Shivering after spinal anesthesia and associated factors in mothers undergoing cesarean delivery at a referral hospital in northcentral Ethiopia: In resource-limited settings





Abstract


Background


Post-spinal anesthesia shivering is one of the potential complications of anesthesia which may increase patient morbidity. Little is known about the incidence and associated factors of post-spinal shivering in our country. This study aims to assess the magnitude of post-spinal anesthesia shivering and its associated factors among mothers who underwent cesarean section at Debre Tabor Comprehensive Specialized Hospital, Ethiopia.


Methods


A Hospital-based cross-sectional study was conducted on a total of 113 patients who underwent cesarean section under spinal anesthesia. A systematic random sampling method was employed to select 113 study subjects. A structured questionnaire was used to collect data. Bivariable and multivariable logistic regression were used to show an association between independent variables and the dependent variable (post-spinal anesthesia shivering). Variables with a p-value of less than 0.2 were transformed into multivariate analysis. The odds ratios with 95 % CI and p-values of less than 0.05 were used to show the strength of association and level of significance.


Results


The overall incidence of post-spinal shivering was 39 (34.5 %) and variables such as not administering intrathecal pethidine 3.01 (AOR=3.01; 95 % CI: 1.08,8.40), blood loss 500–1000 ml (AOR=4.02;95 % CI: 1.46,11.07), co-loading with less 500 ml (AOR=4.97;95 % CI: 1.48,16.72), intraoperative maternal hypothermia(AOR=4.17;95 % CI: 1.44,12.10) were significantly associated with post-spinal anesthesia shivering.


Conclusions


The overall incidence of post-spinal anesthesia shivering in the study area was 39 (34.5 %). We suggest the introduction of the post-spinal anesthesia shivering management protocol.


Acronyms and abbreviations


AOR


adjusted odds ratio


CI


confidence


C/S


cesarean section interval


COR


crudes odds ratio


DTCSH


Debre Tabor Comprehensive Specialized Hospital


MAP


mean arterial blood pressure


1


Introduction


Shivering is a physiological response to hypothermia manifested as tonic muscular activity secondary to a non-thermoregulatory heat preservation mechanism. , Post-spinal anesthesia shivering is among the leading causes of maternal morbidity during cesarean delivery. , Post-spinal anesthesia shivering may increase oxygen consumption by about two to three fold. This could be due to the prolonged shivering of several muscular groups which might increase metabolic demands. Post-spinal anesthesia shivering is associated with poor patient outcomes by increasing carbon dioxide production, bleeding, and poor wound healing, and it interferes with monitoring. Initial post-spinal anesthesia shivering is believed to be developed as a physiological response to hypothermia, but studies report its occurrence in normothermic patients. The pathophysiology of post-spinal anesthesia shivering in parturients undergoing C/S is not well established. ,


In the intraoperative period, muscle activity may be increased with normothermia suggesting mechanisms other than heat loss resulting in decreased core body temperature may be attributed to post-spinal anesthesia shivering due to inhibited spinal reflexes, pyrogen release, adrenal suppression, and respiratory alkalosis. ,


Shivering could cause arterial hypoxemia, lactic acidosis, increased intracranial pressure, and intraocular pressure. Even perioperative monitoring interference (pulse rate, blood pressure, ECG) is reported, and this may predispose the patient to unwanted morbidity. It is uncomfortable for the parturient as well as for the operating room personnel during regional anesthesia.


Post-spinal anesthesia shivering is a common problem for women who undergo C/S and occurs in about 62.5 % of cases. This problem might worsen in a developing setting when there are no adequate preventive and therapeutic facilities like active warming, intravenous fluid warming, and drugs. , , Shivering affects the physiology of the patient so that the pharmacokinetics of anesthetic drugs and adjuvant drugs may be altered. Metabolism and excretion of anesthetic drugs might be prolonged, which leads to delayed functional return and awakening. These conditions in turn may increase the cost to the patient and the health facility.


The incidence of post-spinal anesthesia shivering ranges from 8 % to 62.5 % after neuraxial anesthesia. , Factors like age, duration of anesthesia and cesarean section, and type of surgery were significantly associated with the incidence of post-spinal anesthesia shivering. This post-spinal anesthesia shivering could make patients uncomfortable, due to the stressful sensation of cold caused by surgical site muscular contraction. ,


Therefore, this study aims to assess the magnitude of post-spinal anesthesia shivering and associated factors of mothers who deliver under the cesarean section in Debre Tabor Comprehensive Specialized Hospitals, Ethiopia, 2020. The study will also be helpful for hospital administrators and health professionals to devise different strategies to prevent or at least reduce factors for post-spinal anesthesia shivering in cesarean-delivering mothers.


2


Methods


2.1


Study area and period


The study was conducted at Debre Tabor Comprehensive Specialized Hospital from May 1 to August 31, 2020. Debre Tabor is the capital town of the South Gondar zone which found Amhara Regional state of Ethiopia. According to the 2007 census, the total population of this Zone was 3155,596. The town has a latitude and longitude of 11 0 51′N38°1’E/11.850°N 38.017°E with an elevation of 2706 m (8878 ft.) above sea level.


Based on the hospital standard all study parturients were given two grams of ampicillin, ten milligrams of metoclopramide, and four hundred milligrams of cimetidine prophylaxis two hours ahead of the procedure. Under aseptic technique, the parturient received 2.5 ml of 0.5 % of plain bupivacaine which is the only spinal drug available in the hospital without adjuvant, or 2 ml of 0.5 % of plain bupivacaine with 15 mg of pethidine as an intrathecal adjuvant and 3 l/min of oxygen was given by using nasal prongs. The axiliary temperature was measured for each patient and the room temperature was taken from the monitoring and it was between 17 and 21 °C without air conditioning. Patients who developed grade II and above shivering were given 25 mg of pethidine. The surgical incision was a Pfannenstiel incision and oxytocin or ergometrine was given based on the vital signs. Hypotension was managed based on the hospital standard, first by infusing intravenous fluid, and for those who were not reversed by fluid managed by adrenalin which is the only available vasopressor. This study is reported according to STROBE guidline for observational studies.


2.2


Study design


A hospital-based cross-sectional study was conducted to determine the incidence and associated factors of post-spinal anesthesia shivering for women who underwent C/S.


2.3


Study population


All mothers undergoing cesarean section under spinal anesthesia in DTCSH during the study period and who fulfilled the inclusion criteria.


2.4


Inclusion criteria


All mothers for delivering on C/S under spinal anesthesia and give consent to be part of the study.


2.5


Exclusion criteria


Mothers with a history of head injury and epilepsy, history of neuromuscular disorder, and failed spinal.


2.6


Sample size determination


The sample size was calculated by using a single proportion formula. By considering marginal error (d) 5 %, the confidence interval of 95 % ( Z = 1.96), and from the previous study in sub-Saharan tertiary hospitals the prevalence of post-spinal shivering was 8.15 %.


<SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='N=z2(p)(1−p)D2′>𝑁=𝑧2(𝑝)(1−𝑝)𝐷2N=z2(p)(1−p)D2
N=z2(p)(1−p)D2


Whereas; n =sample size, Z =confidence interval (1.95), P =estimated prevalence (0.0815), d = margin of sampling error to be tolerated (0.05). The final sample size is 113


2.7


Sampling technique


A systematic random sampling technique was used to select study participants. From the situational analysis, there were 13 C/S done per week at DTCSH or 52 C/S per month. The calculated sample size is 113 and the data collection period was four months so there are 208 cases within the study period. The skipping interval is ( K = 208/113 = 1.84) ≈2. The sample was collected in every other case.


2.8


Independent variables


Age, vital signs (MAP, mean heart rate, temperature), preoperative and intraoperative fluid intake time, duration of surgery, operation room temperature, amount of blood loss, level of sensory block, and adjuvant were given.


2.9


Dependent variable


Post-spinalanesthesia shivering (yes/no)


2.10


Data collection technique


Data were collected through observation, face-to-face interviews, and chart review by two trained anesthetists. The chart was reviewed to obtained demographic data after they gave verbal consent to be part of the study and written consent to be operated on before anesthesia and postoperatively. Questionnaires will be prepared in English. Vital signs were recorded starting from before anesthesia was given, intraoperatively every five minutes and postoperatively every fifteen minutes for two hours. An axillary thermometer was used to record core body temperature while an anesthesia machine monitoring thermometer was used to measure operation room temperature.


Intra-operatively patients were covered with a blanket but were not actively warmed and the intravenous fluid was not warmed. Patients were continuously observed for the occurrence of tremor-like muscle hyperactivity starting from 5 min up to 30 min.


The intensity of post-spinal anesthesia shivering was graded by using a five-point scale described by Crossley and Mahjan.


2.11


Data quality assurance


The pretest was done on 5 % of the study participants at the University of Gondar Specialized Hospital in Gondar. After training was given for data collectors, data was collected and properly filled in the prepared format. Throughout the study period, data collection was supervised by the principal investigator.


2.12


Data processing and analysis


The data was coded and entered into SPSS version 23. Independent variables were analyzed by using binary logistic regression with shivering (dependent variable) and those with a p-value of ≤ 0.2 from the bivariable analysis were fitted to a multivariate logistic analysis to check their association with the outcome variable. Crude and adjusted odds ratios with 95 % CI and p-value were computed to identify the strength of association between the dependent variable and independent variables. Tables and figures were used to present data and summarized with frequency and percentage. P-values of < 0.05 were considered as statistically significant.


2.13


Operational definitions


Shivering: a spontaneous, involuntary, tremor-like muscle-hyperactivity that lasts at least 15 min and is greater than or equal to grade II shivering by the Crossley and Mahjan intensity scale. ,


Mild shivering: Grade II shivering as per Crossley and Mahjan intensity scale. ,


Moderate shivering: Grade-III shivering as per Crossley and Mahjan intensity scale. ,


Severe shivering: Grade IV shivering as per Crossley and Mahjan intensity scale. ,


Hypothermia: core temperature of the patient less than 35.5 °C in the intraoperative time.


2.14


Ethical consideration


Ethical clearance and a letter of permission to conduct the study were obtained from the Debre Tabor University’s ethical review committee and Debre Tabor Comprehensive Specialized Hospital respectively. Informed written consent was secured from every study participant before the start of the data collection after telling them about the objective of the study, and the obtained data will only be used for study purposes. Confidentiality and anonymity were ensured.


During data collection, analysis, and writing up all methods were carried out per relevant guidelines and regulations. Standard of care was given based on the existing protocols and guidelines of the hospital.


3


Results


3.1


Demographic characteristics and clinical conditions of study subjects


A total of 113 patients were included with a response rate of 100 %. Out of 113 respondents in the study, 84(74.3 %) were aged 18–30 years old. The majority of 101(89.4 %) of the study participants underwent C/S on an emergency basis and most of the C/S was done for an indication of fetal distress( Table 1 ). The baseline vital signs of the study participants were MAP (mean=97.00, SD=14.29), HR (mean=94.69, SD=16.49), and temperature (mean=36.1, SD=0.65).


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May 22, 2025 | Posted by in ANESTHESIA | Comments Off on Shivering after spinal anesthesia and associated factors in mothers undergoing cesarean delivery at a referral hospital in northcentral Ethiopia: In resource-limited settings

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