Applicability of near-infrared spectroscopy for fetal assessment during labour

Uvod: Kardiotokografija (CTG) predstavlja zlati standard za nadzor ploda med porodom, čeprav ima dokazano nizko specifičnost za odkrivanje acidoze ploda. Neinvazivna bližnja infrardeča spektroskopija (NIRS) za nadzor oksigenacije posteljice in plodove cerebralne oksigenacije med porodom do sedaj še ni bila raziskana. Namen naše raziskave je bil ugotoviti ali spremembe v NIRS posteljice in plodove glavice med porodom lahko prepoznajo hipoksijo in razvijajočo se acidozo. Metode: Vključili smo 43 zdravih žensk v aktivni fazi poroda ob roku, pri katerih smo snemali CTG ter izvajali neinvazivne meritve NIRS posteljice in plodove glavice. Parametre CTG in NIRS smo primerjali s preučevanimi izidi: pH in presežkom baz v popkovni arteriji, načinom poroda, oceno po Apgarjevi, sprejemom novorojenca na oddelek za intenzivno nego in terapijo. Diagnostično zanesljivost parametrov CTG in NIRS pri napovedovanju neonatalne acidoze smo ocenili s površino pod krivuljo ROC (receiver-operating-characteristics) ter računalniško-podprto statistično klasifikacijo. S Spearmanovim koeficientom korelacije smo ocenili povezavo med spremembami CTG in NIRS. Rezultati: Deset (23 %) novorojencev se je rodilo s pH popkovne arterije ? 7,20. V primerjavi s skupino novorojencev s pH popkovne arterije > 7,20 je bila acidoza ploda povezana s številčnejšimi skupnimi deceleracijami na CTG (25 (variacijski razmik 3–91) vs. 10 (variacijski razmik 0–60)p = 0,02), daljšim trajanjem deceleracij (71 sekund (variacijski razmik 56–82) vs. 57 sekund (0–265)p = 0,05) in številčnejšimi podaljšanimi deceleracijami (3 (variacijski razmik 0–5) vs. 1 (variacijski razmik 0–5)p = 0,02). Pri meritvah NIRS so bile z acidozo ploda povezane številčnejše epizode dvigov oksigenacije posteljice (5 (variacijski razmik 0–21) vs. 2 (variacijski razmik 0–14)p = 0,03) ter številčnejše epizode deoksigenacije posteljice (9 (variacijski razmik 2–37) vs. 2 (variacijski razmik 0–65)p = 0,001). Deoksigenacije posteljice so bile številčnejše pri operativno dokončanih porodih v primerjavi z vaginalnim porodom (9 (variacijski razmik 2–37) vs. (4 (variacijski razmik 0–65)p = 0,04). Pri meritvi cerebralne oksigenacije ploda so bile pri skupini novorojencev s presežkom baz ? -12,0 mmol/l številčnejše deoksigenacije v primerjavi s skupino z višjim presežkom baz (2 (variacijski razmik 1–8) vs. (0 (variacijski razmik 0–6)p = 0,05). Pri skupini novorojencev z oceno po Apgarjevi ? 7 v prvi minuti po porodu so bile v primerjavi z novorojenci z višjo oceno številčnejše deoksigenacije posteljice (23 (variacijski razmik 9–37) vs. (4 (variacijski razmik 0–65)p = 0,05). Pri prvi skupini novorojencev so bile številčnejše tudi cerebralne deoksigenacije ploda (5 (variacijski razmik 2–8) vs. (0 (variacijski razmik 0–6)p = 0,04). Obstaja pozitivna korelacija med skupnim številom deceleracij na CTG in skupnim številom deoksigenacij posteljice (? = 0,41, p = 0,06) ter skupnim številom dvigov oksigenacije posteljice (? = 0,43, p < 0,01). Površina pod ROC krivuljo za napovedovanje neonatalne acidoze je bila za število deoksigenacij posteljice 0,85 (95 % interval zaupanja (IZ) 0,70–0,99), za število deceleracij na CTG pa 0,75 (95 % IZ 0,57–0,94). Število deoksigenacij posteljice je kot najboljši regresor za napovedovanje neonatalne acidoze prepoznala tudi računalniško-podprta klasifikacija s 25-odstotno lažno pozitivno in 93-odstotno resnično pozitivno vrednostjo na učni množici ter 100-odstotno natančnostjo ob uporabi na testni množici. Zaključek: Naši rezultati kažejo, da bi lahko bile lahko neinvazivne NIRS meritve posteljice koristna dopolnilna metoda spremljanja stanja ploda med porodom, ki bi omogočala natančnejšo prepoznavo obporodne hipoksije.Introduction: Although being the gold standard for intrapartum fetal surveillance, cardiotocography (CTG) has been shown to have poor specificity for detecting fetal acidosis. Non-invasive near-infrared spectroscopy (NIRS) of the placenta and fetal head during labour has yet to be studied. The objective of the study was to determine whether changes in placental and cerebral NIRS values during labour could identify intrapartum fetal hypoxia and resulting acidosis. Methods: We included 43 healthy women in the active stage of labour at term and carried out CTG and non-invasive NIRS measurements of the placenta and fetal head. CTG and NIRS parameters were compared with observed outcomes: pH value and base excess of the umbilical artery, mode of delivery, Apgar score, admission to Neonatal intensive care unit. Receiver-operating-characteristics (ROC) curves were used to estimate predictive values of CTG and NIRS parameters for neonatal pH 䁤 7.20. A computer-based statistical classification was also performed to further evaluate predictive values of CTG and NIRS for neonatal acidosis. Using Spearman\u27s correlation coefficient, we assessed the correlation between CTG and NIRS parameters. Results: Ten (23%) neonates were born with umbilical artery pH 䁤 7.20. Compared to the group with pH > 7.20, fetal acidosis was associated with more decelerations on CTG (25 (range 3–91) vs. 10 (range 0–60)p = 0.02), longer duration of decelerations (71 seconds (range 56-82) vs. 57 seconds (0-265)p = 0.05) and more prolonged decelerations on CTG (3 (range 0–5) vs. 1 (range 0–5)p = 0.02). In NIRS measurements, fetal acidosis was associated with more episodes of rises in placental oxygenation (5 (range 0–21) vs. 2 (range 0–14)p = 0.03), and more episodes of placental deoxygenation (9 (range 2–37) vs. 2 (range 0–65)p = 0.001). Placental deoxygenations were more numerous in the group of operative deliveries in comparison to spontaneous vaginal births (9 (range 2–37) vs. (4 (range 0–65)p = 0.04). In fetal cerebral oxygenation measurements, neonates with base excess 䁤 -12.0 mmol/l had more deoxygenations than the group of neonates with higher base excess (2 (range 1–8) vs. (0 (range 0–6)p = 0.05). Neonates with first minute Apgar score 䁤 7 in comparison to neonates with higher scores have more placental deoxygenations (23 (range 9–37) vs. (4 (range 0–65)p = 0.05) and more cerebral deoxygenations (5 (range 2–8) vs. (0 (range 0–6)p = 0.04). A positive correlation exists between total number of CTG decelerations, total number of placental deoxygenations (ρ = 0.41, p = 0.06) and total number of rises in placental oxygenation (ρ = 0.43, p < 0.01). The area under the ROC curve for predicting neonatal acidosis was 0.85 (95 % confidence interval (CI) 0.70–0.99) for placental deoxygenations vs. 0.75 (95 % CI 0.57-0.94) for CTG decelerations. Computer-based classification also identified the number of placental deoxygenations as the most accurate classifier in the prediction of neonatal acidosis, with a 25% false positive and 93% true positive rate in the training dataset, with 100% accuracy when applied to the testing dataset. Discussion: Non-invasive placental NIRS could be used as an adjunctive method of fetal surveillance for a more accurate diagnosis of intrapartum hypoxia

Near-infrared spectroscopy of the placenta for monitoring fetal oxygenation during labour.

Although being the golden standard for intrapartum fetal surveillance, cardiotocography (CTG) has been shown to have poor specificity for detecting fetal acidosis. Non-invasive near-infrared-spectroscopy (NIRS) monitoring of placental oxygenation during labour has not been studied yet. The objective of the study was to determine whether changes in placental NIRS values during labour could identify intrapartum fetal hypoxia and resulting acidosis. We included 43 healthy women in active stage of labour at term. CTG and NIRS parameters in groups with vs. without neonatal umbilical artery pH ≤ 7.20 were compared using Mann-Whitney-U. Receiver-operating-characteristics (ROC) curves were used to estimate predictive value of CTG and NIRS parameters for neonatal pH ≤ 7.20. A computer-based statistical classification was also performed to further evaluate predictive values of CTG and NIRS for neonatal acidosis. Ten (23%) neonates were born with umbilical artery pH ≤ 7.20. Compared to group with pH > 7.20, fetal acidosis was associated with more episodes of placental NIRS deoxygenation (9 (range 2-37) vs. 2 (range 0-65); p<0.001), higher velocity of placental NIRS deoxygenation (2.31 (range 0-22) vs. 1 (range 0-49) %/s; p = 0.03), more decelerations on CTG (25 (range 3-91) vs. 10 (range 10-60); p = 0.02), and more prolonged decelerations on CTG (2 (range 0-4) vs. 1 (range 0-3); p = 0.04). Number of placental deoxygenations had the highest prognostic value for fetal/neonatal acidosis (area under the ROC curve 0.85 (95% confidence interval 0.70-0.99). Computer-based classification also identified number of placental deoxygenations as the most accurate classifier, with 25% false positive and 93% true positive rate in the training dataset, with 100% accuracy when applied to the testing dataset. Placental deoxygenations during labour measured by NIRS are associated with fetal/neonatal acidosis. Predictive value of placental NIRS for neonatal acidosis was superior to that of CTG