Effects of acute postoperative pain on catecholamine plasma levels, hemodynamic parameters, and cardiac autonomic control

Possibility of Using Surgical Pleth Index in Predicting Postoperative Pain in Patients after Vitrectomy Performed under General Anesthesia

Adequacy of anesthesia concept (AoA) in the guidance of general anesthesia (GA) is based on entropy, and it also reflects the actual depth of anesthesia and the surgical pleth index (SPI). Therefore, this study aimed to analyze the potential existence of relationships between SPI values at certain stages of the AoA-guided GA for vitreoretinal surgeries (VRS) and the incidence of intolerable postoperative pain perception (IPPP). A total of 175 patients were each assigned to one of five groups. In the first, the VRS procedure was performed under GA without premedication; in the second group, patients received metamizole before GA; in the third, patients received acetaminophen before GA; in the fourth group, patients received Alcaine before GA; and, in the peribulbar block group, the patients received a peribulbar block with a mix of the solutions of lignocaine and bupivacaine. Between the patients declaring mild and statistically significant differences in the IPPP in terms of SPI values before induction (52.3 ± 18.8 vs. 63.9 ± 18.1, p < 0.05) and after emergence from GA (51.1 ± 13 vs. 68.1 ± 8.8; p < 0.001), it was observed that the patients postoperatively correlated with heart rate variations despite the group allocation. The current study proves the feasibility that preoperative SPI values help with predicting IPPP immediately after VRS under AoA guidance and discrimination (between mild diagnoses and IPPP when based on postoperative SPI values) as they correlate with heart rate variations. Specifically, this applies when the countermeasures of IPPP and hemodynamic fluctuations are understood to be of importance in reducing unwelcome adverse events.

The association of hemodynamic parameters and clinical demographic variables with acute postoperative pain in female oncological breast surgery patients: A retrospective cohort study

OBJECTIVES

Appropriate administration of intraoperative analgesia is an essential factor in care and reasonable recovery times. Inappropriate intraoperative analgesia puts the patient at risk of acute postoperative pain (APOP). The absence of an objective standard for intraoperative nociceptive monitoring complicates pain care. Heart rate (HR) and mean arterial blood pressure (MABP) have been suggested as useful parameters during general anesthesia for nociceptive monitoring. However, studies focusing on whether intraoperative heart rate variability (HRv) and mean arterial blood pressure variability (MABPv) during general anesthesia can accurately monitor nociception in patients have remained inconclusive. The current study aimed to (1) identify the association of intraoperative heart rate and blood pressure variability in patients undergoing low-risk surgery with the incidence of APOP in the immediate postoperative setting and (2) evaluate the associations of clinical demographic factors with the incidence of APOP.

METHODS

A retrospective observational cohort study was conducted. The outcome was moderate-to-severe APOP, defined as a numeric rating scale score of ≥ 4. HRv, MABPv, and potential confounders, such as age, body mass index, duration of surgery, smoking, depression, preoperative use of analgesics, and type of surgery, were used as independent variables.

RESULTS

Data from 764 female oncological breast surgery patients were analyzed. No statistically significant association of HRv and MABPv with APOP was found. Lower age was associated with higher odds of APOP (odds ratio [OR] 0.978, p = 0.001). Increased length of surgery (OR 1.013, p = 0.022) and a history of depression were associated with increased odds of APOP (OR 2.327, p = 0.010). The subtype of surgery was statistically significantly associated with APOP (p = 0.006).

CONCLUSIONS

Our results suggest that heart rate and blood pressure variability intraoperatively, in female patients undergoing low-risk surgery, are not associated with, and thus not predictive of, APOP in the immediate postoperative setting.

[New Approaches in Perioperative Algesimetry]

The measurement of anaesthetic depth and muscle relaxation have been routine procedures during general anaesthesia for years. Quantification of intraoperative nociception, on the other hand, is still largely impossible. Various methods have been tested and commercialised for more than 10 years. However, a real breakthrough has not yet been achieved and the routine application of all methods available so far is not without problems. This article explains methodological similarities, but also points to specific aspects of various commercial solutions for perioperative algesimetry.

[The effects of hypnosis by virtual reality on tolerance to flexible bronchoscopy]

INTRODUCTION

Patients often perceive flexible bronchoscopy as an unpleasant procedure. The aim of this study was to investigate the effect of virtual reality (VR) hypnosis on tolerance to flexible bronchoscopy.

MATERIALS AND METHODS

We conducted a prospective, randomized, controlled, monocentric study comparing flexible bronchoscopy with VR-induced hypnosis to the usual procedure. Patient tolerance was evaluated using a visual analogue scale (VAS), the state-trait anxiety inventory (STAI) before and after the procedure and, finally, willingness to repeat the examination under the same conditions (WTR).

RESULTS

Among the 70 patients included, 34 were randomized to the VR hypnosis group and 36 to the control group. There was no difference between the 2 groups in terms of modification of the pre-/post-bronchoscopy VAS for anxiety, pain, cough, choking, nausea and overall discomfort, or modification of the STAI score and WTR. Subgroup analysis among patients who were more anxious before the procedure revealed a trend toward reduced anxiety in the VR hypnosis group.

CONCLUSION

This study did not observe any effect of VR hypnosis on the tolerance of patients during routine flexible bronchoscopy. However, VR hypnosis may be beneficial in patients with higher anxiety score before bronchoscopy, a hypothesis that needs to be confirmed by further studies with a larger number of subjects.

The Effect of Aromatherapy with Citrus aurantium Aroma on Pain after Orthopedic Surgery: A Randomized Clinical Trial

Introduction

Postoperative pain is one of the most common physiological and psychological stress in patients that disrupts body function and can endanger patients' health. This study aims to determine the effect of aromatherapy with Citrus aurantium essential on pain after orthopedic surgery.

Methods

This randomized clinical trial was performed on 60 candidates for orthopedic surgery. Patients were selected through convenience sampling and divided into intervention and control groups through randomized block allocation. If the visual analogue scale (VAS) score was above 3, patients in the intervention group received aromatherapy with C. aurantium essential and the patients in the control group received a placebo (almond oil). VAS was used to measure pain. Data analysis was performed using independent t test, paired t test, and analysis of variance with repeated measures using SPSS software version 13.

Results

Mean (SD) of pain intensity after intervention in experimental and control groups within 4, 8, and 12 hours after surgery was 7.30 (1.23) vs. 7.90 (0.99), 5.30 (0.98) versus 5.53 (0.68) and 2.53 (0.9) vs. 3.60 (0.77) respectively. The findings indicated that there was a significant difference in mean pain intensity between the experimental and control groups at 4 and 12 hours after surgery. Use of analysis of variance with repeated measures test with taking into account the interaction of time and group also showed a significant difference in mean pain intensity between the two experimental and control groups.

Conclusion

Aromatherapy with Citrus aurantium essential can be effective in reducing mild to moderate pain after orthopedic surgery. Further studies are recommended to confirm this finding.

Ultrasonography Causes Agitation and Pain Leading to Hemodynamic Disturbance in Neonates: A Prospective Observational Study

BACKGROUND

Ultrasonography is widely used in neonatological practice and studies investigating the hemodynamic effects of various treatment protocols or clinical situations. On the other hand, pain causes changes in the cardiovascular system; so, in the case of ultrasonography leading to pain in neonates, it may cause hemodynamic alterations. In this prospective study, we evaluate whether ultrasonographic application causes pain and changes in the hemodynamic system.

METHODS

Newborns undergoing ultrasonographic examination were enrolled in the study. Vital signs, cerebral and mesenteric tissue oxygenation (StO₂) levels, and middle cerebral artery (MCA) Doppler measurements were recorded, and NPASS scores were calculated before and after ultrasonography.

RESULTS

We enrolled 39 patients in the study. After ultrasonography, Neonatal Pain, Agitation, and Sedation Scale (NPASS) scores were significantly higher (p < 0.01), and all vital signs (heart rate, respiratory rate, SpO₂, diastolic and systolic blood pressure; p = 0.03; p < 0.01, p < 0.01, p < 0.01, p = 0.02, p = 0.03, respectively) were altered. Cerebral (p = 0.008) and mesenteric (p = 0.039) StO₂ levels were significantly lower in the whole study group, MCA end-diastolic velocity decreased (p = 0.02), and the resistive index (p = 0.03) increased in patients whose NPASS score was >7 after ultrasonography.

CONCLUSIONS

This study is the first to show that ultrasonography may cause pain in newborn patients, and alters vital signs and hemodynamic parameters. Therefore, precautions should be taken to protect newborn babies from pain during ultrasound applications, as they are already exposed to many noxious stimuli. Furthermore, pain scores should be considered in studies using ultrasonography and evaluating hemodynamic parameters to increase the reliability of the studies.

Elevated Surgical Pleth Index at the End of Surgery Is Associated with Postoperative Moderate-to-Severe Pain: A Systematic Review and Meta-Analysis

Despite acceptance of the surgical pleth index (SPI) for monitoring the intraoperative balance between noxious stimulation and anti-nociception under general anesthesia, its efficacy for predicting postoperative moderate-to-severe pain remains unclear. We searched electronic databases (e.g., Google Scholar, MEDLINE, Cochrane Library, and EMBASE) to identify articles focusing on associations of SPI at the end of surgery with immediate moderate-to-severe pain in the postanesthesia care unit from inception to 7 July 2022. A total of six observational studies involving 756 adults published between 2016 and 2020 were eligible for quantitative syntheses. Pooled results revealed higher values of SPI in patients with moderate-to-severe pain than those without (mean difference: 7.82, 95% CI: 3.69 to 11.95, p = 0.002, I2 = 46%). In addition, an elevated SPI at the end of surgery was able to predict moderate-to-severe pain with a sensitivity of 0.71 (95% confidence interval (CI): 0.65–0.77; I2 = 29.01%) and a specificity of 0.58 (95% CI: 0.39–0.74; I2 = 79.31%). The overall accuracy based on the summary receiver operating characteristic (sROC) curve was 0.72. In conclusion, this meta-analysis highlighted the feasibility of the surgical pleth index to predict postoperative moderate-to-severe pain immediately after surgery. Our results from a limited number of studies warrant further investigations for verification.

Risk Factors for Intravenous Propacetamol-Induced Blood Pressure Drop in the Neurointensive Care Unit: A Retrospective Observational Study

BACKGROUND

Intravenous propacetamol is commonly used to control fever and pain in neurocritically ill patients in whom oral administration is often difficult. However, several studies reported that intravenous propacetamol may cause blood pressure drop. Thus, we aimed to investigate the occurrence and risk factors for intravenous propacetamol-induced blood pressure drop in neurocritically ill patients.

METHODS

This retrospective study included consecutive patients who were administered intravenous propacetamol in a neurointensive care unit at a single tertiary academic hospital between April 2013 and June 2020. The exact timing of intravenous propacetamol administration was collected from a database of the electronic barcode medication administration system. Blood pressure drop was defined as a systolic blood pressure below 90 mm Hg or a decrease by 30 mm Hg or more. Blood pressure, pulse rate, and body temperature were collected at baseline and within 2 h after intravenous propacetamol administration. The incidence of blood pressure drop was evaluated, and multivariable logistic regression analysis was performed to identify risk factors for blood pressure drop events.

RESULTS

A total of 16,586 instances of intravenous propacetamol administration in 4916 patients were eligible for this study. Intravenous propacetamol resulted in a significant decrease in systolic blood pressure (baseline 131.1 ± 17.8 mm Hg; within 1 h 124.6 ± 17.3 mm Hg; between 1 and 2 h 123.4 ± 17.4 mm Hg; P < 0.01). The incidence of blood pressure drop events was 13.5% within 2 h after intravenous propacetamol. Older age, lower or higher baseline systolic blood pressure, fever, higher Acute Physiology and Chronic Health Evaluation II score, and concomitant administration of vasopressors/inotropes or analgesics/sedatives were significant factors associated with the occurrence of blood pressure drop events after intravenous propacetamol administration.

CONCLUSIONS

Intravenous propacetamol can induce hemodynamic changes and blood pressure drop events in neurocritically ill patients. This study identified the risk factors for blood pressure drop events. On the basis of our results, judicious use of intravenous propacetamol is warranted for neurocritically ill patients with risk factors that make them more susceptible to hemodynamic changes.

Scoping review of the association between postsurgical pain and heart rate variability parameters

Supplemental Digital Content is Available in the Text. This scoping review provides some evidence of a possible association between heart rate variability and postsurgical pain, although significant variability exists among included studies.

Surgical interventions can elicit neuroendocrine and sympathovagal responses, leading to cardiac autonomic imbalance. Cardiac complications account for approximately 30% of postoperative complications. Altered heart rate variability (HRV) was initially described in the 1970s as a predictor of acute coronary syndromes and has more recently been shown to be an independent predictor of postoperative morbidity and mortality after noncardiac surgery. In general, HRV reflects autonomic balance, and altered HRV measures have been associated with anesthetic use, chronic pain conditions, and experimental pain. Despite the well-documented relationship between altered HRV and postsurgical outcomes and various pain conditions, there has not been a review of available evidence describing the association between postsurgical pain and HRV. We examined the relationship between postsurgical pain and HRV. MEDLINE and EMBASE databases were searched until December 2020 and included all studies with primary data. Two reviewers independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Review of Interventions. A total of 8 studies and 1002 participants were included. Studies examined the association of postsurgical pain and HRV or analgesia nociception index derived from HRV. There was a statistically significant association between HRV measures and postsurgical pain in 6 of 8 studies. Heterogeneity of studies precluded meta-analyses. No studies reported cardiovascular outcomes. There is a potential association between postsurgical pain and HRV or analgesia nociception index, although results are likely impacted by confounding variables. Future studies are required to better delineate the relationship between postsurgical pain and HRV and impacts on cardiovascular outcomes.

Takotsubo syndrome and cancer, clinical and prognostic implications, insights of RETAKO

BACKGROUND AND OBJECTIVES

A relationship between neoplasms and Takotsubo syndrome (TS) has been postulated. Our goal was to determine its prevalence in patients with TS, compare the clinical profile of TS with or without cancer and study its long-term evolution.

MATERIALS AND METHODS

The oncological situation of patients included in the National Registry on TAKOtsubo syndrome (RETAKO), admitted between 2002 and 2019, provided by 38 hospitals throughout the country is analysed. Any history of malignancy or tumour, even benign, that received chemotherapy, radiotherapy or specific surgery, current or past, was considered.

RESULTS

Any type of neoplasm was described in 129 (11.8%), within a cohort of 1,097 patients with TS. The cohort of patients with neoplasm, with a lower percentage of women (79.1 vs. 88.3%; P=.003), showed a non-significant tendency at an older age, hyperuricaemia, sleep apnoea and lower LVEF on admission, with a similar cardiovascular risk factor profile, but more chronic anaemia and immunosuppression. The most common neoplasm was breast cancer. During their hospital stay, the cancer patients suffered more complications, highlighting heart failure/shock, acute renal failure and a trend towards combined infections. On follow-up, they presented higher mortality and more combined MACE events, with a non-significant trend in the occurrence of cardiovascular recurrences or readmissions.

CONCLUSIONS

The prevalence of neoplasms in patients with TS is high. The clinical presentation is different in relation to patients who do not have neoplasms and they probably represent a risk factor for a worse hospital and long term prognosis.

Cognitive self-regulation influences pain-related physiology

Cognitive self-regulation can shape pain experience, but its effects on autonomic responses to painful events are unclear. In this study, participants (N = 41) deployed a cognitive strategy based on reappraisal and imagination to regulate pain up or down on different trials while skin conductance responses (SCRs) and electrocardiogram activity were recorded. Using a machine learning approach, we first developed stimulus-locked SCR and electrocardiogram physiological markers predictive of pain ratings. The physiological markers demonstrated high sensitivity and moderate specificity in predicting pain across 2 data sets, including an independent test data set (N = 84). When we tested the markers on the cognitive self-regulation data, we found that cognitive self-regulation had significant impacts on both pain ratings and pain-related physiology in accordance with regulatory goals. These findings suggest that self-regulation can impact autonomic nervous system responses to painful stimuli and provide pain-related autonomic profiles for future studies.

Usefulness of ANI (analgesia nociception index) monitoring for outpatient saphenectomy surgery outcomes: an observational study

The Analgesia Nociception Index (ANI), derived from heart rate variability is a proposed guide to obtain an adequate control of the analgesic component during anaesthesia. This single blind observational study was designed to evaluate the relationship between intraoperative ANI values and length of stay in Day Surgery Units (DSU) in patients undergoing varicose vein intervention. 131 patients (ASA I-II) scheduled for elective varicose vein surgery were studied. A propofol closed-loop TCI was used to maintain a specific level of BIS. To control analgesia, a remifentanil TCI was used, modifying the target according to hemodynamic changes. Patients were included in the ANI > 50 sub-group or in the ANI < 50 sub-group depending on whether the ANI value was greater than 50 for at least 60% of the anaesthesia maintenance period (AMP) or not. The primary endpoint was the length of stay in DSU. Other variables studied were ANI values, duration of the AMP, remifentanil TCI target average, postoperative pain, rescue-analgesia needs and postoperative nausea and vomiting (PONV) were analysed. Statistical analysis of length of stay in DSU was performed with Mann-Whitney test. ANI > 50 sub-group showed a lower length of stay in the DSU [165 min (118-212) vs 186.5 min (119-254), p = 0.0425]. Discharge timing from DSU was statistically different among study sub-groups (p = 0.005). An adequate nociception level measured by ANI during varicose vein surgery might reduce the length of stay at DSU. Further studies are needed to assess the usefulness of ANI in other anaesthesia conditions.

The relationship between chest pain intensity and physiological indicators after coronary artery bypass grafting: A correlational study

Background

This study aims to evaluate the relationship between chest pain intensity and physiological indicators in patients undergoing coronary artery bypass grafting.

Methods

In this correlational study, chest pain intensity and physiological responses of a total of 126 coronary artery bypass grafting patients (104 males, 22 females; mean age 62.3±8.5 years; range, 45 to 80 years) during respiratory exercise were evaluated in a referral hospital setting between December 2016 and March 2018. On the second day after surgery, pain intensity was measured by a numerical rating scale. Physiological indicators were collected using the Nihon Kohden (MU65) monitoring device.

Results

The mean pain intensity score was 7.8±1.9 (range, 1 to 10). There was no significant correlation between the pain intensity and physiological indicators (p>0.05). There was a negative correlation between the pain intensity and age of the patient (r=- 0.183 and p=0.04). Pain intensity was not significantly different between male and female gender (p=0.064).

Conclusion

Our study results show no significant relationship between the chest pain intensity and physiological responses in patients undergoing coronary artery bypass grafting.

Tumescent anesthesia or epidural anesthesia combined with intercostal block in bitches submitted to mastectomy

Abstract The present study aimed to evaluate the use of tumescent local anesthesia or epidural anesthesia associated with an intercostal nerve block in bitches submitted to mastectomy. Fourteen bitches from the clinical routine of the Veterinary Hospital of the Federal University of Pelotas were premedicated with acepromazine (0.03 mg/kg) and morphine (0.3 mg/kg) intramuscularly, then induced with propofol (2 to 6 mg/kg/IV) and maintained with 1,4V% isoflurane (calibrated vaporizer). The patients were randomly allocated into: GALT Group (n=7), which received tumescent local anesthesia (0.16%) at the dose of 15 mL/kg, and the GEBI Group (n=7) which received epidural anesthesia with lidocaine (5 mg/kg) and morphine (0.1 mg/kg) associated with an intercostal nerve block from the 6th to 12th intercostal space with lidocaine (2 mg/kg). An increase higher than 10% in heart rate, respiratory rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were considered as possible signs of nociception, to which fentanyl was administered intravenously as rescue analgesia. Postoperative analgesia was evaluated by means of the modified Glasgow scale at 30, 60, 120, 240 and 360 minutes. There were no differences in physiological parameters (0>0.05) in the transoperative period intra-group and inter-group the groups. The GEBI Group required more frequent transoperative rescue analgesia (9) in comparison to the GALT Group (5), but with no statistical difference. During the postoperative period, there was no need for rescue analgesia in either group. Results suggest that epidural anesthesia associated with intercostal nerve block can be used as an alternative technique in patients with restrictions against the use of local tumescent anesthesia.

Objective monitoring of nociception: a review of current commercial solutions

Nociception, in contrast to pain, is not a subjective feeling, but the physiological encoding and processing of nociceptive stimuli. However, monitoring nociception remains a challenge in attempts to lower the incidence of acute postoperative pain and the move towards a more automated approach to analgesia and anaesthesia. To date, several commercialised devices promise a more accurate reflection of nociception than the traditionally used vital signs, blood pressure and heart rate. This narrative review presents an overview of existing technologies and commercially available devices, and offers a perspective for future research. Although firm conclusions about individual methods may be premature, none currently appears to offer a sufficiently broad applicability. Furthermore, there is currently no firm evidence for any clinically relevant influence of such devices on patient outcome. However, the available monitors have significantly aided the understanding of underlying mechanisms and identification of potential pitfalls.

Surgical pleth index: prediction of postoperative pain and influence of arousal

BACKGROUND

There are conflicting reports concerning the outcome after anaesthesia guided by the surgical pleth index (SPI; GE Healthcare, Helsinki, Finland). One potential explanation may be the lack of evidence for the selection of SPI cut-off values. The aim of this trial was to investigate the correlation between SPI, arousal, and postoperative pain and to define a cut-off value for SPI to predict moderate-to-severe pain.

METHODS

After obtaining ethical approval and written informed consent, 70 patients undergoing non-emergency surgery were enrolled. Data relating to SPI, heart rate, mean arterial pressure, and state entropy were recorded every 10 s for the last 10 min of surgery (state entropy <60 at all times). Subsequently, recordings continued during the phase of arousal. After recovery room admission, pain scores (numerical rating scale 0-10) were obtained every 3 min for 15 min.

RESULTS

Data from 65 patients were analysed. Receiver-operating characteristic curve analysis revealed an optimal intraoperative cut-off SPI value of 30 to discriminate between numerical rating scale scores 0-3 and 4-10. For this value, the negative and positive predictive values to discriminate between numerical rating scale scores 0-3 and 4-10 were 50 and 89.7%, respectively. The SPI was significantly affected by arousal, and SPI scores obtained during this phase were not predictive of postoperative pain.

CONCLUSIONS

Surgical pleth index values are predictive of postoperative pain only if obtained before patient arousal. In contrast to previous studies, a relatively low SPI, >30, appears to predict pain with a high positive predictive value and may therefore be suggested for future studies of SPI-guided anaesthesia.

CLINICAL TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12615000804583.

Efeitos adversos da morfina, metadona e tramadol no pós-operatório de cães submetidos à cirurgia da coluna vertebral: 180 casos (2011-2016)

RESUMO: A dor pós-operatória em cães que são submetidos a cirurgias da coluna vertebral é considerada severa e seu manejo inadequado pode influenciar no tempo de recuperação do paciente, na qualidade de vida e no resultado cirúrgico. Dentre os analgésicos indicados para uso no pós-operatório dessas cirurgias tem-se os opioides, que podem apresentar inúmeros efeitos adversos que requerem atenção. Devido à escassez de estudos clínicos acerca desse assunto em se tratando do pós-operatório de cães, objetivou-se com o presente estudo retrospectivo apresentar os efeitos adversos da morfina, metadona e tramadol utilizados no pós-operatório de cirurgias da coluna vertebral. Foram revisadas e avaliadas as fichas de 180 cães e anotadas as alterações observadas no pós-operatório e decorrentes do uso de opioides. Os principais efeitos adversos observados foram anorexia, hiporexia, vômito, salivação, vocalização, bradicardia, hipotermia, ofegação e sedação. Também foi observada persistência da dor em alguns cães mesmo com o uso de analgésicos. Houve diferença na ocorrência de anorexia nos cães tratados com morfina e nos tratados com metadona em relação aos tratados com tramadol. Ocorreu diferença também entre a observação de dor dos grupos morfina e tramadol. A associação de dipirona com morfina e com metadona não revelou diferença com relação à ocorrência de efeitos adversos, bem como a variação de doses. Conclui-se que a morfina, a metadona e o tramadol apresentam efeitos adversos quando empregados para tratamento da dor pós-operatória em cães submetidos à cirurgia da coluna vertebral; a anorexia, a hiporexia e o vômito foram os efeitos adversos frequentes com o uso de morfina e de metadona e, mesmo que o tramadol apresente menor ocorrência desses efeitos, seu uso, na dose estudada, pode não ser vantajoso quando se leva em consideração o grau de dor para cirurgias da coluna vertebral.

Association Between Acute Pain and Hemodynamic Parameters in a Postoperative Surgical Intensive Care Unit

I conducted a prospective repeated-measure study in the general surgery intensive care unit to investigate the associations among acute postoperative pain, analgesic therapy, and hemodynamic parameters. I selected 33 patients and recorded 84 episodes of pain. I measured intensity of pain and hemodynamic parameters after patients were transferred from the postanesthesia care unit to the general surgery intensive care unit, immediately before analgesic therapy and at 15, 30, and 45 minutes after analgesic therapy. Acute pain increased systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MAP); pulse rate (PR); and arterial oxygen saturation. Fifteen minutes after analgesic therapy, SBP and PR decreased, and DBP, MAP, and oxygen saturation increased. Thirty minutes after therapy, SBP, MAP, and PR decreased, and DBP and oxygen saturation increased. Forty-five minutes after therapy, SBP, MAP, and PR decreased, and DBP and oxygen saturation increased. I saw no significant hemodynamic parameter changes during postoperative episodes of pain.

Pain reporting and analgesia management in 270 children with a progressive neurologic, metabolic or chromosomally based condition with impairment of the central nervous system: cross-sectional, baseline results from an observational, longitudinal study

Little is known about the prevalence, characterization and treatment of pain in children with progressive neurologic, metabolic or chromosomal conditions with impairment of the central nervous system. The primary aims of this study were to explore the differences between parental and clinical pain reporting in children with life-limiting conditions at the time of enrollment into an observational, longitudinal study and to determine if differences in pain experiences were associated with patient- or treatment-related factors. Pain was common, under-recognized and undertreated among the 270 children who enrolled into the "Charting the Territory" study. Children identified by their parents as experiencing pain (n=149, 55%) were older, had more comorbidities such as dyspnea/feeding difficulties, were less mobile with lower functional skills and used analgesic medications more often, compared to pain-free children. Forty-one percent of children with parent-reported pain (21.8% of all patients) experienced pain most of the time. The majority of clinicians (60%) did not document pain assessment or analgesic treatment in the medical records of patients who were experiencing pain. Documentation of pain in the medical record was positively correlated with children receiving palliative care services and being prescribed analgesics, such as acetaminophen, nonsteroidal anti-inflammatory drugs and opioids, as well as the adjuvant analgesics gabapentin and amitriptyline.

Cerebral oxygenation for pain monitoring in adults is ineffective: A sequence-randomized, sham controlled study in volunteers

BACKGROUND

Pain assessment by Numeric Rating Scale (NRS) is considered to be good clinical practice, but objective pain assessment is still a challenge. Near infrared spectroscopy (NIRS) measures cerebral tissue oxygen saturation (SctO₂) that increases with cortical-neuronal activity and may provide point-of-care bedside pain monitoring. Analogous to promising studies in newborns, we hypothesize that different levels of SctO₂ can probably quantify pain intensity. SctO₂ may increase following painful in contrast to non-painful or sham stimuli and may correlate with pain intensity as assessed by NRS in volunteers.

METHODS

Twenty healthy male students (24.2±1.9 years), recruited via local advertising, were consecutively included in a sequence-randomized, sham-controlled, single-blinded study. SctO₂ was recorded continuously with two NIRS sensors on the forehead. After resting, four stimuli were applied in a random order on the right forearm (unexpected and expected electrical pain, expected non-painful and sham stimuli). Blinded subjects were asked to rate each stimulus on NRS.

STATISTICS

RM-ANOVA; Wilcoxon or paired Student t-test; Spearman's rank correlation; P<.05.

RESULTS

Resting volunteers showed SctO₂ of 72.65%±3.39. SctO₂ significantly increased for about 60 to 70s until a maximum after unexpected painful (74.62%±3.9; P=.022) and sham stimuli (74.07%±3.23; P=.014). Expected painful (P=.139) and non-painful stimuli (P=.455) resulted in no changes in SctO₂. NRS scores (median, IQR) were rated significantly higher after expected (5.25, 3.5 to 6.75) than after unexpected (4.5, 3 to 5; P=.008) pain. No strong correlation was found between NRS and SctO₂.

CONCLUSIONS AND IMPLICATIONS

Contrary to our expectations, measuring SctO₂ via a two-channel NIRS is not able to remediate the lack of objective bedside pain assessment under standardized experimental conditions in alert adults.

TRIAL REGISTRATION

DRKS 00011575 (retrospectively registered).

Hypothalamic-pituitary-adrenal and cardiac autonomic responses to transrectal examination differ with behavioral reactivity in dairy cows

Behavior, hypothalamic-pituitary-adrenal axis, and cardiac autonomic nervous system (ANS) activity were evaluated in response to transrectal examination in nonlactating Holstein-Friesian cows with different behavioral reactivity. According to behavioral reactions shown to the procedure of fixing the heart rate (HR) monitors, the 20 cows with the highest and the 20 cows with the lowest behavioral reactivity were involved in the study (high responder, n=20; and low responder, n=20, respectively). Activity of the ANS was assessed by HR and HR variability parameters. Blood and saliva were collected at 5 min before (baseline) and 0, 5 10, 15, 20, 30, 40, 60, and 120 min after the examination to determine cortisol concentrations. The examination lasted for 5 min. Cardiac parameters included HR, the root mean square of successive differences between the consecutive interbeat intervals, the high frequency (HF) component of heart rate variability, and the ratio between the low frequency (LF) and HF parameter (LF/HF). Following the examination, peak plasma and saliva cortisol levels and the amplitude of the plasma and saliva cortisol response were higher in high responder cows than in low responders. Areas under the plasma and saliva cortisol response curves were greater in high responder cows. Plasma and salivary cortisol levels correlated significantly at baseline (r=0.91), right after examination (r=0.98), and at peak levels (r=0.96). Area under the HR response curve was higher in low responder cows; however, maximum HR and the amplitude of the HR response showed no differences between groups. Minimum values of both parameters calculated for the examination were higher in high responders. Following the examination, response parameters of root mean square of successive differences and HF did not differ between groups. The maximum and the amplitude of LF/HF response and area under the LF/HF response curve were lower in low responder cows, suggesting a lower sympathetic activation of the ANS. Although changes in behaviors indicated that the procedure was painful for the animals, no differences were observed either in vocalization or in attendant behavior between groups during the examination. Our results demonstrate that behaviorally more reactive animals exhibit increased plasma and salivary cortisol concentrations and higher cardiac autonomic responsiveness to transrectal examination than less reactive cows. Salivary cortisol may substitute for plasma cortisol when assessing response of cattle to stress.

The Effect of Regional Analgesia on Vascular Tone in Hip Arthroplasty Patients

BACKGROUND

While it is assumed that neuraxial analgesia and pain management may beneficially influence perioperative hemodynamics, few studies provided data quantifying such effects and none have assessed the potential contribution of the addition of a nerve block.

QUESTIONS/PURPOSES

This clinical trial compared the visual analog scale (VAS) scores and measurement of arterial tone using augmentation index of patients who received combined spinal-epidural (CSE) only to patients who received both CSE and lumbar plexus block.

METHODS

After obtaining written consent, 92 patients undergoing total hip arthroplasty were randomized to receive either CSE or CSE with lumbar plexus block (LPB). Perioperative pain and arterial tone were measured using VAS scores and augmentation index (AI) respectively, at baseline and at various times postoperatively.

RESULTS

After the exclusion of 2 patients, 44 patients received CSE alone and 46 patients received CSE and LPB. Patient demographics and perioperative characteristics were similar in both groups. AI continuously decreased after placement of a CSE with or without LBP, beyond full resolution of neuraxial and peripheral blockade. Although the LPB group demonstrated a statistically significant reduction of VAS pain scores in the postanesthesia care unit (PACU; P < 0.05), overall, the addition of a LPB did not significantly reduce the AI when compared to the control group.

CONCLUSION

The addition of a LPB provided better pain control in the PACU but did not reduce the AI, compared to the control group. We conclude that the addition of a LPB may have limited ability to affect arterial tone in the presence of a continuous infusion of epidural analgesics. In summary, the addition of a LPB in patients undergoing total hip arthroplasty is clinically effective and provided better pain control, especially in the immediate postoperative period. The continuous decrease on the AI in both groups beyond the full resolution of the neuroaxial and LPB will require further studies.

Effect of change in patient's bed angles on pain after coronary angiography according to vital signals

Background:

One of the most common and important diagnostic methods for the detection of heart diseases is coronary angiography. The aim of this study was to determine the optimum angle of the bed by using vital signals to optimize the patient's position after the angiography.

Materials and Methods:

This study was a randomized clinical trial (RCT) on participants after angiography who were divided into five groups. The first group was placed routinely in a supine position. In the other groups, all of the patients were placed in bed by angle 15°, 30°, 45°, and 60° upward. In each group, vital signals were measured that included blood pressure, percent of blood oxygen saturation, heart rate, respiratory rate, and temperature. All of measured data compared with the pain score has been achieved from numerical pain scale. The data were analyzed by descriptive statistics method, variance analysis, and post hoc tests in the Statistical Package for the Social Sciences (SPSS) software, version 16. Estimation of the relationship was done by MATLAB version 2011. The level of significance was considered to be 0.05.

Results:

In various groups, there was no significance difference in demographic variables such as gender, age, height, and weight. The mean of pain score, heart rate, systolic blood pressure, and respiratory rate changed significantly (P < 0.05) but the temperature variation, blood oxygen saturation, and diastolic blood pressure in subjects were not significant (P > 0.05). It showed linear changes between pain and systolic blood pressure, respiratory rate, and heart rate changes. A dramatic reduction was also seen in systolic blood pressure, respiratory rate, heart rate, and also pain at an angle of 45^°.

Conclusion:

This study showed that, 45^° was the best angle of the bed to optimize the patient's position after the procedure, based on his/her vital signs and pain score. Thus, in order to relive pain, this change in bed angle is advised to be planned by postangiography nurses in patients after coronary angiography.

Procedural pain does not raise plasma levels of cortisol or catecholamines in adult intensive care patients after cardiac surgery

The gold standard for quantification of pain is a person's self-report. However, we need objective parameters for pain measurement when intensive care patients, for example, are not able to report pain themselves. An increase in pain is currently thought to coincide with an increase in stress hormones. This observational study investigated whether procedure-related pain is associated with an increase of plasma cortisol, adrenaline, and noradrenaline. In 59 patients receiving intensive care after cardiac surgery, cortisol, adrenaline, and noradrenaline plasma levels were measured immediately before and immediately after patients were turned for washing, either combined with the removal of chest tubes or not. Numeric rating scale scores were obtained before, during, and after the procedure. Unacceptably severe pain (numeric rating scale ≥ 4) was reported by seven (12%), 26 (44%), and nine (15%) patients, before, during and after the procedure, respectively. There was no statistically significant association between numeric rating scale scores and change in cortisol, adrenaline, and noradrenaline plasma levels during the procedure. Despite current convictions that pain coincides with an increase in stress hormones, procedural pain was not associated with a significant increase in plasma stress hormone levels in patients who had undergone cardiac surgery. Thus, plasma levels of cortisol, adrenaline, and noradrenaline seem unsuitable for further research on the measurement of procedural pain.

Physiological Indices of Stress Prior to and Following Total Knee Arthroplasty Predict the Occurrence of Severe Post-Operative Pain

OBJECTIVE

The severe pain and disability associated with osteoarthritis often motivate individuals to undergo arthroplastic surgery. However, a significant number of surgical patients continue to experience pain following surgery. Prior research has implicated both the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) in the sensitization of pain receptors and chronic pain conditions. This study uses a prospective, observational, cohort design to examine whether physiological stress responses before and after surgery could predict post-operative pain severity.

SUBJECTS

Participants included 110 patients undergoing total knee arthroplasty.

METHODS

Physiological indices of stress included the measurement of catecholamine and cortisol levels in 15-hour urine samples collected prior to and 1 month following surgery, as well as in-hospital heart rate and blood pressure (before and after surgery), which were abstracted from medical records. Patients completed the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) [Bellamy et al., J Orthop Rheumatol 1: , 95 (1988)] 2.5 weeks prior to surgery and at a 3-month follow-up.

RESULTS

Contrary to expectations, lower stress hormone levels at baseline were related to more severe post-operative pain. Data at later time points, however, supported our hypothesis: cardiovascular tone shortly before surgery and urinary levels of epinephrine 1 month following surgery were positively related to pain severity 3 months later.

CONCLUSION

Results suggest that the occurrence of post-operative pain can be predicted on the basis of stress physiology prior to and following arthroplastic surgery.

ICU Blood Pressure Variability May Predict Nadir of Respiratory Depression After Coronary Artery Bypass Surgery

Objectives: Surgical stress induces alterations on sympathovagal balance that can be determined through assessment of blood pressure variability. Coronary artery bypass graft surgery (CABG) is associated with postoperative respiratory depression. In this study we aimed at investigating ICU blood pressure variability and other perioperative parameters that could predict the nadir of postoperative respiratory function impairment.

Methods: This prospective observational study evaluated 44 coronary artery disease patients subjected to coronary artery bypass surgery (CABG) with cardiopulmonary bypass (CPB). At the ICU, mean arterial pressure (MAP) was monitored every 30 min for 3 days. MAP variability was evaluated through: standard deviation (SD), coefficient of variation (CV), variation independent of mean (VIM), and average successive variability (ASV). Respiratory function was assessed through maximal inspiratory (MIP) and expiratory (MEP) pressures and peak expiratory flow (PEF) determined 1 day before surgery and on the postoperative days 3rd to 7th. Intraoperative parameters (volume of cardioplegia, CPB duration, aortic cross-clamp time, number of grafts) were also monitored.

Results: Since, we aimed at studying patients without confounding effects of postoperative complications on respiratory function, we had enrolled a cohort of low risk EuroSCORE (European System for Cardiac Operative Risk Evaluation) with < 2. Respiratory parameters MIP, MEP, and PEF were significantly depressed for 4–5 days postoperatively. Of all MAP variability parameters, the ASV had a significant good positive Spearman correlation (rho coefficients ranging from 0.45 to 0.65, p < 0.01) with the 3-day nadir of PEF after cardiac surgery. Also, CV and VIM of MAP were significantly associated with nadir days of MEP and PEF. None of the intraoperative parameters had any correlation with the postoperative respiratory depression.

Conclusions: Variability parameters ASV, CV, and VIM of the MAP monitored at ICU may have predictive value for the depression of respiratory function after cardiac surgery as determined by peak expiratory flow and maximal expiratory pressure.

ClinicalTrials.gov Identifier: NCT02074371.

Clinical utility of an undersized nurse-operated recovery room in the postoperative course: results from an Italian community setting

PURPOSE

In Europe, standardized criteria for recovery room (RR) requirements have not been established. The purpose of this study was to examine the clinical utility of an undersized nurse-operated RR in an Italian community hospital.

DESIGN

Single-center observational study.

METHODS

A total of 1,945 consecutive surgical patients admitted to the RR at the study institution between September 31, 2009, and August 31, 2011, were included in the study. A control group of surgical patients not admitted to the RR, matched for age, gender, American Society of Anesthesiologists score, and type of surgery were also considered. The prevalence of early adverse events occurring within 3 hours of the end of surgery was compared between the two groups.

FINDINGS

Patients admitted to the RR (mean age, 73.6 ± 14.2 years; 42.2% male; and 76.3% having major surgery) showed lower prevalences of hypotension (P < .0001), hypertensive response (P < .0001), new arrhythmias requiring intervention (P = .0036), and oxygen desaturation (P < .0001) in comparison with the control group. No differences in the proportions of patients experiencing postoperative nausea and vomiting, shivering, bleeding, and respiratory events were found. The Numeric Rating Scale for pain was also significantly lower at 2 hours in the study group as compared to the control group (1 [0 to 5] vs 3 [1 to 7]; P < .0001).

CONCLUSION

In this Italian community setting, an undersized nurse-operated RR contributed to a reduced prevalence of adverse postoperative events.

Vital Signs Are Not Associated with Self-Reported Acute Pain Intensity in the Emergency Department

OBJECTIVES

This study aimed to ascertain the association between self-reported pain intensity and vital signs in both emergency department (ED) patients and a subgroup of patients with diagnosed conditions known to produce significant pain.

METHODS

We performed a retrospective analysis of real-time, archived data from an electronic medical record system at an urban teaching hospital and regional community hospital. We included consecutive ED patients ≥16 years old who had a self-reported pain intensity ≥1 as measured during triage, from March 2005 to December 2012. The primary outcome was vital signs for self-reported pain intensity levels (mild, moderate, severe) on an 11-point verbal numerical scale. Changes in pain intensity levels were also compared to variations in vital signs. Both analyses were repeated on a subgroup of patients with diagnosed conditions recognized to produce significant pain: fracture, dislocation, or renal colic.

RESULTS

We included 153,567 patients (mean age of 48.4±19.3 years; 55.5% women) triaged with pain (median intensity of 7/10±3). Of these, 8.9% of patients had diagnosed conditions recognized to produce significant pain. From the total sample, the difference between mild and severe pain categories was 2.7 beats/minutes (95% CI: 2.4-3.0) for heart rate and 0.13 mm Hg (95% CI: -0.26-0.52) for systolic blood pressure. These differences generated small effect sizes and were not clinically significant. Results were similar for patients who experienced changes in pain categories and for those conditions recognized to produce significant pain.

CONCLUSION

Health care professionals cannot use vital signs to estimate or substantiate self-reported pain intensity levels or changes over time.

Assessing pain objectively: the use of physiological markers

Pain diagnosis and management would benefit from the development of objective markers of nociception and pain. Current research addressing this issue has focused on five main strategies, each with its own advantages and disadvantages. These encompass: (i) monitoring changes in the autonomic nervous system; (ii) biopotentials; (iii) neuroimaging; (iv) biological (bio-) markers; and (v) composite algorithms. Although each strategy has shown areas of promise, there are currently no validated objective markers of nociception or pain that can be recommended for clinical use. This article introduces the most important developments in the field and highlights shortcomings, with the aim of allowing the reader to make informed decisions about what trends to watch in the future.

Heart rate and heart rate variability in multiparous dairy cows with unassisted calvings in the periparturient period

Behavioural changes before calving can be monitored on farms; however, predicting the onset of calving is sometimes difficult based only on clinical signs. Heart rate (HR) and heart rate variability (HRV) as non-invasive measures of autonomic nervous system (ANS) activity were investigated in Holstein-Friesian cows (N=20) with unassisted calvings in the periparturient period to predict the onset of calving and assess the stress associated with calving. R-R-intervals were analysed in 5-min time windows during the following three main periods of measurement: 1) between 0 and 96 h before the onset of calving restlessness (prepartum period); 2) during four stages of calving: (I) early first stage; between the onset of calving restlessness and the first abdominal contractions; (II) late first stage (between the first abdominal contractions and the appearance of the amniotic sac); (III) early second stage (between the appearance of the amniotic sac and the appearance of the foetal hooves); (IV) late second stage (between the appearance of the foetal hooves and delivery of the calf), and 3) over 48 h following calving (postpartum period). Data collected between 72 and 96 h before calving restlessness was used as baseline. Besides HR, Poincaré measures [standard deviation 1 (SD1) and 2 (SD2) and SD2/SD1 ratio], the root mean square of successive differences (RMSSD) in R-R intervals, the high-frequency (HF) component of HRV and the ratio between the low-frequency (LF) and the HF components (LF/HF ratio) were calculated. Heart rate increased only following the onset of the behavioural signs, peaked before delivery of the calf, then decreased immediately after calving. Parasympathetic indices of HRV (RMSSD, HFnorm and SD1) decreased, whereas sympathovagal indices (LF/HF ratio and SD2/SD1 ratio) increased significantly from baseline between 12 and 24 before the onset of calving restlessness. The same pattern was observed between 0 and 1h before calving restlessness. Following the onset of behavioural signs, parasympathetic activity increased gradually with a parallel shift in sympathovagal balance towards parasympathetic tone, which was possibly a consequence of oxytocin release, which induces an increase in vagus nerve activity. Parasympathetic activity decreased rapidly between 0 and 0.5h following calving and was lower than measured during all other stages of the study, while sympathetic activity peaked during this stage and was higher than measured during any other stages. Between 0 and 4h after calving vagal tone was lower than baseline, whereas sympathovagal balance was higher, reflecting a prolonged physiological challenge caused by calving. Vagal activity decreased, whereas sympathovagal balance shifted towards sympathetic tone with increased live body weight of the calf during the late second stage of calving, suggesting higher levels of stress associated with the higher body weight of calves. All HRV indices, measured either at the late second stage of calving and between 12 and 24h after calving, were affected by the duration of calving. Our results indicate that ANS activity measured by HRV indices is a more immediate indicator of the onset of calving than behaviour or HR, as it changed earlier than when restlessness or elevation in HR could be observed. However, because of the possible effects of other physiological mechanisms (e.g. oxytocin release) on ANS activity it seems to be difficult to measure stress associated with calving by means of HRV between the onset of calving restlessness and delivery. Further research is needed to enable more precise interpretation of the prepartum changes in HR and HRV in dairy cattle.

Evaluation of the effects of methadone and tramadol on postoperative analgesia and serum interleukin-6 in dogs undergoing orthopaedic surgery

BACKGROUND

Acute postsurgical pain is of great interest due to potential risk of becoming chronic if not treated properly, worsening patient's recovery and quality of life. Twenty-eight dogs with ruptured cruciate ligaments were divided into three groups that received intramuscular injections of 4 mg/kg of tramadol (TRA), 0.5 mg/kg of methadone (MET0.5), or 0.7 mg/kg of methadone (MET0.7). Physiological parameters (heart and respiratory rates and blood pressure) were evaluated at specified times: baseline (TBL), 1 (T1), 2 (T2), 4 (T4), 6 (T6), and 24 (T24) hours after premedication. Pain scores were described by visual analogue scale (VAS), modified Glasgow Composite, and Colorado University Acute Pain scales. Blood samples for measurement of interleukin (IL)-6 were collected at TBL, T1, T6, and T24. This was a prospective, randomised investigation to evaluate the efficacy of tramadol and methadone as premedications in dogs undergoing osteotomies.

RESULTS

There were no statistically significant differences between groups with respect to age, weight, gender, surgery time, and time to extubation. Heart rate, respiratory rate, and blood pressure values were maintained within acceptable ranges, and a reduction was observed at T2 in MET0.5 and MET0.7 compared with TBL. Increases in VAS scores were observed in TRA at T4 compared with TBL, T1, and T24 and between T1 and T6 (p < 0.001). In MET0.5, there was significant increase in VAS score at T4 compared with T1 (p < 0.001). TRA and MET0.5 showed significantly higher mean ± SD VAS scores (3.4 ± 2.5 and 2.5 ± 2.6, respectively) than MET0.7 (1.1 ± 1.5) at T4 (p < 0.001). TRA showed greater demand of rescue analgesia (four animals in T4 and two in T6) (p < 0.037). There were no statistically significant differences in sedation scores, Colorado Scale scores, or interleukin levels between groups and time points.

CONCLUSIONS

Methadone given as premedication in doses of 0.7 mg/kg was better at controlling pain compared with lower doses and tramadol. However, dosage increases, administered as rescue analgesia, promoted adequate pain control even in tramadol group. Influence of these analgesics on IL-6 release could not be demonstrated, but significant levels were not found.

Cardiac responses to palpation per rectum in lactating and nonlactating dairy cows

Interest in the monitoring of heart rate variability (HRV) has increased recently, as it gives more detailed and immediate information about the level of stress than traditional behavioral or hypothalamus-pituitary-adrenal measures. In this study, we evaluated heart rate (HR) and parasympathetic HRV parameters to monitor cardiac stress responses to palpation per rectum (PPR) in lactating (LACT; n = 11) and nonlactating (NLACT; n = 12) dairy cows. Heart rate and HRV were recorded from 40 min before PPR until 120 min after it was completed. Heart rate, the root mean square of successive differences (RMSSD), and the high-frequency component (HF) of HRV were analyzed by examining 5-min time windows. To compare cardiac responses to PPR between groups, changes in HR and HRV parameters were calculated as area under the curve (AUC) for LACT and NLACT cows. An immediate increase in HR was detected during PPR in both LACT (+21.4 ± 2.4 beats/min) and NLACT cows (+20.6 ± 2.3 beats/min); however, no differences were found between groups on the basis of parameters of AUC. The increase in HR in both groups along with a parallel decrease in RMSSD (LACT cows: -5.2 ± 0.4 ms; NLACT cows: -5.1 ± 0.4 ms) and HF [LACT cows: -10.1 ± 0.8 nu (where nu = normalized units); NLACT cows: -16.9 ± 1.2 nu] during PPR indicate an increase in the sympathetic, and a decrease in the parasympathetic tone of the autonomic nervous system. The increase in RMSSD (LACT cows: +7.3 ± 0.7 ms; NL cows: +17.8 ± 2.2 ms) and in HF (LACT cows: +24.3 ± 2.6 nu; NLACT cows: +32.7 ± 3.5 nu) immediately after PPR indicated a rapid increase in parasympathetic activity, which decreased under the baseline values 10 min following PPR. The amplitude and the maximum RMSSD and HF values were greater in NLACT cows than in LACT animals, suggesting a higher short-term cardiac responsiveness of NLACT cows. However, the magnitude and the duration of the stress response were greater in LACT cows, as indicated by the analysis of AUC parameters (area under the HRV response curve and time to return to baseline). Cow response to the PPR was more prominent in parasympathetic HRV measures than in HR. Based on our results, the effect of PPR on the cows' cardiac stress responses may have an impact on animal welfare on dairy farms, and investigating the effect of lactation on the cardiac stress reactions could prove useful in modeling bovine stress sensitivity. Further research is needed to find out whether the differences due to lactation are physiological or management related.

The effect of low-level laser on postoperative pain after tibial fracture surgery: a double-blind controlled randomized clinical trial

Background:

Postoperative pain is a common complication that can lead to serious morbidities and delayed recovery.

Objectives:

The aim of this study was to investigate the effect of low-level laser therapy on acute pain after tibial fracture surgery.

Patients and Methods:

In this randomized clinical trial, 54 patients who were candidate for tibial fracture surgery were allocated randomly to two groups, namely, control and laser therapy. Both groups had the same type of surgery and technique of spinal anesthesia. Patients in laser group were treated with the combination of two lasers (GaALAs, 808 nm; and GaALInP, 650 nm) at the end of the surgery while control group received laser in turn-off mode with the same duration as laser group. Patients were evaluated for pain intensity according to the visual analogue scale (VAS) and the amount of analgesic use during 24 hours after surgery.

Results:

Laser group experienced less pain intensity in comparison with control group at second, fourth, eighth, 12^th, and 24^th hours after surgery (P Value < 0.05). In addition, the amount of consumed opioid in laser group was significantly less than the control group (51.62 ± 29.52 and 89.28 ± 35.54 mg, respectively; P Value, 0.008).

Conclusions:

Low Level Laser Therapy is a proper method to reduce postoperative pain because it is painless, safe, and noninvasive and is easily accepted by patients.

Assessment of postoperative pain intensity by using photoplethysmography

PURPOSE

Timely assessment of acute postoperative pain is very important for pain management. No objective and reliable method to assess postoperative pain intensity exists till now. The aim of the study was to investigate the feasibility of photoplethysmography (PPG) signals in postoperative pain assessment.

METHODS

Thirty patients scheduled for elective abdominal surgery under general anesthesia were examined. Finger PPG signals and visual analogue scale (VAS) score were acquired before and 5, 10, 20, and 30 min after sufentanil administration when the patients were awake and transferred to the post-anesthesia care unit (PACU). During each pain rating, the patient's blood pressure, heart rate, and pulse oxygen saturation were recorded. The amplitude of alternating current (AC) and direct current (DC) extracted from finger PPG signals were analyzed, and the ratio of AC and DC (AC/DC) was calculated. Receiver operating characteristic (ROC) curves were built to assess the performance of AC and AC/DC to detect patients with VAS >4 in the PACU.

RESULTS

After administration of sufentanil, VAS scores decreased significantly (p < 0.05), as did blood pressure and heart rate. Simultaneously, both values of AC and AC/DC increased significantly. The VAS score had significant correlations with AC (r = -0.477; p < 0.01), AC/DC (r = -0.738; p < 0.01) and heart rate (r = 0.280; p < 0.01). In contrast, no statistical correlations between VAS score and blood pressure were found. Further analysis found significant differences in both AC and AC/DC among different pain levels, but no obvious differences in blood pressures and heart rate. The area under the ROC curves were 0.754 for AC and 0.795 for AC/DC, respectively.

CONCLUSION

The finger PPG signal can be used in acute postoperative pain assessment. Both AC/DC and AC had significant correlations with the pain rating levels, while blood pressure and heart rate were unreliable in pain assessment.

Effectiveness of local anaesthetic pain catheters for abdominal donor site analgesia in patients undergoing free lower abdominal flap breast reconstruction: A meta-analysis of comparative studies

The use of an infusion pain pump with local wound catheters has increased among different surgical specialities. Autologous breast reconstruction with deep inferior epigastric perforator (DIEP) and transverse rectus abdominis myocutaneous (TRAM) flaps may cause severe abdominal donor site morbidity, and infusion devices delivering local anaesthetic are suggested to improve postoperative analgesia. This study performed a meta-analysis comparing pain pump use vs control to evaluate this issue. A systematic literature search was performed. Primary outcome was the amount of opioid use. Secondary outcomes were the amount of antiemetic drugs and the length of hospital stay. Five studies involving 248 patients were retrieved and included in the present analysis. A significantly decreased use of opioids was observed after using pain pump vs control (MD = -15.13, 95% CI = -24.20, -6.06, p = 0.001). Although not statistically significant, the pooled results showed a trend toward reduction of antiemetic medicament use (MD = -0.71, 95% CI = -2.14, 0.72, p = 0.33) and hospital stay time (MD = -0.53, 95% CI = -1.18, 0.11, p = 0.10). The use of local anaesthetic pain catheters for abdominal donor sites in microsurgical breast reconstruction might be associated with a decreased use of narcotics and antiemetic medicaments and shorter hospital stay. Further studies are needed to validate this promising treatment modality.