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Endotracheal Tube Extubation - Who is to blame?

A recent report from The Telegraph stated that an accredited expert from the National Crime Agency, Dr Dewi Evans, who is registered with the GMC under the name Dr David Richard Evans, has made fresh claims against Lucy Letby. Dr Evans has taken the unusual step of giving multiple interviews to Britain's newspaper groups, in his capacity as an accredited expert with the NCA and as an Expert Witneess in th trial of Lucy Letby.

Unusually, there is little distinction between Dr Evans' role as an accredited expert for the NCA and his role as an expert witness as per "the duty that is owed to the court," which "overrides any obligation to the party from whom the expert is receiving instructions - see Criminal Procedure Rule 19.2 CrimPR 19."

Dr Evans makes new claims of harm by Lucy Letby

During his interview with the Daily Mail Podcast presenters, Dr Evans stated that in his forensic investigation, which he carried out between May 2017 to November 2020, at the Countess of Chester Hospital (CoCH), he made additional determinations as to whether Ms Letby attempted to harm other neonates under her care. Strikingly, Dr Evans claimed:

"I found several cases that are highly suspicious where an endotracheal tube – placed in a baby’s throat when they need breathing support – had been displaced, had come out.”

It is uncertain as to how Dr Evans' expertise as a retired paediatrician could be used to make such findings. However, Dr Evans went on to claim:

"for so many [endotracheal tubes] to come out is very, very unusual, especially in what I consider to be a good unit. ‘I suspect these tubes were displaced intentionally.'"

Dr Evans additionally claimed that there were some ten cases of unplanned extubations (where the endotracheal tube becomes displaced), and that these may be attributed to Ms Letby. The claims put forth by Dr Evans give great insight into the methodology applied by Dr Evans in conducting complex forensic investigations into the deaths of neonates at CoCH.

In his capacity as a retired paediatrician, whose main occupation in the 15 years prior was as an expert witness in family law cases, Dr Evans was able to make scientific findings in the 32 cases from the Countess of Chester hospital. Dr Evans' most recent statements suggest that his investigation yielded more cases of murder and attempted murder than were contained in the indictment. Dr Evans provides no insights into what independently verified test, procedure, analysis or examination he performed to arrive at these claims, nor those in the indictment.

The standard to publish a scientific paper is higher than that applied in Dr Evans' investigation

A recent review article investigating the causes of unplanned extubations (UEs) in neonatal ICUs is instructive in identifying a method Dr Evans could have applied in his investigation (Silva et al., 2013). In keeping with the basic investigative approaches required to perform a reliable forensic investigation it would be necessary for Dr Evans to demonstrate that his claims against Ms Letby were based on accepted practices. This would require an assessment, which minimally aligned with the standards in the relevant scientific disciplines.

In their review, Silva et al., identified 192 studies detailing unplanned extubations (UE) in the neonatal population. Of those 192 studies, 15 studies met the inclusion criteria. Of those fifteen studies, 11 were prospective cohort studies, 3 were retrospective cohort studies, and 1 was a retrospective and prospective cohort study. The review of 15 studies identified that over a period of the last 30 years:

Unplanned extubation (UE) rates ranged from 0.14 to 5.3 UEs/100 intubation days, or 1% to 80.8%... One study showed that every day on mechanical ventilation increased the UE risk 3% (relative risk 1.03, P < .001)..

It was further stated that the range of UEs had not changed over the last five year period. Taking the highest number of UEs/100 days, and applying this ratio to the period between June 2015 -June 2016, the highest rate of UEs one might observe, would be 19.3 UEs per year (Silva et al., 2013). Thus based on actual clinical findings the number of UEs reported by Dr Evans (10 UEs) are nearly half that observed in separate studies. It is apparent that there is nothing exceptional about the number of UEs Dr Evans observed in his review of the clinical notes.

Turning to the causes of UE, separate studies have identified that patient agitation, and poor tape adhesion plays a primary role in UE in the neonatal population. This was summarized by Silva et al., as follows:

Risk factors included restlessness/agitation (13–89%), poor fixation of endotracheal tube (8.5–31%), tube manipulation at the time of UE (17–30%), and performance of a patient procedure at bedside (27.5–51%).

A separate study lent support to the role of agitation in causing UE. Little et al., studied the incidence of UE in patients in the PICU and NICU. They showed that a primary cause of UE was the failure to administer sedation in the 2 h before the UE. This failure in the sedation protocol was associated with 65% of all UEs (Little et al., 1990). It was apparent that a common theme at CoCH in the 2015-2016 period was the failure to properly sedate the infants, or provide analgesia. This failure may have played a primary role in the UE reported by Dr Evans.

Another study analysed the data of 543 newborns from public neonatal intensive care units (NICUs) over a 6 month period, during which 136 newborns required mechanical ventilation. The researchers found that there were 117 adverse events during the 6 month period. The larger the number of newborns classified by care demand per nurse and nursing technician, the more likely the occurrence of intermediate adverse events linked to mechanical ventilation (Filho et al., 2011). This study demonstrates that over burdened nursing staff, with high patient care demand incur greater adverse events. This may have been a finding observed in CoCH due to staffing issues on the NNU.

The impact of an investigation into the the body of evidence specific to the field under study

Contrary to the one speculative claim made by Dr Evans, that Ms Letby might be responsible for the UEs he observed, it appears that a multitude of factors may contribute to UE in the neonate. These factors include increased agitation, high patient care demands, and failure to ensure adequate sedation. Additional studies demonstrate that inadequate ETT fixation may also contribute to UE.

A study of one hundred and four neonates with a total ventilation time of 14495 h identified 12 UEs in the patients. The level of care in the NICU was high, as the neonates were cared for by experienced nursing staff with a median of 10 years nursing experience. However, the workload for each individual nurse was high. The study revealed that during shifts when UE happened, each nurse had to take care of 3.85 patients (range 1.8-5 patients), which was higher than average. The main cause of UE was inadequate tube fixation. Importantly, the researchers also found that UE did not result in an adverse outcome in terms of mortality (Veldman et al., 2006).

Dr Evans’ claims appear to be made based on little else but supposition. He cannot call to any real evidence to support his claims and it is not clear whether he is making the statements surrounding UE as an accredited expert on behalf of the NCA or in some other capacity. Still given his standing as a medical doctor one would hope he would take some caution before speculating as to the cause of UEs in neonates, in light of the available evidence to explain the assortment of causes of UE..

Dr Evans' reliance on his subjective opinion, as a body of evidence, upon which to reach independent decisions, is clearly an improper basis to make scientific findings. Indeed the basis of a scientific investigation requires more than just a hypothesis, and then a search for a correlate to the claim.

A Feature and Not a Bug

A particularly curious feature of the Criminal Justice System in England and Wales is the primacy given to medical doctors in the context of complex forensic investigations. The role of the medical doctor in such cases is poorly defined which naturally gives rise to confusion as to their actual scope of expertise. In the case of the UEs observed by Dr Evans it appears that his investigative techniques warranted greater scrutiny and would not be permitted as they are devoid of objectivity.

Rule 19.2 of the Criminal Procedure Rules provides that an expert has an overriding duty to give opinion evidence which is objective and unbiased.

The rules on experts further states:

"An expert is independent of the parties to the proceedings and should not be seen to usurp the role of the advocate in the proceedings by seeking to make submissions to the court."

During the trial of Lucy Letby, Dr Evans engaged in speculation above that permitted of an expert witness. His most recent coverage in the national media is instructive in gaining greater insight into the exact scientific basis applied in his investigation of the neonates at CoCH. His most recent commentary should provoke real questions on how he carried out an investigation with no new evidence, and why he was specially equipped to conduct the investigation, and why his findings were of such import that they could be used to disregard the coroner's findings.

In the case of UEs in neonates, one can swiftly rebut the claims put forth by Dr Evans, both at trial, and with regard to allegations that Ms Letby tampered with her patient's breathing tubes. This is made abundantly clear upon review of the outcomes of the Silva et al., review:

The graph demonstrates that the majority of UEs in neonates occur due to agitation. It is most likely that given the poor standard of care described at CoCH during the trial, that many of the infants were highly agitated and this adversely impacted their breathing tubes.



Lamy Filho F, Silva AA, Lopes JM, Lamy ZC, Simões VM, Dos Santos AM. Staff workload and adverse events during mechanical ventilation in neonatal intensive care units. J Pediatr (Rio J). 2011 Nov-Dec;87(6):487-92.

Little LA, Koenig JC Jr, Newth CJ. Factors affecting accidental extubations in neonatal and pediatric intensive care patients. Crit Care Med. 1990 Feb;18(2):163-5.

Veldman A, Trautschold T, Weiss K, Fischer D, Bauer K. Characteristics and outcome of unplanned extubation in ventilated preterm and term newborns on a neonatal intensive care unit. Paediatr Anaesth. 2006 Sep;16(9):968-73.

Silva P, Reis M, Aguiar V, and Fonseca M. Unplanned Extubation in the Neonatal ICU: A Systematic Review, Critical Appraisal, and Evidence-Based Recommendations. Respiratory Care July 2013, 58 (7) 1237-1245;


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The moment the police became involved and Dewi Evans became anointed as "THE EXPERT", is the moment when any chance for justice... any chance for a search for valid medical/scientific factors at play during the cluster of deaths at CoCH, went out the window, and into the gutter, where the MSM could sensationalize the "serial child killer", and the public could demonize Ms. Letby.

How any rational person, could think the myriad problems at CoCH did NOT play a major role in the deaths of these vulnerable premies... is beyond me.

A short list: Inadequate consultant staffing and too infrequent ward rounds/inadequate nursing staff and lack of 1:1 surveillance/monitoring/care - antiquated facility (and all that entails) - inadequate transport resource…


I read that Dr Dewi Evans was not on the GMC register during the trial? is this true? surely this invalidates his opinions as an "expert" witness if so?


Gareth Howell
Gareth Howell
Sep 26, 2023

Clearly Evans has little knowledge of "Relational Science". Mr Justice Goss none whatsoever. In his ivory tower, even after the Inquiry/Appeal he intends to retry a different case of murder most foul by Ms Letby. He is not satisfied with the superior wisdom of a Lady justice of the Lords of Appeal chamber, Rt hon Judge Lady Thirlwall. He is not a woman.

Replying to

Judge Goss has retired hasn't he.


Further to my previous comment, having now digested the news of the Baby K re-trial for what it is – a distractor from Lucy’s appeal and another shot in the information war of excluding all narratives except their ‘monster’ one from popular consciousness – it occurs to me that said re-trial could be a Trojan horse for undermining Lucy’s convictions.

I say this based on my (medical lay-person) understanding that the extubation at the heart of the Baby K case is the same type as dealt with by Sarrita’s article here: essentially, this article alone should be sufficient to put reasonable doubt in any juror’s mind. I just cannot see any jury aware of it convicting Lucy. Unless there is…

Gareth Howell
Gareth Howell
Sep 26, 2023
Replying to

No need. Inquiry/Appeal will deal with the whole matter. Not a Trojan horse for his own judgements, just does not want to lose credibility by way of an anticipated much superior judgement.


Just seen news that there is to be a re-trial in one of the cases in which the jury could not reach a verdict, the Child K case (Feb 2016) where Dr Jayaram give evidence that he was uneasy at Lucy being alone in a room with a child given his suspicions of her and so popped into the room to check and alleges he saw her doing nothing except looking down at the child who was 30-60 seconds into a desaturation episode associated with an extubation.

On this basis - once the murder investigation began progressing on the basis of the so-called insulin cases two years later - he concluded that Lucy must have deliberately dislodged the tube to…

Replying to

I think I saw the same interview and thought he came across as disingenuous. Also, if he was really that concerned (check him wiping away tears in the interview) - enough to feel the need to go and check on her - and saw her standing over the incubator “doing nothing” whilst a desat was happening - WHY didn’t he report this? Had enough of hearing about the consultants banging on about not being listened to - ANYONE can report a nurse to the NMC - even anonymously - he didn’t need to go through the hospital management - I think this is a cop out on their part.

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