Pharmacogenetics: implications for obstetric anesthesia

Longrange PCR-based next-generation sequencing in pharmacokinetics and pharmacodynamics study of propofol among patients under general anaesthesia

The individual response of patients to propofol results from the influence of genetic factors. However, the state of knowledge in this matter still remains insufficient. The aim of our study was to determine genetic predictors of variable pharmacokinetics and pharmacodynamics of propofol within selected 9 genes coding for propofol biotransformation enzymes, receptors and transporters. Our studies are the first extensive pharmaocgenetics research of propofol using high throughput sequencing technology. After the design and optimization of long range PCR-based next-generation sequencing experiment, we screened promoter and coding sequences of all genes analyzed among 87 Polish patients undergoing general anaesthesia with propofol. Initially we found that two variants, c.516 G > T in the CYP2B6 gene and c.2677 T > G in the ABCB1 gene, significantly correlate with propofol’s metabolic profile, however after Bonferroni correction the P-values were not statistically significant. Our results suggest, that variants within the CYP2B6 and ABCB1 genes correlate stronger with propofol’s metabolic profile compared to other 7 genes. CYP2B6 and ABCB1 variants can play a potentially important role in response to this anaesthetic and they are promising object for further studies.

The impact of genetic factors on response to anaesthetics

In recent years, exceptional progress has been observed in pharmacogenetics, i.e. investigations of inherited conditioning of the organism's response to drugs or xenobiotics. On the other hand, modern molecular biology techniques have been implemented, making it possible to perform studies determining the involvement of genetic factors in differing responses to agents employed in general anaesthesia. Unexpected and incorrect response of the organism to the administration of specific anaesthetics is most commonly associated with a genetic defect of the metabolic pathway of a given agent or its receptor. The majority of agents used in anaesthesia are metabolised in the liver by the cytochrome P450 superfamily enzymes (CYPs) and phase II drug-metabolising enzymes: glutathione S-transferases (GSTs), sulphotransferases (SULTs), UDP-glucuronosyltransferases (UGTs) and NAD(P)H:quinone oxidoreductase (NQO1). Propofol is presently widely used for gastrointestinal (GI) and several other procedures. Among genes associated with metabolism of the most commonly applied anaesthetics such as propofol and sevoflurane, the following ones can be mentioned: CYP2E1, CYP2B6, CYP2C9, GSTP1, UGT1A9, SULT1A1 and NQO1. Moreover, the basic mechanism of propofol action involves its interaction with an ionotropic receptor GABAA inhibiting transfer of nerve impulses. Molecular studies have shown that polymorphic changes in GABRG2 receptor gene turn out to be important in the propofol anaesthesia. Planning of optimal anaesthesia can be considerably assisted by the determination of genetic factors of prognostic value taking advantage of genotyping and making it possible to select anaesthetics and reduce risk of side effects as well as undesirable actions.

Postoperative analgesia for gynecological laparoscopy

Gynecological laparoscopy is a commonly performed procedure. Providing anesthesia for this can present a challenge, particularly in the day surgery population. Poor analgesia, nausea, and vomiting can cause distress to the patient and increased cost for the health system, because of overnight admission. In this review we discuss anesthetic and analgesic techniques for day-case gynecological laparoscopy. The principles include multimodal analgesia, the use of the oral route wherever possible, and the contribution of the surgeon.

[Anesthetic management of parturients with pre-eclampsia and eclampsia]

Preeclampsia is a pregnancy-associated illness affecting multiple organ systems. Symptoms typically occur after the 20th week of gestation and consist of hypertension (>140/90 mmHg) and proteinuria (>300 mg/day). It is one of the leading causes of premature birth worldwide and early diagnosis and treatment are essential for both fetal and maternal health. Therapy is aimed at lowering blood pressure sufficiently to prevent the most severe complications such as intracranial hemorrhages. At the same time attention must be paid to the possible untoward effects of blood pressure medications on uteroplacental perfusion and fetal well being. Magnesium is the cornerstone for both prevention and control of eclamptic cerebrovascular events. In cases of severe preeclampsia and eclampsia prompt delivery is indicated, often carried out by Cesarean section (>34 weeks of gestation). Compared to general anesthesia, regional anesthesia techniques offer certain advantages to both mother and fetus and in the absence of contraindications are the methods of choice.

The role of the anaesthetist in the management of the pre-eclamptic patient

PURPOSE OF REVIEW

Recent literature on the anaesthetist's role in the management of the patient with severe pre-eclampsia is reviewed, with particular emphasis on the role of regional anaesthesia.

RECENT FINDINGS

Laboratory findings in pre-eclamptic women include increased levels of markers of oxidative stress and circulating tyrosine kinase 1, and inflammatory activation of leucocytes. Magnesium sulphate is the most effective agent for seizure prophylaxis. The optimal pharmacological agents for acute control of blood pressure remain controversial. The benefits of epidural analgesia in labour are well established. Single-shot spinal anaesthesia for caesarean section is safe in the absence of contraindications. Successful use of combined spinal-epidural anaesthesia has been described. Most studies on maternal haemodynamics have employed heart rate and blood pressure data as surrogate measures of cardiac output. Noninvasive cardiac output studies provide further insight into the haemodynamic response during neuraxial techniques for caesarean section.

SUMMARY

The value of regional anaesthesia cannot be over-emphasized. Recent research into spinal anaesthesia for caesarean section suggests a lower susceptibility to hypotension and probably less impairment of cardiac output than in healthy parturients. Noninvasive cardiac output measurement may also have advantages in critical care management.