Partial amniotic carbon dioxide insufflation (PACI) facilitates fetoscopic interventions in complicated monochorionic twin pregnancies

Lifesaving Treatments for the Tiniest Patients-A Narrative Description of Old and New Minimally Invasive Approaches in the Arena of Fetal Surgery

Fetal surgery has become a lifesaving reality for hundreds of fetuses each year. The development of a formidable spectrum of safe and effective minimally invasive techniques for fetal interventions since the early 1990s until today has led to an increasing acceptance of novel procedures by both patients and health care providers. From his vast personal experience of more than 20 years as one of the pioneers at the forefront of clinical minimally invasive fetal surgery, the author describes and comments on old and new minimally invasive approaches, highlighting their lifesaving or quality-of-life-improving potential. He provides easy-to-use practical information on how to perform partial amniotic carbon dioxide insufflation (PACI), how to assess lung function in fetuses with pulmonary hypoplasia, how to deal with giant CPAMS, how to insert shunts into fetuses with LUTO and hydrothorax when conventional devices are not available, and how to resuscitate a fetus during fetal cardiac intervention. Furthermore, the author proposes a curriculum for future fetal surgeons, solicits for the centralization of patients, for adequate maternal counseling, for adequate pain management and adequate hygienic conditions during interventions, and last but not least for starting the process of academic recognition of the matured field as an independent specialty. These steps will allow more affected expectant women and their unborn children to gain access to modern minimally invasive fetal surgery and therapy. The opportunity to treat more patients at dedicated centers will also result in more opportunities for the research of rare diseases and conditions, promising even better pre- and postnatal care in the future.

Anesthesia for fetal operative procedures: A systematic review

Objective

The anesthetic management of fetal operative procedures (FOP) is a highly debated topic. Literature on fetal pain perception and response to external stimuli is rapidly expanding. Nonetheless, there is no consensus on the fetal consciousness nor on the instruments to measure pain levels. As a result, no guidelines or clinical recommendations on anesthesia modality during FOP are available. This systematic literature review aimed to collect the available knowledge on the most common fetal interventions, and summarize the reported outcomes for each anesthetic approach. Additional aim was to provide an overall evaluation of the most commonly used anesthetic agents.

Methods

Two systematic literature searches were performed in Embase, Medline, Web of Science Core Collection and Cochrane Central Register of Controlled Trials up to December 2021. To best cover the available evidence, one literature search was mostly focused on fetal surgical procedures; while anesthesia during FOP was the main target for the second search. The following fetal procedures were included: fetal transfusion, laser ablation of placental anastomosis, twin-reversed arterial perfusion treatment, fetoscopic endoluminal tracheal occlusion, thoraco-amniotic shunt, vesico-amniotic shunt, myelomeningocele repair, resection of sacrococcygeal teratoma, ligation of amniotic bands, balloon valvuloplasty/septoplasty, ex-utero intrapartum treatment, and ovarian cyst resection/aspiration. Yielded articles were screened against the same inclusion criteria. Studies reporting anesthesia details and procedures’ outcomes were considered. Descriptive statistical analysis was performed and findings were reported in a narrative manner.

Results

The literature searches yielded 1,679 articles, with 429 being selected for full-text evaluation. A total of 168 articles were included. Overall, no significant differences were found among procedures performed under maternal anesthesia or maternal-fetal anesthesia. Procedures requiring invasive fetal manipulation resulted to be more effective when performed under maternal anesthesia only. Based on the available data, a wide range of anesthetic agents are currently deployed and no consistency has been found neither between centers nor procedures.

Conclusions

This systematic review shows great variance in the anesthetic management during FOP. Further studies, systematically reporting intraoperative fetal monitoring and fetal hormonal responses to external stimuli, are necessary to identify the best anesthetic approach. Additional investigations on pain pathways and fetal pain perception are advisable.

The effects of partial amniotic carbon dioxide insufflation in an ovine model

OBJECTIVE

We aim to assess the effect of partial amniotic carbon dioxide insufflation (PACI) at increasing pressures on fetal acid-base, fetal-placental perfusion, and fetal membrane morphology in an ovine model.

METHOD

Pregnant ewes and fetuses were instrumented under isoflurane anesthesia at 105 days gestation (term 145 days) to monitor utero-placental blood flow, fetal and maternal blood pressure, heart rate, and blood gas status. One group (n = 6) was exposed to PACI (unheated dry CO₂ ), involving 10 mm Hg stepwise increases in insufflation pressure (5 to 25 mm Hg), for 80 minutes followed by 20 minutes of desufflation. Un-insufflated controls (n = 5) were monitored for 100 minutes. At postmortem, fetal membranes were collected for histological analysis.

RESULTS

PACI at 25 mm Hg caused severe fetal hypercapnia (PaCO₂  = 143 ± 5 vs 54 ± 5 mm Hg, P < 0.001), acidosis (pH = 6.85 ± 0.02 vs 7.25 ± 0.02, P < 0.001), hypoxia (SaO₂  = 31 ± 4% vs 57 ± 4%, P = 0.01), and reduced uterine artery flow (50 ± 15 vs 196 ± 13 mL/min/kg, P = 0.005) compared with controls. These effects were greater at higher PACI pressures. PACI resulted in leukocyte infiltration in the amnion (1.77 × 10^-5  ± 0.61 × 10^-5 vs 0.38 × 10^-5  ± 0.19 × 10^-5  cells/μm² , P = 0.04) and chorionic membranes (2.94 × 10^-5  ± 0.67 × 10^-5 vs 0.84 × 10^-5  ± 0.42 × 10^-5  cells/μm² , P = 0.01).

CONCLUSION

Higher PACI pressures results in larger disturbances in fetal acid-base, uterine blood flow, and fetal membrane inflammation in sheep. Differences between human and sheep utero-placental structure should be considered.

Partial amniotic carbon dioxide insufflation (PACI) during minimally invasive fetoscopic surgery: early clinical experience in humans

BACKGROUND

The technical performance of minimally invasive fetoscopic surgery may be severely hindered by poor visualization of intra-amniotic contents. Partial amniotic carbon dioxide insufflation (PACI) allows the visual limitations of operating within the fluid environment to be overcome.

PATIENTS AND METHODS

When amniotic fluid exchange failed to improve fetoscopic visualization, PACI was attempted during 37 fetoscopic procedures between 17 + 5 and 33 + 2 weeks of gestation. PACI was attempted with filtered carbon dioxide using a commercially available insufflator via one to three trocars that were percutaneously introduced into the amniotic cavity. The maximum pressure during PACI was limited by the maximum insufflation pressure (30 mmHg) generated by the insufflator. Improvement of fetoscopic visualization as well as technical, maternal, and fetal safety aspects surrounding PACI were analyzed.

RESULTS

PACI could successfully be instituted in 36 of the 37 procedures. In one case, when in the presence of increased uterine tone the opening pressure exceeded the maximum insufflation pressure of the insufflator, the strategy was abandoned. In all cases where PACI could be instituted successfully, the approach offered far superior visualization of the fetoscopic procedure than would have been possible within amniotic fluid. Acute or chronic maternal or fetal complications were observed in only one case (intraoperative membrane rupture).

CONCLUSION

PACI greatly improves fetal visualization during fetoscopic interventions when fetoscopy within fluid meets with difficulties. Continued assessment of its benefits, risks, and safety margins at specialist centers is required.

Stage I twin-twin transfusion syndrome: rates of progression and regression in relation to outcome

OBJECTIVES

Twin-twin transfusion syndrome (TTTS) results in high rates of perinatal mortality and neurological morbidity. Fetoscopic laser ablation of placental anastomoses is now established as the treatment of choice for advanced disease. However, there remains controversy about its use in early-stage TTTS, in which laser-related fetal losses need to be balanced against relatively favorable outcomes with more conservative approaches. We investigated rates of progression and regression in Stage I TTTS and determined factors influencing the course of the disease.

METHODS

We undertook a retrospective observational study of all TTTS cases referred to our tertiary referral fetal medicine service from 2000 to 2006. In patients presenting with Stage I TTTS, the following variables were evaluated for their ability to predict the course and progression of the disease: gestational age (GA) at presentation, amniotic fluid index, recipient and donor deepest vertical pool, presence of artery-artery anastomoses, small-sized bladder compared to normal donor bladder and fetal size discordance. Study end-points were disease regression or progression, and neonatal survival at 28 days.

RESULTS

Among 132 consecutive cases of TTTS, 46 women presented with Stage I disease. In the majority (69.6%), disease remained stable (28.3%) or regressed (41.3%). Of cases that progressed, 79% did so within 2 weeks and 93% progressed to at least Stage III. No factor was significantly linked with progression or regression, although there was a trend towards the absence of an artery-artery anastomosis (P = 0.10) and the presence of a small rather than normal donor bladder (P = 0.10) influencing progression, and later GA at presentation (P = 0.07) influencing regression. At least one infant survived in 83% of cases and there was double survival in 59%. Perinatal outcome was significantly better in cases that regressed (the rates of at least one survivor and double survival being 89% and 89%, respectively) or remained Stage I (77% and 61%, respectively), compared with those cases that progressed (79% and 14%, respectively). Treatment with amnioreduction at first presentation did not influence progression or regression.

CONCLUSIONS

This study demonstrates that a high percentage of Stage I TTTS cases regress or remain early stage. Identification of factors predicting progression would facilitate the selection of patients for definitive therapy, while avoiding treatment-related morbidities in mild or transient disease.