Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model

Laparoscopic surgery is associated with increased risk of postoperative peritoneal metastases in T4 colon cancer: a propensity score analysis

BACKGROUND

This study aims to evaluate the postoperative safety, long-term survival, and postoperative peritoneal metastases (PPM) rate associated with laparoscopic surgery (LS) for T4 colon cancer.

MATERIALS AND METHODS

After propensity score matching, there were 68 patients in each of the LS and Open surgery groups. The primary outcomes were the 3-year OS, DFS, and PPM rates.

RESULTS

After matching, 68 patients in each of the groups. The LS group had a higher cumulative 3-year peritoneal metastasis rate (19.8% vs. 6.7%, P = .036), while the 3-year OS (82.3% vs. 83.8%, P = .750) and 2-year DFS (69.0% vs. 75.7%, P = .310) showed no significant difference, compared to the open surgery group. The LS group had a significantly longer operation time (201 ± 85.7 min vs. 164 ± 65.9 min, P = .008) but less postoperative complications (P = .036). Additionally, patients in the LS group removed gastric tube more quickly (1.91 ± 1.18 days vs. 2.69 ± 2.41 days, P = .048). The multivariate analysis revealed that LS (HR = 3.496, 95% CI = 1.108-11.030, P = .033), underweight (HR = 11.650, 95% CI = 2.155-62.990, P = .004), and lymphovascular invasion (HR = 3.123, 95% CI = 1.010-9.664, P = .048) were all predictive factors of PPM. For the pN + subgroup, the 3-year cumulative PPM rate was 29.6% in the LS group, significantly higher than 15.3% in the open group (P = .029), but there was no significant difference after PSM (P = .100).

CONCLUSION

LS offers faster postoperative recovery and comparable long-term survival outcomes. Therefore, it should remain a viable option for locally advanced T4 colon cancer. However, it is crucial to fully recognize the potential risk of increased PPM associated with LS, especially in patients with preoperative suspicion of positive lymph nodes. Further multicenter prospective studies are necessary to validate the potential risks of LS and gain insight into treatment efficacy in different patient populations. In addition, future studies should assess prognosis based on the grade and extent of peritoneal dissemination to provide a more nuanced understanding.

Fetal cardiovascular changes during open and fetoscopic in-utero spina bifida closure

OBJECTIVE

Fetoscopic closure of spina bifida using heated and humidified carbon dioxide gas (hhCO2) has been associated with lower maternal morbidity compared with open closure. Fetal cardiovascular changes during these surgical interventions are poorly defined. Our objective was to compare fetal bradycardia (defined as fetal heart rate (FHR) < 110 bpm for 10 min) and changes in umbilical artery (UA) Doppler parameters during open vs fetoscopic closure.

METHODS

This was a prospective cohort study of 22 open and 46 fetoscopic consecutive in-utero closures conducted between 2019 and 2023. Both cohorts had similar preoperative counseling and clinical management. FHR and UA Doppler velocimetry were obtained systematically during preoperative assessment, every 5 min during the intraoperative period, and during the postoperative assessment. FHR, UA pulsatility index (PI) and UA end-diastolic flow (EDF) were segmented into hourly periods during surgery, and the lowest values were averaged for analysis. Umbilical vein maximum velocity was measured in the fetoscopic cohort. At each timepoint at which FHR was recorded, maternal heart rate and systolic and diastolic blood pressure were measured.

RESULTS

Fetal bradycardia occurred in 4/22 (18.2%) cases of open closure and 21/46 (45.7%) cases of fetoscopic closure (P = 0.03). FHR decreased gradually in both cohorts after administration of general anesthesia and decreased further during surgery. FHR was significantly lower during hour 2 of surgery in the fetoscopic-repair cohort compared with the open-repair cohort. The change in FHR from baseline in the final stage of fetal surgery was significantly more pronounced in the fetoscopic-repair cohort compared with the open-repair cohort (mean, -32.4 (95% CI, -35.7 to -29.1) bpm vs -23.5 (95% CI, -28.1 to -18.8) bpm; P = 0.002). Abnormal UA-EDF (defined as absent or reversed EDF) occurred in 3/22 (13.6%) cases in the open-repair cohort and 23/46 (50.0%) cases in the fetoscopic-repair cohort (P = 0.004). There were no differences in UA-EDF or UA-PI between closure techniques at the individual stages of assessment.

CONCLUSIONS

We observed a decrease in FHR and abnormalities in UA Doppler parameters during both open and fetoscopic spina bifida closure. Fetal bradycardia was more prominent during fetoscopic closure following hhCO2 insufflation, but FHR recovered after cessation of hhCO2. Changes in FHR and UA Doppler parameters during in-utero spina bifida closure were transient, no cases required emergency delivery and no fetoscopic closure was converted to open closure. These observations should inform algorithms for the perioperative management of fetal bradycardia associated with in-utero spina bifida closure. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal bradycardia in open versus fetoscopic prenatal repair of spina bifida

OBJECTIVE

To compare the occurrence of fetal bradycardia in open versus fetoscopic fetal spina bifida surgery.

METHODS

This is a single-institution retrospective cohort study of patients undergoing open (n = 25) or fetoscopic (n = 26) spina bifida repair between 2017 and 2022. From October 2017 to June 2020, spina bifida repairs were performed via an open classical hysterotomy, and from November 2020 to June 2022 fetoscopic repairs were performed following transition to this technique. Fetal heart rate (FHR) in beats per minute (bpm) was recorded via echocardiography every 15 min during the procedure. Cohort characteristics, fetal bradycardia and maternal physiologic parameters were compared between the groups.

RESULTS

Fetuses undergoing an open repair more frequently developed bradycardia defined as <110 bpm (32% vs. 3.8%, p = 0.008), and a trend was observed for FHR decreases more than 25 bpm from baseline (20% vs. 3.8%, p = 0.073). Profound bradycardia less than 80 bpm was rare, occurring in only three operations (two in open, one in fetoscopic repair) with two fetuses (one in each group) requiring emergency cesarean delivery.

CONCLUSION

When compared to open fetal surgery, fetal bradycardia occurred less frequently in fetoscopic surgery despite a significantly greater anesthetic exposure and the use of the intraamniotic carbon dioxide insufflation.

Preterm membranes are mechanically more resistant than term membranes

OBJECTIVE

To compare the biomechanical properties of fetal preterm membranes (20 + 0 weeks to 30 + 0 weeks) to those of the term (37 + 0 to 41 + 0 weeks).

METHOD

Amnion and chorion were manually separated and samples were cut to the required geometry. Rectangular samples with (mode 1) and without (uniaxial) a notch, were tested for tearing energy, critical elongation, and tangent stiffness. Suture retention and inter-suture distance testing investigated the effect of suture placement.

RESULTS

From the 15 preterm and 10 term placentas studied, no notable differences were observed in uniaxial testing. Mode 1 fracture testing showed a difference in tearing energy between the preterm and term chorion (0.025 ± 0.005 vs. 0.017 ± 0.005 J/m-1 ; p = 0.027) but not in the amnion (0.030 ± 0.017 vs. 0.029 ± 0.009 J/m-1 ; p = 0.895). Both preterm amnion and chorion showed a higher critical elongation compared with term (1.229 ± 0.057 vs. 1.166 ± 0.046; p = 0.019 and 1.307 ± 0.049 vs. 1.218 ± 0.058; p = 0.012). Preterm amnion had a higher suture retention strength than its term counterpart (0.189 ± 0.065 vs. 0.121 ± 0.031 N; p = 0.023). In inter-suture distance tests, no significant interaction was observed beyond 3 mm, but the preterm chorion showed less interaction at 1-2 mm distances.

CONCLUSION

Preterm membranes have equivalent or superior tensile properties to term membranes. The chorion appears to contribute to the mechanical integrity of fetal membranes, particularly in preterm stages.

Exteriorization of the uterus reduces fetoscopic cannula-induced stress and strain: A finite element model analysis

OBJECTIVE

To estimate stresses and strains in the uterine wall and fetal membranes with single/multi-port fetoscopy, simulating either a percutaneous access or via exteriorized uterus.

STUDY DESIGN

Finite element models based on anatomical dimensions, material properties and boundary conditions were created to simulate stresses, strains and displacements on the uterine wall and fetal membranes during simulated fetal surgery either via exteriorized uterus or percutaneous approach, and with one or three cannulas. Clinically, we measured the anatomical layer thickness and cannula entry point displacement in patients undergoing single port percutaneous fetoscopy.

RESULTS

Simulations demonstrate that single port percutaneous fetoscopy increases stress on the fetal membranes (+105%, 128 to 262 kPa) and uterine wall (+115%, 0.89 to 1.9 kPa) compared to exteriorized uterine access. Using three ports increases stress by 110% (148 to 312 kPa) on membranes and 113% (1.08 to 2.3 kPa) on uterine wall. Finite Element Method showed 0.75 cm uterine entry point displacement from the cutaneous entry, while clinical measurements demonstrated displacement of more than double (1.69 ± 0.58 cm), suggesting modeled measurements may be underestimations.

CONCLUSION

The stresses and strains on the fetal membranes and uterus are double as high when entering percutaneously than via an exteriorized uterus. Based on what can be clinically measured, this may be an underestimation.

Duration of fetoscopic spina bifida repair does not affect the central nervous system in fetal lambs

BACKGROUND

Prenatal spina bifida aperta repair improves neurologic outcomes yet comes with a significant risk of prematurity and uterine scar-related complications. To reduce such complications, different fetoscopic techniques, for example, with varying numbers of ports, are being explored. This has an effect on the duration of the procedure, potentially affecting central nervous system development. Both the condition and anesthesia can affect the central nervous system, particularly the hippocampus, a region crucial for prospective and episodic memory. Previous animal studies have shown the potential influence of anesthesia, premature delivery, and maternal surgery during pregnancy on this area.

OBJECTIVE

This study aimed to compare the effects of 2- vs 3-port fetoscopic spina bifida aperta repair in the fetal lamb model using neuron count of the hippocampus as the primary outcome.

STUDY DESIGN

Based on the hippocampal neuron count from previous lamb experiments, we calculated that we required 5 animals per group to achieve a statistical power of ≥ 80%. A spina bifida aperta defect was developed in fetal lambs at 75 days of gestation (term: 145 days). At 100 days, fetuses underwent either a 2-port or 3-port fetoscopic repair. At 143 days, all surviving fetuses were delivered by cesarean delivery, anesthetized, and transcardially perfused with a mixture of formaldehyde and gadolinium. Next, they underwent neonatal brain and spine magnetic resonance imaging after which these organs were harvested for histology. Hippocampus, frontal cortex, caudate nucleus, and cerebellum samples were immunostained to identify neurons, astrocytes, microglia, and markers associated with cell proliferation, myelination, and synapses. The degree of hindbrain herniation and the ventricular diameter were measured on magnetic resonance images and volumes of relevant brain and medulla areas were segmented.

RESULTS

Both treatment groups included 5 fetuses and 9 unoperated littermates served as normal controls. The durations for both skin-to-skin (341±31 vs 287±40 minutes; P=.04) and fetal surgery (183±30 vs 128±22; P=.01) were longer for the 2-port approach than for the 3-port approach. There was no significant difference in neuron density in the hippocampus, frontal cortex, and cerebellum. In the caudate nucleus, the neuron count was higher in the 2-port group (965±156 vs 767±92 neurons/mm2; P=.04). There were neither differences in proliferation, astrogliosis, synaptophysin, or myelin. The tip of the cerebellar vermis was closer to the foramen magnum in animals undergoing the 2-port approach than in animals undergoing the 3-port approach (-0.72±0.67 vs -2.47±0.91 mm; P=.009). There was no significant difference in the ratio of the hippocampus, caudate nucleus, or cerebellar volume to body weight. For the spine, no difference was noted in spine volume-to-body weight ratio for the lower (L1-L2), middle (L3-L4), and higher (L5-L6) levels. Compared with controls, in repaired animals, the cerebellar vermis tip laid closer to the foramen magnum, parietal ventricles were enlarged, and medulla volumes were reduced.

CONCLUSION

In the experimental spina bifida fetal lamb model, a 2-port repair took 40% longer than a 3-port repair. However, there was no indication of any relevant morphologic differences in the fetal brain.

Advances in Fetal Surgical Repair of Open Spina Bifida

Spina bifida remains a common congenital anomaly of the central nervous system despite national fortification of foods with folic acid, with a prevalence of 2-4 per 10,000 live births. Prenatal screening for the early detection of this condition provides patients with the opportunity to consider various management options during pregnancy. Prenatal repair of open spina bifida, traditionally performed by the open maternal-fetal surgical approach through hysterotomy, has been shown to improve outcomes for the child, including decreased need for cerebrospinal fluid diversion surgery and improved lower neuromotor function. However, the open maternal-fetal surgical approach is associated with relatively increased risk for the patient and the overall pregnancy, as well as future pregnancies. Recent advances in minimally invasive prenatal repair of open spina bifida through fetoscopy have shown similar benefits for the child but relatively improved outcomes for the pregnant patient and future childbearing.

Fetoscopic insufflation of heated-humidified carbon dioxide during simulated spina bifida repair is safe under controlled anesthesia in the fetal lamb

OBJECTIVE

To assess the safety of Partial-Amniotic-Insufflation-of-heated-humidified-CO₂ (hPACI) during fetoscopic spina bifida repair (fSB-repair).

METHOD

A simulated fSB-repair through an exteriorized uterus under hPACI was performed in 100-day fetal lambs (term = 145 days) under a laboratory anesthesia protocol (n = 5; group 1) which is known to induce maternal-fetal acidosis and hypercapnia. Since these may not occur clinically, we applied a clinical anesthesia protocol (n = 5; group 2), keeping maternal parameters within physiological conditions, that is, controlled maternal arterial carbon dioxide (CO2) pressure (pCO₂  = 30 mmHg), blood pressure (≥67 mmHg), and temperature (37.1-39.8°C). Our superiority study used fetal pH as the primary outcome.

RESULTS

Compared to group 1, controlled anesthesia normalized fetal pH (7.23 ± 0.02 vs. 7.36 ± 0.02, p < 0.001), pCO₂ (70.0 ± 9.1 vs. 43.0 ± 1.0 mmHg, p = 0.011) and bicarbonate (27.8 ± 1.1 vs. 24.0 ± 0.9 mmol/L, p = 0.071) at baseline. It kept them within clinically acceptable limits (pH ≥ 7.23, pCO₂  ≤ 70 mmHg, bicarbonate ≤ 30 mm/L) for ≥120 min of hPACI as opposed to ≤30 min in group one. Fetal pO₂ and lactate were comparable between groups and generally within normal range. Fetal brain histology demonstrated fewer apoptotic cells and higher neuronal density in the prefrontal cortex in group two. There was no difference in fetal membrane inflammation, which was mild.

CONCLUSION

Fetoscopic insufflation of heated-humidified CO₂ during simulated fSB-repair through an exteriorized uterus can be done safely under controlled anesthesia.

Complex gastroschisis: a new indication for fetal surgery?

Gastroschisis (GS) is a congenital abdominal wall defect, in which the bowel eviscerates from the abdominal cavity. It is a non-lethal isolated anomaly and its pathogenesis is hypothesized to occur as a result of two hits: primary rupture of the 'physiological' umbilical hernia (congenital anomaly) followed by progressive damage of the eviscerated bowel (secondary injury). The second hit is thought to be caused by a combination of mesenteric ischemia from constriction in the abdominal wall defect and prolonged amniotic fluid exposure with resultant inflammatory damage, which eventually leads to bowel dysfunction and complications. GS can be classified as either simple or complex, with the latter being complicated by a combination of intestinal atresia, stenosis, perforation, volvulus and/or necrosis. Complex GS requires multiple neonatal surgeries and is associated with significantly greater postnatal morbidity and mortality than is simple GS. The intrauterine reduction of the eviscerated bowel before irreversible damage occurs and subsequent defect closure may diminish or potentially prevent the bowel damage and other fetal and neonatal complications associated with this condition. Serial prenatal amnioexchange has been studied in cases with GS as a potential intervention but never adopted because of its unproven benefit in terms of survival and bowel and lung function. We believe that recent advances in prenatal diagnosis and fetoscopic surgery justify reconsideration of the antenatal management of complex GS under the rubric of the criteria for fetal surgery established by the International Fetal Medicine and Surgery Society (IFMSS). Herein, we discuss how conditions for fetoscopic repair of complex GS might be favorable according to the IFMSS criteria, including an established natural history, an accurate prenatal diagnosis, absence of fully effective perinatal treatment due to prolonged need for neonatal intensive care, experimental evidence for fetoscopic repair and maternal and fetal safety of fetoscopy in expert fetal centers. Finally, we propose a research agenda that will help overcome barriers to progress and provide a pathway toward clinical implementation. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Implementation Process and Evolution of a Laparotomy-Assisted 2-Port Fetoscopic Spina Bifida Closure Program

INTRODUCTION

Prenatal closure of open spina bifida via open fetal surgery improves neurologic outcomes for infants in selected pregnancies. Fetoscopic techniques that are minimally invasive to the uterus aim to provide equivalent fetal benefits while minimizing maternal morbidities, but the optimal technique is undetermined. We describe the development, evolution, and feasibility of the laparotomy-assisted 2-port fetoscopic technique for prenatal closure of fetal spina bifida in a newly established program.

METHODS

We conducted a retrospective cohort study of women consented for laparotomy-assisted fetoscopic closure of isolated fetal spina bifida. Inclusion and exclusion criteria followed the Management of Myelomeningocele Study (MOMS). Team preparation involved observation at the originating center, protocol development, ancillary staff training, and surgical rehearsal using patient-matched models through simulation prior to program implementation. The primary outcome was the ability to complete the repair fetoscopically. Secondary maternal and fetal outcomes to assess performance of the technique were collected prospectively.

RESULTS

Of 57 women screened, 19 (33%) consented for laparotomy-assisted 2-port fetoscopy between February 2017 and December 2019. Fetoscopic closure was completed in 84% (16/19) cases. Over time, the technique was modified from a single- to a multilayer closure. In utero hindbrain herniation improved in 86% (12/14) of undelivered patients at 6 weeks postoperatively. Spontaneous rupture of membranes occurred in 31% (5/16) of fetoscopic cases. For completed cases, median gestational age at birth was 37 (range 27-39.6) weeks and 50% (8/16) of women delivered at term. Vaginal birth was achieved in 56% (9/16) of patients. One newborn had a cerebrospinal fluid leak that required postnatal surgical repair.

CONCLUSION

Implementation of a laparotomy-assisted 2-port fetoscopic spina bifida closure program through rigorous preparation and multispecialty team training may accelerate the learning curve and demonstrates favorable obstetric and perinatal outcomes.

The effects of cold, dry and heated, humidified amniotic insufflation on sheep fetal membranes

INTRODUCTION

Uterine distension with pressurised carbon dioxide (CO₂) (amniotic insufflation) is used clinically to improve visibility during keyhole fetal surgery. However, there are concerns that amniotic insufflation with unconditioned (cold, dry) CO₂ damages the fetal membranes which leads to post-operative preterm prelabour rupture of membranes (iatrogenic PPROM). We assessed whether heating and humidifying the insufflated CO₂ could reduce fetal membrane damage in sheep.

METHODS

Thirteen pregnant ewes at 103-106 days gestation underwent amniotic insufflation with cold, dry (22 °C, 0-5% humidity, n = 6) or heated, humidified (40 °C, 95-100% humidity, n = 7) CO₂ at 15 mmHg for 180 min. Twelve non-insufflated amniotic sacs acted as controls. Fetal membrane sections were collected after insufflation and analysed for molecular and histological markers of cell damage (caspase 3 and high mobility group box 1 [HMGB1]), inflammation (interleukin 1-alpha [IL1-alpha], IL8 and vascular cell adhesion molecule [VCAM]) and collagen weakening (matrix metalloprotease 9 [MMP9]).

RESULTS

Exposure to cold, dry CO₂ increased mRNA levels of caspase 3, HMGB1, IL1-alpha, IL8, VCAM and MMP9 and increased amniotic epithelial caspase 3 and HMGB1 cell counts relative to controls. Exposure to heated, humidified CO₂ also increased IL8 levels relative to controls however, HMGB1, IL1-alpha and VCAM mRNA levels and amniotic epithelial HMGB1 cell counts were significantly lower than the cold, dry group.

DISCUSSION

Amniotic insufflation with cold, dry CO₂ damaged the amniotic epithelium and induced fetal membrane inflammation. Heated, humidified insufflation partially mitigated this damage and inflammation in sheep and may prove an important step in reducing the risk of iatrogenic PPROM following keyhole fetal surgery.

Why Do the Fetal Membranes Rupture Early after Fetoscopy? A Review

Iatrogenic preterm premature rupture of the fetal membranes (iPPROM) remains the Achilles' heel of keyhole fetal surgery (fetoscopy) despite significant efforts in preclinical models to develop new therapies. This limited success is partially due to incomplete understanding why the fetal membranes rupture early after fetoscopy and notable differences in membrane physiology between humans and domestic species. In this review, we summarize aspects of fetoscopy that may contribute to iPPROM, the previous efforts to develop new therapies, and limitations of preclinical models commonly used in fetal membrane research.

Fetal heart rate monitoring during fetoscopic repair of open spinal neural tube defects: a single-centre observational cohort study

BACKGROUND

During fetal surgery, the haemodynamic stability of the fetus depends on the haemodynamic stability of the mother. The primary objective of this study was to assess changes in fetal heart rate (FHR) throughout the different stages of surgery. The secondary objective was to assess potential changes in maternal physiological parameters and their association with FHR.

METHODS

This was a single-center observational cohort study conducted between 2015 and 2019 in 26 women undergoing intra-uterine fetoscopic repair of open spina bifida. The primary outcome was FHR. Maternal physiologic parameters were measured at the beginning, during and after surgery. The linear mixed-effects model fitted by maximum likelihood was used to assess changes in each variable at specific times throughout the surgery, and the repeated measures correlation coefficient was used to study the association between FHR and maternal physiological parameters.

RESULTS

One (3.8%) case of fetal bradycardia (FHR <110 beats per minute) required the administration of intramuscular atropine. No other significant FHR changes were observed during surgery. Maternal oesophageal temperature (P <0.001), lactate levels (P=0.002), and mean arterial pressure (P=0.016) changed significantly during surgery, although none of these changes was clinically relevant. The FHR showed a significant association with maternal carbon dioxide tension (r=0.285, 95% CI 0.001 to 0.526) and maternal heart rate (r=0.302, 95% CI 0.025 to 0.535).

CONCLUSION

The FHR remained stable during intra-uterine fetoscopic repair of open spina bifida. Maternal carbon dioxide tension and heart rate may have a mild influence on FHR.

Fetal blood gases after in utero carbon dioxide insufflation for percutaneous fetoscopic spina bifida repair

BACKGROUND

Prenatal repair of open spina bifida via the percutaneous fetoscopic approach does not require maternal laparotomy, hysterotomy, or exteriorization of the uterus. This technique requires intrauterine partial CO₂ insufflation. Limited data exist on the physiological effects of CO₂ insufflation on human fetuses, with no data on open spina bifida repair performed using the entirely percutaneous fetoscopic surgical technique.

OBJECTIVE

Our aim was to examine the effects of intrauterine partial CO₂ insufflation on fetal blood gases after percutaneous fetoscopic open spina bifida repair.

STUDY DESIGN

This was a prospective study of patients who underwent percutaneous fetoscopic open spina bifida repair from February 2019 to July 2020. Fetal cordocentesis of the umbilical vein was performed in cases with favorable access to the umbilical cord. The umbilical vein cord blood samples were obtained under ultrasound guidance immediately at the conclusion of the open spina bifida repair. Simultaneous maternal arterial blood gas samples were also obtained. The results are reported as median (range).

RESULTS

Of the 20 patients who underwent percutaneous fetoscopic open spina bifida repair during the study period, 7 patients (35%) underwent fetal blood sampling. The gestational age at the time of surgery was 27.4 (24.0-27.9) weeks and the operative time was 183 (156-251) minutes. The CO₂ exposure time was 122 (57-146) minutes with maximum pressure of 13.5 (12.0-15.0) mm Hg. Fetal umbilical vein results were as follows: pH 7.35 (7.30-7.39), partial pressure of O₂ 56.2 (47.1-99.9) mm Hg, partial pressure of CO₂ 43.8 (36.2-53.0) mm Hg, HCO₃ 23.9 (20.1-25.6) mmol/L, and base excess -2.2 (-4.5 to -0.4) mmol/L. Simultaneous maternal arterial blood gas results were as follows: pH 7.37 (7.28-7.42), partial pressure of O₂ 187.5 (124.4-405.2) mm Hg, partial pressure of CO₂ 36.6 (30.7-46.0) mm Hg, HCO₃ 21.3 (18.0-22.8) mmol/L and base excess -3.2 (-5.9 to -1.8) mmol/L.

CONCLUSION

Despite prolonged CO₂insufflation of the uterus, fetal umbilical vein pH and base excess values did not approach those associated with potentially pathologic fetal acidemia.

Fetoscopic myelomeningocoele closure: Is the scientific evidence enough to challenge the gold standard for prenatal surgery?

Since the completion of the Management of Myelomeningocoele Study, maternal-fetal surgery for spina bifida has become a valid option for expecting parents. More recently, multiple groups are exploring a minimally invasive approach and recent outcomes have addressed many of the initial concerns with this approach. Based on a previously published framework, we attempt to delineate the developmental stage of the surgical techniques. Furthermore, we discuss the barriers of performing randomized controlled trials comparing two surgical interventions and suggest that data collection through registries is an alternative method to gather high-grade evidence.

Placental gas exchange during amniotic carbon dioxide insufflation in sheep

OBJECTIVE

Insufflation of the amniotic cavity with carbon dioxide (CO₂ ) is used clinically to improve visibility during complex fetoscopic surgery. Insufflation with heated, humidified CO₂ has recently been shown to reduce fetal hypercapnia and acidosis in sheep, compared with use of cold and dry CO₂ , but the underlying mechanisms are unclear. The aim of this study was to investigate whether differences in placental CO₂ and oxygen (O₂ ) exchange during insufflation with heated and humidified vs cold and dry CO₂ could explain these findings.

METHODS

Thirteen fetal lambs at 105 days of gestation (term, 146 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and instrumented with an umbilical artery catheter, an umbilical vein catheter and a common umbilical vein flow probe. Arterial and venous catheters and flow probes were also inserted into the maternal uterine circulation. Six ewes were insufflated with cold, dry CO₂ (22°C; 0-5% humidity) and seven with heated, humidified CO₂ (40°C; 95-100% humidity) at 15 mmHg for 180 min. Blood-flow recordings and paired arterial and venous blood gases were sampled from uterine and umbilical vessels. Rates of placental CO₂ and O₂ exchange were calculated.

RESULTS

After 180 min of insufflation, fetal survival was 33% (2/6) using cold, dry CO₂ and 71% (5/7) using heated, humidified CO₂ . By 120 min, fetuses insufflated with heated, humidified CO₂ had lower arterial CO₂ levels and higher arterial pH compared to those insufflated with cold, dry gas. Insufflation decreased significantly placental gas exchange in both groups, as measured by rates of both (i) fetal CO₂ clearance and O₂ uptake and (ii) maternal O₂ delivery and CO₂ uptake from the fetal compartment.

CONCLUSIONS

Lower arterial CO₂ and higher pH levels in fetuses insufflated with heated and humidified, compared to cold and dry, CO₂ could not be explained by differences in placental gas exchange. Instead, heated and humidified insufflation appeared to reduce fetal CO₂ absorption from the uterus, supporting its use in preference to cold, dry CO₂ . © 2019 International Society of Ultrasound in Obstetrics and Gynecology.

Fetoscopic insufflation modeled in the extrauterine environment for neonatal development (EXTEND): Fetoscopic insufflation is safe for the fetus

BACKGROUND

Minimally invasive fetal surgery, or fetoscopy, is an alternative to open fetal surgery to repair common birth defects like myelomeningocele. Although this hysterotomy-sparing approach reduces maternal morbidity, the effects of in utero insufflation on the fetus are poorly understood. Our purpose was to determine the optimal fetal insufflation conditions.

METHODS

Fetal sheep at gestational age 104 to 107 days were studied under insufflation conditions in utero and ex utero. The ex utero fetuses were cannulated via their umbilical vessels into a support device, the EXTra-uterine Environment for Neonatal Development (EXTEND). EXTEND fetuses were exposed to four different insufflation conditions for four hours: untreated carbon dioxide (CO₂) (n=5), warm humidified (whCO₂) (n=4), whCO₂ with the umbilical cord exposed (n=3), and whCO₂ without amniotic fluid (skin and cord exposed) (n=3).

RESULTS

In utero insufflation led to significant increases in fetal CO₂ and reductions in fetal pH. Ex utero insufflation with whCO₂ did not lead to changes in fetal blood gas measurements or cerebral perfusion parameters. Insufflation with whCO₂ with an exposed umbilical cord led to reduced umbilical blood flow.

CONCLUSIONS

Insufflation with warm humidified CO₂ with an amniotic fluid covered umbilical cord is well tolerated by the fetus without significant changes in hemodynamics or cerebral perfusion parameters.

TYPE OF STUDY

Basic science LEVEL OF EVIDENCE: N/A.

Chorioamniotic membrane separation following fetal myelomeningocele repair: incidence, risk factors and impact on perinatal outcome

OBJECTIVES

Prenatal myelomeningocele (MMC) repair has been shown to provide significant benefits to the infant, decreasing the postnatal need for ventriculoperitoneal shunt and improving motor outcome. Chorioamniotic membrane separation (CAS) is a potential complication following prenatal MMC repair and may increase the risk of preterm prelabor rupture of membranes (PPROM) and preterm birth. The objectives of this study were: (1) to evaluate the incidence of CAS after prenatal MMC repair; (2) to determine risk factors associated with its occurrence; and (3) to assess its association with adverse perinatal outcomes.

METHODS

This was a retrospective cohort study of patients who underwent fetal MMC repair between November 2011 and December 2018. Surgery was performed using either a fetoscopic (laparotomy or exteriorized uterus) approach or an open-hysterotomy approach. Eligibility criteria were those reported in the Management of Myelomeningocele Study. If CAS was detected on ultrasound (US), its severity was graded as 'mild' if amnion detachment involved < 25% of the uterine cavity, 'moderate' if it involved 25-50% and 'severe' if it involved > 50%. Evolution of CAS was classified as stable, increasing or decreasing based on the difference in severity grading between the time at first diagnosis and the last US scan before delivery. Logistic regression analysis was performed to identify pre- or perisurgical factors associated with the development of CAS and to determine the risk of adverse perinatal outcome associated with CAS.

RESULTS

In total, 91 cases were included. Fetoscopic or open-hysterotomy repair of MMC was performed in 52/91 (57.1%) and 39/91 (42.9%) cases, at a median gestational age (GA) of 25.0 weeks (range, 22.9-26.0 weeks) and 25.0 weeks (range, 21.3-25.9 weeks), respectively. CAS was diagnosed in 31/91 (34.1%) patients, at a median GA of 28.1 weeks (range, 24.4-37.6 weeks). Anterior placenta was identified as a risk factor for the postoperative development of CAS (odds ratio (OR), 3.72 (95% CI, 1.46-9.5); P < 0.01). This risk was dependent on the repair technique. An anterior placenta significantly increased the risk of CAS after fetoscopic repair (OR, 3.94 (95% CI, 1.14-13.6); P = 0.03) but not after open repair (OR, 2.8 (95% CI, 0.6-12.5); P = 0.16). There was no significant difference in the rate of CAS after fetoscopic repair (21/52 (40.4%)) vs open-hysterotomy repair (10/39 (25.6%)) (P = 0.14), nor were there any differences in GA at diagnosis of CAS, interval between surgery and diagnosis, distribution of CAS severity or progression of CAS between the two groups. CAS increased the risk of PPROM (50% in those with vs 12% in those without CAS) (OR, 7.6 (95% CI, 2.5-21.9); P < 0.01) and preterm delivery (70% vs 38%) (OR, 3.2 (95% CI, 1.3-8.1); P < 0.01). Fetoscopically repaired cases with CAS had a higher rate of PPROM (12/20 (60.0%) vs 2/31 (6.5%); P < 0.01) and preterm delivery (13/20 (65.0%) vs 5/31 (16.1%); P < 0.01) than those that did not develop CAS, while the differences were not significant in cases with open-hysterotomy repair. Early detection of CAS (before 30 weeks' gestation) was a risk factor for preterm delivery (90% before 30 weeks vs 36% at or after 30 weeks) (OR, 15.7 (95% CI, 2.3-106.3); P < 0.01). There was no association between PPROM or preterm delivery and the severity or progression of CAS.

CONCLUSIONS

The presence of an anterior placenta was the only factor that increased the risk for CAS after fetoscopic MMC repair. Detection of CAS after fetoscopic MMC repair significantly increases the risk for PPROM and preterm delivery. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Effect of different carbon dioxide (CO2) insufflation for laparoscopic colorectal surgery in elderly patients: A randomized controlled trial

BACKGROUND

Evidence suggests that dry CO2 insufflation during laparoscopic colorectal surgery results in greater structural injury to the peritoneum and longer hospital stay than the use of warm, humidified CO2. We aimed to test the hypothesis that warm, humidified CO2 insufflation could reduce postoperative pain and improve recovery in laparoscopic colorectal surgery.

METHODS

One hundred fifty elderly patients undergoing laparoscopic colorectal surgery under general anesthesia from May 2017 to October 2018 were randomly divided into 3 groups. The primary outcomes were resting pain, cough pain, and consumption of sufentanil at 2, 4, 6, 12, 24, and 48 hours postoperatively. Quality of visual image, hemodynamic changes, esophageal temperature, mean skin temperature, mean body temperature, recovery time, days to first flatus and solid food intake, shivering, incidence of postoperative ileus, length of hospital stay, surgical site infections, patients and surgeon satisfaction scores, adverse events, prothrombin time, activated partial thromboplastin time, and thrombin time were recorded.

RESULTS

Group CE patients were associated with significantly higher early postoperative cough pain and sufentanil consumption than the other 2 groups (P < .05). Compared with group CE, patients in both groups WH and CF had significantly reduced intraoperative hypothermia, recovery time of PACU, days to first flatus and solid food intake, and length of hospital stay, while the satisfaction scores of both patients and surgeon were significantly higher (P < .05). Prothrombin time, activated partial thromboplastin time, and thrombin time were significantly higher in group CE from 60 minutes after pneumoperitoneum to the end of pneumoperitoneum than the other 2 groups (P < .05). The number of patients with a shivering grade of 0 was significantly lower and grade of 3 was significantly higher in group CE than in the other 2 groups (P < .05).

CONCLUSION

Use of either warm, humidified CO2 insufflations or 20°C, 0% relative humidity CO2 combined with forced-air warmer set to 38°C during insufflations can both reduce intraoperative hypothermia, dysfunction of coagulation, early postoperative cough pain, sufentanil consumption, days to first flatus, solid food intake, and length of hospital stay.

Heated humidified carbon dioxide for partial uterine insufflation in fetoscopic myelomeningocele repair: insights from animal model

Linked Comment: Ultrasound Obstet Gynecol 2018; 53: 340-347.