Welsh Anaesthetic Trainees Journal Club


March 2017

Chewing gum & PONV

Chewing gum for the treatment of postoperative nausea and vomiting: a pilot randomized controlled trial. Darvall JN, Handscombe M, Leslie K.  British Journal Anaesthesia 2017;118(1):83-89.

Presented by: Dr K James


 Two main areas of  which paper aims of addressing:

  1. Pilot study to test feasibility of a larger Randomised Controlled Trial
  1. Chewing gum may be non-inferior to ondansetron in inhibiting Post Operative Nausea and Vomiting (PONV)
    • Currently no existing study examining the effect of gum chewing on PONV.
    • It is postulated to reduce nausea and vomiting via the ‘sham feeding’ effect linked to vagal stimulation.
    • Meta-analysis (272 patients, 7 RCTs) demonstrated reduced time to first flatus and bowel motion and a non-significant trend towards earlier hospital discharge.
  • Chewing gum may be beneficial in the post operative care setting because:
    • It is a non-pharmacological agent,
    • There are very few side effects
    • It can be self administered

Design & setting

  • Randomized controlled non-inferiority trial to test the hypothesis:

“Chewing gum in the PACU would prove to be non-inferior to ondansetron for the treatment of PONV in female patients after laparoscopic or breast surgery and to test the feasibility of a large multicentre RCT”

  • Non Inferiority defined as a difference between groups of <15% in a per protocol analysis
  • Study was carried out in PACU, Department of Pain and Anaesthesia in Royal Melbourne Hospital,
  • Ethical approval gained 


  • Female adult patients
  • Laparoscopic or breast surgery
  • January – June 2016.
  • Written consent was gained from patients
  • Patient/doctor/anaesthetist blinded until patient experienced nausea or vomiting in PACU


  • 155 patients eligible, 53 excluded. Not all reasons for exclusion were disclosed, but a high proportion was due to failure to recruit both anaesthetist and patient.
  • 94 randomized pre-operatively
  • Control arm (n = 46)
    • Received IV anti-emetics on the occurrence of PONV in PACU (current standard of care.)
    • Ondansetron 4mg IV
  • Chewing gum arm (n = 48)
    • Chewing gum administered as first line on occurrence of PONV in PACU
    • Rescue IV anti-emetics available if required.
  • Relief of PONV graded on four point verbal descriptive scale


  • Primary outcome:
    • Full resolution of PONV after either ondansetron or chewing gum.
  • Secondary outcomes:
    • Duration of PACU stay
    • Anti-emetic rescue use
    • Patient acceptability of anti-emetic treatment.
  • Feasibility outcomes:
    • Recruitment rate
    • Protocol compliance
    • Incidence of PONV
    • Ability to chew gum


The investigators state that:

  • Chewing gum was non-inferior to ondansetron for the treatment of PONV.
    • (Symptoms resolution of 75% and 39% respectively)
  • Non-inferiority statistics demonstrated a p-value of 0.07. (Not significant)
  • No difference in secondary outcomes between groups.
  • Recruitment was satisfactory, protocol acceptable to anaesthetists and nurses, data collection was complete.


On face value, with little critical appraisal of the paper the following conclusions can be made from reading the authors conclusions:

  • Chewing gum was not inferior to ondansetron for treatment of PONV after general anaesthesia for laparoscopic or breast surgery in female patients.
  • Larger multi-centred RCT is feasible


  • Clearly states only a pilot study throughout the report
  • Transparent data collection and data representation
  • Data and results presented thoroughly. Very nice paper to read which looks very appealing.
  • Novel and interesting treatment and solution to PONV


  • It is only a pilot study, not a RCT (and they had already performed a pilot study for this debate in question)
  • A power calculation was performed, but them not adhered too.
  • They assessed whether PONV was present or absent, its severity was not assessed.
  • There was a variation in medications used intraoperatively which may have effected the results:
    • Additional opioids
    • Reversal agent
    • Intra-op. antiemetics
  • Variation in surgery:
    • Laraoscopic and breast surgery which have two very different profiles of emesis.
  • Peppermint flavour of the chewing gum used may be a confounding factor as it has been reported that peppermint settels the stomach
  • More than 50% of patients of the Chewing Gum group received pharmacological anti emetics. 

Implications and Potential for impact

  • Future RCT could be feasible
  • Interesting study, well presented
  • No conclusions can be drawn about chewing gum as an anti emetic
  • I wont be prescribing Wrigley’s Extra on anaesthetic charts!

Although the paper was written and presented very well, it is trying to find an answer to a problem that does not exist because ondansetron is very well tolerated by most patients, is cheap and not very labour intensive to administer. Conversely, chewing gum, if administered to patients who are too sleepy, could cause harm. The data is analysed in such a way that it is very difficult to follow, and indeed gain any conclusions from.

March 2017

Written by Dr C. Williams

Preparing residents effectively in emergency skills training with a serious game. Simulation in Healthcare 2017;12:9-16 doi:10.1097/SIH.0000000000000194

Technology-enhanced training programmes provide learning opportunities without risk to patients. Full-scale computer-based simulators are expensive to buy and run. With increasing demands on required competencies for doctors there is a need for new and more cost-effective training methods.

This study aimed to look at whether residents preparing for classroom teaching and used a video game and a course manual had better cognitive skills and motivation than those who just the course manual. They found that at the start of a two-week classroom teaching course, residents who had used the video game had better clinical competencies. Yet by the end of the two weeks there was no difference between the groups.

Video games for learning may feature more in the future………Of course this isn’t the first time that video games have been used in teaching – literature has been published on the use of video games to improve surgical skills.

Effects of fluid restriction on measures of circulatory efficacy in adults with septic shock. Acta Anaesthesiologica Scandinavica 2017 doi:10.1111/aas.12862

It is well known that fluid resuscitation is recommended initially in septic shock and continued as long as circulation improves. Hypotension, low urine output and vasopressor requirements are commonly used indicators for giving fluid. Sepsis increases vascular permeability  which can lead to fast redistribution of fluids in the extracellular space and shorten the positive haemodynamic effects of giving fluid. This post-hoc analysis of the multi centre CLASSIC randomised trial compared tow groups of patients with sepsis – either randomised to standard treatment or a restricted resuscitation fluid protocol. They found that fluid restriction had no negative effects on plasma lactate levels, noradrenaline requirements or urine output in the first 24 hours.

This study suggests, but presents no hard evidence, that liberal fluid after the initial fluid resuscitation in the first hour may be harmful. It raises questions regarding fluid resuscitation and highlights the need for further studies.

Normal gastric emptying time of a carbohydrate-rich drink in elderly patients with acute hip fracture: a pilot study. BMC Anesthesiology 2017;17:23 doi:10.1186/S12871-016-0299-6

Fasting guidelines for elective surgery are changing. We now recommend clear fluids until up to 2 hours before surgery. But for patients considered at risk of delayed gastric emptying, which includes trauma patients, the fasting guidelines remain unchanged. Hip fracture patients are often elderly with multiple co-morbidities and many have a pre-existing poor nutritional state. Yet they are often fasted for prolonged periods of time, particularly as trauma lists change and their cases get re-prioritised.

This pilot study looked at whether preoperative gastric emptying was delayed in women with hip fractures awaiting surgery. Nine patient with acute hip fractures were given 400ml of carbohydrate drink along with a paracetamol solution and compared with a group of 10 patients having elective hip replacements and 10 healthy female volunteers. Gastric emptying was assessed by looking at paracetamol absorption. There was very little difference between the three groups.

This is a small pilot study but the results look promising and means that maybe we will no longer have to starve hip fracture patients for hours on end……..

Targeting urine output and 30-day mortality in goal-directed therapy: a systematic-review with meta-analysis and meta-regression. BMC Anesthesiology 2017;17:22 doi:10.1186/S12871-017-0316-4

Urine output is often used as a surrogate measure for organ perfusion and to guide fluid administration. But oliguria is not always due to a suboptimal haemodynamic status and it has been shown that targeting urine output does not prevent acute renal failure. More recently permissive oliguria has been allowed, especially in the immediate post-operative phase.

But there is increasing evidence that a reduced urine output is a risk factor for mortality especially in critically ill patients. Whether this is a casual relation or not has yet to be determined. This study aimed to look at whether including urine output as a target in fluid management protocols reduced 30-day mortality. It looked at 36 randomised controlled trials and 6 observational studies. Analysis of these studies showed that goal-directed therapy decreased 30-day mortality, but when urine output was included as a target this increased 30-day mortality. But once adjustment for confounders was made there was insufficient evidence to associate urine output with mortality. Once again further questions have been raised and more research is needed.

Alpha-range visual and auditory stimulation reduces the perception of pain. European Journal of Pain 2017;21(3):562-572 doi:10.1002/ejp.960

The alpha rhythm (7-14 Hz) is the most studied frequency band in the human brain. They arise from the thalamus and are transmitted via the thalamocortical tracts to the cortex. Alpha rhythms can be influenced by inputs to the thalamus. Neurofeedback studies have found that increasing alpha power can lead to a long-term reduction in chronic pain. But this needs concentration and weeks of training to be effective.

Participants were subjected to a ‘moderately painful acute laser stimulus’ both as a control and following 10 minutes of flashing LED goggle stimulations and 10 minutes of binaural beat stimulation across the alpha range. Both auditory and visual stimulation seemed to reduce pain, although visual stimulation seemed more effective at reducing acute pain. This study provides further evidence that external stimulation can affect pain perceptions. Clinically how relevant this is remains to be seen. Maybe in the future we may be prescribing flashing LED goggles for pain relief??

Maternal deaths in the UK: pre-eclampsia deaths are avoidable. Lancet 2017;389:573-670

Between 2012 and 2014 the Confidential Enquiries into Maternal Deaths and Morbidity found that 241 women died, equating to less than one in 10,000 women. This is the lowest death rate recorded since surveillance been in 1952. In fact, when comparing with age-matched male death rates, a man is more likely to die while his partner is pregnant than she is.

Cardiac disease is the leading cause of indirect deaths while thrombosis and thromboembolism feature as a major issue and are the leading cause of direct death. 59% of indirect maternal deaths related to exacerbation of an underlying condition by being pregnant.

What is clear is that specialist care for women with pre-existing medical problems or mental health problems is paramount. Sadly suicide was the leading cause of maternal death in the first year after pregnancy.

On a positive note deaths due to pre-eclampsia are the least represented category and have substantially reduced since the last report. Pre-eclampsia deaths have been associated with substandard care and should be avoidable. Possibly the introduction of UK evidence-based guidelines which have focused on the systematic use of interventions may have contributed to the reduction? However hypertensive diseases of pregnancy are unlikely to reduce so complacency must be avoided. Pre-eclampsia is only safe for the mother if identified and well-managed.

Resuscitation training for school children worldwide: Kids Save Lives. Anesthesia and Analgesia 2017 doi:10.1213/ANE.0000000000001745

Survival from out of hospital cardiac arrest (OHCA) is low (<6%). A recent study in Europe found that 96.4% of OHCA occurred in a private residence. 54.3% of cases were witnessed by bystanders. 47.7% of cases had bystander initiated CPR. The positive effects of bystander CPR have repeatedly been demonstrated and shown to increase survival by an average factor of 2 to 3. 35.1% of bystanders trained in CPR initiate resuscitation in cases of cardiac arrest versus only 4.8% of those with no CPR training.

To motivate bystanders to perform CPR requires delivering the message that they can do little wrong – the only wrong thing would be to do nothing. There is an argument that CPR training should be incorporated into school curriculum so that the proportion of CPR-trained individuals increased gradually over time. It is mandatory in a few countries and in many more local, regional or national campaigns have been started.

A study published in 2016 showed that the best time to start CPR training was at 12 years of age, and a 2 hour course every year maintained adequate performance. It also showed that children schoolteachers were equally as effective at teaching CPR as healthcare professionals. This had been recognised by the ‘Kids Save Lives’ statement published jointly by the European Patient Safety Foundation, the European Resuscitation Council, the International Lisbon Committee on Resuscitation and the World Federation of Societies of Anaesthesiologists and endorsed by the World Health Organisation. UK schools are not currently obliged to teach first-aid in schools.

There have been various campaigns to make it compulsory but so far without success. In November 2015, a bill to make first aid training compulsory in schools was blocked by MPs talking non-stop until time to discuss and vote on it ran out……………

Can early postoperative oral intake reduce pain & PONV?


Early postoperative oral fluid intake in paediatric day case surgery influences the need for opioids and postoperative vomiting: a controlled randomized trial

British Journal of Anaesthesia. 2017;118(3): 407-414

Presented by: Dr T. Sheppard


  • Assessing young children in recovery is difficult and challenging
  • Distress post-operatively is multi-factorial
  • With children too young to communicate effectively, inappropriate treatments can be given

Design & Setting

  • Prospective randomised controlled trial
  • Placebo-controlled
  • Day case paediatric surgery
  • Wide variety of surgery types


  • Ages 6m-4yr
  • ASA 1-3
  • GA (Day surgery)

Exclusion criteria

  • Surgery constraining post operative fluid intake
  • Known digestive pathology pre-disposing to POV
  • Enrolment in another study


Randomised to 2 groups

  1. Liberal group (offered 10ml/kg apple juice post op)
  • FLACC score ≥4 (Face Legs Activity Crying COnsolability sore)
  • Apple juice offered
  1. Control group (protocolised opioid administration)
  • Opioid given as per unit protocol
  • 2mg/kg nalbuphine
  • Morphine titrated to effect

Also recorded:

  • Number & location of POV (i.e. in PACU/on ward)
  • Ondansetron given on 2nd incidence of POV
  • Prophylactic anti-emetic (dexamethasone/droperidol) if POVOC ≥3


Primary outcome: global incidence of post-operative vomiting during first 3 days after surgery (aim to include delayed POV)

Secondary outcome

  • Total dose opioid analgesics in PACU
  • Length of PACU stay
  • Number of episodes POV in PACU/on ward/on 1st and 3rd post-op days
  • Post-operative adverse events e.g. difficulty swallowing/desaturation



Use of opioid post-op

Post operative vomiting PACU stay duration
Liberal group



53.45 minutes

Control group



65.05 minutes

  p=0.001 p=0.006


Further split into subgroups

  • Subgroup 1: children randomised as liberal, FLACC score ≥4, accepted apple juice
  • Subgroup 2: children randomised as liberal, FLACC score ≥4, refused drink AND controls
  • Subgroup 1 vs 2: significantly less POV in subgroup 1


If apple-juice offered:

  • Significant reduction in incidence of post-operative vomiting
  • Significant reduction in use of post-op opioids
  • Significant reduction in recovery stay


  1. Original study
  2. Randomised controlled trial
  3. Standardised anaesthetic technique
  4. Including pre-med & paracetamol
  5. Prophylactic anti-emetic according to protocol (anaesthetist blinded)
  6. 93-97% use of N2O


  1. Un-blinded
  2. Study stopped early
  3. Higher incidence of POV in children in this study than previous audit carried out before study completed
  4. Unable to distinguish causes of maladaptive post anaesthesia behaviour
  5. Variations in subgroups 1 & 2
  • Male:female ratio – more males in subgroup 1
  • Less intraoperative fluids given to subgroup 1
  • Fasting times


  1. This study suggests that early re-instatement of oral fluids significantly reduces incidence of post-operative vomiting
  2. Potential for reduction in opioid use post-op

Potential for Impact

  • Impact of fasting times: 11.3hr pre-op seems excessively long for day case paediatric surgery
  • Could increase list efficiency due to shorter time in recovery
  • Risk assess for use of prophylactic anti-emetic
  • Using standardised criteria for POV in children
  • Should we be prescribing apple juice? Concentrate or pressed? Does it need to be apple juice? Would water be sufficient and have the same effect?

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