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Hemodynamic, airway pressure, and capnometric changes and perioperative outcome in pediatric laparoscopic inguinal herniorrhaphy: A comparison with open inguinal herniorrhaphy

Background: Laparoscopic procedures which are now established in pediatric population as well exposes the child to supplemental cardiorespiratory changes due to increase in intraabdominal pressure (IAP) and hypercarbia. Aims: This study aims to analyze the effects of pneumoperitoneum and postural modifications on cardiorespiratory system (primary outcome) during pediatric laparoscopic herniorrhaphy (LH) and its comparison with open herniorrhaphy (OH) and assessment of overall perioperative outcome (secondary outcome). Settings and Design: A prospective, observational study conducted in a tertiary care hospital. Materials and Methods: Fifty children undergoing either LH (n = 25) or OH (n = 25) were included in the study. Anesthetic procedure was standardized. Parameters monitored were heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressures (MAP), electrocardiogram lead-II, end-tidal CO2(ETCO2), airway pressures PPeak, PPlateau, PMean, pulse oximetry, IAP, minute ventilation/respiratory rate alterations. Statistical Analysis Used: Student's t-test and Chi-square test were applied to compare different variables between the two groups. Intragroup analysis was done using the analysis of variance test. Results: The HR was comparable in both groups. The rise in SBP, DBP, and MAP was 9% (102.88 ± 6.91–121.32 ± 6.63), 19% (60.88 ± 4.94–77.00 ± 9.75), and 14.8% (73.92 ± 4.65–90.40 ± 8.42), respectively, in group LH. The rise in peak, plateau, and mean airway pressures was 19.4% (14.20 ± 2.00–18.00 ± 2.54), 20.1% (13.32 ± 1.89–16.89 ± 2.60), and 16.1% (6.20 ± 1.00–7.47 ± 0.96), respectively, in group LH. ETCO2showed a maximum rise of 19.4% (34.52 ± 3.61–41.21 ± 3.99) in group LH. In laparoscopic group, recurrence was seen in 3 patients. Conclusions: We found significant hemodynamic, airway pressure, and capnometric changes during pediatric LH with comparable perioperative outcome among the two groups.


MaterIals and Methods
This prospective observational study was conducted in our hospital after approval from the Institutional Ethical Committee on 50 children between age group of 3 − 10 years belonging to American Society of Anesthesiologists (ASA) physical status class I and II of either gender after obtaining a written informed consent from parents or guardians. Twenty-five patients each scheduled to undergo laparoscopic (group LH) and open (group OH) herniorrhaphy were included, while children with coexisting cardiorespiratory, congenital diseases, or on chronic medications were excluded from the study.
All patients were premedicated with oral midazolam 0.25 mg/kg given 1 h before surgery and eutectic mixture of local anesthetics cream was applied on the dorsum of the hand. An intravenous line was secured in the preoperative area in the presence of parents just before surgery. In the operating room, standard monitoring including electrocardiogram (ECG), noninvasive blood pressure, and pulse oximetry (SpO 2 ) was instituted and lactated ringer's solution was started. General anesthesia (GA) was induced with fentanyl 2 µg/kg and propofol 2.0−2.5 mg/kg and endotracheal intubation was facilitated with vecuronium 0.1 mg/kg with an appropriate size of an endotracheal tube. GA was maintained with an oxygen, nitrous oxide, and isoflurane (0.8%−1.2%), supplemented with fentanyl 0.5−1.0 µg/kg and vecuronium boluses at appropriate intervals. Intraoperative fluid was given using Holliday-Segar formula.
Patients were mechanically ventilated with Datex Ohmeda Aestiva 5/7100 ventilator using oxygen and nitrous oxide with tidal volume of 12 ml/kg, an inspiration: expiration ratio of 1:2 and respiratory rate (RR) was adjusted initially to maintain end-tidal CO 2 (ETCO 2 ) below 30−35 mmHg with the aim of keeping it below 45 mmHg at all times after creating pneumoperitoneum. Peak airway pressure alarm limit was set at 30 cmH 2 O beyond which intervention was done.
Pneumoperitoneum was created following insertion of verres insufflations cannula with the patient in supine position and CO 2 was insufflated at the rate of 0.5 L/min using Karl Storz electronic endoflator to maintain an intraabdominal pressure of 10−12 mmHg. After allowing 5 min for intraabdominal pressure to stabilize, the patient was positioned in the final surgical position of 15° Trendelenburg tilt.
After completion of surgery, isoflurane and nitrous oxide were discontinued and patients extubated after neuromuscular reversal with neostigmine 50 µg/kg and glycopyrrolate 10 µg/kg. No blood, blood products, or plasma expanders were required at any stage. Postoperative analgesia was provided with rectal paracetamol suppository 20 mg/kg and local infiltration of port sites with 0.25% bupivacaine in laparoscopic cases and caudal bupivacaine in open cases.
The hemodynamic parameters monitored were ECG lead-II, heart rate (HR), noninvasive systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). The respiratory parameters monitored were peak, plateau, and mean airway pressures (P Peak , P Plateau , and P Mean ), end-tidal CO 2 (ETCO 2 ), SpO 2 , and RR alterations. These variables were recorded at the following intervals in group LH: 5 min postintubation (baseline), after creation of pneumoperitoneum (B), following Trendelenburg tilt (C), during surgery every 5 min until desufflation (D), postdesufflation (E), postextubation (F) and postoperatively every 15 min for 1 h. In group OH, parameters were recorded 5 min postintubation (baseline), after final position (C), during surgery every 5 min (D), postextubation (F), and postoperative every 15 min till 1 h. Other parameters monitored were intraabdominal pressure, duration of pneumoperitoneum, total CO 2 consumed, postoperative anesthetic, and surgical sequelae.

Statistical analysis
Data were analyzed using statistical package for social sciences software (SPSS) for Windows, Version 16.0. Chicago, SPSS Inc. Data variables were expressed as mean ± standard deviation. Student's t-test and Chi-square test were applied to compare different variables between the two groups. Intragroup analysis was done using analysis of variance test for repeated measurements to test for time effects. P < 0.05 was considered statistically significant.

results
Patients' demographic profile and duration of surgery are presented in Table 1. The two groups (group LH; n = 25 and group OH; n = 25) were comparable in terms of age, gender distribution, and duration of surgery. HR did not show statistically significant variations in either group from the baseline, P > 0.05 as shown in Figure 1 nor were there any ECG abnormalities. SBP, DBP, and MAP were significantly greater (P < 0.001) after  Heart rate was comparable in both the groups, P > 0.05 creation of pneumoperitoneum in group LH compared to baseline which was 9% (102.88 ± 6.91-121.32 ± 6.63) [ Figure 2], 19% (60.88 ± 4.94-77.00 ± 9.75) [ Figure 3], and 14.8% (73.92 ± 4.65-90.40 ± 8.42) [ Figure 4], respectively, in group LH and the rise was sustained throughout insufflation, not returning to the baseline even 10 min postextubation. No significant changes were observed in the open group.
In group LH, mean total CO 2 insufflated was 4.64 L, while mean duration of pneumoperitoneum was 27.60 ± 5.42 min, and mean IAP maintained was 10.3 mmHg. In all patients, peripheral oxygenation remained stable throughout the perioperative period. Postoperative complications are shown in Table 3.

dIscussIon
Hemodynamic and respiratory repercussions seen during laparoscopic surgery are mainly related to an increase in IAP, postural modifications (head up or head down tilt), and hypercarbia. [4] As compared to adults, there is a paucity of literature in pediatric population and simple translation of adult data is not possible because of unique and different physiology of children. [4] We conducted a study on ASA physical status class I and II children and analyzed the effects of pneumoperitoneum and postural changes on hemodynamic and respiratory parameters which was the measure of the   There were no significant variations seen in HR from baseline throughout the surgery in either of the groups. No dysrhythmias or ECG changes were observed. Gentili et al., [5] Kardos et al., [6] Baroncini et al., [2] Schäfer et al., [7] and Manner et al. [8] also observed no significant change in the HR in children during pneumoperitoneum.
In our study, SBP, DBP, and MAP increased significantly by 9%, 19%, and 14.8%, respectively, after pneumoperitoneum. The higher increase in DBP and MAP as compared to SBP correlates with an increase in systemic vascular resistance (SVR) caused by mechanical compression of splanchnic vascular bed, a sympathetic reflex from the splanchnic region, and a release of humoral vasoconstrictive mediators such as renin or vasopressin. [5] Similarly, Gentili et al. [5] and Schäfer et al. [7] also documented a significant increase in DBP during pneumoperitoneum and attributed it to an increase in SVR. Elevated IAP produces complex changes in hemodynamics through its effects on SVR, venous return, and myocardial performance. A study in children revealed that IAP of 5−8 mmHg produces no significant change in cardiac output (CO), while IAP of 12 mmHg decreases CO by 13%. [9] In our study, we kept IAP at or below 10 mmHg to minimize its consequences on the hemodynamics.
In the laparoscopic group, a progressive rise in the ETCO 2 was seen after creation of pneumoperitoneum, reaching a plateau after 10−15 min. The maximum rise of 19.4% was seen in spite of increasing respiratory rate by 42%. In 5 patients, ETCO 2 increased beyond 45 mmHg in spite of all ventilatory adjustments. Gentili et al. [5] observed a significant increase in ETCO 2 after CO 2 insufflation with a maximum rise of 16.7% from baseline, while plateau was reached 10−15 min after insufflation in children undergoing diagnostic/operative laparoscopy. Similarly, Baroncini et al. found a significant increase (P < 0.05) in ETCO 2 by 23.4% from a baseline after CO 2 insufflation. [2] In children, CO 2 absorption may be more efficient due to the physiological properties of peritoneum such as reduced thickness of tissues between the gas containing cavity and the capillaries and larger absorption area in comparison to weight. [8] Postdesufflation, although ETCO 2 started falling, it reached the baseline only after a time lag of 10 min. This has been explained to be due to large amounts of CO 2 being buffered in muscle and fat, resulting in an additional load of CO 2 which must be eliminated through the lungs postoperatively. [10] Hsing et al. [11] and Tobias et al. [1] also observed a time lag of 8-10 min for ETCO 2 to reach the baseline value postdesufflation.
Also further, ETCO 2 is shown to correlate well to partial pressure of arterial CO 2 in children excepting those with respiratory pathology, neonates, and infants or during prolonged surgery. [2,12] We followed the above assumption considering that we had ASA class I/II patients undergoing short procedure and therefore avoided doing an arterial blood gas.
Both pneumoperitoneum and Trendelenburg position contribute to the rise in airway pressures during pediatric LH. In our study, the peak, plateau, and mean airway pressures increased significantly from baseline after pneumoperitoneum, the increase being 13.8%, 13.5%, and 12.3% with a further rise to 19.4%, 20.1%, and 16.1%, respectively, after Trendelenburg position. Bergesio et al. [13] and Tobias et al. [1] also found a significant increase in peak airway pressure. Manner et al. [8] found that the rise in peak inspiratory pressure (PIP) correlated well with the fall in lung compliance. The rise in IAP during pneumoperitoneum causes a decrease in lung compliance with proportionate increase of both peak and plateau pressures. This may be complicated further during LH by a rise in airway resistance due to causes such as kinking of an endotracheal tube, endobronchial intubation, tracheal tube abutting on carina, or bronchospasm which will lead to a selective rise in peak airway pressure without affecting the plateau airway pressure. Thus, comparing and analyzing peak and plateau airway pressures were used as a simple guide to detect and treat any additive cause of increased airway resistance, especially when facilities of directly measuring lung compliance and resistance, are not available. Mean airway pressure signifies overall oxygenation and increased by 16% in our study but did not caused any fall in oxygenation, lowest oxygen saturation during laparoscopy being 97%.
One of the claimed benefits of laparoscopy is reduced postoperative pain and in our experience, early postoperative pain was comparable in two groups probably because of inclusion of caudal epidural block in open cases, but subsequently pain and discomfort decreased dramatically over next 12 − 48 h in laparoscopic group and these children returned to normal activity much earlier and were discharged by 2 nd postoperative day. Incidence of postoperative nausea and vomiting (PONV) was higher in laparoscopic group, probably due to peritoneal irritation by insufflated CO 2 . [3,14] Surgical sequelae such as scrotal edema, hematoma, urinary retention, and infection were comparable in both groups. Recurrence had occurred among three patients in laparoscopic group while none in the open one. Endoscopic surgical procedures are associated with specific complications that are generally not encountered with open procedures, for example, air embolism, subcutaneous emphysema, and capnothorax, [10] which were not seen in our study.
Strength of the study includes totality of the comparison by including intraoperative cardiorespiratory and perioperative outcomes. Limitation of this study may include the relatively smaller size of the study population and inability to extrapolate these results on children belonging to ASA physical status class III and IV. conclusIons Significant hemodynamic, airway pressure, and capnometric changes were seen following pneumoperitoneum with trendelenburg position during laparoscopic hernoirrhaphy in ASA physical status class I and II children aged 3−10 years at an intraabdominal pressure of 10 mmHg. These changes were well tolerated by our group of patients, but whether they would be tolerated by high-risk children is still a matter of further research. Although the advantages of decreased postoperative pain and early return to activity were seen in the laparoscopic hernoirrhaphy group, a higher incidence of PONV and more significantly recurrence in three cases mandating a repeat surgery can turn the balance against the laparoscopic hernoirrhaphy group. Combining the above factors with significant cardiorespiratory effects of pneumoperitoneum along with recurrence, our study did not reveal an overall improved perioperative outcome in laparoscopic group as compared to the open group.