Tag Archives: ventilation

All Updates, Kids

Newborn mask ventilation

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Seventy doctors and nurses from neonatal units administered positive pressure ventilation to a term newborn manikin using a Neopuff T-piece device. Recordings were made (1) before training, (2) after training in mask handling and (3) 3 weeks later. Leak and obstruction were calculated.
Median (IQR) leak was 71% (32–95%) before training, 10% (5–37%) directly after training and 15% (4–33%) 3 weeks later (p<0.001). When leak was minimal, gas flow obstruction was observed before, directly after training and 3 weeks later in 46%, 42% and 37% of inflations, respectively.
The training provided included the following demonstrated mask technique:

  1. Place the manikin’s head in a neutral position and gently roll the mask upwards onto the face from the tip of the chin.
  2. Hold the mask with the two-point-top hold where the thumb and index finger apply balanced pressure to the top flat portion of the mask where the silicone is thickest.
  3. The stem is not held and the fingers should not encroach onto the skirt of the mask.
  4. The thumb and index finger apply an even pressure on top of the mask.
  5. The third, fourth and fifth fingers perform a chin lift with the same pressure upwards as applied by the thumb and index finger downwards.


In this technique the mask is squeezed onto the face, between the downward thrust of the fingers and upward pull of the chin lift.
Leak and obstruction with mask ventilation during simulated neonatal resuscitation
Arch Dis Child Fetal Neonatal Ed 2010;95:F398-F402
Even with the right technique, adequacy of ventilation can be hard to assess. Principles to bear in mind are:

  • International guidelines recommend that infants with inadequate breathing or bradycardia be given positive pressure ventilation (PPV) via a face mask with a self-inflating bag, flow-inflating bag or T-piece device.
  • Adequacy of ventilation is then judged by assessing the heart rate.
  • However, if the heart rate does not increase, chest wall movements should be assessed to gauge adequacy of ventilation.
  • A human observational study reported a mean VT of 6.5 ml/kg in spontaneous breathing preterm infants in the first minutes of life.
  • When assisted ventilation is required, a peak inflating pressure (PIP) is chosen with the assumption that this will deliver an appropriate VT.
  • However, lung compliance and therefore the PIP required to deliver an appropriate VT vary in the minutes after birth.
  • It is likely that there are even greater differences between infants as the mechanical properties of the lung vary with gestational age and disease states.
  • In addition, many infants breathe during PPV adding to the inconsistency of VT delivered with a set PIP. Therefore, relying on a fixed PIP and subjective assessment of chest wall movement may result in either under- or over-ventilation.
  • Animal studies have shown that PPV with VT >8 ml/kg or inflations with large VTs can damage the lungs.

In an observational study of actual newborn resuscitations in Melbourne, researchers measured inflating pressures and VT delivered using a respiratory function monitor, and calculated face mask leak. After 60 seconds of PPV, resuscitators were asked to estimate VT and face mask leak. These estimates were compared with measurements taken during the previous 30 s.
In 20 infants, the median (IQR) expired tidal volume (VTe) delivered was 8.7 ml/kg (5.3–11.3). VTe and mask leak varied widely during each resuscitation and between resuscitators, who were also poor at estimating VT and mask leak.
Assessment of tidal volume and gas leak during mask ventilation of preterm infants in the delivery room.
Arch Dis Child Fetal Neonatal Ed. 2010 Nov;95(6):F393-7

All Updates, Guidelines, ICU

H1N1 Update from UK Intensive Care

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H1N1 Update 16 December 2010 sent from the UK Intensive Care Society
As many of you will already be aware, the predicted second wave of swine flu seems to becoming a reality. The HPA have received information that there has been a rise in the number of confirmed H1N1 cases and has restarted regular teleconferences to discuss the current situation and to disseminate the latest advice and information. The initial teleconference was held last Friday and the first question asked was how many cases have units seen. Although the total numbers were not high, the fact that there are confirmed cases throughout the UK gave support to the decision that hospitals should prepare for an increase in the numbers.
Subsequent updates have confirmed that the case numbers are rising and although not all patients admitted to ICUs with a suspected diagnosis of H1N1 have required mechanical ventilation or had H1N1 confirmed. As of Wednesday this week the numbers of H1N1 related ICU cases had risen to 140.  An additional concern is that the number of cases with probable H1N1 referred for ECMO is now 13 and this has resulted in a policy that there should be support for all the centers in the UK who can provide ECMO.
It is still too early to predict what the level escalation is going to be required, but there are real concerns that the combination of adverse weather conditions, the current financial restrictions in the NHS, and an H1N1 peak could place ICUs in a more seriously challenging situation than occurred in the previous outbreak.
For this reason, it is recommended that clinicians should once again have a low threshold for considering the possibility of H1N1 in patients who are referred to intensive care. Trusts should reconvene regular meetings to plan for any necessary expansion of critical care services. It is important that staff have up to date training in the use of personal protection equipment.  One of the most important points learned from the first outbreak was that early antiviral therapy can reduce the need for mechanical ventilation and it is recommended that any patients admitted to hospital with a history and symptoms suggestive of an influenza-like illness should be given antiviral therapy.
The following points were made in the HPA–led teleconference on 10 December:

  • be vigilant: have a low threshold for considering the diagnosis.
  • start antivirals whenever there is a suspicion of flu (oseltamivir 75or 150 mg bd po).
  • In patients with resistance or not tolerating NG medication, there is an IV preparation which is currently undergoing clinical trial. GSK produces it (zanamavir) and may provide it on patient-name compassionate grounds.
  • Use ARDSnet ventilation especially for those with normal lung compliance.
  • Consider HFO for those with poor compliance
  • Fluid restrict patients
  • Consider referral for ECMO early if conventional ventilation is failing. ECMO beds are occupied almost all occupied by ‘flu patients and elective surgery has been curtailed to accomodate them. Surge funding has been agreed for extra ECMO. In cases where conventional ventilation is failing and there are no other options, patients should be referred to Glenfield before seven days of MV.
  • HPA adviced has not changed with respect to infection control measures; these can be found here:http://www.dh.gov.uk/prod_consum_dh/groups/dh_digitalassets/@dh/@en/@ps/documents/digitalasset/dh_110899.pdf
  • The RCoA site still has an adult practice note from last year which will be updated
  • The HPA link to seasonal flu can be found here:http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/SeasonalInfluenza/Guidelines/
  • There will be advice re pregnant women after discussion with the RCOG
  • In some cases, URT specimens may be negative in severe cases and LRT samples may be needed for the diagnosis.
  • Point of care testing may have inadequate  sensitivity for this strain of H1N1

The current rate is 21.5/100,000.
We aim to provide updates on the ICS website and copy of this document is available to download via http://www.ics.ac.uk/ under ‘Latest News – H1N1 Latest News’.
Update by the Executive Committee of the Intensive Care Society.
Sent from the email of:
Pauline Kemp
Head of Secretariat

All Updates, ICU, PHARM, Resus

LMA to stoma ventilation

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Level 1 evidence is great, but for useful tips that can add options to your resuscitation toolbox there are some great finds in journal letters pages.
Try this one: An apneoic patient requires assisted ventilation in your resuscitation room. Bag-mask ventilation is ineffective. You then notice a mature tracheostomy at the same time that you’re told he had a laryngectomy. How would you ventilate him?
The obvious answer is to intubate the stoma with a size 6.0 tracheal tube or a tracheostomy tube if you have one. However prior to that you could bag-‘mask’ ventilate with a size 2 laryngeal mask airway applied to the stoma, holding the cuff in place with pressure through an index finger.

Such a technique is desribed in the context of an elective anaesthesia case in this month’s Anaesthesia. The LMA cuff provided an effective seal around the stoma, thereby allowing leak-free ventilation.
Stoma ventilation using a paediatric facemask is another option.

Tracheostomy ventilation using a laryngeal mask as a ‘bridge to extubation’
Anaesthesia 2010;65(12):1232–1233

All Updates, ICU

Cis-atracurium for ARDS

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The ACURASYS study of atracurium vs placebo in ARDS: three ml rapid intravenous infusion of 15 mg of cis-atracurium besylate or placebo was administered, followed by a continuous infusion of 37.5 mg per hour for 48 hours. There appeared to be benefits in the intervention group, although the mechanisms are not clear. Further studies are needed.

BACKGROUND: In patients undergoing mechanical ventilation for the acute respiratory distress syndrome (ARDS), neuromuscular blocking agents may improve oxygenation and decrease ventilator-induced lung injury but may also cause muscle weakness. We evaluated clinical outcomes after 2 days of therapy with neuromuscular blocking agents in patients with early, severe ARDS.
METHODS: In this multicenter, double-blind trial, 340 patients presenting to the intensive care unit (ICU) with an onset of severe ARDS within the previous 48 hours were randomly assigned to receive, for 48 hours, either cisatracurium besylate (178 patients) or placebo (162 patients). Severe ARDS was defined as a ratio of the partial pressure of arterial oxygen (PaO2) to the fraction of inspired oxygen (FIO2) of less than 150, with a positive end-expiratory pressure of 5 cm or more of water and a tidal volume of 6 to 8 ml per kilogram of predicted body weight. The primary outcome was the proportion of patients who died either before hospital discharge or within 90 days after study enrollment (i.e., the 90-day in-hospital mortality rate), adjusted for predefined covariates and baseline differences between groups with the use of a Cox model.
RESULTS: The hazard ratio for death at 90 days in the cisatracurium group, as compared with the placebo group, was 0.68 (95% confidence interval [CI], 0.48 to 0.98; P=0.04), after adjustment for both the baseline PaO2:FIO2 and plateau pressure and the Simplified Acute Physiology II score. The crude 90-day mortality was 31.6% (95% CI, 25.2 to 38.8) in the cisatracurium group and 40.7% (95% CI, 33.5 to 48.4) in the placebo group (P=0.08). Mortality at 28 days was 23.7% (95% CI, 18.1 to 30.5) with cisatracurium and 33.3% (95% CI, 26.5 to 40.9) with placebo (P=0.05). The rate of ICU-acquired paresis did not differ significantly between the two groups.
CONCLUSIONS: In patients with severe ARDS, early administration of a neuromuscular blocking agent improved the adjusted 90-day survival and increased the time off the ventilator without increasing muscle weakness. (Funded by Assistance Publique-Hôpitaux de Marseille and the Programme Hospitalier de Recherche Clinique Régional 2004-26 of the French Ministry of Health; ClinicalTrials.gov number, NCT00299650.)

Neuromuscular blockers in early acute respiratory distress syndrome
N Engl J Med. 2010 Sep 16;363(12):1107-16

All Updates, ICU

T-piece SBT harder work

24 difficult to wean patients underwent three spontaneous breathing trials in random order, with PA catheter monitoring in place. T-piece spontaneous ventilation was compared with pressure support ventilation 7 cmH20 without PEEP, and with pressure support ventilation 7 cmH20 with 5 cmH20 PEEP. T-piece was associated with higher SBT failure rates and more patient effort, left ventricular failure, and smaller tidal volumes. The study suggests that in selected difficult-to-wean patients, clinical and physiological responses differ depending on the type of SBT used to ascertain whether or not a patient is ready for extubation. Of note, the authors did not extubate the patients who succeeded a PSV trial, because it has been shown that a spontaneous breathing trial using T-piece mimics the work of breathing performed after extubation, and an extubation failure is associated with high mortality.
Physiological comparison of three spontaneous breathing trials in difficult-to-wean patients
Intensive Care Med. 2010 Jul;36(7):1171-9

All Updates, ICU, Resus

ALI / ARDS strategies

A CME article in Critical Care Medicine summarises the literature on ARDS (including its limitations) and provides evidence based recommendations on what to do about severe hypoxaemia. They summarise:
For life-threatening hypoxaemia, initial management with a recruitment manoeuvre and/or high PEEP should be undertaken if plateau airway pressures and lack of barotrauma allow. If not, or if these are not effective, then proceed to the prone position or HFOV. If hypoxemia still persists, then consider the administration of inhaled NO. If NO fails, then glucocorticoids can then be administered. For elevated plateau airway pressures when tidal volumes are 4 mL/kg, consider prone positioning or HFOV. For life- threatening respiratory acidosis, consider the use of a buffer or continuous veno-venous hemofiltration. It is most important to assess for objective physiologic improvement in the appropriate time period for each intervention. If no benefit is evident, then the therapy should be discontinued to minimise harm and delay in the initiation of another therapy. If the patient continues to have life-threatening hypoxemia, acidosis, or elevated plateau airway pressures, then consider ECMO or extracorporeal carbon dioxide removal.


Therapeutic strategies for severe acute lung injury
Crit Care Med. 2010 Aug;38(8):1644-50

All Updates, Kids

HFOV in preterms – no clear benefit

Pre-term infants lacking surfactant often require mechanical ventilation, but the consequent barotrauma and volutrauma may contribute to chronic lung disease, or bronchopulmonary dysplasia. Consequently high frequency oscillatory ventilation (HFOV) has been tried, but results from trials are mixed. A new systematic review of 3229 preterm newborns of less than 35 weeks’ gestation in 10 randomised trials fails to show a benefit of HFOV over conventional ventilation.
Elective high-frequency oscillatory versus conventional ventilation in preterm infants: a systematic review and meta-analysis of individual patients’ data
The Lancet, Volume 375, Issue 9731, Pages 2082 – 2091, 12 June 201o

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Is ETT muck delaying weaning?

Organised secretions can build up in a tracheal tube. This increases airway resistance so during a spontaneous breathing trial in a patient being considered for extubation the patient may have increased work of breathing and unfairly fail the trial, delaying extubation.
How can you spot it? Increased airways resistance can increase peak airway pressure. However inspiratory plateau pressure will not be affected (obtained by performing an inspiratory hold). Identifying a big difference between peak and plateau pressures should prompt a search for increased airway resistance, which includes a narrowed tracheal tube lumen. The amount of accumulated secretion is not necessarily related to the duration of intubation.
Increases in endotracheal tube resistance are unpredictable relative to duration of intubation
Chest 2009; 136:1006-1013

All Updates, ICU

No sedation for patients receiving mechanical ventilation

Danish intensivists demonstrate that just bolusing morphine without sedatives results in fewer days on a ventilator and a shortened ICU and hospital stay. Obviously not appropriate for some patients (therapeutic hypothermia, head injury with raised ICP, etc.) and some patients randomised to the no sedation group eventually required sedation. Delirium was three times more common in the no sedation group (20% vs 7%).
A protocol of no sedation for critically ill patients receiving mechanical ventilation: a randomised trial
Lancet. 2010 Feb 6;375(9713):475-80

All Updates, ICU

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