Factors associated with acute postoperative pain in preschool children in a referral clinic in eastern Colombia

doi:10.21203/rs.3.rs-3249868/v1

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Factors associated with acute postoperative pain in preschool children in a referral clinic in eastern Colombia

https://doi.org/10.21203/rs.3.rs-3249868/v1

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Purpose

Pain is one of the most difficult variables to quantify in the pediatric population, besides being the most determinant parameter of the length of stay in a post-anesthetic recovery room. The aim of this study is to characterize the most determinant variables in postoperative pain in our pediatric population.

Methods

An observational cross-sectional study was conducted in preschoolers and school children operated at Clínica Materno Infantil San Luis in Bucaramanga, between January and June 2018. Postoperative pain was evaluated and characterized using the LLANTO pain scale in addition to other related variables.

Results

Postoperative pain prevalence was 65.6%. Propofol and fentanyl were identified as protective factors to prevent postoperative pain with a RR of 0.55 and 0.44, respectively. The urology and laparotomy surgical groups were associated with less postoperative pain with a RR of 0.63 and 0.6, respectively.

Conclusion

Propofol and fentanyl use was identified as the most important protective factor for postoperative pain. In addition, there is a close relationship between anxiety and postoperative pain. According to the surgery type, it is suggested to use different adjusted anesthetic methods for each case.

Risk factors

Postoperative Pain

Anxiety

Child

Preschool Child

Pain corresponds to a multidimensional experience defined as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage" [1], which depends on anatomical, psychological and social variables. In this particular case, the tissue injury originates by an elective invasive surgical procedure secondary to some patient’s pathology or underlying condition [2].

Each year more than 230 million people undergo surgery globally. Acute postoperative pain (APP) occurred in more than 80% patients and less than half report adequate pain relief [3]. The prevalence of APP in Spain in the first 24 hours was estimated to be up to 96.9% without differentiating between mild, moderate or severe [4]; likewise, the data according to the numeric pain rating scale and an additional variable of rest or movement state, demonstrate values of 33% and 66%, respectively [5], this last value is similar to that found in the United States and Canada [6, 7]. Similarly, the prevalence of moderate postoperative pain was 31.3% in Medellin [8], similar to the data obtained in Bogota [9].

Estimating the APP’s prevalence in children is more complex due to the difficulty of quantification and communication of pain in this population; however, recent studies have shown that approximately 50% experience postoperative pain as the main complaint after outpatient surgical procedures [10, 11].

From the pathophysiological mechanisms of pain, the etiology consists of two components. The first component involve the nociceptive pain, in which there is tissue injury associated with an inflammatory process that triggers the response mediated by the Aδ receptors that constitute the fast response or primary pain, and by the C receptors that determine the slow response or secondary pain, which is determined by the fibers thickness and their conduction speed [12]. Additionally, depending on the receptor’s location, pain can be somatic if the lesion is located in soft tissue, skin, musculoskeletal or bone, and visceral if it is located in internal abdominal organs [13]. The second component corresponds to neuropathic pain which originates from an alteration at the level of the central and peripheral nervous system characterized by demyelination and retraction [12, 13].

The physiology of pain is composed of 4 phases. Firstly, the transduction phase is given by the conversion of the painful stimulus to an action potential that is mediated by the response of inflammatory factors; then occurs the transmission phase where the action potential propagates from the periphery to the somatosensory cortex; thirdly, in the modulation phase, two processes occur: sensitization, which corresponds to the neurochemical activation that favors the capacity to respond to stimuli, and inhibition, which can be opioid, non-opioid and segmental, also known as pain gating. Finally, the last phase consists of perception where the stimulus that reaches the cortex connects with the limbic area and frontal cortex triggering the individual's response and assimilation to pain [12, 13].

Some factors have been associated with poor control of acute APP, thus, in 2019, a systematic review and meta-analysis identified nine factors statistically significant and supported by greater evidence, such as female sex, smoking, history of depressive and anxious symptoms, sleep disorders, high body mass index, presence of preoperative pain, use of preoperative analgesia and young age [14], mainly in under 30 year old patients with a greater tendency to report APP [5].

Therefore, APP requires a comprehensive approach to its management. Multiple studies have established that inadequate treatment is associated with negative outcomes such as increased psychological stress, elevated proinflammatory cytokines, sympathetic activation, cardiopulmonary complications, delayed mobilization, increased hospital stay and sleep disturbances [15–17]. This demonstrates the importance of a thorough knowledge of this entity in order to opportunely intervene the associated modifiable factors.

Therefore, the aim of this study is to analyze the factors associated with acute postoperative pain in a preschool population of Clínica Materno Infantil San Luis in Bucaramanga, Santander, Colombia in 2018; on the other hand, it is intended to describe the sociodemographic and clinical characteristics and factors associated with APP in this population.

An observational, analytic, cross-sectional study was undertaken among the preschoolers and school children operated at Clínica Materno Infantil San Luis in Bucaramanga, Santander, between January and June 2018.

Inclusion criteria were defined as pediatric patients between 3 and 7 years, with preanesthetic assessment ASA score of I or II and who had the consent of the parent or guardian. On the other hand, patients with mental cognitive deficits, neurological or psychiatric diseases, as well as those where the procedure required less than 10 minutes of general anesthesia or where the planning of regional anesthesia was the only anesthetic technique were not contemplated.

The present study had the ethics committee’s support of the Universidad Industrial de Santander and the Clínica Materno Infantil San Luis, where it was established as a research without risk, evaluated by the data treatment to the study population. Data collection was standardized by means of a clinical history and informed consent, as well as the adequate application of the LLANTO pain scale, which evaluates physiological parameters associated with acute pain in children, including crying, attitude, normal respiration, postural tone and facial observation, assigning scores from 0–2, with a maximum score of 10, ranging from no pain (score 0), mild pain (score 1–3), moderate pain (score 4–6) and intense pain (score 7–10) [18].

To set the sample size, the volume of surgeries in the institution for the established time period was estimated, taking into account the incidence of the dependent variable, as well as the power and precision error and using Epidat 3.1. The required sample was determined to be 244 participants. Postoperative pain, defined as tissue injury caused by an elective invasive surgical procedure secondary to some patient’s pathology or underlying condition, was also used as the dependent variable [2]. Likewise, sociodemographic variables were considered, including age, sex, socioeconomic stratum, as well as the context of the surgical procedure, i.e., the type of surgery schedule, the treating specialty, the duration and type of anesthesia.

For the bivariate analysis of the association between APP and independent variables such as preoperative anxiety, the short version of the modified Yale preoperative scale (mYPAS-SF) was employed, which allows measuring preoperative anxiety through 18 items distributed in 4 categories: activity, vocalization, emotional expressiveness and state of agitation, with a score range of 22.7–100, indicating that the higher the score, the greater the anxiety [19].

The data obtained were processed using descriptive statistics with the STATA version 14 program; for qualitative variables with the 95% confidence interval (95% CI), while for quantitative variables minimum and maximum averages were used.

A total of 224 patients were included. The mean age was 4.75 years and male patients represented 59.82%. Regarding preanesthetic assessment, the most patients obtained an ASA I classification (83.5% n= 187). The sociodemographic and clinical variables of the study population are shown in Table 1. Additionally, the variables related to the surgical procedure correspond to the preoperative, anesthetic and surgical conditions described in Table 2.

Variables	Mean	Min- Max
Age	4,75	3-7
Height(cm)	109,2	87-135
Eeight	19,2	11-36
Temperature	36,1	35,6-38,8
	Frequency(%)	CI 95%
Sex
Male	134 (59,8)	53,3-66,3
Stratum
1	71 (31,9)	25,8-38,2
2	67 (30,2)	24,1-36,3
3	63 (28,4)	22,4-34,3
4	21 (9,5)	5,57-13,3
ASA classification
I	187 (83,5)	78,5-88,3
II	37 (16,5)	11,6-21,4
Surgical group
Abdominal wall	80 (35,7)	29,3-42,0
Urology	61 (27,2)	21,3-33,1
Orthopedics	32 (14,3)	9,6-18,9
Laparotomy	18 (8,0)	4,4-11,6
Respiratory tract	8 (3,6)	1,1-6,0
Oncology	18 (8,0)	4,4-11,6
Other	7 (3,1)	0,08-5,4

Table 1. Sociodemographic and clinical variables of the study population.

Pre-surgical variable	% (Fr)	CI 95%
Preanesthetic assessment	70,5 (162)	64,5-76,5
Elective surgery	72,6 (162)	66,7-78,5
Premedication	71,4 (160)	65,5-77,3
Parent preparation	20,5 (46)	15,2-25,8
Anesthetic and surgical variables
Anesthesia induction
Inhalational	1,8 (4)	0,66-4,6
Endovenous	98,2 (220)	95,3-99,3
Airway management
Intubation	23,7 (53)	18,0-29,3
Laryngeal mask airway	76,3 (171)	70,7-81,9
Anesthesia type
Inhalational anesthesia	1,34 (3)	0,01-2,8
Combined	53,6 (120)	46,9-60,1
TIVA	28,6 (64)	22,6-34,5
Balanced	16,5 (37)	11,6-21,4
Analgesic block
None	46,4 (104)	39,8-53,0
Ilioinguinal	10,7 (24)	6,6-14,7
Inf HX QX	33,9 (76)	27,6-40,1
Periumbilical	6,25 (14)	3,1-9,4
Caudal analgesia	2,7 (6)	0,05-4,8
Surgery time
Less than 30	24,6 (55)	18,8-30,2
30-45	22,8 (51)	17,2-28,3
46-60	40,2 (90)	33,7-46,6
More than 60	15,5 (28)	8,1-16,8

Table 2. Preoperative, anesthetic and surgical conditions.

To evaluate the APP, the LLANTO pain scale was used to calculate and categorize pain. It was found that the general score was mild (mean value of 2.8). Only 34% of the patients had no pain and severe pain occurred in 14.7% of the patients (Table 3).

Postoperative pain	% (Fr)	CI 95%
No pain	34,4 (77)	28,1 – 40,6
Mild pain(1-3)	30,8 (69)	24,7-36,9
Moderate pain (4-6)	20,1 (45)	14,8-25,3
Intense pain (7-10)	14,7 (33)	10,0-19,4
Mean		2.8

Table 3. Pain incidence according to the LLANTO scale.

As for the associated factors, the relationship between pain and type of surgery was evaluated. It was found that the surgical groups with the lowest and highest incidence of pain were abdominal wall (61.3%) and orthopedics (75%) respectively. On the other hand, moderate and severe pain was reported in a greater proportion in the orthopedic, airway and abdominal wall groups; however, no statistically significant differences were found when evaluating the distribution of the surgical groups in relation to the evaluation of acute pain (p 0.08) (table 4).

Surgical group			Type of pain - LLANTO pain scale
Surgical group	n	Pain incidence % (Fr)	Mild % (Fr)	Moderate % (Fr)	Intense % (Fr)	p
Abdominal wall	80	61,3 (49)	26,3 (21)	20,0 (16)	15,0 (12)	0,08
Urology	61	62,3 (38)	36,1 (22)	14,7 (9)	11,5 (7)
Orthopedics	32	75,0 (21)	18,7 (6)	43,7(14)	12,5 (4)
Laparotomy	18	66,7 (12)	38,9 (7)	16,7 (3)	11,1 (2)
Respiratory tract	8	62,5 (5)	25,0 (2)	25,0 (2)	12,5 (1)
Oncology	18	72,2 (13)	50,0 (9)	-	22,2 (4)
Other	7	85,7 (6)	28,6 (2)	14,3 (1)	42,9 (3)

Table 4. Relationship between the LLANTO pain scale and surgical group.

Upon evaluating the relationship of APP with anesthetic drugs, propofol and fentanyl were identified as protective factors to prevent postoperative pain. Orthopedic surgery (RR: 2.34 CI 95%: 0.30 - 1.31) and head and neck surgery (RR: 7.28 CI 95%: 0.77 - 68.38) had a higher risk of postoperative pain (Table 5).

Medicaments	RR	CI 95%
Propofol	0,55	0.38-0,79
Fentanyl	0,44	0,31-0,63
Local anesthetics	0,48	0.22-1,01
Surgical group
Urology	0,63	0,30 - 1,31
Orthopedics	2,34	1,01 - 5,40
Laparotomy	0,6	0,17 - 2,06
Otolaryngologist	1,09	0,24 - 4,91
Oncology	1,52	0,15 - 1,73
Head-Neck	7,28	0,77 - 68,38

Table 5. Postoperative relative risk of pain according to medications and surgical groups.

The association between pain and anxiety variables showed that 32.1% of the children who reported anxiety had mild pain; however, there was no statistically significant evidence in the distribution of these variables (p 0.07) (Table 6). On the other hand, severe pain was associated with a higher risk of anxiety in children (Table 7).

*LLANTO pain scale*	Anxiety	P value*
Mild	52 (32,1)	0,07
Moderate	34 (20,9)
Intense	28 (17,3)
Total	162 (100,0)

Table 6. Relationship between the pain and anxiety scale in the study population.

Anxiety	RR	P value	CI 95%
Pain(Ref. Absence)	1	-	-
Mild	1,20	0,091	0,97-1,50
Moderate	1,21	0,117	0,95-1,54
Severe	1,36	0,007	1,08-1,70

Table 7. Anxiety relative risk with the mYPAS-SF scale, according to pain with the LLANTO pain scale.

Pain is defined as a subjective experience and is determined by external factors that influence pain’s perception; therefore, in order to achieve more objective approaches, it is essential to recognize those determinants. Postoperative pain prevalence reported in the study population, including mild, moderate and severe pain corresponds to 65.6%, mainly associated with abdominal wall, urology and orthopedic procedures, consistent with Bertólez SP et al. that reports a higher risk of postoperative pain in abdominal wall and urology surgical procedures [20].

Pain in pediatric population has a greater emotional component compared to adults; children during hospital stay present fear, anxiety, anger and sadness, conditions that are usually underestimated and have a greater negative impact on pain recovery; a bidirectional relationship of pain and anxiety has been documented [20, 21], Bertolez et al. report a close relationship with the type of surgical procedure to be treated. In addition to the type of anesthesia and analgesia used during hospitalization, although we found a non-statistically significant association between variables (p = 0,07), we consider that this relationship does have a clinical correlation, taking into account that patients with some degree of anxiety were those who presented greater pain intensity, therefore the therapeutic effort should be directed to the two variables in order to obtain better pre and post-surgical results [20].

Evaluating the anesthetic agents used in the procedures, we found that propofol and fentanyl behaved as protective factors against the presence of APP, which is consistent with that described by Zhao et al [22] where they found that pediatric patients in whom sevoflurane-propofol balanced anesthesia was used as general anesthesia had a lower risk of postoperative pain, emergency agitation, postoperative nausea and vomiting compared to general anesthesia with sevoflurane, however children who received sevoflurane alone recovered slightly faster than those who received balanced anesthesia; Miranda [23] also compared balanced general anesthesia with sevoflurane vs total intravenous anesthesia (TIVA) based on propofol and fentanyl in a pediatric population scheduled for outpatient surgery, where they reported that patients with TIVA had lower opioid consumption, in addition to a milder postoperative awakening, a lower incidence of postoperative pain and a shorter stay in the postanesthesia care unit. These results differ from those found in adult population given that several studies as described by Jaime et al [24]; where they compared different anesthetics such as propofol, sevoflurane, isoflurane and sevoflurane during laparoscopic cholecystectomy and evidenced that there were no significant differences in the intensity of postoperative pain; However, other studies such as that described by Zaballos et al. described different results in adult patients who underwent laryngeal microsurgeries where the occurrence of pain was found in 33% of patients operated with propofol, compared to 5% with sevoflurane [25], which makes it necessary to perform a different approach in anesthesia depending on the type of patient population.

Acute postoperative pain is a difficult variable to measure and quantify, especially in the pediatric population; however, tools such as LLANTO pain scale have been able to identify and stratify it, which allows the implementation of preoperative control measures to improve operative results and prevent complications. Post-surgical pain was related to orthopedic procedures and surgeries lasting more than 1 hour. Additionally, a decrease in pain was identified when propofol, fentanyl and mixed anesthesia were administered; however, several studies have found different conclusions in the adult population. Bearing in mind these results, according to the surgical group, it is suggested to use other analgesic methods such as caudal anesthesia, regional blocks guided by ultrasound and epidural catheters in order to reduce intraoperative anesthetic requirements and therefore reduce postoperative pain, although anxiety was not found as a statistically significant variable, there is evidence of a close relationship with APP. Finally, our study allows us to broaden the field of research in Colombia about postoperative pain, its characteristics and associated factors and represents a starting point for new research projects. Additionally will also allow in our population to generate new strategies to stratify, prevent and manage pain and thus improve our professional practice to give a better quality of life to our patients.

Acute postoperative pain (APP), American Society of Anesthesiologists (ASA), Frequency (Fr), Relative Risk (RR), Total intravenous anesthesia (TIV).

Acknowledgements: Universidad Industrial de Santander, as well as Clínica Materno Infantil San Luis.

Author contributions: Study conception and design: DJGL, HHTW and HJM. Data acquisition: DJGL and AFMS. Analysis and interpretation of data: DJGL, AFMS, HJM, PADG, MJLM, JSHM and HHTW. Drafting of the manuscript: DJGL, AFMS, PADG, JSHM and MJLM. Critical revision of the manuscript for important intellectual content: All authors. All authors read and approved the final manuscript.

Funding: This study was funded in part by Universidad Industrial de Santander, as well as by the authors.

Data availability: The datasets generated during and/or analyzed during the current study are available from the corresponding author on request.

Conflict of interests: The authors declare that they have no competing interest.

Ethical approval: In this research, the process related to reviewing the clinical history, monitoring the patient and asking the parents for the scales’ application was done under authorization by the ethics committee’s of the Universidad Industrial de Santander and Clinica Materno Infantil San Luis. The procedure described in the methodology for the collection of information was applied, always with prior consent of the parents and explanation about the personal data treatment, which would not be used in a way that would allow their identification by any person external to the research group and the publication of any result would always be anonymous. The confidentiality of the data obtained is guaranteed and the privacy of the subjects is prioritized.

The development of this research project followed the Belmont Report’s principles, CIOMS guidelines and the World Medical Association Declaration of Helsinki on ethical principles for medical research involving human subjects; the life, health, dignity, integrity, right to self-determination, privacy and confidentiality of the personal information of the research subjects were protected, and the privacy, integrity and anonymity of the individual research subject were protected.

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No competing interests reported.

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Factors associated with acute postoperative pain in preschool children in a referral clinic in eastern Colombia

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