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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 1  |  Issue : 2  |  Page : 105-110

Hemodynamic changes during pneumoperitoneum and reverse Trendelenburg position in bariatric surgery: An observational study using noninvasive cardiac output monitoring


1 Department of Anaesthesiology, Pain Medicine and Critical Care, All India Institute of Medical Sciences, New Delhi, India
2 Department of Anaesthesiology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India
3 Department of Surgery, All India Institute of Medical Sciences, New Delhi, India

Date of Submission04-Jul-2022
Date of Acceptance03-Sep-2022
Date of Web Publication21-Sep-2022

Correspondence Address:
Dr. Ravinder Kumar Pandey
Department of Anaesthesiology, Pain Medicine and Critical Care, Room No. 5016, 5th Floor Teaching Block, All India Institute of Medical Sciences, Ansari Nagar, New Delhi - 110 029
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jbs.jbs_12_22

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  Abstract 


Background: Patients undergoing bariatric surgeries are at higher perioperative risk due to multiple comorbidities. We studied the hemodynamic changes during pneumoperitoneum and reverse Trendelenburg position in bariatric surgery, using noninvasive cardiac output (CO) monitoring. Methods: In this prospective observational study, 60 patients of the American Society of Anesthesiologists Grade I–II, aged between 18 and 60 years, planned for elective laparoscopic bariatric surgery were included. During the intraoperative period, hemodynamic monitoring was done using an estimated continuous CO (esCCO) monitor. We noted oxygen saturation (SpO2), heart rate, blood pressure (BP), and CO values obtained before induction of general anesthesia and were compared with values obtained after induction, postintubation, after pneumoperitoneum, after reverse Trendelenburg, and every 10 min during the procedure and postextubation. Results: The mean baseline SpO2, pulse rate (PR), systolic BP (SBP), diastolic BP (DBP), and CO was 99.17 ± 1.7, 99.9 ± 1.35 bpm, 136.3 ± 14.5 mm Hg, 83.11 ± 10.5 mm Hg, and 7.59 ± 1.44 L/min, respectively. There was a significant fall in PR, SBP, DBP, and CO after induction of anesthesia and intubation (P = 0.001). After creating pneumoperitoneum and reverse Trendelenburg, the fall in hemodynamic parameters was also significant (P = 0.001). Conclusions: The esCCO noninvasive CO monitor can be used in patients undergoing bariatric surgeries and predict CO during surgery.

Keywords: Bariatric surgery, non-invasive cardiac output, hemodynamics, pneumoperitoneum, reverse Trendelenburg


How to cite this article:
Poudel D, Pandey RK, Bhalla AP, Sharma A, Ray BR, Punj J, Darlong V, Aggarwal S. Hemodynamic changes during pneumoperitoneum and reverse Trendelenburg position in bariatric surgery: An observational study using noninvasive cardiac output monitoring. J Bariatr Surg 2022;1:105-10

How to cite this URL:
Poudel D, Pandey RK, Bhalla AP, Sharma A, Ray BR, Punj J, Darlong V, Aggarwal S. Hemodynamic changes during pneumoperitoneum and reverse Trendelenburg position in bariatric surgery: An observational study using noninvasive cardiac output monitoring. J Bariatr Surg [serial online] 2022 [cited 2022 Dec 4];1:105-10. Available from: http://www.jbsonline.org/text.asp?2022/1/2/105/356579




  Introduction Top


Patients undergoing bariatric surgeries pose an extra burden for surgeons, anesthetists, and physicians in terms of the requirement of particular demands on health care significantly different from regular patients.[1] They tend to require the involvement of multiple specialties in preoperative optimization, including cardiopulmonary assessment (compromised respiratory system dynamics, and obstructive sleep apnea). Comorbidities such as coronary artery disease, Type II diabetes mellitus, hypertension, left ventricular failure, and pulmonary hypertension are associated with these patients, making them significantly higher perioperative risk than their normal-weight counterparts, mandating extensive preoperative evaluation.[2]

Bariatric surgery is rapidly evolving due to its promising outcome. The anesthetic management of bariatric patients poses a significant challenge to the anesthetist.[3] Anesthesia for these patients has many challenges during ventilation, intubation, oxygenation, selection of doses of anesthetics, fluid management, perioperative management of anesthesia and analgesia, and overall surgical outcome.[4],[5],[6]

Laparoscopic procedures in bariatric patients require the creation of pneumoperitoneum and keeping the patients in reverse Trendelenburg position, which have been postulated to cause changes in cardiac output (CO) and peripheral tissue perfusion. Under general anesthesia, the reverse Trendelenburg position causes a gravity-induced redistribution of blood volume to the lower body, often resulting in a substantial reduction in CO and blood pressure (BP).[7],[8]

Goal-directed therapy is a revolutionary concept in anesthesia that entails extensive monitoring and aggressive hemodynamic control during surgery. Rather than assessing the fluid status and calculating treatments, it is based on the attainment of specified values. The term “fluid responsiveness” refers to the heart's capacity to increase stroke volume in response to volume expansion.[7]

As the patient's hemodynamic state may change abruptly, constant CO monitoring offers information enabling prompt treatment modification. Pulse wave transit time (PWTT) is a novel technique to measure continuous CO and monitor changes in hemodynamic parameters. PWTT is useful in measuring CO, which has a correlation to heart activity with electrocardiography (ECG). The calculation of PWTT is done from the time gap between the ECG-R wave and peripheral pulse detected by the pulse oximetry.[9],[10] This study aimed to observe the hemodynamic changes during pneumoperitoneum and reverse Trendelenburg position in bariatric surgery, using noninvasive CO monitoring based on the principle of PWTT.


  Methods Top


This prospective observational study was conducted in the operation theater of a tertiary care hospital. After institutional ethical committee approval and informed written consent were obtained, 60 patients aged 18–60 years, belonging to the American Society of Anesthesiologists (ASA) Grade I-II, planned for elective laparoscopic bariatric surgery, were included in the study. The exclusion criteria were ASA Grade III/IV patients, unwilling or uncooperative patients, weight more than 150 kg, hemodynamically unstable patients, and positive Allen's test.

Ideal body weight (IBW) was calculated using the J. D. Robinson formula[11] as 52 kg + 1.9 kg/inch over 5 feet (male) and 49 kg + 1.7 kg/inch over 5 feet (female).

A thorough history and physical examination of the individuals who had been referred for bariatric surgery were conducted. Allen's test was performed during a preanesthetic check-up to know the patency of the collateral circulation in hand. In all patients, fasting for more than 8 h and premedication with tablet alprazolam 0.25 mg and ranitidine 150 mg orally was advised before the night of surgery and on the morning of surgery.

After being shifted to the operating room, patients were placed in the supine position. Their heads and shoulders were elevated using pillow and folded sheets to align the sternal notch and external auditory meatus. It gives a better laryngeal view than other tracheal intubation positions and reduces the likelihood of difficult intubation in patients undergoing bariatric surgeries. ECG, noninvasive BP (NIBP), and pulse oximetry were attached using a monitor (Nihon Khoden BSM6000 Series life scope TR, Japan) [Figure 1]. This estimated continuous CO (esCCO) monitor was calibrated after entering the patient's age, sex, height, and weight. If the calibration was successful with NIBP, the induction was done, but if the calibration was not successful with NIBP, radial artery cannulation was done under local anesthesia infiltration and after taking all aseptic precautions. Baseline readings of BP, CO, heart rate (HR), and oxygen saturation (SpO2) were taken.
Figure 1: NIHON KHODEN monitor for noninvasive cardiac output monitoring

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All patients were preoxygenated for 3 min with 100% oxygen (6 L/min) before induction. In all patients, general anesthesia was induced with fentanyl 2 mcg/kg of IBW, propofol 2–2.5 mg/kg (IBW), and atracurium 0.5–1 mg/kg (IBW), and all patients were ventilated with a mixture of 6–7 L of oxygen and air (50:50) along with 1%–2% of isoflurane. After 3 min of lung ventilation, in all patients, endotracheal intubation was performed by the appropriate size of the endotracheal tube. After that, mechanical ventilation was initiated in all patients, and all patients received volume control ventilation with a tidal volume of 8–10 ml/kg of IBW and a respiratory rate of 12–16 breaths/min.

Pneumoperitoneum was created with carbon dioxide insufflation keeping the maximum pressure limit up to 15 mm Hg. After 10 min of CO2 insufflation, i.e. postpneumoperitoneum values of various parameters were noted. The patients were monitored for any fall in CO. Any decrease in CO of more than 20% was supplemented with a bolus of 300 ml of balanced salt solution over 5–10 min. Response of hemodynamic parameters to the bolus fluid was noted. If no improvement in the CO is seen, another bolus of 300 ml balanced salt solution was administered. If no improvement in CO is noted despite the above two-fluid boluses, then intravenous ephedrine 6 mg bolus was administered. Any episode of bradycardia (HR <50/min) was treated with 0.6 mg of atropine administered intravenously. Any episode of desaturation (Spo2 <85%) was treated immediately by administrating 100% oxygen or applying positive end-expiratory pressure (PEEP) of 5–8 cm H20.

During the surgery, when the patient was put in reverse Trendelenburg position, hemodynamic parameters were recorded after 10 min of change in position. After the insufflation of CO2 pneumoperitoneum and when the patient is put back to a supine position, these parameters were recorded after 10 min. The amount of blood loss and total fluid administered during surgery were also noted.

Various parameters were recorded at the following time points: (1) baseline-initial values before induction of anesthesia, (2) after induction–after administration of the induction agents, (3) after intubation–after placement of the endotracheal tube, (4) after pneumoperitoneum creation–after insufflation of carbon dioxide gas in the peritoneal cavity, (5) after reversing Trendelenburg position–after placing the patient in reverse Trendelenburg position, i.e. head-up position, (6) every 10 min interval during the surgery with pneumoperitoneum and reverse Trendelenburg position, and (7) after desufflation of peritoneum and normal leveling of the patient.

Baseline hemodynamic parameters were compared with values obtained postinduction, postintubation, after pneumoperitoneum, after reverse Trendelenburg, and every 10 min during the procedure and postextubation.

The primary outcome was to assess the hemodynamic changes using esCCO monitor following pneumoperitoneum and reverse Trendelenburg's position during bariatric surgery. The secondary outcome was to note various complications during this period.

Sample size calculation

Based on a previous study,[12] the standard deviation (SD) of baseline CO before the surgery as 1.45 and the SD of CO after surgery as 0.78, and the mean difference of 0.7; the sample size was calculated as 58. Hence, we decided to enroll 60 patients. The type I error was kept as 5%, and the power of the study was 90.

Statistical analysis

The statistical analysis was done by Statistical Package for Social Sciences (SPSS; IBM Corp.,IBM SPSS Statistics for Windows, Version 20.0. Armonk,NY: IBM Corp). The data were presented in mean ± S.D and frequency percentage. Repeated measure ANOVA was used to see the within changes in various parameters followed by post hoc comparison using the Bonferroni test. A P value < 0.05 was considered statistically significant.


  Results Top


In this study, a total of 60 patients were studied. Out of 60, 45 were female (75%), and 15 were male (15%). The demographic distribution of participants and various comorbidities is shown in [Table 1]. The mean ± SD duration of surgery was 72 ± 18.02 min. The mean ± SD blood loss was minimal, 50 ± 15.7 ml. The mean ± SD intraabdominal pressure (IAP) was 12 ± 1.33 cm H2O.
Table 1: Demography and comorbidities of participants

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The mean baseline SpO2, pulse rate (PR), systolic BP (SBP), diastolic BP (DBP), and CO were 99.17 ± 1.7, 99.9 ± 1.35 bpm, 136.3 ± 14.5 mmHg, 83.11 ± 10.5 mmHg, and 7.59 ± 1.44 L/min, respectively. These values were compared with other recorded values during the surgery and are displayed in [Table 2] and [Figure 2].
Table 2: Variation in oxygen saturation, pulse rate, systolic blood pressure, diastolic blood pressure, and cardiac output at various time points

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Figure 2: Changes in cardiac output, systolic blood pressure, diastolic blood pressure, heart rate, and SpO2 at various time points (T1 [Baseline], T2 (After induction], T3 [After intubation], T4 [After pneumoperitoneum], T5 [After reverse Trendelenburg], T6 [10 min after reverse Trendelenburg], T7 [20 min after reverse Trendelenburg], T8 [30 min after reverse Trendelenburg], T9 [40 min after reverse Trendelenburg] and T10 [50 min after reverse Trendelenburg]). SpO2: Oxygen saturation

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Anesthesia induction

There was significant variation in HR after induction which decreased to 93.3 ± 13.1 bpm (P = 0.001). The mean SBP decreased to 122.9 ± 13.1 mmHg after induction of anesthesia (P = 0.001). The mean DBP decreased to77.6 ± 15.8 mm Hg (P = 0.001). The mean CO decreased to 6.89 ± 2.0 L/min after the administration of GA (P = 0.001).

Intubation

There was significant variation in HR from baseline postintubation, which decreased to 90.3 ± 14.8 bpm (P = 0.001). The mean SBP decreased to 117 ± 24.0 mmHg after intubation from baseline (P = 0.001). The mean DBP decreased to 71.6 ± 11.6 mmHg from baseline (P = 0.001). This was associated with a fall in CO from baseline value to 6.49 ± 1.41 L/min (P = 0.001).

Pneumoperitoneum

There was significant variation in HR from baseline after pneumoperitoneum, which decreased to 90.9 ± 14.1 bpm (P = 0.001). The mean SBP decreased to 114.9 ± 19.1 mmHg from baseline (P = 0.001). The mean DBP decreased to 72.6 ± 11.8 mmHg from baseline (P = 0.001). The mean CO decreased to 6.18 ± 1.92 L/min from baseline after the creation of pneumoperitoneum (P = 0.001).

Reverse Trendelenburg position

There was significant variation in HR from the baseline value after the patients were positioned in the reverse Trendelenburg position, which decreased to 90.7 ± 13.4 bpm (P = 0.001). The mean SBP decreased to 116 ± 21.9 mmHg from baseline (P = 0.001). The mean DBP decreased to 77.6 ± 10.6 mmHg from baseline (P = 0.001). This was associated with a fall in CO from baseline to 6.30 ± 1.54 L/min (P = 0.001).

Complications and interventions

The numbers of patients developing bradycardia were 21 (35%). Out of these, 14 (23%) patients required intravenous atropine administration. The bradycardia developed primarily after the creation of pneumoperitoneum. The number of patients developing desaturation was 14 (23.3%). Prompt action was taken by giving 100% oxygen, checking the endotracheal tube, and applying positive PEEP of 5–8 cm H2O. The patients developed these episodes during insufflation of the peritoneum and after reverse Trendelenburg position. The number of patients who developed hypotension was 40 (66.7%). Most of these episodes occurred after the creation of pneumoperitoneum, accompanied mainly by bradycardia. The intervention was required in the form of intravenous fluid (ringers lactate or normal saline) bolus and injection of ephedrine 6 mg IV bolus, and all of them responded to the intervention. One patient had an episode of intraoral extubation during the reverse Trendelenburg position, which was quickly identified, and the endotracheal tube was repositioned [Table 3] and [Figure 3].
Table 3: Various complications and interventions

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Figure 3: Various complications and interventions

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  Discussion Top


The combination of obesity-related comorbidities, pneumoperitoneum, and significant postural alterations in morbidly obese patients undergoing laparoscopic bariatric surgery poses a substantial risk of perioperative hemodynamic consequences. BP readings might be erroneous if the cuff used is the wrong size. For this reason, advanced hemodynamic monitoring is necessary.

Various monitoring techniques are available today for CO measurement, ranging from invasive to noninvasive, continuous or intermittent, such as pulmonary artery catheter, pulse-contour CO monitoring, or transesophageal echocardiography. While invasive artery catheterization is technically challenging, transesophageal echocardiography is not recommended owing to the surgical technique. However, the greater the degree of invasiveness, the greater the risk of monitoring-related complications such as infection, ischemia, and thromboembolism. Therefore, this research examined a noninvasive CO monitor that may predict hemodynamic changes in patients undergoing bariatric surgeries.

Monitoring CO promotes enhanced recovery after surgery. It provides accurate and up-to-date information on the cardiovascular state and determines the need for postoperative care. It may minimize intraoperative complications resulting from fluid overload or hypovolemia. Fluid overload may cause generalized edema, anastomotic leakage, and a delay in the recovery of gastrointestinal functions. Hypovolemia may lead to hypoperfusion and kidney injury. It may help in reducing postoperative hospital stays and limiting readmissions.

In the present study, there was a significant fall in HR, systolic, and DBP after induction of anesthesia (P = 0.001). This decrease in HR and BP was significantly reflected in a fall in CO (P = 0.001). This finding was consistent with the results obtained by Yamada et al., where they analyzed 74 patients. They compared esCCO values with the thermodilution CO (TDCO) method, which had a correlation coefficient of 0.79 (P < 0.0001), a bias (mean difference between esCCO and TDCO) of 0.13 L/min, and a precision (1 SD) of 1.15 L/min.[13]

In our study, the variation in hemodynamic parameters after the creation of pneumoperitoneum was also significant (P = 0.001). As IAP rises, systemic vascular resistance increases as a result of both mechanical compression of the abdominal aorta and the release of neurohumoral hormones such as vasopressin and activation of the renin-angiotensin-aldosterone axis. Constriction of the inferior vena cava decreases preload, which may have resulted in reduced CO and, therefore, decreased arterial pressure. This may be worsened by the diaphragm cephalad displacement, which increases intrathoracic pressure and reduces blood flow through the inferior vena cava, as well as compression of the pulmonary parenchyma raises pulmonary vascular resistance, further decreasing CO.[12] We could not find any studies using noninvasive esCCO monitor in these patients.

There was a significant variation in hemodynamic parameters after the patient was positioned in the reverse Trendelenburg position (P = 0.001). Reverse Trendelenburg posture may result in hypotension due to decreased preload caused by venous pooling in the lower extremities and pelvis, which is worsened by decreased femoral venous flow due to elevated IAP.

Our finding of a decrease in HR, BP, and CO after induction of anesthesia and the creation of pneumoperitoneum was similar to those reported by Darlong et al. They observed a significant decrease in stroke volume, CO, and cardiac index in 15 patients undergoing robot-assisted laparoscopic resection of prostate using FloTrac/Vigileo™.[14]

Min et al. studied the effect of reverse Trendelenburg position on CO in ASA I and II patients.[15] They put anesthetized patients in reverse Trendelenburg position and evaluated the changes in CO compared to baseline values using FloTrac/Vigileo™. Their study showed that CO decreased significantly with the reverse Trendelenburg position (P = 0.045). Our study also showed the same findings.

Perilli et al. studied the effect of reverse Trendelenburg position on CO during open bariatric surgery.[16] They obtained continuous CO values by the minimally invasive esophageal echo-Doppler device (Hemosonic 100–Arrow). They studied 20 patients and found that the reverse Trendelenburg position significantly decreased CO, which is consistent with our findings. However, the type of surgery was different in our study (laparoscopic vs. open).

In our study, there was significant variation in all parameters throughout surgery which did not reach the preinduction values after the release of pneumoperitoneum and when the patient was put in a neutral position. This can be explained by the residual effects of the anesthetic agents in the body.

There were many limitations of the study. The esCCO monitor is not validated in bariatric patients, and we did not come across any study conducted to evaluate noninvasive CO in these patients. Another limitation of this study was that we did not compare the esCCO monitor with the gold standard invasive CO method for CO monitoring. The calibration time taken by the esCCO monitor was sometimes long, ranging from 5 to 13 min. The simple movement of the pulse oximeter and BP cuff would interrupt the esCCO recordings. Artifacts produced by electrocautery would also create interruptions.


  Conclusions Top


The esCCO noninvasive CO monitor can be used in patients undergoing bariatric surgeries, and this can predict CO changes during the surgery. During laparoscopic bariatric surgery, there are specific hemodynamic changes, such as a fall in PR, SBP, DBP, and CO.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Yamada T, Tsutsui M, Sugo Y, Sato T, Akazawa T, Sato N, et al. Multicenter study verifying a method of noninvasive continuous cardiac output measurement using pulse wave transit time: A comparison with intermittent bolus thermodilution cardiac output. Anesth Analg 2012;115:82-7.  Back to cited text no. 13
    
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Darlong V, Kunhabdulla NP, Pandey R, Chandralekha, Punj J, Garg R, et al. Hemodynamic changes during robotic radical prostatectomy. Saudi J Anaesth 2012;6:213-8.  Back to cited text no. 14
    
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Min JH, Lee SE, Lee HS, Chae YK, Lee YK, Kang Y, et al. The correlation between the Trendelenburg position and the stroke volume variation. Korean J Anesthesiol 2014;67:378-83.  Back to cited text no. 15
    
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Perilli V, Sollazzi L, Modesti C, Annetta MG, Sacco T, Bocci MG, et al. Comparison of positive end-expiratory pressure with reverse Trendelenburg position in morbidly obese patients undergoing bariatric surgery: Effects on hemodynamics and pulmonary gas exchange. Obes Surg 2003;13:605-9.  Back to cited text no. 16
    


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