Indian Journal of Pain

ORIGINAL ARTICLE
Year
: 2020  |  Volume : 34  |  Issue : 1  |  Page : 39--42

Incidence and severity of pruritus in pregnant women undergoing lower-segment cesarean section under spinal anesthesia with fentanyl and bupivacaine


Mohammed R Al-Tamimi, Rashid M Khan 
 Department of Anesthesia and ICU, Khoula Hospital, Muscat, Oman

Correspondence Address:
Dr. Mohammed R Al-Tamimi
Department of Anesthesia and ICU, Khoula Hospital, Muscat
Oman

Abstract

Background: Regional anesthesia and analgesia are being widely used nowadays, especially for lower-segment cesarean section (LSCS). However, according to some studies, as well as our observation, there is a high incidence of pruritus among patients undergoing LSCS under regional technique as compared to nonpregnant female patients. To enhance the quality of analgesia and increase the duration of spinal anesthesia, fentanyl is often added as an adjuvant drug. Till date, only few studies have reported the incidence of pruritus among this group after spinal anesthesia with added fentanyl, but none compared it to nonpregnant patients. Aim and Objective: The primary aim of this study was to estimate the magnitude of pruritus after intrathecal fentanyl in parturient patients. The secondary objective was to establish other pathophysiological mechanisms such as patient's body habitus and sex of the baby, which might influence the incidence and severity in this population as compared to nonpregnant patients. Materials and Methods: One hundred and sixty American Society of Anesthesiologists I and II female patients aged between 18 and 45 years were divided into two equal groups. Pregnant women group underwent LSCS, while nonpregnant patients had lower limb orthopedic surgery. Spinal anesthesia was administered using 20 mcg of fentanyl with 2.5 ml of 0.5% bupivacaine. Frequency and severity of pruritus were recorded in the patients of either group. Statistical analysis of the data was done using Chi-square test and logistic regression using SPSS version 22. A P < 0.05 was considered statistically significant. Results: The incidence of pruritus among pregnant women was noted to be 21.5%, which is significantly higher (P < 0.05) than that in the nonpregnant patients (3.75%). Pregnant patient's body habitus and gender of the baby were not found to influence the incidence or severity of pruritus (P > 0.05). Conclusions: Pregnancy is not only a risk factor for pruritus after intrathecal fentanyl but is also responsible for increasing the severity of pruritus.



How to cite this article:
Al-Tamimi MR, Khan RM. Incidence and severity of pruritus in pregnant women undergoing lower-segment cesarean section under spinal anesthesia with fentanyl and bupivacaine.Indian J Pain 2020;34:39-42


How to cite this URL:
Al-Tamimi MR, Khan RM. Incidence and severity of pruritus in pregnant women undergoing lower-segment cesarean section under spinal anesthesia with fentanyl and bupivacaine. Indian J Pain [serial online] 2020 [cited 2021 Oct 25 ];34:39-42
Available from: https://www.indianjpain.org/text.asp?2020/34/1/39/282558


Full Text

 Introduction



Spinal anesthesia is being widely used nowadays for various surgical procedures below the level of the umbilicus, including cesarean section and lower limb orthopedic procedures.[1],[2] In addition to local anesthetic drugs that are injected, opioids are now the preferred adjuncts that have been shown to fasten the onset, increase the density, and prolong the duration of anesthesia.[3] In our center, it is common to add fentanyl to hyperbaric bupivacaine. There are several side effects of intrathecal opioids, most commonly experienced by patients is itching.

The incidence of pruritus after intrathecal fentanyl has been reported to be significantly higher among pregnant women who underwent lower-segment cesarean section (LSCS) in comparison to nonpregnant women who were operated for other types of surgeries.[4],[5] In uncontrolled observation in our anesthetic practice in Oman, we have also observed relatively higher incidence of pruritus among patients undergoing LSCS.

However, it is not well established if there are pathophysiological risk factors such as parturient's obesity or gender of the baby, which may contribute to increased incidence and severity of pruritus after intrathecal fentanyl in these patients. In this prospective study, our primary objective was to estimate the incidence of pruritus in pregnant women undergoing LSCS under spinal anesthesia with fentanyl and bupivacaine, while the secondary objective was to correlate the implication of pregnant patient's body habitus and baby gender as a risk factor on the incidence and severity of pruritus after intrathecal fentanyl.

 Materials and Methods



Following approval by the hospital ethical issues committee, 160 American Society of Anesthesiologists (ASA) I and II Omani female patients (80 in each group) aged between 18 and 45 years who gave consent for spinal anesthesia were included in this trial. We calculated the sample size based on the incidence of pruritus. With an expected proportion of 0.7, precision of 10%, and a desired confidence level (1-alpha) of 95%, required 80 patients in each group. We excluded candidate who had a preexisting disease with pruritus, allergy to opioids or local anesthetics, contraindication to regional anesthesia, and diabetic patients on insulin sliding scale. Pregnant women (study group) underwent LSCS, while nonpregnant patients (control group) had lower limb orthopedic surgery. All patients were premedicated with metoclopramide, antacid, and ranitidine for the study group, while midazolam was administered to the control group. Intravenous (IV) Ringer lactate or normal saline was administered at a rate as per the attending anesthetist's preference. Following strict aseptic precautions, in sitting position, patients received 20 mcg fentanyl + bupivacaine intrathecally through L2/L3 interspace by an experienced anesthetist. A 25G pencil-point needle was used to inject the drugs over an average of 10 s. Vital signs (blood pressure, SpO2, and pulse rate) were monitored in all patients. After drug injection, patients were assisted to lie down immediately and oxygen 4–6 L was administered by Venturi facemask. Any decrease in the blood pressure (systolic <90 mmHg or/and diastolic <60 mmHg) was treated with ephedrine 5–10 mg titrated accordingly and IV fluids.

Intraoperatively, the pruritus was assessed by the attending anesthesiologist who was not part of the study team. Time from injection of intrathecal drug to the time of development of itching was recorded. This was continued at 15-min interval until discharge to the recovery room. Subsequently, a recovery room nurse carried out the assessment until discharge to the ward. On an average, the assessment duration was 90 min.

When noted (scratching nose, face, or chest; restlessness; or development of redness on the named areas), candidates were asked if they had itching, and if so, a prepared picture of the visual analog scale was used to determine the severity of pruritus (mild = 1–3, moderate 4–6, and severe >6). Patient's body weight, gender of the delivered baby, development of pruritus, and its severity were recorded in the data collection form by an independent observer not associated with the study.

Those who developed pruritus were treated with either naloxone 0.1 mg IV two doses 5 min apart, propofol 10 mg IV two doses 5 min apart, or a single dose of lidocaine 1 mg/kg IV as per choice of the attending anesthetist.

All our patients were monitored in recovery room as per guidelines for a period of 30-60 minutes. Patients who developed itching were kept to the maximum allowed duration for monitoring and data collection (60 min), while the patients who did not have itching were discharged earlier (30 min) when no other complications were noted. We did not monitor the patients after this period; however, we provided a contact number to the ward to call if the patient continued to have itching or increase in severity. Note: We did not receive any call in this regard.

Standard ASA monitor was applied to all patients and that included electrocardiogram, heart rate, pulse oximetry, and blood pressure. Pain was monitored clinically (no specific tools were used as this was out of our scope since all patients were discharged to the ward). All patients were started on regular oral/IV paracetamol. Further pain management was carried out as per the hospital guidelines. There was no restriction from our side to treat with opioids when required.

Statistical analysis of the data was done using Chi-square test and logistic regression using SPSS version 22 (International Business Machines Corporation, Statistical Product & Service Solutions, New York, USA). A P < 0.05 was considered statistically significant in this study.

 Results



Two groups were involved in the study, a study group: pregnant women assigned for LSCS and a control group: those who underwent lower limb orthopedic surgery. All candidates were ASA I and II, aged between 18 and 45 years. The incidence of pruritus was far higher in the study group in comparison to the control group (25% vs. 3.8%). This was statistically significant (P < 0.05).

Of the 20 cases who developed pruritus, 17 patients belonged to the pregnant group as compared to only three in the nonpregnant group [Table 1]. All patients in the nonpregnant group had only mild itching as compared to more severe grades of itching in the pregnant group.{Table 1}

The effects of body mass index (BMI) and baby gender on pruritus were not statistically significant, accounting for 21.7% (<30 kg/m2) versus 26.3% (≥30 kg/m2) for the former, while 21.9% male babies versus 27.1% female babies for the latter [Table 2].{Table 2}

The calculation of relative risk in both groups is provided in [Table 3].{Table 3}

 Discussion



Regional anesthesia and analgesia have been used widely nowadays, especially for the procedure below the umbilicus such as LSCS, lower limb orthopedic operations, and urological procedures. In the United States of America, approximately 80%–90% of cesarean sections are performed under regional anesthesia.[1]

Spinal analgesia/anesthesia with opioids is associated with several side effects, including pruritus that is defined as an unpleasant sensation of the skin, provoking the desire to scratch or rub it. The frequency and severity of pruritus have been found to rise by increasing the dose of opioid injected. However, in this study, we had kept the dose of fentanyl constant. Few studies have shown that the incidence of pruritus is considerably higher (60%–100%) among pregnant women.[1],[6] This study confirms the finding in the Omani population as well. However, the incidence remained between 30% and 60% in other surgical procedures.[7],[8],[9] Fentanyl, a short-acting opioid, is a popular drug used in combination with local anesthetics to provide regional anesthesia and/or analgesia. The incidence of pruritus has not been studied in our region, and a search of worldwide literature shows very limited data in relation to the intensity of itching among pregnant women who undergo LSCS.

It is believed that itching results from triggering receptors in the spinal nucleus of the trigeminal nerve that is, in turn, continuous with the substantia gelatinosa and Lissauer tract at C3–C4.[10] Furthermore, it is theorized that hormonal changes during pregnancy might contribute to the increased incidence of itching among the pregnant patients.[11],[12] This could be a result of alteration in the number of receptors or their sensitivity under the influence of increased maternal hormones during pregnancy. However, this is a matter of conjecture, and well-executed studies are needed to reach a cause-and-effect relationship.

Our secondary objectives were not validated in this study. We did not observe any significant correlation between patient's BMI and sex of the babies in parturient patients on the incidence of pruritus.

In this study, patients with inadequate block or those converted to general anesthesia were excluded from our study (due to difficulty to collect data). Intraoperative hypotension was treated with ephedrine boluses and IV fluids as per the hospital guidelines. Further management was left to the attending anesthesiologist to decide as per his/her preference and experience; we did not compare the severity of hypotension and its treatment between the two groups as this was outside of the scope of this study. Other complications including postoperative nausea and vomiting and urinary retention were not recorded in this study; they were managed accordingly as per the hospital guidelines.

This research had its share of limitations. First, we did not study the impact of other narcotics as adjuvants to bupivacaine. Second, the effect of escalating doses of fentanyl was not included in the study design. Finally, we did not try to identify the most efficacious treatment to fentanyl-induced pruritus in patients undergoing spinal anesthesia for LSCS.

 Conclusions



Pregnancy was found to play an aggravating role in the incidence of pruritus following spinal anesthesia with heavy 0.5% bupivacaine that contained 20 mcg or fentanyl without any influence from patients BMI or sex of the baby.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Butterworth JF, Mackey DC, Wasnick JD. Morgan and Mikhail's Clinical Anesthesiology. 5th ed. New York: McGraw Hill; 2013.
2Eroglu A. Regional anesthesia techniques in orthopedic surgery. J Anesth Crit Care Open Access 2016;5:182.
3Farzi F, Mirmansouri A, Naderi Nabi B, Atrkar Roushan Z, Ghazanfar Tehran S, Nematollahi Sani M, et al. Comparing the effect of adding fentanyl, sufentanil, and placebo with intrathecal bupivacaine on duration of analgesia and complications of spinal anesthesia in patients undergoing cesarean section. Anesth Pain Med 2017;7:e12738.
4Szarvas S, Harmon D, Murphy D. Neuraxial opioid-induced pruritus: A review. J Clin Anesth 2003;15:234-9.
5Kumar K, Singh SI. Neuraxial opioid-induced pruritus: An update. J Anaesthesiol Clin Pharmacol 2013;29:303-7.
6Shah MK, Sia AT, Chong JL. The effect of the addition of ropivacaine or bupivacaine upon pruritus induced by intrathecal fentanyl in labour. Anaesth 2000;55:1008-13.
7Colbert S, O'Hanlon DM, Galvin S, Chambers F, Moriarty DC. The effect of rectal diclofenac on pruritus in patients receiving intrathecal morphine. Anaesth 1999;54:948-52.
8Törn K, Tuominen M, Tarkkila P, Lindgren L. Effects of sub-hypnotic doses of propofol on the side effects of intrathecal morphine. Br J Anaesth 1994;73:411-2.
9Dimitriou V, Voyagis GS. Opioid-induced pruritus: Repeated vs single dose ondansetron administration in preventing pruritus after intrathecal morphine. Br J Anaesth 1999;83:822-3.
10Kam PC, Tan KH. Pruritus: Itching for a cause and relief? Anaesth 1996;51:1133-8.
11Krajnik M, Zylicz Z. Understanding pruritus in systemic disease. J Pain Symptom Manage 2001;21:151-68.
12LaBella FS, Kim RS, Templeton J. Opiate receptor binding activity of 17-alpha estrogenic steroids. Life Sci 1978;23:1797-804.