Several studies have examined the cardiovascular effects of pneumoperitoneum in children. Direct measurement of flow in the thoracic aorta by transesophageal echocardiography (TEE) in healthy 6- to 30-month-old infants and children undergoing laparoscopic assisted orchiopexy for undescended testicles with a maximum insufflation pressure of 10 mmHg showed significantly decreased flow, decreased stroke volume, and increased systemic resistance. However, these changes resolved completely after desufflation of the abdominal cavity. Significant changes in mean arterial pressure (MAP) or end-tidal CO₂ were not observed during these relatively short procedures, nor were any clinically important sequelae [10]. In another study of healthy 2- to 6-year-old children undergoing laparoscopic inguinal herniorrhaphy, an initial insufflation to an abdominal pressure of 12 mmHg decreased cardiac index (CI ) as measured by TEE [11]. Interestingly, CI returned to baseline with a decrease in insufflation pressure to 6 mmHg and did not decrease with a subsequent increase in abdominal pressure to 12 mmHg, suggesting an adaptation to the change in afterload induced by abdominal insufflation. A recent study exposed neonatal and adolescent piglets to 180 min of abdominal insufflation, which caused a decrease in CI and MAP that persisted well into the recovery period after insufflation ended. This effect was more pronounced in the neonates [12]. The extended response to the pressure stimulus suggests a need for vigilant monitoring in the postoperative period to ensure that hypotension does not ensue. Prolonged exposure to higher insufflation pressures (>8–10 mmHg) may also induce capillary microcirculatory changes and impair venous return [1]. In contrast, a study using low-pressure insufflation no greater than 5 mmHg combined with reverse Trendelenburg positioning in children ages 6 to 36 months undergoing laparoscopic fundoplication actually increased CI, heart rate, and MAP [13].

In summary, in the otherwise healthy infant or child, abdominal insufflation pressures of 12 mmHg or less for short- to medium-length procedures may cause changes in CI, MAP, or systemic resistance when specifically measured but rarely (3.2 % of cases) produce clinically significant effects requiring intervention [4]. The location of monitoring may not affect the accuracy of blood pressure measurements. In a piglet model, no difference was found between measured carotid and femoral arterial blood pressures with up to 24 mmHg abdominal insufflation, a level nearly twice that of the highest commonly used clinically [14].

The pulmonary effects of pneumoperitoneum in pediatric patients are the result of anatomic and physiologic differences between adults and children. The alveolar surface area to body surface area ratio in infants and children is smaller than that of adults. Therefore, children have a significantly higher minute ventilation and oxygen consumption (up to twice that of an adult) even at baseline to maintain PaCO₂ in the normal range [1]. In patients younger than 1 year of age, the space-occupying effects of abdominal insufflation lead to increased peak inspiratory pressure, reduced tidal volume, and decreased compliance [15]. These changes in turn produce decreased functional residual capacity (FRC) , increased pulmonary vascular resistance, and increased shunt fraction, which in combination with the increased CO₂ absorption can lead to hypercarbia if the minute ventilation is not increased concomitantly [15].

Hypercapnia is a significant concern in minimally invasive surgery, especially in children with underlying pulmonary disease. In one series of laparoscopic and thoracoscopic procedures performed in neonates (i.e., <1 month of age), hypercapnia >45 mmHg was reported in 2.3 % of cases [4]. The degree of hypercapnia depends on insufflation pressure and duration of pneumoperitoneum. In piglet models, PaCO₂ has been shown to increase 25 % with stepwise increases in insufflation pressure with associated increases in mortality from CO₂ embolism [16]. In a study of low-pressure (i.e., maximum 5 mmHg) insufflation for fundoplication, CO₂ rose 28 % on average when patients up to 3 years of age were exposed for more than an hour [17]. Careful monitoring for hypercapnia is warranted for all pediatric minimally invasive procedures, and laparoscopic insufflation pressures should be limited, with a maximum recommended pressure of 12 mmHg for neonates [15].

An important consideration for respiratory monitoring is that a gradient will develop between the PaCO₂ and the end-tidal CO₂ after abdominal insufflation because of an increased CO₂ and diminished functional residual volume. This gradient has been documented to increase significantly in adults during the first 60 min of insufflation for laparoscopic colorectal surgery but to stabilize or decrease thereafter [18]. In young children with cyanotic congenital heart disease undergoing laparoscopic fundoplication, the gradient increased by a factor of nearly 2.5 soon after initial insufflation of the abdomen [19]. This gradient was shown to be as high as 8 mmHg in one study of laparoscopic fundoplication in children without underlying cardiac or respiratory disease; as in other studies, the gradient decreased with longer insufflation stimulus [20]. Measuring CO₂ elimination has also been used to monitor this process. End-tidal CO₂ increases disproportionately for younger patients compared to older children with the same insufflation pressures and duration, and it remains elevated even after the conclusion of the procedure [15]. For these reasons, postoperative monitoring of respiratory rate is critical to safely performing laparoscopy in infants and neonates.

Another potential problem in infants undergoing laparoscopy is hypoxemia. In neonates and infants, there is a close relationship between functional residual capacity (FRC) and airway closing pressure. When FRC decreases in response to the increased intra-abdominal pressure, airway closure will exacerbate right-to-left intrapulmonary shunt and can lead to hypoxemia [5].

In children, data from a study of procedures for acute abdominal pain suggested that laparoscopic compared to open operations did not result in differences in major inflammatory mediators such as cortisol and IL-6 [21]. However, several subsequent studies have demonstrated a lesser degree of increase in inflammatory mediators including IL-6, CRP, TNF-α, and cortisol with laparoscopy compared to open approach for a variety of operations [22–25]. Cellular responses are also affected by laparoscopy, in a manner similar to the cytokine responses. Both macrophages and neutrophils are recruited to the peritoneal cavity with insufflation, though the numbers are lower with CO₂ insufflation compared to air [26].

Compared with adults, children have a greater body surface area to volume ratio [27] and thus are at increased risk for hypothermia . During minimally invasive surgical procedures in infants and children, hypothermia is reported to occur in 1.8 % of cases [4]. Temperature monitoring is especially important in newborns. Dry CO₂ insufflation on continuous flow of 5–8 L/min will lead to massive evaporative losses relative to body size, and the accompanying heat loss can approach 40 % of a neonate’s metabolic power capacity, despite their higher-per-kilogram power capacity compared to adults [3]. Additionally, gas leaks around port sites in a neonate can result in a much greater loss of insufflation gas, thereby requiring higher flow rates and potentially exacerbating hypothermia if non-humidified CO₂ is used.