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Year : 2020  |  Volume : 3  |  Issue : 1  |  Page : 1-3

First do no harm

Former Professor, Department of Anaesthesiology, All India Institute of Medical Sciences, New Delhi, India

Date of Submission23-Apr-2020
Date of Acceptance23-Apr-2020
Date of Web Publication30-May-2020

Correspondence Address:
Dr. Dilip Pawar
1401 Gautam, Grihapravesh, Section 77, Noida - 201 301, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ARWY.ARWY_16_20

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How to cite this article:
Pawar D. First do no harm. Airway 2020;3:1-3

How to cite this URL:
Pawar D. First do no harm. Airway [serial online] 2020 [cited 2021 Jul 27];3:1-3. Available from: https://www.arwy.org/text.asp?2020/3/1/1/285426

One of the promises within the Hippocratic Oath that we as physicians make is ‘ first, do no harm’ (or ‘primum non nocere,’ the Latin translation from the original Greek.) Robert H Shmerling, senior faculty editor, Harvard health publishing, wrote in a Harvard Health Blog, ‘when real decision has to be made it is hard to apply this dictum because estimates of risk and benefit are so uncertain and prone to error.

But it is a reminder that we need high-quality research to help us better understand the balance of risk and benefit for the tests and treatments we recommend. Ultimately, it is also a reminder that doctors should neither overestimate their capacity to heal, nor underestimate their capacity to cause harm'.[1]

Injury to the larynx and trachea due to intubation is not well recognised amongst anaesthesiologists. While I was working at the paediatric section of KK Hospital, Singapore, Dr Holzki visited us. Besides talks to the staff and residents of the department, he also demonstrated endoscopy in infants and children in the operating theatre. Many of us, who believed that we were masters in intubation in kids, were shaken to see the postintubation endoscopy picture. Our signatures were there, that too in routine smooth uneventful intubations. Howsoever minor that might be which eventually heal on their own, there were injuries.

Trauma to larynx and trachea caused by uncuffed endotracheal tube was recognised to be the primary cause of postintubation laryngeal oedema. As early as 1954, Pender reported from seven published reports, frequent injury to pharynx, larynx and trachea due to intubation, some of the patients leading to tracheostomy.[2] Weber et al. reported that 44 out of 62 children who had acquired tracheal stenosis was due to endotracheal intubation.[3] Large size tube was the suspect.

Koka et al. from Boston Children looked into the incidence and contributory factors for postintubation laryngeal oedema in 7875 children. Large-sized endotracheal tube was suspect in half of the cases. They suggested that emphasis should not be placed upon having a snug-fitting tube. Instead, they recommended choosing a tube which allows an audible leak at patient's mouth at 20 cm H2O.[4]

When cuffed tubes for children became available in the market, they were not designed specifically for children but were smaller version of adult tubes. Weiss et al. studied 15 of these cuffed tubes and showed how these tubes can be harmful as they lie inside the lower end of the larynx when the tip is positioned at the mid trachea.[5] Then, the Microcuff tube was introduced by Kimberly Clark. Marcus Weiss, Andreas Gerber and colleagues authored many studies dealing with various aspects of this tube and popularised it.

Injury to the larynx and trachea by Microcuff tube is not often discussed. In this issue of Airway, Dr Holzki has reported a detailed study of injury to the larynx and trachea of infants and small children by Microcuff tubes from literature as well as his personal anatomical experiments.[6] When we try to analyse as to why we are not aware of these serious complications following intubation with Microcuff tube, two factors come to mind.

Today, we live in a culture of instant satisfaction even in science which I call as McDonald culture. Reading the headline of an article, we start believing that we have found the absolute truth and start instantly applying it on our patients. Do not have patience (and skill? probably) to analyse the design of the study and understand if the results have scientific validity and their applicability to patient care. Recently, a Cochrane review analysed the data of over 50 years (1966–2017) in literature on cuffed versus uncuffed tubes in infants and children <8 years. There was only very low-quality to low-quality evidence of the so-called advantages of cuffed tube over uncuffed tube.[7] Grading of quality of evidence is provided in [Table 1].[8]
Table 1: Grading the quality of the evidence

Click here to view

Evidence-based practice is ‘the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research'.[9] To carry out evidence-based practice, common essential requirement is availability of high-quality research.

As of today, as no good-quality evidence is available in favour of cuffed tubes in infants and small children, it is not possible to provide evidence-based practice in this age group.

The second factor is the influence of market forces. The influence of market forces in our day-to-day practice is unbelievably very high. Almost 75% of US clinical trials in medicine are paid for by private companies.[10] Several studies have found that research funded by pharmaceutical companies is more likely to produce results favouring the company's product than is research with other funding sources.

Cleverly, they influence our decision-making by published results of sponsored studies. They approach an eminent, well-respected physician especially from reputed institutions to conduct study on their product, devices or drugs. The protocol is usually prepared by them. It is cleverly done, so it is difficult to detect the bias ('bias’ is a systematic ‘error’ or mistake in the judgements and decisions made that influence the results of a study or a review).

For example, the study of cuffed tube versus uncuffed tube with largest number of patients by Weiss et al. did not have a robust study design. It was not known if their control over the study design was limited as the study was sponsored by Microcuff GmbH. It was a great lost opportunity I would say. They conducted a multicentre study in European countries together with the European paediatric endotracheal intubation study group. The number of patients studied was large (2246). Unfortunately, the main concern of injury to larynx was not studied.[11] Andreas Gerber (colleague of Marcus Weiss and a co-author of that article) is an old friend from Mangalore airway workshop days. In our last conversation few years back, he told me that they were planning one study with endoscopic observation of post-laryngeal trauma which would settle the concern scientifically. We are waiting for the results of such a study which would guide our clinical practice.

Injury to larynx is a big concern and in the Western world, now there is a call to go back to uncuffed tubes in the paediatric age group. Fortunately in our country, most of the children are intubated with uncuffed tubes (probably because of the cost of Microcuff tube!).

The uncuffed tube has a problem which needs to be addressed too. In tube selection, the emphasis is on internal diameter (ID), whereas it is the outer diameter (OD) which is negotiated through the larynx and trachea. Moreover, the OD of the available tubes is not uniform for different ID sizes. That needs correction as the OD is the one which causes trauma to the mucosa of larynx and trachea.

Weiss and Dullenkopf in 2007 in a review gave an outlook on future developments in the design of paediatric cuffed tracheal tubes and an overview of tasks to be performed in evaluating them.[12] How wise and thought provoking. There is a need for cuffed tubes in children of all age groups including neonates, and there is a need to develop one which is safer. Whenever such a tube is available, it should be made mandatory for the makers to provide a safety report after conducting post-intubation endoscopy. It should be subjected to high-quality research and hopefully, we will be able to provide the benefit of evidence-based practice to our children. And probably do no harm (or minimise the risks).

  References Top

Shmerling RH, editor. Harvard Health Blog. Boston: Harvard Health Publishing; 2015.  Back to cited text no. 1
Pender JW. Endotracheal anesthesia in children: Advantages and disadvantages. Anesthesiology 1954;15:495-506.  Back to cited text no. 2
Weber TR, Connors RH, Tracy TF Jr. Acquired tracheal stenosis in infants and children. J Thorac Cardiovasc Surg 1991;102:29-34.  Back to cited text no. 3
Koka BV, Jeon IS, Andre JM, MacKay I, Smith RM. Postintubation croup in children. Anesth Analg 1977;56:501-5.  Back to cited text no. 4
Weiss M, Dullenkopf A, Gysin C, Dillier CM, Gerber AC. Shortcomings of cuffed paediatric tracheal tubes. Br J Anaesth 2004;92:78-88.  Back to cited text no. 5
Holzki J. Anatomy of infant larynx and cuffed endotracheal tubes. Airway 2020;3:4-12.  Back to cited text no. 6
  [Full text]  
De Orange FA, Andrade RG, Lemos A, Borges PS, Figueiroa JN, Kovatsis PG. Cuffed versus uncuffed endotracheal tubes for general anaesthesia in children aged eight years and under. Cochrane Database Syst Rev 2017;11:CD011954.  Back to cited text no. 7
Atkins D, Best D, Briss PA, Eccles M, Falck-Ytter Y, Flottorp S, et al. Grading quality of evidence and strength of recommendations. BMJ 2004;328:1490.  Back to cited text no. 8
Sackett DL, Rosenberg WMC, Gray JAM, Haynes RB, Richardson WS. Evidence based medicine: what it is and what it isn't. BMJ 1996;312:71-2.  Back to cited text no. 9
Bodenheimer T. Uneasy alliance – Clinical investigators and the pharmaceutical industry. N Engl J Med 2000;342:1539-44.  Back to cited text no. 10
Weiss M, Dullenkopf A, Fischer JE, Keller C, Gerber AC; European Paediatric Endotracheal Intubation Study Group. Prospective randomized controlled multi-centre trial of cuffed or uncuffed endotracheal tubes in small children. Br J Anaesth 2009;103:867-73.  Back to cited text no. 11
Weiss M, Dullenkopf A. Cuffed tracheal tubes in children: Past, present and future. Expert Rev Med Devices 2007;4:73-82.  Back to cited text no. 12


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