Successful Resuscitation of Neonatal Kittens Delivered by a Perimortem Cesarean Section Following Maternal Cardiopulmonary Arrest
ABSTRACT
A 9 yr old, unknown weight, intact female domestic shorthair presented for evaluation of dystocia with dyspnea. En route to the hospital for treatment, the owners noted the queen stopped breathing. On presentation, cardiopulmonary arrest was confirmed. The exact cause was unknown but suspected to be secondary to acute fulminant congestive heart failure or acute respiratory distress syndrome due to a large volume of serosanguineous fluid within the mouth and nose. Cardiopulmonary resuscitation (CPR) was immediately started. After 2 min of CPR without return of spontaneous circulation, the owners consented to perimortem Cesarean section. Two kittens were removed via emergency hysterotomy within 3–4 min. Both kittens were successfully resuscitated. CPR efforts were continued on the queen for 2 min after delivery of the kittens, at which time the owners elected to stop further resuscitative efforts. Both kittens were discharged from the hospital and were alive at last follow-up, 2 yr and 4 mo after birth. There are no previous reports regarding the use of a perimortem Cesarean section to deliver neonates in small animal medicine. Therefore, this report represents a novel treatment approach that can be considered in the case of maternal arrest during dystocia.
Introduction
Difficult or abnormal parturition (dystocia) is a common small animal emergency. The incidence rate for dystocia in dogs and cats is around 5% of all parturitions1; however, the incidence can be as high as 22% in certain purebred cats2 and is highly variable in dogs depending on their breed.3 Dystocia can occur because of maternal factors or fetal factors. Common maternal factors include breed predisposition, primary or secondary uterine inertia, and abnormal conformation of the reproductive tract. Fetal factors that contribute to dystocia include abnormal fetal development, fetal oversize, or abnormalities in presentation, position, or posture. Regardless of the cause, dystocia is a life-threatening emergency that increases the risk of mortality to the dam and the fetuses. Dystocia can be managed medically, through the use of manipulation and ecbolic agents, or surgically with a Cesarean section (C-section).4
To the author’s knowledge, there are no previous reports regarding use of a perimortem C-section to deliver neonates in small animal veterinary medicine. Therefore, this report represents a novel approach that can be considered in the case of maternal cardiopulmonary arrest during dystocia.
Case Report
A 9 yr old, unknown weight, intact female domestic shorthair presented to the emergency service at a tertiary referral hospital for evaluation of dystocia and dyspnea. Externally visible abdominal contractions, consistent with stage 2 labor, had been noted by the owner starting 10 hr before presentation, without production of a kitten. Several hours before presentation, the queen developed an increased respiratory rate and effort. En route to the hospital, the owners noted that the queen had stopped breathing. A full history, including further information regarding her breeding and pregnancy, was not able to be obtained owing to the emergent nature of her presentation.
On presentation, the queen was unresponsive and apneic. Cardiopulmonary arrest (CPA) was confirmed, and cardiopulmonary resuscitation (CPR) was started immediately. External cardiac compressions at a rate of 100–120 compressions per min were performed in right lateral recumbency. A large volume of serosanguineous fluid was noted to be present coming from the mouth and nose. This fluid obscured the airway and caused initial attempts at intubation to be unsuccessful. Suction of the oral cavity was performed to improve visualization, but intubation remained difficult, and a patent airway was unable to be obtained.
At this time, consent was obtained from the owners to move forward with a perimortem C-section. One team, consisting of two veterinarians and two veterinary technicians, continued CPR efforts on the queen while a second team, consisting of two veterinarians and a veterinary technician, performed the emergency hysterotomy and neonatal resuscitation.
Maternal Resuscitation
External chest compressions were continued during the emergency hysterotomy. Three to 4 min after starting cardiopulmonary resuscitation, at the time the abdominal incision was being made, intubation with a 4 mm cuffed endotracheal tube was achieved. Ventilation was provided at a rate of 10 breaths per min via an AmbuBag connected to supplemental oxygen. A mainstream capnograph was connected once intubation was achieved. End-tidal CO2 readings were not recorded on the arrest record but remained low throughout resuscitation. Resuscitation efforts continued after the emergency hysterotomy for 2 min. At that time, given the poor prognosis for return of spontaneous circulation (ROSC) of the queen, the owners elected to stop resuscitative efforts.
Perimortem Cesarean Section
Two minutes after the start of CPR, the owners consented to a perimortem C-section. With the queen still in right lateral recumbency and receiving CPR, the ventral abdominal midline was minimally shaved and scrubbed once with dilute chlorhexidine solution. A scalpel was used to incise the skin and subcutaneous tissue from the xyphoid to pubis through to the level of the linea alba. The linea was retracted using thumb forceps and a stab incision was used to enter the abdominal cavity. Care was taken to avoid penetration into the gravid uterus. The incision into the linea was extended using scissors. The uterus was exteriorized, and it was noted to have a markedly cyanotic discoloration. A scalpel was used to enter the uterus, and two kittens were removed through the incision at 3 and 4 min after the start of the emergency hysterotomy procedure. There was no bleeding noted from any of the incisions, and none of the incisions were closed during the 2 min of continued resuscitative efforts on the queen before the owners elected to stop CPR. The owners did not consent to a necropsy; therefore, the exact cause of cardiopulmonary arrest remained unknown.
Neonatal Resuscitation
Following removal via the emergency hysterotomy, the kittens, a gray male weighing 92 g and a tuxedo female weighing 101 g, were handed off to other members of the neonatal resuscitation team. Neonatal resuscitation was provided to both kittens. The fetal membranes were immediately removed from the face and mouth. Towels were used to dry the kittens. A bulb syringe was used to suction the airway. After 10 sec, neither of the kittens was spontaneously breathing, and therefore, a tight-fitting face mask was placed over each of their muzzles for flow-by oxygen supplementation; however, noninvasive ventilation was not started because an appropriately sized bag for ventilation was not immediately available. With continued tactile stimulation, both kittens began to take sporadic breaths within the next 10 sec. A 25-gauge needle was used on the GV26 acupuncture point to stimulate additional respiratory drive, and oxygen delivery was continued via a tight-fitting face mask. One minute after the start of neonatal resuscitation, both kittens were taking spontaneous breaths with a normal respiratory rate. The kittens were fully dried and maintained on supplemental heat with a warming blanketa and flow-by oxygen delivered via tubing without a mask. Eight minutes after the start of neonatal resuscitation, both kittens were active and vocalizing. Both kittens had normal suckle, righting, rooting, and stimulation responses with calculated neonatal reflex scores5 of 6. Both kittens appeared full term with fur extending to the feet and muzzle. No clinically apparent congenital defects were noted with either kitten.
Both kittens were discharged to the owners on the day of presentation with instructions on orphaned kitten care. Provision of antibodies through healthy feline plasma was recommended as a substitute for colostrum; however, the owners were financially unable to afford the cost of plasma. Therefore, no further treatments were provided to the kittens before discharge. Both kittens were alive with no health concerns reported by the owner at the time of last follow-up, 2 yr and 4 mo after their delivery via perimortem C-section.
Discussion
In human literature, perimortem C-section refers to a C-section in cases in which the patient is in extremis or is undergoing CPR.6 Cardiopulmonary arrest during pregnancy occurs infrequently in humans, with an incidence of 1 in 30,000 pregnancies.6 The incidence of maternal CPA is unknown in veterinary literature, and to the author’s knowledge, there have been no previous reports of perimortem C-sections in dogs or cats.
Human literature has documented survival with good neurologic outcomes for fetuses delivered via perimortem C-section in cases of maternal CPA.7,8 Neurologically intact fetal survival is inversely related to time from maternal arrest to delivery, with 70% of fetal survivors born within 5 min of maternal death.9,10 This finding has led to the development of the “4-minute rule”. The Royal College of Obstetricians and Gynecologists guideline recommends that a perimortem C-section be performed if there is no ROSC after 4 min of CPR, with delivery of the fetus within 5 min of CPR. In this case, the decision to pursue a perimortem C-section was made after only 2 min of CPR, owing to the difficulties obtaining a patent airway for provision of adequate basic life support during CPR. With the queen’s initial presenting complaint of dyspnea and the copious fluid within her airways, there was concern that further resuscitation of the queen without a patent airway would be futile. Therefore, although CPR on the queen continued, the main goal became an attempt to save the kittens. The kittens were delivered within 6 and 7min after the onset of CPR; however, the exact time from maternal arrest to delivery of the neonates is unknown. The queen was noted to have stopped breathing en route to the hospital, reportedly only a few minutes or less before arrival. The prompt recognition of maternal CPA and the early consideration for a perimortem C-section likely contributed to the successful outcome of these neonates, as it prevented further delay to delivery. It remains to be determined if small animal neonates have similar factors associated with neurologically intact survival as humans following maternal arrest and if the “4-minute rule” to considering perimortem C-section would apply in veterinary patients. However, until more cases of fetuses delivered via perimortem C-section are reported, rapid delivery of the fetuses following diagnosis of maternal arrest during parturition or dystocia is recommended. As there are case reports of successful fetal outcomes with delays as long as 15–45 min following human maternal arrest,11,12 a perimortem C-section could be considered in small animal patients even when the time or duration of maternal arrest is unknown.
An additional factor associated with fetal survival in human perimortem C-sections is gestational age.6 This is likely a factor that would contribute to fetal survival in small animal patients as surfactant production occurs late in gestation in dogs, from day 57 to day 60 following ovulation.13 If delivered before significant surfactant production, fetal survival is unlikely with the currently available therapeutic options. Therefore, gestational age should be known before considering a perimortem C-section. In this case, the queen was in active labor and the fetuses were presumed to be of sufficient gestational age for delivery.
The queen in this case report presented in cardiopulmonary arrest of unknown duration. To minimize further delay between onset of cardiopulmonary arrest and delivery of the fetuses, no specific evaluation was performed to assess fetal viability before the perimortem C-section. Assessment of fetal viability and distress via fetal heart rate is routinely used in cases of dystocia and could be considered before performing a perimortem C-section. Further fetal assessment, such as ultrasonographic evaluation of intestinal motility, may indicate a fetus is at term in cases in which gestational age is unknown.14 However, there may be benefit in performing a hysterotomy in cases of maternal arrest even when the fetuses are known to be nonviable.
As there are several physiologic changes that occur during pregnancy that influence the maternal resuscitative efforts, perimortem C-section may also improve maternal outcomes. In the pregnant state, cardiac output is increased significantly because of increased stroke volume, increased heart rate, and reduced systemic vascular resistance.15 The human uterus receives 30% of the maternal blood volume, and therefore, delivery of the fetus is associated with an immediate and significant increase in cardiac output.16,17 Furthermore, the gravid uterus can cause compression of intraabdominal vessels, which reduces venous return. Decompression of the uterus via fetal delivery can restore the venous return and further improve cardiac output, thus increasing the chance of successful maternal resuscitation.18,19 Overall, in humans, a perimortem C-section has been shown to be beneficial in 31.7% and not harmful in any case.7 Given the possible benefits to the mother, the term “resuscitative hysterotomy” has been proposed as alternative terminology instead of perimortem C-section in the human literature.20
In this case, ROSC of the queen was not achieved, despite performing a perimortem C-section. The queen was originally presenting for dyspnea after 10 hr of stage 2 labor without production of a kitten. Initial attempts at intubation were unsuccessful because of the quantity of fluid present within the airway, even despite suctioning. Past medical history for this queen was unknown; however, acute fulminant congestive heart failure or acute respiratory distress syndrome were differentials for her acute-onset dyspnea associated with queening. Rapid intubation and provision of oxygen is critically important in cases of maternal arrest. Pregnancy reduces functional residual capacity and increases oxygen consumption; therefore, pregnant patients are susceptible to earlier and more severe hypoxia.19 The delay in establishing a patent airway and providing oxygenation likely contributed to the lack of ROSC in this case.
Advanced life support during CPR (such as administration of drugs or defibrillation) was not provided, which may have also contributed to the lack of ROSC for the queen. The resuscitation algorithms for basic and advanced life support in humans with CPA are applied to pregnant women with the additional recommendations for (1) earlier endotracheal intubation instead of bag mask ventilation, (2) performing left lateral displacement of the uterus, and (3) considering delivery of the fetus via perimortem C-section early on during resuscitation.19 There are no recommended changes to the use of resuscitative drugs, in either type or dose. Similarly, the same defibrillation protocols are recommended for both pregnant and nonpregnant human patients. There is no evidence in veterinary literature to support or refute the use of the current RECOVER basic and advanced life support algorithms in pregnant veterinary patients.
Conclusion
Despite the lack of ROSC for the queen, the two kittens were successfully delivered via emergency hysterotomy during CPR and resuscitated despite maternal CPA before presentation to the hospital. Given the successful fetal outcomes and the potential for improvement in maternal outcomes, a perimortem C-section should be considered in cases of maternal arrest during parturition or dystocia in small animal patients, as demonstrated by this case report.
Contributor Notes
