain injury whose end-tidal CO2 was kept with the Brain Trauma Foundation recommended limits of 30-35 mmHg (3.9-4.6 kPa) had a lower mortality than those whose CO2 was outside this range. The group in which the target was not achieved had a greater injury severity, which may have contribute to the difficulty in optimising ETCO2.

Prehospital Hypocapnia and Poor Outcome After Severe Traumatic Brain Injury
J Trauma. 2009 Jun;66(6):1577-82

Paeds BVM for adult resus

Smaller self-inflating bags produce greater guideline consistent ventilation in simulated cardiopulmonary resuscitation

A comparison between two sizes of self-inflating resuscitation bags revealed improved adherence to resuscitation guidelines with the smaller bag. Student paramedics were more likely to produce suboptimal tidal volumes and ventilation rates with a 1500ml bag than a 1000ml bag during simulated ventilation of an artificial lung model.

BMC Emerg Med. 2009 Feb 20;9:4


Full text at http://www.biomedcentral.com/1471-227X/9/4

NIV for weaning

Use of non-invasive ventilation to wean critically ill adults off invasive ventilation: meta-analysis and systematic review

The growing evidence base in support of liberating patients from invasive mechanical ventilation by means of non-invasive weaning is summarised in this systematic review of 12 randomised trials. Non-invasive weaning was associated with decreased mortality, ventilator associated pneumonia, length of stay in intensive care and hospital, total duration of mechanical ventilation, and duration of invasive ventilation. It should be noted that most of the trials exclusively enrolled patients with exacerbation of chronic obstructive pulmonary disease; benefits in other types of ventilated patients remain to be firmly proven.

BMJ. 2009 May 21;338:b157



Ventilator-associated tracheobronchitis

Ventilator associated pneumonia (VAP) is a well recognised complication of ICU care, but colonisation and infection further up the respiratory tract may be a risk factor for VAP that is worth identifying and treating. Ventilator-associated tracheobronchitis (VAT) has similar diagnostic criteria to VAP, but without the radiographic infiltrates.

Ventilator-associated tracheobronchitis: the impact of targeted antibiotic therapy on patient outcomes
Chest. 2009 Feb;135(2):521-8