Anaesthesia and the lung: can oxygen be harmful?
Göran Hedenstierna, Uppsala, Sweden
  Euroanaesthesia 2013, Sir Robert Macintosh lecture on ‘anaesthesia and the lung: can oxygen be harmful?’ was presented by Professor Goran Hedenstierna, University Hospital, Uppsala, Sweden. He used, as the basis for his talk, the paper he has authored in Acta Anaesthesiologica Scandinavica in 2012: ‘Oxygen and anaesthesia: what lung do we deliver to the postoperative ward?’
  Anaesthetics reduce functional residual capacity (FRC) and promote airway closure. The reason for this is loss of respiratory muscle tone that allows the elastic forces of the lung to pull in the chest wall and to reduce the lung volume. Resistance in the lungs of healthy people can, under anaesthesia, reach those of people with moderate-to-severe asthma.
  Oxygen (O2) is breathed during the induction of anaesthesia, and increased concentration of O2 is given during the surgery to reduce the risk of hypoxemia. However, oxygen is rapidly adsorbed behind closed airways, causing lung collapse (atelectasis) and shunt. Atelectasis occurs to some degree in 90% of anaesthetised patients, and may be a locus for infection and may cause pneumonia.
  Hedenstrierna discussed that post-operative pulmonary complications have been found in 2–20% of patients after non-cardiac surgery, and in a huge retrospective study of 161,000 patients after major, noncardiac surgery pneumonia was found in 1.5%. “This may not seem terrifyingly high, but the mortality was 21% in this group,” he said.
  Measures to prevent atelectasis and possibly reduce post-operative pulmonary complications are based on moderate use of oxygen and preservation or restoration of FRC. Pre-oxygenation with 100% O2 causes atelectasis and should be followed by a recruitment manoeuvre (inflation to an airway pressure of 40 cm H2O for 10 seconds and to higher airway pressures in patients with reduced abdominal compliance (obese and patients with abdominal disorders). Pre-oxygenation with 80% O2 may be sufficient in most patients with no anticipated difficulty in managing the airway, but time to hypoxemia during apnoea decreases from mean 7 to 5 min. An alternative, possibly challenging, procedure is induction of anaesthesia with continuous positive airway pressure/positive end-expiratory pressure to prevent fall in FRC enabling use of 100% O2. A continuous PEEP of 7–10 cm H2O may not necessarily improve oxygenation but should keep the lung open until the end of anaesthesia. An inspired oxygen concentration of 30–40%, or even less, should suffice if the lung is kept open.
  “The goal of the anaesthetic regime should be to deliver a patient with no atelectasis to the post-operative ward and to keep the lung open,” said Hedenstierna.
  He also discussed in his lecture how the critical dependence of atelectasis formation on inspired oxygen concentration increased interest in the pre-oxygenation during induction of anaesthesia. “Again, strong oxygen dependence can be seen. Thus, patients whose anaesthesia has been induced during pre-oxygenation with 100% O2 for 3 min had atelectasis, on average, in 10% of the lung area (corresponding to 15–20% of lung tissue) Pre-oxygenation with 80% O2 for a similar time causes much less atelectasis, with a mean of 2%,” he said. Lower oxygen concentrations reduce atelectasis even further.
  Hedenstierna also discussed the role positive end-expiratory pressure (PEEP) has in anaesthesia. Because the net effect is that arterial oxygenation is not improved by PEEP, the Nunn group (back in the 1970s) concluded that ‘there is no role for the indiscriminate use of PEEP in routine anaesthesia’. Rather, says Hedenstierna, it may be looked at as a tool for post-operative care than for optimising intraoperative gas exchange.
  Suctioning of the airways also covered, and Hedenstierna believes this process may promote atelectasis formation in addition to other harmful effects. “It is my opinion that the airway suctioning and post-oxygenation do more harm than benefit and is highly questionable. At least, there should be a clear indication for it.”
  Hedenstierna made a number of conclusions/recommendations:
Pre-oxygenation with 100% O2 should be followed by a recruitment maneuverer (see point 2) to reopen collapsed alveoli, or induction of anaesthesia can be done with CPAP/PEEP to maintain FRC (that would allow 100% O2 with no atelectasis formation), alternatively. Pre-oxygenation with 80% O2 may be possible in the lung-healthy, non-obese patient with no anticipated difficulty in airway management, followed by a gentle inflation of the lung (shorter apnoea tolerance time but easier to open closed airways than collapsed alveoli).
Recruitment by inflation of the lung to an airway pressure of 40 cm H2O for 10 seconds in lung-healthy, normal-weight patients and to higher airway pressures in patients with reduced abdominal compliance (obese and patients with abdominal disorders) after pre-oxygenation with 100% O2 and every 30 min, or a continuous PEEP of 7–10 cm H2O.
Low inspired oxygen concentration, 30–40% or even less, if no need of higher concentration.
High inspired oxygen concentration shall be given only together with PEEP.
Post-oxygenation with or without a recruitment manoeuvre and with or without airway suctioning should not be done routinely but on indication.
Deliver a patient with no atelectasis to the post-operative ward and keep the lung open.
  Figure: CT in anaesthetised obese patients. The first row of images show the patients awake and spontaneously breathing, the next after induction of anaesthesia where atelectasis readily forms. As seen in the top image series, PEEP had no effect on the amount of initial atelectasis. In the two lower image series, a recruitment maneuver (RM) was done right after induction. In the middle series where RM was followed by PEEP, atelectasis was reduced and the effect was sustained for 20 min. In the bottom image series with zero PEEP (ZEEP), the RM caused a temporary reduction of atelectasis, but this effect was gone already after 5 min.
  References :
  1.Sir Robert Macintosh lecture: Anaesthesia and the lung: can oxygen be harmful? - Göran Hedenstierna, Uppsala, Sweden. Euroanaesthesia 2013, Barcilona, Spain.
  2.Oxygen and anesthesia: what lung do we deliver to the post-operative ward? Acta Anaesthesiologica Scandinavica, Volume 56, Issue 6, pages 675–685, July 2012
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  Checklists for Airway Experts
Tim Leeuwenburg
  We are all looking for things that will make a difference during critical procedures – whether this be relatively new concepts like use of apnoeic diffusion oxygenation in RSI, developing robust airway equipment and algorithms for airway management. The use of checklists in a crisis helps deliver quality care.
  Checklists aren’t just for routine – they should be used in crisis management – whether this is emergency RSI, dealing with unexpected hypoxia, a rare emergency such as MH or similar.
  The main benefits for use of a checklist regardless of experience include:
Reduced task fixation & improve situational awareness
Reduced cognitive overload
Reduced stress
Defined team member roles
Improved team function
Improved team communication
Team understanding of potential complications and what they will be expected to do
Use can make crisis management & high-stakes procedures such as RSI smoother and quicker(when well practiced at using the checklist)
  So what actually IS a checklist?
  Humans make mistakes, especially when tired, when distracted or interrupted…or in a crisis when under cognitive load. Moreover, the expert does not function as an individual – he or she is part of a team, and members may have varying levels of expertise. We know this from the extensive human factors work, championed in healthcare (and anaesthesia has lead the way)
  In the true sense of the word, a checklist is exactly that – a list against which a check (or tick) is placed, to confirm an action has been completed. However it is not just learners who benefit – the true power of a checklist is to establish routine and so allow cognitive offloading by experts in an emergency, as well as to strengthen team performance and establish shared mental models.
  Delving a little deeper, the literature describes FOUR main types of checklist (Winters et al, 2009) which differ in terms of number of operators and the extent to which information is verified :
Static parallel :usually completed by a single operator and executed in the form of a series of ‘read-do’ tasks. The anaesthetic machine check is a good example, as is restocking of equipment
Static sequential with verification : this involves a challenge-response, with one operator reading a series of items for verification of completion or normality by another. The central line checklist in ICU is such an example as is an RSI challenge-response checklist
Static sequential with verification and confirmation : these are used more in team-based settings, with sets of tasks completed by different team members. A designated person reads the items (challenge) and each responsible party verifies the completion of a specific task. The WHO Surgical Checklist is such an example, with separate activities for scrub, surgical and anaesthetic teams
Dynamic:these typically use a flowchart to guide complex decision-making. There may be multiple options to choose from and the team must decide optimal course – in essence, an algorithm. The UK’s Difficult Airway Society algorithms & Australian Resuscitation Council ACLS algorithms are such examples.
  Of course it’s not just in medicine that we use a checklist – we write a shopping list before visiting the supermarket and most of us will perform some sort of mental checklist before leaving for work (have I got my car keys? My wallet? My sunglasses? Is today even a work day?). Humans use cognitive aids most days. Why would we abandon them at work?
  Checklists in Anaesthesia
  Top 10 Airway Check List:
  1. The WHO Surgical Checklist
  • Deckchairs
  2. Rapid Sequence Induction Check List!
  Checklist from from the Royal North Shore Hospital ED via
  • Deckchairs
  3. Default Strategy for failed RSI in Adults!
  Algorithms from the Austin Hospital ED, Melbourne,
  • Deckchairs
  4. Resuscitate and Intubate!
  • Deckchairs
  5. Out-of-theatre airway management!
  • Deckchairs
  6. RSI Challenge!
  • Deckchairs
  7. Obstetrics RSI Check List!
  • Deckchairs
  8.EMCrit Call/Response Check List!
  • Deckchairs
  9. Patient’s Teamwork Checklist!
  • Deckchairs
  10. A Check List for CHECK LISTS!
  • Deckchairs
  Should Real Airway Experts Use Checklists?
KI Doc, Kangaroo Island doctor blogging about Rural Medicine in Australia.
  Lessons from the Bromiley Case
  Tessa Davis
  In 2007, Martin Bromiley’s wife died due to medical error. The Bromiley case will be familiar to many of us. The lessons from this case can teach us stark lessons about our own leadership and teamwork.
  Martin’s story
  Martin and his wife, Elaine had two young children. Elaine went into hospital for a routine sinus operation and during anaesthetic induction, it all went horribly wrong.
  Her airway obstructed and the team was unable to gain a secure airway. For 20 minutes they attempted to achieve a stable airway, during which time her sats were around 40%.
  Although she survived, she sustained serious hypoxic brain injury and 13 days later her life support was turned off.
  Martin is an airline pilot with an interest in human factors and formed the Clinical Human Factors Group in 2007.
  Watch the story!
  Bromiley - Just A Routine Operation
  Incredibly moving account of failed intubation and sequelae, raising important issues regarding CICV algorithms and crisis resource management for ANY doctor involved in airway management.
  View this
  Here are the key teamwork lessons from his wife, Elaine’s case.
  1. Communication
  Communication between team members is crucial and in Elaine’s case, the communication process dried up completely. There were three senior and experienced doctors in the room – two anaesthetic consultants and an ENT consultant. They did not communicate with each other and nobody actually vocalised what was happening (i.e. this patient is in trouble, this is a ‘can’t intubate, can’t ventilate’ situation).The key in resus situations is to have clear communication. The other team members need to know what’s going on and this can help the team formulate a plan.
  2. Have a plan
  This team planned to start with a laryngeal mask but when this failed the only alternative considered was tracheal intubation. They did attempt to use different mask sizes for bagging, but other than that the attempts to intubate persisted for 25 minutes in spite of the sats being 40% throughout.Before starting any procedure, there should be a clear plan. Never is this needed more so than when planning an intubation. Whatever the local difficult airway algorithm is – know it well.Again, vocalising is essential. Talk through the plan with the team before the procedure starts so everyone knows what will happen in the event of a crisis.
  3. Listen to all the team members
  In Elaine’s case, as well as the three doctors, there were three experienced nurses. Although the doctors did not appear to recognise the seriousness of the situation, the nurses did.During the resus, one of the nurses fetched a surgical airway kit and told the consultants that she had brought it in – but there was no response. One of the other nurses called for an ICU bed early on in the resus – when she told the consultants this they made her feel like she was overreacting (and she cancelled it).It transpired that the nursing staff didn’t know how to broach the subject with the doctors. Every member of the team needs to be able to show assertiveness, particularly when they can recognise trouble and have suggestions for a solution.But more than that, there must be culture of listening. Every team member is valuable and may have something helpful to add. Questioning what is happening and suggesting possible options is an important part of any resus and is essential for good team work. Everyone must be listened to.
  4. Take control
  In this case, the lead anaesthetist ‘lost control’ and there was no clear leadership.Someone must take charge of any resus situation. It is their job to share what is actually happening, keep an overview of the whole situation and plan for alternatives. Without a good leader, there are just lots of people working independently to achieve their own goal.The leader is essential to ensure that all the other points above can actually benefit the team.
  As Martin Bromiley identifies, ‘we are all wrong no matter how good we are’.
  We need people around us to tell us.
  Be open to suggestions. Listen to your team. Step up and lead.


  Lessons from the Bromiley Case,December 12, 2013 by Tessa Davis.


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