Minimally invasive surgery (MIS) in children, particularly in those under the age of 1 year, requires sophisticated equipment and techniques and has been developed since the late 1990s.1–3 In neonates and infants, friable and delicate tissue, a small intra-abdominal or intrathoracic space, a steep learning curve, and distinct anesthetic deliberation for dissimilar physiological characteristics have resulted in MIS being utilized less frequently than other techniques.1,3–5 In addition to technological limitations and the need for precise surgical skills, MIS in neonates and infants is challenging because of their vulnerability to hypothermia and hypercarbia, which may lead to acidosis, reduced cerebral perfusion, and other unfavorable outcomes.2,4
Although heat loss caused by large incisions is averted in neonates and infants receiving MIS, extended surgical duration with prolonged exposure to the environment, the use of dry and cold carbon dioxide (CO2) gas, and gas leaks from port sites or instruments all contribute to hypothermia.2,4 A small airway and large dead space may result in reduced gas exchange. Furthermore, a high peritoneal absorption surface per unit of weight, little peritoneal fat, and thin vessel walls leading to rapid CO2 diffusion all contribute to hypercarbia in neonates and infants undergoing MIS.2,4,6 We retrospectively collected clinical data of neonates and infants who received laparoscopic surgery at our institute and analyzed their perioperative data, surgical outcomes, and related complications to clarify the safety and feasibility of MIS in such patients.
Between January 2007 and August 2015, 82 patients (42 male and 40 female) less than 1 year of age who received laparoscopic surgeries at our institute were included. All of the neonates and infants received laparoscopic-related interventions for various diseases. In a typical laparoscopic procedure, the patient was placed in the supine or lithotomy position. The first transumbilical port was introduced using the open Hasson technique. A 5-mm 30° endoscope (KARL STORZ-Endoskope, Surgimed Corporation, Taichung, Taiwan) was inserted via a transumbilical port, and the positions of the other two or three work ports (5 mm or 3 mm) were determined according to operational needs. The pneumoperitoneal space was maintained using CO2 insufflation, and the pressure was 8–10 mmHg in neonates and 10–12 mmHg in infants.
The patients’ medical charts were reviewed to obtain data on general information, diagnosis, perioperative parameters, surgical outcomes, complications, and follow-up durations. The perioperative parameters were the operative age, operative body weight, operative time, CO2 insufflation time, intraoperative end-tidal CO2 (EtCO2) levels, body temperature (BT), and peak inspiratory pressure (PIP). Among these factors, EtCO2 was monitored using a capnometer, which continuously measured the concentration of CO2 in exhaled air via the endotracheal tube connecting to the respirometer of the anesthesia machine. The data were analyzed using the Spearman rank correlation coefficient. The procedure for enrolling all patients in this research was approved by the Institutional Committee on Human Research of Taichung Veterans General Hospital (TCVGH), according to the guidelines of the Declaration of Helsinki and the International Conference on Harmonisation for Good Clinical Practice (Institutional Review Board TCVGH No. CE15260B).
The definite diagnoses and corresponding operative procedures of the included patients are listed in Table 1. The central measurement results of the preoperative data of these patients are shown in Table 2. The operative age ranged from 1 day to 11.4 months (median 2.2 months), and the operative weight ranged from 2 kg to 11 kg (median 4.2 kg). The operative time ranged from 1.0 hours to 7.5 hours (median 3.5 hours), and CO2 insufflation time ranged from 0.2 hours to 5.0 hours (median 2.0 hours). The mean intraoperative EtCO2 level was 37.6 mmHg, the median BT was 35.8°C, and the mean PIP was 23.3 cmH2O. Although the EtCO2 level increased and BT was reduced at the start of insufflation, in most patients the EtCO2 level was maintained below 42.1 mmHg, PIP was below 26.3 cmH2O, and BT was above 35.1°C, as shown in Table 2. Hypercarbia-related intraoperative respiratory acidosis and transient hypothermia (BT < 35°C) were observed in three and four patients, respectively. All of these patients recovered soon after CO2 insufflation was temporarily stopped or the pressure gradient was lowered by about 2 mmHg, and no unfavorable outcomes were observed until the end of the postoperative follow-up period.
The results of perioperative parameters analyzed using the Spearman rank correlation coefficients are listed in Table 3. Patients at a younger operative age or with lower operative weight had longer operative time than did those at an older operative age or with higher operative weight; however, this correlation was not statistically significant (p = 0.03, rs = −0.23 and p < 0.001, rs = −0.32, respectively). Prolonged operative or CO2 insufflation time depends on the surgeon's experience and the corresponding operative procedures. The intraoperative EtCO2 level seemed to be higher for longer operative time (p = 0.01, rs = 0.28) and CO2 insufflation time (p < 0.001, rs = 0.39), but with poor correlation. It seems significant that lower intraoperative BT may occur in those patients with lower operative age (p < 0.001, rs = 0.52) and lower body weight (p < 0.001, rs = 0.59). The mean ventilator PIP levels did not correlate with the other preoperative parameters. The scatter graph of the operative weight and other preoperative parameters is shown in Fig. 1. The operative weight significantly influenced intraoperative BT with favorable negative correlation. No hypotension was observed in any of the patient, even during CO2 insufflation.
Immediate operative complications were observed in five patients. One patient with colorectal anastomotic leakage (Hirschsprung disease) received diversion ileostomy, whereas one patient with Y-enteroenterostomy leakage (biliary atresia) received exploratory laparotomy for anastomosis revision. Urine leakage (ureteropelvic junction stenosis) was spontaneously resolved through local drainage in one patient and percutaneous nephrostomy in another patient, and the patient with (anorectal malformation) urine retention recovered gradually 1 month after surgery. Blood loss was minimal in most patients, except in one patient who received partial nephrectomy; in this case, the estimated blood loss was 40 mL, and thus the patient required blood transfusion. The follow-up duration ranged from 1 month to 102.6 months (median 23.4 months). One patient died 1 month after laparoscopic surgery for hiatal hernia due to severe sepsis caused by central venous catheter infection. Another patient died of congenital heart disease 1 year after laparoscopic surgery for Hirschsprung disease.
During the early development of pediatric MIS, traditional pediatric surgeons claimed that they consistently used small wounds in open surgery. Therefore, the benefits of MIS (such as minimal postoperative pain, early mobilization, and early restoration of normal activities) were not apparent in infants and young children, and a lack of appropriate instruments and surgical skills restricted the development of pediatric MIS.7 With the advancements of instruments and enhanced surgical and anesthetic techniques, increasingly more endoscopic surgeries have been performed in neonates and infants, despite the steep learning curve. MIS procedures are safe and feasible, even in young children and infants, as reported in the literature,8–11 and these features were observed in our study. The most challenging task is to perform intestinal anastomosis in the small pneumoperitoneal space; however, this concern may be resolved by introducing surgical robots or using alternative devices for anastomosis.8,9,12 In our series, the umbilical trocar wound was enlarged slightly to perform extracorporeal anastomosis, thereby yielding favorable cosmetic results, shortening CO2 insufflation time, and saving the additional cost of alternative devices for anastomosis.
Hypothermia and hypercarbia are the most crucial and noteworthy concerns in pediatric MIS, because systemic hypothermia and hypercarbia may lead to arrhythmias and acidosis, respectively. Furthermore, these conditions may subsequently yield irrevocable results, such as brain injury or even death.2,4,13 However, well-known corresponding strategies have been devised for avoiding these complications, such as using an external warming blanket, warming intravenous fluids, humidifying CO2 gas, reducing gas leaks to minimize persistent cold gas inflow, increasing the ventilator minute volume and PIP, and increasing the respiratory rates disproportionately during CO2 insufflation (such as respiratory rate set at 50–60/min in patients with body weight less than 4 kg).2,4–6 All of the aforementioned strategies had been introduced in this series, although patients in this series with lower body weight had significantly longer operative time and CO2 insufflation time, as well as lower intraoperative BT. Low insufflation pressure below 8 mmHg in neonates undergoing laparoscopic surgery to avoid hemodynamic instability was advised in some papers.4,14 However, some papers reported that no significant threat was observed even with the CO2 insufflation pressures up to 15 mmHg in neonates.9,15,16 The line charts of perioperative parameters (EtCO2 at different time points, PIP, BT, systolic blood pressure, and respiratory rate) in three patients with transient hypercarbia are shown in Fig. 2. In this series, CO2 insufflation was temporarily stopped or the pressure gradient was lowered by about 2 mmHg (namely 6–8 mmHg in neonates and 8–10 mmHg in infants) when EtCO2 reached above 50–55 mmHg, until hypercarbia resolved. Anesthesiologists, of course, would adjust PIP and respiratory rate to resume EtCO2 level less than 45–50 mmHg. As for hypothermia resulting from persistent cool CO2 inflow, lowering the gas flow at 3–4 L/min was also introduced in this series to decrease evaporative losses in neonates and infants.
The overall complication rate reported in the literature is approximately 1–4%, with mortality seldomly reported.7,11 In this series, two patients died of other comorbidities unrelated to laparoscopic surgery. In addition, no patient was converted to open surgery, and the operative complication rate was 6.1% (5/82). The relatively higher complication rate may be attributed to the smaller sample size and steep learning curve. Some papers reported that the incidence of complications in pediatric MIS may be reduced drastically with proper training and increased experience in laparoscopic surgery.3,7
In conclusion, laparoscopic surgery in neonates and infants has become more feasible and safe due to the development of technology and instruments, as well as advanced surgical skills and anesthetic reliability. Transient hypercarbia may rapidly ameliorate after CO2 insufflation is stopped, and can be carefully managed by experienced pediatric surgeons and anesthesiologists.
The authors thank Mr Chang Kuang-Hsi (Biostatistics Task Force of Taichung Veterans General Hospital, Taichung, Taiwan, R.O.C.) for assistance in biostatistics and also thank Taichung Veterans General Hospital for funding this project (TCVGH-104DHA0500058).
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