A prospective, up-down sequential allocation study investigating the effectiveness of vital capacity breaths using high-flow nasal oxygenation versus a tight-fitting face mask to pre-oxygenate term pregnant women.

BACKGROUND: The role of high flow nasal oxygenation (HFNO) for pre-oxygenation before obstetric general anaesthesia remains unclear. This study aimed to determine the number of vital capacity breaths using HFNO required to pre-oxygenate 90% of parturients to an end-tidal oxygen concentration fraction (FETO2) of ≥0.90 (termed EN90). METHODS: Using up-down, sequential allocation trial design, volunteer term parturients undergoing caesarean delivery were investigated with HFNO with their mouth closed, followed by mouth open, and if FETO2 ≥0.90 was not achieved after a maximum of 20 vital capacity breaths, pre-oxygenation was attempted with a face mask. The primary outcome was the number of vital capacity breaths required using HFNO (mouth open and closed) to achieve EN90. Secondary outcomes included assessment of EN90 using mouth open versus mouth closed and face mask pre-oxygenation, maternal satisfaction and evaluation of fetal cardiotocography. RESULTS: Twenty women at term were recruited. Successful pre-oxygenation occurred in 4 (20%), 3 (15%) and 14 (70%) women with HFNO mouth closed, HFNO mouth open, and via face mask respectively. At up to 20 vital capacity breaths, face mask pre-oxygenation was more successful at achieving EN90 compared with both HFNO with a closed (P=0.006) or open (P=0.001) mouth. Closed mouth HFNO did not outperform open mouth pre-oxygenation. CONCLUSION: Face mask pre-oxygenation is more effective at achieving EN90 compared with to HFNO within a clinically acceptable number of vital capacity breaths. Further studies are needed to determine the role of HFNO in optimising the time before desaturation and for apnoeic oxygenation in term parturients.

Gastric point-of-care ultrasound (PoCUS) during pregnancy and the postpartum period: a systematic review.

Personalised risk assessment of the likelihood of pulmonary aspiration is recommended for pregnant women undergoing general anaesthesia and gastric point-of-care ultrasound (PoCUS) may help to achieve this. Traditionally, risk assessment is based upon adherence to fasting times, but gastric emptying may vary during pregnancy and surgery often needs to be expedited. We systematically reviewed the evidence for gastric PoCUS up to August 2018 in pregnant and postpartum women to determine whether it can identify and quantify stomach contents, provide aspiration risk assessment via qualitative or quantitative means, and determine how gastric emptying is affected by pregnancy. Twenty-two articles comprising 1050 participants were included and studies were classified by qualitative or quantitative findings. The evidence suggests that gastric PoCUS is a reliable and feasible method of imaging the stomach in pregnancy in clinical practice. Qualitative assessment via the Perlas grading system can provide rapid assessment of gastric volume states. If fluid is visible, identification of patients at high risk of pulmonary aspiration requires measurement of antral cross-sectional area. Cut-off values of 608 mm2 and 960 mm2 are recommended in the semi-recumbent and right lateral semi-recumbent positions, respectively. Validated methods to quantify stomach volumes are available, however their usefulness is currently restricted to research. Gastric PoCUS also provides evidence that gastric emptying of ingested food is delayed by term pregnancy, labour and during the early postpartum period. However, the passage of fluids through the stomach appears unaffected throughout the peripartum period.

Evaluation of the Obstetric Quality-of-Recovery score (ObsQoR-11) following non-elective caesarean delivery.

BACKGROUND: Few robust scoring tools exist to assess recovery following caesarean delivery (CD). We evaluated a new obstetric quality of recovery score (ObsQoR-11, initially formulated for elective CD) following non-elective CD. METHODS: ObsQoR-11 questionnaires were completed by women at day one post non-elective CD. Convergent validity was assessed by correlation of ObsQoR-11 with a 100 mm numerical rating scale (NRS) of general health status; discriminant validity by correlation with good vs poor recovery (NRS of ≥70 vs <70 mm, respectively); and content validity by correlation with length of stay (LOS), CD category, parity, gestation, previous CD, duration, blood loss, haemoglobin, age and body mass index. Cronbach's alpha, inter-item, split-half and test-retest correlation assessed reliability. Feasibility was tested by recruitment rate and time for ObsQoR-11 completion. RESULTS: One hundred women completed ObsQoR-11 at 24 h and 20 women repeated it at 25 h. ObsQoR-11 correlated strongly with NRS (r = 0.72 [95% CI 0.61 to 0.81], P <0.0001); discriminated well between good versus poor recovery (median [IQR] score 97 [86.5-101] vs 64 [50.5-78.5], P <0.0001); correlated to LOS (r = -0.24 [-0.42 to -0.04], P=0.02) and parity (r = 0.24 [0.04 to 0.42], P=0.02). Reliability was acceptable: Cronbach's alpha 0.75; inter-item correlation >0.15; split-half reliability 0.96; and intra-class correlation >0.6; no floor or ceiling effects. One hundred percent completed the ObsQoR-11 (median [IQR] completion time 117 [89-156] s). CONCLUSIONS: ObsQoR-11 is valid and reliable in assessing recovery after non-elective CD. Further research should assess generalisability and use following vaginal delivery.