Due to copyright issues, an electronic copy of the thesis must be ordered from the faculty. For the faculty to have time to process the order, the order must be received by the faculty at the latest 2 days before the public defence. Orders received later than 2 days before the defence will not be processed. After the public defence, please address any inquiries regarding the thesis to the candidate.
Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Associate Professor Arash Afshari, University of Copenhagen, Denmark
- Second opponent: Senior Consultant Mariann Haavik Lysfjord Bentsen, University of Bergen, Norway
- Third member and chair of the evaluation committee: Associate Professor Mads Nikolaj Holten-Andersen, University of Oslo
Chair of the Defence
Professor II Marte Lie Høivik, University of Oslo
Principal Supervisor
Professor II Anne Lee Solevåg, University of Oslo
Summary
Introduction
Perinatal asphyxia causes an estimated 900,000 deaths among term and near-term infants worldwide each year, with most occurring in low-resource settings. Effective ventilation is the cornerstone of neonatal resuscitation, yet endotracheal intubation (ETI) has become increasingly infrequent due to the availability of non-invasive respiratory support. Reduced procedural exposure limits opportunities for clinicians to acquire and maintain neonatal intubation skills. Despite recent efforts, no universal algorithm exists for managing the unanticipated difficult airway in neonatal resuscitation. Initial manoeuvres—such as tactile stimulation, head repositioning, mask adjustments, and airway suctioning—are attempted prior to considering ETI.
Evaluation of cardiovascular function in newborns relies on assessments such as blood pressure and point-of-care echocardiography. Non-invasive cardiac output (CO) monitoring, widely implemented in adult intensive care, is being explored for neonatal use. Impedance cardiography (ICG; PhysioFlow®) is one such method, but no published data exists on its application in perinatal asphyxia or neonatal experimental models.
Airway suctioning during neonatal resuscitation has been debated. Since 2015, the procedure has been recommended only when airway obstruction is suspected. Further research is required on neonatal airway management—including intubation and suctioning—and on the feasibility of ICG in newborn models.
The aims of this thesis were to: 1. describe and investigate advanced airway management with emphasis on unanticipated difficult intubation, identify areas for improvement, and propose a literature-supported neonatal difficult airway algorithm; 2. evaluate the feasibility of ICG for non-invasive CO monitoring in asphyxiated newborn piglets during and after cardiopulmonary resuscitation (CPR); and 3. assess clinical practice and short-term outcomes associated with delivery-room airway suctioning of clear amniotic fluid in term and preterm infants.
Materials and Methods
The thesis comprises one observational clinical study and one experimental animal study. 1. Observational clinical study (Akershus University Hospital, Lørenskog, Norway) All neonatal resuscitations between August 2014 and November 2016 were video recorded and analysed to assess airway management, deviations from the neonatal life support algorithm, and clinical practice regarding delivery-room suctioning of clear and meconium-stained amniotic fluid in term and preterm infants born vaginally or by caesarean section. Short-term outcomes were evaluated in moderately and severely depressed infants receiving airway suctioning. Recordings had been transcribed using Interact software prior to the thesis work. 2. Experimental animal study (Oslo University Hospital Rikshospitalet, Oslo, Norway) Fifteen piglets (12–36 hours old) were anaesthetised, intubated, mechanically ventilated, and subjected to controlled asphyxia until asystole. PhysioFlow® ICG was used to record stroke volume, heart rate, and cardiac output to evaluate feasibility for trend monitoring under critical conditions.
Main Findings
1. Endotracheal intubation is infrequent and technically challenging, even in infants with normal airway anatomy. ETI was rarely performed and often required three or more attempts, even in infants with normal airway anatomy (i.e., without known congenital airway malformations). This highlights both the procedural difficulty and the limited opportunities for clinicians to maintain intubation competence. Based on these findings, a neonatal difficult airway algorithm was developed.
2. Impedance cardiography is feasible for trend monitoring but limited by poor signal quality. In the piglet model, ICG was capable of detecting changes in cardiac function during asphyxia and CPR; however, a large proportion of signals were of low quality. Improvements in electrode design, placement, and system software may be needed before clinical implementation in compromised newborns.
3. Airway suctioning is performed more often than recommended, yet no direct harm was observed. More than half of all resuscitated infants were suctioned, frequently without guideline-based indication. However, most infants showed immediate improvement in muscle tone and skin colour following suctioning of clear amniotic fluid. Moderately and severely depressed infants were often admitted to the neonatal intensive care unit, although this was related to the underlying clinical status rather than the suctioning itself. No evidence of harm from airway suctioning was identified in the video transcripts.
Conclusions
This dissertation supports the development of more structured and evidence-informed approaches to neonatal airway management, including algorithms for the difficult airway and the evaluation of non-invasive cardiac output monitoring. Impedance cardiography requires further technical refinement. In the clinical study, airway suctioning was frequently performed without a clear indication, reflecting practice variation relative to recommended guidelines. However, no direct harm was identified in the present material. Taken together, the dissertation provides new insight into critical procedures and decision-making processes in the resuscitation of newborn infants in Norwegian clinical practice. The findings may form a basis for further quality improvement and contribute to more evidence-based care of newborn infants requiring acute medical support.
Additional information
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