Abstract

Pregnancy and obesity are both independently associated with increased anaesthetic risks. This study sought to determine the incidence and severity of hypotension in patients undergoing CS under spinal anesthesia at the Limbe Regional Hospital.

Method: This study was a retrospective study carried out at the Limbe Regional Hospital in the South West Region of Cameroon. A total of 450 files of women that underwent caesarean delivery under spinal anesthesia were studied and a total of 150 files were recruited for the study.

The outcome of interest was the development of hypotension during spinal anaesthesia and its severity and a comparison was made between the obese and the non obese patients.  Data collection was done during a structured extraction form and analyzed using SPSS version 20

Results: Of the 150 files that were included in this study (76.7%) developed hypotension after administration of spinal anaesthesia, (45.3%) developed mild hypotension, (19.3%) patients had moderate hypotension and (12%) had severe hypotension.

.Conclusion: The study revealed that there is no significant difference in the development of hypotension between the obese and the non obese patients.

CHAPTER ONE

INTRODUCTION

1.1 Background 

Pregnancy and obesity are independently associated with increased anaesthetic risks. Hence when both situations present together, compounded by other medical conditions the risks are increased.

Obesity is a significant public health problem with increasing incidence in both the developed and the developing world. Body mass index (BMI) has increased by 0.4% worldwide over the last thirty years [1], and in the United States one in three adults have a BMI greater than 30 kg/m2 [2]. Data from the Behavioural Risk Factor Surveillance System revealed that morbid obesity, defined as the presence of a BMI > 40 kg/m2 [3], doubled between 1986 and 2000 [4]. Morbidly obese individuals are at high risk for the coexistence of several comorbid conditions that affect different organ systems.

Hypotension is one of the most common complications of spinal anaesthesia with an incidence of 15% to 33% in the general population. In obstetric patients, hypotension has a higher incidence of 20-100% and may be associated with maternal and foetal complications ranging from an increased incidence of nausea and vomiting to foetal hypoxia due to changes in utero-placental blood flow with consequent foetal acidosis [11].

Many anaesthesiologists are giving more regional anaesthesia as compared to general anaesthesia for caesarean section unless contra-indicated due to the fewer adverse outcomes noted with the use of regional anaesthesia as compared to general anaesthesia. With the increasing numbers of overweight and obese women many of them are also receiving the regional anaesthesia in the form of spinal, epidural or combined spinal- epidural anaesthesia [5]. It also acknowledges the change in the health and age of many of the women of childbearing age.

Post-regional anaesthesia hypotension has several definitions such as a fall of systolic blood pressure below 100 mmHg or a 10% to 30% fall from baseline levels. Currently the tendency is to maintain blood pressure as close as possible to the initial levels. Some measures are adopted to prevent hypotension and its consequences such as; moving the uterus to the left crystalloid or colloid infusion use of vasopressors like ephedrine, metaraminol and compression of the lower limbs.

There is a lack of studies comparing complications of spinal anaesthesia in pregnant women with increased weight to those of eutrophic patients for caesarean section [11] including hypotension which makes this analysis important due to the high incidence of obesity in pregnant women.

The objective of this study was to analyse the frequency and severity of hypotension in overweight pregnant women when compared to non-obese pregnant women after regional anaesthesia in order to effectively improve anaesthesia in this type of patient, analyse the influence of comorbidities, and to determine the hemodynamic behaviour pattern within different strata of obese patients.

The physiological changes of pregnancy include an increase in body weight. The increase is due to an increase in blood volume, the weight of the foetus, placenta and amniotic fluid, and increase in body fat stores. Recent advances in Bioelectrical Impedance Analysis (BIA) allow direct measurements of fat and fat distribution to be made during pregnancy. Studies on weight gain in pregnancy have suggested that maternal weight on average increased by 0.5–2.0 kg in the first trimester of pregnancy.

Critically the mean maternal weight and thus, mean BMI do not change significantly. There is also no alteration in mean maternal body composition especially in reference to mean body fat measurements. The prevalence rate of obesity in Cameroon rose from 39% in 2003 to 41% in 2009. In females of childbearing age (15-45 years) the prevalence of obesity stands at 23% countrywide [3].

1.2 Problem Statement

Despite the advantages of regional anaesthesia it is not free of complications and already known limitations such as difficult puncture in some cases,  hypotension,  total spinal anaesthesia,  post-Dural puncture headache and nerve lesions.

Hypotension is one of the most common complications with an incidence of 15% to 33% in the general population after spinal anaesthesia and directly related to greater mortality [13]. In obstetric patients’ hypotension is even more worrisome because besides showing greater incidence (20-100%) it can have serious maternal-fatal consequences from an increased incidence of nausea and vomiting to fatal hypoxia due to changes in uteroplacental blood flow with consequent fatal acidosis.

There is a lack of studies comparing complications of spinal anaesthesia in pregnant women with increased weight to those of eutrophic patients for caesarean section [11] including hypotension which makes this analysis important due to the high incidence of obesity in pregnant women. The objective of this study was to analyse the frequency and severity of hypotension in overweight pregnant women when compared to non-obese pregnant women after regional anaesthesia in order to effectively improve anaesthesia in this type of patient, analyse the influence of comorbidities, and to determine the hemodynamic behaviour pattern within different strata of obese patients.

1.3 Research Questions

1. What is the incidence of hypotension in women undergoing a caesarean section under spinal anaesthesia in the Limbe regional hospital?
2. Is the risk of developing hypotension dependent on the parturient body mass index?
3. What are the Foetal outcome of obese mothers following cesarean delivery under spinal anesthesia.

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