Abstract Background: Hypoxaemia during tracheal intubation in obstetrics remains a lifethreatening complication. This study aimed to identify common clinical preinduction predictors of difficult intubation. Methods: A retrospective analysis was performed of data pertaining to tracheal intubation in patients requiring general anaesthesia for caesarean delivery, with a gestational age from 20 weeks, and until 7 days post-delivery, obtained from an obstetric airway management registry (ObAMR) at the University of Cape Town. Data was entered anonymously into a secure UCT REDCap database. Data categories were: patient and pregnancy characteristics, airway characteristics, details of management, and operator experience. The primary aim of the study was to identify anatomical and physiological risk factors for hypoxaemia. The primary outcome was defined as arterial desaturation to < 90% during obstetric airway management. For this purpose, multivariable binary logistic regression was performed. Hypoxaemia was thus used as a composite indicator of anatomical and physiological difficulty. Results: Data was collected for 1095 general anaesthetics in the ObAMR. Overall, 143/1091 of patients (13.1%, 95%CI 11.1 to 15.4%) experienced peripheral oxygen saturation below 90%. Univariate analysis showed that 91/142 (64.1%) of patients who desaturated were obese (body mass index [BMI]> 30 kg/m2 ), compared with 347/915 (37.9%) who were obese and did not experience desaturation (p< .001). A receiver operating curve (ROC) was constructed post hoc, which showed a cut-point for BMI of 29.76, and a sensitivity of 0.66, and specificity 0.62 for the prediction of hypoxaemia. Desaturation occurred in 17.0% of patients with hypertensive disorders of pregnancy, versus 11.0 % without (p=0.005). Increasing Mallampati class was associated with an increased incidence of hypoxaemia. The incidence of hypoxaemia was 25.8% for interns, compared with 8.0 % for consultant anaesthesiologists (p=0.005). In the multivariate analysis of factors associated with hypoxaemia, body mass index (p< 0.001), room air saturation prior to preoxygenation (p=0.008), and the presence of airway oedema (p=0.027), were independently associated with hypoxaemia. Conclusions: In this study, both anatomical and physiological predictors of hypoxaemia were identified. Using this concept, a predictive tool could be developed to aid in the identification of a difficult airway in obstetrics. Simple interventions such as face mask ventilation and the use of high flow nasal oxygenation, could be introduced to protect the parturient from the consequences of life-threatening hypoxaemia.

The thesis is focused on perioperative use of opioids during caesarean section. The general part is concerned with pharmacology of opioids due to their practical use during general and regional anaesthesia and postoperative analgesia with particular focus on remifentanil. Emphasis is put on the placental transfer of opioids into breast milk which has the possible influence on postnatal adaptation of the newborns and breastfeeding/lactation. The first part of the research describes current anaesthetic practice and opioid use in obstetrics in the Czech Republic according to the OBAAMA-CZ study in 2011. The second study on a unique group of 151 parturients showed that bolus application of remifentanil at a dose of 1 μg/kg at the time of 30 seconds before induction of general anaesthesia for caesarean section significantly stabilizes maternal hemodynamic parameters (blood pressure, heart rate) and reduces the stress response to tracheal intubation and skin incision. On the contrary, no influence on depth of anaesthesia (monitored by BIS) was found. But we demonstrated a slight effect of remifentanil on the assessment of postnatal adaptation of newborns at first minute after delivery. However, this attenuation was very short and in the fifth minute the results were already fully comparable to the control...

The thesis is focused on perioperative use of opioids during caesarean section. The general part is concerned with pharmacology of opioids due to their practical use during general and regional anaesthesia and postoperative analgesia with particular focus on remifentanil. Emphasis is put on the placental transfer of opioids into breast milk which has the possible influence on postnatal adaptation of the newborns and breastfeeding/lactation. The first part of the research describes current anaesthetic practice and opioid use in obstetrics in the Czech Republic according to the OBAAMA-CZ study in 2011. The second study on a unique group of 151 parturients showed that bolus application of remifentanil at a dose of 1 μg/kg at the time of 30 seconds before induction of general anaesthesia for caesarean section significantly stabilizes maternal hemodynamic parameters (blood pressure, heart rate) and reduces the stress response to tracheal intubation and skin incision. On the contrary, no influence on depth of anaesthesia (monitored by BIS) was found. But we demonstrated a slight effect of remifentanil on the assessment of postnatal adaptation of newborns at first minute after delivery. However, this attenuation was very short and in the fifth minute the results were already fully comparable to the control...