Skip to main content

Association between preoperative toe perfusion index and maternal core temperature decrease during cesarean delivery under spinal anesthesia: a prospective cohort study

Abstract

Background

The main mechanism of body temperature decrease during cesarean delivery under spinal anesthesia is core-to-peripheral redistribution of body heat, attributable to vasodilation. Perfusion index (PI) obtained with a pulse oximeter helps to assess peripheral perfusion dynamics by detecting the change in peripheral vascular tone. This study aimed to examine whether preoperative toe PI could predict the decrease in core temperature induced by spinal anesthesia during cesarean delivery.

Methods

Parturients undergoing scheduled cesarean delivery under combined spinal-epidural anesthesia from September 2019 to March 2020 were enrolled in this single-center prospective cohort study. All parturients received 0.5% hyperbaric bupivacaine (10 mg) with fentanyl (15 μg) intrathecally. A pulse oximeter probe was placed on the left second toe for continuous PI measurement. The 3 M™ Bair Hugger™ Temperature Monitoring System placed over the right temporal region was used to record core temperature over time. We evaluated the association between the maximum core temperature decrease, which is the primary outcome, and the preoperative toe PI at operating room (OR) admission using a segmented regression model (SRM) and a generalized additive model (GAM). The maximum core temperature decrease was defined as the difference between core temperature at OR admission and minimum intraoperative core temperature.

Results

Forty-eight patients were evaluated. In the SRM, the slope for the association between the maximum core temperature decrease and the preoperative toe PI changed from 0.031 to 0.124 after PI = 2.4%. Likewise, with the GAM, there was a small core temperature decrease when preoperative toe PI was greater than 2.0 to 3.0%.

Conclusions

Low preoperative toe PI was associated with maternal core temperature decrease during cesarean delivery under spinal anesthesia. Preoperative toe PI is a simple, non-invasive, and effective tool for the early prediction of perioperative core temperature decrease during cesarean delivery.

Trial registration

UMIN Clinical Trials Registry (registry number: UMIN000037965).

Peer Review reports

Background

Neuraxial (spinal, epidural, or combined spinal-epidural technique) anesthesia is currently the anesthetic technique of choice for cesarean delivery. Spinal and epidural anesthesia cause body heat redistribution by vasodilation below the level of neuraxial sensory blockade [1]. Additionally, neuraxial techniques decrease the vasoconstriction and shivering thresholds even above the level of the sensory block, and directly block the efferent nerves that control vasoconstriction and shivering in the lower body [1]. Perioperative hypothermia (< 36.0 °C) has been estimated to occur in more than 60% of parturients undergoing cesarean delivery [2] and should be avoided because it generally contributes to serious complications such as coagulopathy, wound infections, myocardial ischemia, shivering, and patient discomfort [3,4,5,6].

Active warming of parturient during cesarean delivery reduces perioperative maternal hypothermia and shivering [7]. However, the benefits of single active warming on maternal temperature are limited, with most studies reporting no more than 0.2–0.5 °C core temperature difference between active warming and control groups [2]. Recently, several clinical studies have been conducted to preoperatively identify parturients at high risk of perioperative body temperature decrease and hypothermia during cesarean delivery; however, the results remain unclear [8].

Perfusion index (PI) obtained with a pulse oximeter is calculated as the ratio of pulsatile blood flow to non-pulsatile blood in the peripheral tissues [9]. It can be measured continuously and non-invasively and helps in the assessment of peripheral perfusion dynamics by detecting the change in peripheral vascular tone. The PI value varies dramatically from 0.02 to 20% and correlates with the change in blood flow at the monitored site. Low PI usually reflects peripheral vasoconstriction with or without severe hypovolemia, and high PI usually reflects peripheral vasodilation. The change in peripheral PI is a rapid indicator of the change in peripheral perfusion. This change is related to the vascular status, sympathetic responses, and anesthetic effects [10, 11]. Additionally, the change in peripheral PI also reflects the change in core-to-peripheral temperature gradients [9, 12]. Although these gradients have been used as a measure of peripheral vasoconstriction [13], temperature gradients before the induction of anesthesia affect the magnitude of body heat redistribution by vasodilation following anesthetic administration [14,15,16]. A prospective observational pilot study demonstrated that low baseline peripheral PI was the most relevant factor for the development of intraoperative hypothermia under general anesthesia [17]; therefore, this suggests that preoperative peripheral PI may be useful in predicting the magnitude of redistributive hypothermia. To our knowledge, no previous reports have investigated the association between baseline peripheral PI and body temperature decrease during cesarean delivery under spinal anesthesia. We hypothesized that low preoperative toe PI is associated with maternal core temperature decrease during cesarean delivery under spinal anesthesia. Our study aimed to examine whether preoperative toe PI could predict the decrease in core temperature induced by spinal anesthesia during cesarean delivery.

Methods

This single-center prospective cohort study was conducted at the National Hospital Organization Nagasaki Medical Center, Nagasaki, Japan. This study was approved by our institutional research ethics committee (approval number: 2019059) on 2nd September 2019 and follows the Declaration of Helsinki. The study was registered with UMIN Clinical Trials Registry (Trial registry number: UMIN000037965, registration date: 8th September 2019) before the onset of participant enrollment. Written informed consent was obtained from each participant before study participation. This manuscript adheres to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

Participant selection

The inclusion criteria included the American Society of Anesthesiologists (ASA) physical status classification I-II parturient, between 18 and 40 years of age, with term gestation (≥ 37 weeks), and scheduled cesarean delivery with combined spinal-epidural anesthesia. Exclusion criteria were as follows: unscheduled cesarean delivery, morbid obesity (body mass index [BMI] ≥ 40 kg/m2), preoperative hyperthermia (> 38 °C) or preoperative hypothermia (< 36 °C), cardiovascular or cerebrovascular disease, hypothyroidism or hyperthyroidism, history of anxiety disorder, difficulty in maintaining the supine position, and contraindication to spinal anesthesia. The study recruitment period was from 17th September 2019 to 9th March 2020.

Study protocol

No parturient received any premedication. Each parturient was kept off solid food for at least 6 h, and off clear water for 2 h before spinal anesthesia. A 20-gauge peripheral intravenous cannula was inserted at the obstetric ward. Room temperature Ringer’s lactate solution was administered at a flow rate of 80 mL/h, about 2 h before entering the operating room (OR). All parturients were directly transported from the ward to the OR without preoperative active warming (e.g., wearing socks, using body warming blanket), and the OR temperature was maintained at 27 °C.

Each parturient was rapidly infused intravenously with 500 mL of 6% hydroxyethyl starches 130/0.4 (Voluven®; Fresenius Kabi, Tokyo, Japan) for hydration before spinal anesthesia. Thereafter, Ringer’s lactate solution was infused about 10 mL/kg/h until the end of the surgery. Their infusion fluids in the OR were kept warm preoperatively at 38 °C in the heat insulating cabinet. Standard monitoring was performed with an electrocardiogram, automated non-invasive arterial pressure measurement on the right arm, and finger pulse oximetry on the left index finger. Besides, the pulse oximeter probe (Masimo Rainbow SET Pulse CO-Oximeter Radical 7; Masimo Corp., Irvine, CA, USA) was placed on the left second toe for continuous monitoring of the toe PI. For core temperature measurement, we attached the 3 M™ Bair Hugger™ Temperature Monitoring System (3 M Company, St. Paul, MN, USA) over the right temporal region. This Food and Drug Administration-approved Temperature Monitoring System can measure core temperature by heating the skin sensor attached to the forehead and reaching thermal equilibrium between sensor temperature and core temperature [18]. The mean error in measurement accuracy of this device was found to be − 0.23 °C (95% limits of agreement of ± 0.82 °C) compared with pulmonary artery temperature [18].

All parturients received combined spinal-epidural anesthesia in the right lateral decubitus position. After inserting an epidural catheter at the T12-L1 or L1–2 vertebral interspace, spinal anesthesia was performed at the L2–3 or L3–4 vertebral interspace. A 25-gauge Quincke spinal needle was inserted into the subarachnoid space, and 10 mg (2.0 mL) of 0.5% hyperbaric bupivacaine (Marcain®; Aspen Japan, Tokyo, Japan) with 15 μg (0.3 mL) fentanyl (Fentanyl®; Janssen Pharmaceutical K.K., Tokyo, Japan) were administered intrathecally. Following the securing of the epidural catheter, each parturient was returned to the supine position with a 15° left lateral tilt to facilitate the left displacement of the uterus. The tilted position was returned to the horizontal supine position after the maternal hemodynamics stabilized. The sensory blockade level was checked after spinal injection using cold ice. If T4 sensory block level was not achieved, 2% lidocaine (Xylocaine® Injection Polyamp 2%; Aspen Japan, Tokyo, Japan) was administered through the epidural catheter in 5 mL increments until it was achieved. To prevent post-spinal hypotension, phenylephrine at 0.3 μg/kg/min was started immediately after the induction of spinal anesthesia. Once the systolic blood pressure (SBP) was less than 80 mmHg or there were symptoms consistent with hypotension (e.g., dyspnea, nausea, or vomiting) even without SBP < 80 mmHg, a bolus of 50 to 100 μg phenylephrine or 4 mg ephedrine was administered depending on the patient’s heart rate (HR). When the patient’s HR was less than 60 beats/min without the occurrence of post-spinal hypotension, a bolus of 0.5 mg atropine was given. When the patient’s SBP was stable, the continuous administration of phenylephrine was gradually reduced, and was terminated at the discretion of the anesthesiologist.

Since the start of the surgery, the patient’s upper body was warmed using a 3 M™ Bair Hugger™ multi-position upper body warming blanket (Model 622; 3 M Company, St. Paul, MN, USA) attached to a 3 M™ Bair Hugger™ warming unit (Model 675; 3 M Company, St. Paul, MN, USA) set to 38 °C. The OR temperature was changed from 27 °C to 24 °C after placing the newborn baby in the infant incubator.

Measurements

Patient characteristics and baseline parameters were obtained from electronic medical and anesthetic records. Toe PI and core temperature were recorded at one-minute intervals from entering the OR until the end of the surgery. Preoperative toe PI was defined as the average PI value measured for 3 min in the horizontal supine position, immediately before right lateral decubitus repositioning. All parturients were instructed to remain motionless and rested during the preoperative toe PI measurement. To evaluate the redistribution of body temperature after spinal anesthesia, we investigated the maximum core temperature decrease in the perioperative period. The primary outcome was the maximum core temperature decrease. In this study, the perioperative period was defined as the time from entering the OR until the end of the surgery, and the maximum core temperature decrease was defined as the difference between the core temperature at OR admission and the minimum intraoperative core temperature. Moreover, we evaluated shivering severity and thermal comfort when leaving the OR. Shivering severity was assessed using the Bedside Shivering Assessment Scale: 0 = no shivering, 1 = shivering localized to the core and neck, 2 = shivering including the upper extremities, 3 = total body shivering [19]. Thermal comfort was measured using the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) scale, which is a seven-point Likert scale: Hot (+ 3), Warm (+ 2), Slightly warm (+ 1), Neutral “just right” (0), Slightly cool (− 1), Cool (− 2), and Cold (− 3) [20].

Surgery time was defined as the time between the start of the surgery and the end of the wound closure. Total volume of intravenous fluids, total dose of cardiovascular drugs administered, and estimated blood loss were also recorded.

Statistical analysis

Patient characteristics and surgical data are presented as median [interquartile range], or the number of patients (%). Patient body temperature and toe PI, and data related to the decrease in maternal body temperature are presented as mean ± standard deviation (SD), median [interquartile range], or the number of patients (%). The Shapiro–Wilk test was used to determine normality. The sample size was not calculated since this was an observational study, and all patients meeting the eligibility criteria during the study period were included.

To analyze whether there is a relationship between preoperative toe PI and decreased maximal core temperature, firstly, correlation analysis was performed. Secondly, a segmented regression model (SRM) and a generalized additive model (GAM) were used. We suspected that the relationship between preoperative toe PI and decreased maximal core temperature was nonlinear from the scatter plot; thus, we conducted analyses using SRM and GAM.

SRM (also called change-point regression) is a practical analysis if we expect to have several slopes between dependent and independent variables different from a simple linear regression. These slopes quantify the change in the relationship between the two variables. Points where the slope changes are called “change-points.” The change-point can be interpreted as a critical, safe, or threshold value beyond or below which desired effects occur and is important in decision making [21]. In this study, we considered that two slopes exist between the dependent and independent variables from the scatter plot. We pre-determined four expected preoperative toe PI change-points based on quartile ranges (first, second, and third quartiles) and mean, created four SRMs, and evaluated the Akaike’s Information Criterion (AIC) of each model to determine the best fit model. GAM provides a modeling approach that combines powerful statistical methods with interpretability, smooth functions, and flexibility. Although generalized linear models, such as simple regression analysis, can only express linear relationships, GAM can also express non-linear relationships while maintaining interpretability and flexibility using multiple smoothing functions (smoothers). To find the smoother that best fits the data, the choice of smoothing parameters—i.e., the parameters that control the smoothness of the predictive functions—is key as in SRM [22]. We created several models to find the optimal parameters in GAM. The results of each model were evaluated using root mean squared error (RMSE) to determine the model that best fit the data. SRM and GAM included covariates associated with maternal hypothermia, which are BMI and core temperature at OR admission [23].

Statistical significance was defined as P value < 0.05. All statistical analyses were performed with R version 3.6.3 (R Foundation for Statistical Computing, Vienna, Austria).

Results

A total of 52 patients were assessed for eligibility. Of those, three patients were excluded, resulting in the enrollment of 49 patients. One patient was excluded due to inadequate accuracy of PI measurement; 48 patients were finally evaluated. The flow diagram for excluded patients is shown in Fig. 1.

Fig. 1
figure1

Flow diagram of patient enrollment and analysis in this study. BMI: body mass index; PI: perfusion index

Patient characteristics are summarized in Table 1. No parturients began labor before surgery. Surgical characteristics and anesthesia management data are summarized in Table 2. The median [interquartile range] phenylephrine requirement was 620 [345 to 870] μg. Ephedrine was not administered to any parturient. The median [interquartile range] atropine requirement was 0 [0 to 0.5] mg.

Table 1 Patient characteristics
Table 2 Surgical characteristics and anesthesia management data

Figure 2 shows a parallel plot, which represents the profile of an individual and the mean ± SD of the core temperature at each observation point. The core temperature tended to decrease gradually after spinal anesthesia. Data related to the decrease in maternal body temperature are listed in Table 3. The maximum core temperature decrease ranged from − 0.1 °C to − 1.1 °C, with a mean ± SD of − 0.4 ± 0.2 °C.

Fig. 2
figure2

Parallel plot and mean ± SD of the core temperature. SD: standard deviation

Table 3 Data related to the decrease in maternal body temperature

Figure 3 shows a parallel plot and the mean ± SD of the toe PI at each observation point. Preoperative toe PI ranged from 0.5 to 5.4%, with a mean ± SD of 1.8 ± 1.1%. The toe PI gradually increased after spinal anesthesia and did not change significantly after 20 min of anesthesia.

Fig. 3
figure3

Parallel plot and mean ± SD of the toe PI. PI: perfusion index; SD: standard deviation

Figure 4 shows the scatter plots of the maximum core temperature decrease and the preoperative toe PI, and the predicted curve fitted by SRM and GAM. In the SRM, the slope for the association between the maximum core temperature decrease and the preoperative toe PI, regression coefficients, changed from 0.031 to 0.124 after PI = 2.4%. In the GAM, there was a small decrease in core temperature when preoperative toe PI was greater than 2.0 to 3.0%.

Fig. 4
figure4

Scatter plots of the maximum core temperature decrease and the preoperative toe PI, and the predicted curve fitted by SRM and GAM. Maximum core temperature decrease: the difference between the core temperature at OR admission and the minimum intraoperative core temperature. SRM: segmented regression model; GAM: generalized additive model; OR: operating room; PI: perfusion index

Discussion

In this prospective cohort study, we demonstrated that low preoperative toe PI was associated with the decrease in core temperature induced by spinal anesthesia during cesarean delivery. To the best of our knowledge, this study is the first to identify preoperatively parturients at high risk of intraoperative core temperature decrease during cesarean delivery.

The results of this study indicate that peripheral perfusion should be considered in the perioperative management of body temperature for parturients undergoing cesarean delivery under spinal anesthesia. The main mechanism of body temperature decrease in the early phase after spinal anesthesia is core-to-peripheral redistribution of body heat, just as during general anesthesia [1]. Spinal anesthesia causes the redistribution of body temperature by vasodilation below the level of neuraxial sensory blockade. The magnitude of this redistribution is affected by the temperature gradient between the core and peripheral thermal compartments before the induction of spinal anesthesia. This core-to-peripheral temperature gradient is maintained by thermoregulatory vasoconstriction; in particular, the vascular response is remarkable at the acral regions (e.g., fingers, toes, or nose), which have well-developed arteriovenous shunts and counter-current heat exchange mechanisms. Low peripheral perfusion due to vasoconstriction results in low peripheral temperature, which may lead to a decrease in core temperature after spinal anesthesia. Peripheral PI reflects perfusion changes associated with the thermoregulatory vascular responses, and the PI correlates with the core-to-peripheral temperature gradients [9, 12]. Therefore, patients with low peripheral PI have a greater redistribution of body temperature after the induction of anesthesia due to low peripheral temperature, resulting in core temperature decrease. Some researchers reported that low baseline peripheral PI was the most relevant factor in the development of intraoperative hypothermia under general anesthesia [17]. Their study results are similar to our findings that low preoperative toe PI can be a risk for intraoperative hypothermia in parturients undergoing cesarean delivery under spinal anesthesia.

Several previous studies have demonstrated that toe PI during cesarean delivery under spinal anesthesia correlates with the post-anesthesia blood pressure and partial pressure of oxygen in the umbilical vein [24, 25]; however, no reports have investigated the association between the baseline peripheral PI and body temperature decrease. We selected toe as the site of PI measurement in this study for two reasons: first, the toes are the prominent site for thermoregulatory vascular responses; second, the core temperature decrease in the early phase after spinal anesthesia is mainly attributed to the redistribution of body temperature from the core thermal compartment to the distal legs (lower leg and foot), which is greater than its redistribution to the proximal legs [26]. In the present study, toe PI also increased significantly after the induction of spinal anesthesia, which probably reflects increased toe perfusion due to the blood flow shift from the core compartment. Therefore, preoperative toe PI in parturients undergoing cesarean delivery under spinal anesthesia may be suitable for identifying those at high risk of intraoperative core temperature decrease. On the other hand, a previous secondary analysis in a randomized controlled trial showed that preoperative anterior thigh temperature does not correlate with the maximum perioperative temporal temperature decrease during cesarean delivery under spinal anesthesia [8]. This may have been influenced by the choice of anterior thigh temperature as peripheral temperature measurement site, where the magnitude of body temperature redistribution is small. Thus, anterior thigh temperature might not be reliable for measuring peripheral temperature related to core-to-peripheral temperature gradients.

In the present study, the maximum intraoperative core temperature decrease was − 0.4 ± 0.2 °C, which was within normal physiological variation in temperature (about − 0.5 °C) [27]. This decrease was small compared to the results of a previous observational study [7, 28], and this probably influenced the low incidence of maternal intraoperative hypothermia (< 36.0 °C) and shivering. The main reasons for this small decrease were maintenance of a relatively higher operating room temperature in our study [28, 29], continuous administration of phenylephrine after spinal anesthesia, and the omission of neuraxial hydrophilic opioids. Continuous phenylephrine administration suppresses the redistributive hypothermia after spinal anesthesia without contracting the arteriovenous shunts [30]. Additionally, a randomized double-blind controlled study showed that intrathecal morphine administration may exacerbate hypothermia [31]. However, in this study, preoperative toe PI was significantly associated with the magnitude of maternal core temperature decrease, despite the small decrease in the core temperature. It is necessary to confirm whether similar results as obtained by our study can be reproduced in parturients with a larger decrease in the core temperature.

The early identification of parturients at high risk of intraoperative core temperature decrease is desirable to prevent maternal hypothermia in the perioperative period of cesarean delivery under spinal anesthesia [8, 32]. Herein, our study results suggest that low preoperative toe PI may be an effective tool for the early prediction of maternal core temperature decrease during cesarean delivery. Furthermore, in parturients with low preoperative toe PI, preoperative active warming, which has been effective in patients undergoing cesarean delivery under spinal anesthesia, may have a greater effect on preventing perioperative maternal hypothermia [33]; however, it remains unclear which parturients benefit more. In general, preoperative active warming aims to prevent the redistribution of body temperature by increasing the peripheral temperature and decreasing the core-to-peripheral temperature gradient before the induction of anesthesia. Parturients with low preoperative toe PI are expected to have low peripheral temperature and a large core-to peripheral temperature gradient; therefore, preoperative active warming may prevent perioperative maternal hypothermia. However, since no previous study has examined the efficacy of preoperative active warming considering the preoperative peripheral PI in perioperative temperature management, further investigation is needed to elucidate this topic.

This study has several limitations. Firstly, the incidence of maternal hypothermia in the study population was lower than in those of similar prospective studies, which may have limited our ability to detect major differences within the population. Accordingly, we have been unable to determine a specific preoperative toe PI cutoff value to predict maternal hypothermia. Secondly, we did not measure the toe temperature, owing to insufficient equipment. Therefore, we could not measure the changes in peripheral temperature and core-to-peripheral temperature gradients; thus, the association between these changes and toe PI changes in this study is unclear. Thirdly, this study had a small sample size and was conducted at a single institution. Another limitation is that peripheral PI values widely vary among individuals [13]. A large prospective cohort study is required to confirm whether the results of SRM and GAM in our study are useful for screening all parturients at high risk of intraoperative maternal temperature decrease.

Conclusions

We demonstrated that low preoperative toe PI was associated with maternal core temperature decrease during cesarean delivery under spinal anesthesia. Preoperative toe PI is a simple, non-invasive, and effective tool for the early prediction of perioperative core temperature decrease during cesarean delivery; therefore, its efficacy and clinical application should be further evaluated by future studies.

Availability of data and materials

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Abbreviations

ASA:

American Society of Anesthesiologists

ASHRAE:

American Society of Heating, Refrigerating and Air-Conditioning Engineers

AIC:

Akaike’s Information Criterion

BMI:

Body mass index

GAM:

Generalized additive model

HR:

Heart rate

OR:

Operating room

PI:

Perfusion index

RMSE:

Root mean squared error

SBP:

Systolic blood pressure

SD:

Standard deviation

SRM:

Segmented regression model

STROBE:

Strengthening the Reporting of Observational Studies in Epidemiology

References

  1. 1.

    Sessler DI. Perioperative thermoregulation and heat balance. Lancet. 2016;387:2655–64.

    Article  Google Scholar 

  2. 2.

    Cobb B, Cho Y, Hilton G, Ting V, Carvalho B. Active warming utilizing combined IV fluid and forced-air warming decreases hypothermia and improves maternal comfort during cesarean delivery: A randomized control trial. Anesth Analg. 2016;122:1490–7.

    Article  Google Scholar 

  3. 3.

    Rajagopalan S, Mascha E, Na J, Sessler DI. The effects of mild perioperative hypothermia on blood loss and transfusion requirement. Anesthesiology. 2008;108:71–7.

    Article  Google Scholar 

  4. 4.

    Melling AC, Ali B, Scott EM, Leaper DJ. Effects of preoperative warming on the incidence of wound infection after clean surgery: a randomized controlled trial. Lancet. 2001;358:876–80.

    CAS  Article  Google Scholar 

  5. 5.

    Frank SM, Fleisher LA, Breslow MJ, Higgins MS, Olson KF, Kelly S, et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. JAMA. 1997;277:1127–34.

    CAS  Article  Google Scholar 

  6. 6.

    Lenhardt R, Marker E, Goll V, Tschernich H, Kurz A, Sessler DI, et al. Mild intraoperative hypothermia prolongs postanesthetic recovery. Anesthesiology. 1997;87:1318–23.

    CAS  Article  Google Scholar 

  7. 7.

    Sultan P, Habib AS, Cho Y, Carvalho B. The effect of patient warming during caesarian delivery on maternal and neonatal outcomes: a meta-analysis. Br J Anaesth. 2015;115:500–10.

    CAS  Article  Google Scholar 

  8. 8.

    Cobb B, Abir G, Carvalho B. Preoperative anterior thigh temperature does not correlate with perioperative temporal hypothermia during cesarean delivery with spinal anesthesia: secondary analysis of randomized control trial. Int J Obstet Anesth. 2018;33:40–5.

    CAS  Article  Google Scholar 

  9. 9.

    Lima AP, Beelen P, Bakker J. Use of a peripheral perfusion index derived from the pulse oximetry signal as a noninvasive indicator of perfusion. Crit Care Med. 2002;30:1210–3.

    Article  Google Scholar 

  10. 10.

    Mowafi HA, Ismail SA, Shafi MA, Al-Ghamdi AA. The efficacy of perfusion index as an indicator for intravascular injection of epinephrine-containing epidural test dose in propofol-anesthetized adults. Anesth Analg. 2009;108:549–53.

    CAS  Article  Google Scholar 

  11. 11.

    Ginosar Y, Weiniger CF, Meroz Y, Kurz V, Bdolah-Abram T, Babchenko A, et al. Pulse oximeter perfusion index as an early indicator of sympathectomy after epidural anesthesia. Acta Anaesthesiol Scand. 2009;53:1018–26.

    CAS  Article  Google Scholar 

  12. 12.

    Kuroki C, Godai K, Hasegawa-Moriyama M, Kuniyoshi T, Matsunaga A, Kanmura Y, et al. Perfusion index as a possible predictor for postanesthetic shivering. J Anesth. 2014;28:19–25.

    Article  Google Scholar 

  13. 13.

    Hasanin A, Mukhtar A, Nassar H. Perfusion indices revisited. J Intensive Care. 2017;5:24.

    Article  Google Scholar 

  14. 14.

    Yamakage M, Kamada Y, Honma Y, Tsujiguchi N, Namiki A. Predictive variables of hypothermia in the early phase of general anaeshtesia. Anesth Analg. 2000;90:456–9.

    CAS  PubMed  Google Scholar 

  15. 15.

    Just B, Trévien V, Delva E, Lienhart A. Prevention of intraoperative hypothermia by preoperative skin-surface warming. Anesthesiology. 1993;79:214–8.

    CAS  Article  Google Scholar 

  16. 16.

    Hynson JM, Sessler DI, Moayeri A, McGuire J, Schroeder M. The effects of preinduction warming on temperature and blood pressure during propofol/nitrous oxide anesthesia. Anesthesiology. 1993;79:219–28.

    CAS  Article  Google Scholar 

  17. 17.

    Lee S, Kim KS, Park SW, You AH, Lee SW, Kim YJ, et al. Correlation between the perfusion index and intraoperative hypothermia: a prospective observational pilot study. Medicina (Kaunas). 2021;57:364.

    Article  Google Scholar 

  18. 18.

    Eshraghi Y, Nasr Y, Parra-Sanchez I, Duren AV, Botham M, Santoscoy T, et al. An evaluation of zero-heat-flux cutaneous thermometer in cardiac surgical patients. Anesth Analg. 2014;119:543–9.

    Article  Google Scholar 

  19. 19.

    Badjatia N, Strongilis E, Gordon E, Prescutti M, Fernandez L, Fernandez A, et al. Metabolic impact of shivering during therapeutic temperature modulation: the bedside shivering assessment scale. Stroke. 2008;39:3242–7.

    Article  Google Scholar 

  20. 20.

    Khiavi NM, Maerefat M, Zolfaghari SA. A new local index for predicting local thermal response of individual body segments. J Therm Biol. 2018;78:161–73.

    Article  Google Scholar 

  21. 21.

    Lerman PM. Fitting segmented regression models by grid search. Appl Stat. 1980;29:77–84.

    Article  Google Scholar 

  22. 22.

    Liu H. Generalized additive model. Duluth: Department of Mathematics and Statistics University of Minnesota Duluth; 2008. p. 55812.

    Google Scholar 

  23. 23.

    Desgranges FP, Bapteste L, Riffard C, Pop M, Cogniat B, Gagey AC, et al. Predictive factors of maternal hypothermia during cesarean delivery: a prospective cohort study. Can J Anaesth. 2017;64:919–28.

    Article  Google Scholar 

  24. 24.

    Xu Z, Xu T, Zhao P, Ma R, Zhang M, Zheng J. Differential roles of the right and left toe perfusion index in predicting the incidence of postspinal hypotension during cesarean delivery. Anesth Analg. 2017;125:1560–6.

    Article  Google Scholar 

  25. 25.

    Jia L, Chao YC, Feng Z, An X, Xu Z. Maternal toe perfusion index change after spinal anesthesia for cesarean delivery correlates with a decreased oxygen partial pressure of the umbilical vein. J Clin Anesth. 2021;75:110458.

    Article  Google Scholar 

  26. 26.

    Matsukawa T, Sessler DI, Christensen R, Ozaki M, Schroeder M. Heat flow distribution during epidural anesthesia. Anesthesiology. 1995;83:961–7.

    CAS  Article  Google Scholar 

  27. 27.

    Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson L, Loscalzo J. Harrison’s principles of internal medicine. 18th ed. New York: McGraw-Hill; 2011. isbn:978-0-07-174889-6.

    Google Scholar 

  28. 28.

    du Toit L, van Dyk D, Hofmeyr R, Lombard CJ, Dyer RA. Core temperature monitoring in obstetric spinal anesthesia using an ingestible telemetric sensor. Anesth Analg. 2018;126:190–5.

    Article  Google Scholar 

  29. 29.

    Duryea EL, Nelson DB, Wyckoff MH, Grant EN, Tao W, Sadana N, et al. The impact of ambient operating room temperature on neonatal and maternal hypothermia and associated morbidities: a randomized controlled trial. Am J Obstet Gynecol. 2016;214:505.e1–7.

    Article  Google Scholar 

  30. 30.

    Ro Y, Huh J, Min S, Han S, Hwang J, Yang S, et al. Phenylephrine attenuates intra-operative hypothermia during spinal anaesthesia. J Int Med Res. 2009;37:1701–8.

    CAS  Article  Google Scholar 

  31. 31.

    Hui CK, Huang CH, Lin CJ, Lau HP, Chan WH, Yeh HM. A randomised double-blind controlled study evaluating the hypothermic effect of 150 microg morphine during spinal anaesthesia for caesarean section. Anaesthesia. 2006;61:29–31.

    Article  Google Scholar 

  32. 32.

    Allen TK, Habib AS. Inadvertent perioperative hypothermia induced by spinal anesthesia for cesarean delivery might be more significant than we think: are we doing enough to warm our parturients? Anesth Analg. 2018;126:7–9.

    Article  Google Scholar 

  33. 33.

    Ni TT, Zhou ZF, He B, Zhou QH. Effects of combined warmed preoperative forced-air and warmed perioperative intravenous fluids on maternal temperature during cesarean section: a prospective, randomized, controlled clinical trial. BMC Anesthesiol. 2020;20:48.

    CAS  Article  Google Scholar 

Download references

Acknowledgements

We would like to thank Editage (www.editage.com) for English language editing.

Funding

Not applicable.

Author information

Affiliations

Authors

Contributions

SK: conceptualization, methodology, investigation, data curation, original draft preparation, project administration; K.Hara: conceptualization, methodology, investigation, review & editing; SS: formal analysis, visualization, review & editing; TN: formal analysis, visualization, review & editing; YK: formal analysis, visualization, review & editing; MT: conceptualization, investigation, review & editing; SU: conceptualization, investigation, review & editing; AN: conceptualization, investigation, review & editing. K.Hamada: conceptualization, investigation, review & editing; MY: conceptualization, investigation, review & editing; TH: review & editing, supervision. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Shohei Kaneko.

Ethics declarations

Ethics approval and consent to participate

This study protocol was approved by the Clinical Research Ethical Committee of National Hospital Organization Nagasaki Medical Center (approval number: 2019059) on 2nd September 2019 and follows the Declaration of Helsinki. The study was registered with UMIN Clinical Trials Registry (Trial registry number: UMIN000037965, registration date: 8th September 2019) before the onset of participant enrollment. Written informed consent was obtained from each participant before study participation.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kaneko, S., Hara, K., Sato, S. et al. Association between preoperative toe perfusion index and maternal core temperature decrease during cesarean delivery under spinal anesthesia: a prospective cohort study. BMC Anesthesiol 21, 250 (2021). https://doi.org/10.1186/s12871-021-01470-y

Download citation

Keywords

  • Toe perfusion index
  • Parturient
  • Cesarean delivery
  • Core temperature
  • Perioperative hypothermia
  • Spinal anesthesia