Intraoperative care during gynaecology surgery

20.1

Introduction

Obesity is associated with various conditions, including diabetes mellitus, hypertension, hypercholesterolemia, heart disease, asthma, and arthritis. All these conditions contribute to increased morbidity and mortality in gynaecology surgery. Obese women with metabolic syndrome (specifically hypertension and diabetes) who underwent general, vascular, and orthopaedic surgery are at increased risk of perioperative morbidity and mortality compared with normal-weight patients.

Based on the data, the American College of Obstetricians and Gynecologists made the following recommendations in a recent committee opinion paper:

• 1.

  Gynaecological surgeons should have the knowledge to counsel obese women on the risks specific to this group.

• 2.

  As with all patients, evidence demonstrates that, in general, vaginal hysterectomy is associated with better outcomes and fewer complications than laparoscopic or abdominal hysterectomy.

• 3.

  Wound complications, surgical site infections, and venous thromboembolism are the main cause of morbidity in obese women who underwent gynaecology surgery.

• 4.

  Every effort should be made to offer all patients, regardless of BMI, the least invasive procedure in order to decrease complications, length of hospital stay, and postoperative recovery time.

20.2

Decision-making about surgery

• 1.

  Ensure that surgery is appropriate and there are no other alternative nonsurgical management options to deal with immediate issues until weight management has been addressed.

• 2.

  Consider conservative therapies, such as the Levonorgestrel-releasing intrauterine system for menstrual dysfunction, bladder retraining and physiotherapy for urinary problems, and pessaries for prolapse, should be considered as an option.

• 3.

  Obese women and their families should receive careful counselling about the increased risk of complications during surgery, possible technical challenges which may be encountered during surgery, and specific issues related to postoperative recovery

• 4.

  It is the clinician’s duty to help them understand the problem from a medical point of view, and how risks related to surgery can be reduced. There is a case to offer bariatric surgery for morbidly obese woman, if conservative treatment had failed, and she has other significant comorbidities.

20.3

Physiological changes in obese women

• 1.

  Central (visceral) obesity leads to several cardiovascular and haemodynamic changes associated with physiological abnormalities. A Scottish survey reported that the prevalence of cardiovascular disease was 37% in adults with a BMI >30 compared to only 10% in adults with a BMI of <25.

• 2.

  Hypertension is common in obese patients with 60% of obese patients having mild–moderate hypertension and 5%–10% having severe hypertension.

• 3.

  Cardiac arrhythmias are more common in obese patients and may be caused by a number of factors, including hypoxia, electrolyte imbalance, myocardial hypertrophy, and myocardial infiltration of the conducting system.

• 4.

  Autopsy studies have shown that there is an association between obesity and cardiomyopathy with a 20%–55% increase in cardiac diameter, ventricle size, and cardiac weight for the obese patients compared to the nonobese patient.

• 5.

  Class III obesity is associated with a decrease in functional residual capacity, shallow breathing pattern, an increase in peak inspiratory pressure, decreased expiratory reserve volume, and total lung capacity.

• 6.

  The functional residual capacity (FRC) is reduced in the obese patients when lying in supine position with an impaired tolerance for the Trendelenburg position for the laparoscopic surgery.

• 7.

  Steep Trendelenburg position along with CO ₂ Pneumoperitoneum results in a greater arterial partial pressure of CO ₂ (paCO ₂ ) during Laparoscopic and robotic surgery. The end-tidal CO ₂ remains constant and therefore leads to an elevated PaCO ₂ -EtCO ₂ gradient (hypercapnia), which in turn reflects increased dead space, “Obesity hypoventilation syndrome.” The FRC is further compromised by anaesthesia to levels lower than closing capacity resulting in airway closure and hypoxemia.

• 8.

  Obesity is a well-established risk factor for developing obstructive sleep apnoea; the higher the BMI, the higher the risk.

• 9.

  As the FRC and expiratory reserve volume drops, the mismatch in ventilation perfusion promotes alveolar collapse and atelactasis at the lung bases. The decrease in chest wall compliance can be as high as 60% after pneumoperitoneum is created.

• 10.

  Morbidly (Class III) obese patients are at a higher risk of developing hypercapnia and acidosis which can cause cardiac arrhythmias and vasoconstriction of pulmonary vessels, depressive effect on cardiac myocardial contractility, and tachycardia.

• 11.

  Obese patients are at increased risk of gastric acid aspiration, especially during minimal access/or invasive abdominopelvic surgery, because of increased intragastric pressure, large gastric volume, altered secretion of adipokines, predisposition to reflux, lower gastric pH, and delayed gastric emptying.

• 12.

  Increased intraabdominal pressure during minimally invasive surgery can reduce the peak femoral systolic velocity and increase the femoral vein cross-sectional area. Sequential compression devices should be used to reverse this effect along with the use of prophylactic antithrombotic agents to prevent deep venous thrombosis.

20.4

Preoperative evaluation

• 1.

  Preoperative detailed assessment by the anaesthetic team should be considered.

• 2.

  The anaesthetist will consider whether tracheal intubation and airway management will be difficult due to adipose tissue in the neck and limited neck/cervical spine movement.

• 3.

  Obese patients with metabolic syndrome undergoing noncardiac surgery are at increased risk of cardiovascular complications. A 12-lead cardiogram is recommended at preoperative evaluation and other tests, such as echocardiogram, based on the class of obesity and findings of physical examination, should also be considered.

• 4.

  In patients with diabetes mellitus, blood glucose evaluation and counselling the woman on the importance of euglycemia to improve postoperative wound healing are important.

• 5.

  Specialist investigations are required if obstructive sleep apnoea is suspected from a history of daytime somnolence, morning headaches, nocturnal wakening, and partner reports of loud snoring and apnoeic episodes during sleep.

• 6.

  Thorough abdominal and pelvic assessment should be carried out to decide upon the best route for surgery with the help of ultrasound scanning and magnetic resonance imaging to determine the best route of surgery. Even an examination under anaesthesia may provide more guidance.