Two-week cast immobilization induced chronic widespread hyperalgesia in rats.

It has been postulated that physical immobilization is an essential factor in developing chronic pain after trauma or surgery in an extremity. However, the mechanisms of sustained immobilization-induced chronic pain remain poorly understood. The present study, therefore, aimed to develop a rat model for chronic post-cast pain (CPCP) and to clarify the mechanism(s) underlying CPCP. To investigate the effects of cast immobilization on pain behaviours in rats, one hindlimb was immobilized for 2 weeks with a cast and remobilization was conducted for 10 weeks. Cast immobilization induced muscle atrophy and inflammatory changes in the immobilized hindlimb that began 2 h after cast removal and continued for 1 week. Spontaneous pain-related behaviours (licking and reduction in weight bearing) in the immobilized hindlimb were observed for 2 weeks, and widespread mechanical hyperalgesia in bilateral calves, hindpaws and tail all continued for 5-10 weeks after cast removal. A sciatic nerve block with lidocaine 24 h after cast removal transitorily abolished bilateral mechanical hyperalgesia in CPCP rats, suggesting that sensory inputs originating in the immobilized hindlimb contribute to the mechanism of both ipsilateral and contralateral hyperalgesia. Intraperitoneal injection of the free radical scavengers 4-hydroxy-2,2,6,6-tetramethylpiperydine-1-oxy1 or N-acetylcysteine 24 h after cast removal clearly inhibited mechanical hyperalgesia in bilateral calves and hindpaws in CPCP rats. These results suggest that cast immobilization induces ischaemia/reperfusion injury in the hindlimb and consequent production of oxygen free radicals, which may be involved in the mechanism of widespread hyperalgesia in CPCP rats.

Increased heart rate variability correlation between mother and child immediately pre-operation.

BACKGROUND: Maternal distress would correlate with the children's mental status, thereby influencing the activity of the autonomic nervous system (ANS) of the children and mothers. We hypothesized that pre-anesthetic maternal ANS activity, when approaching close to their children's operation time, would correlate with children's ANS activity, and that the values of heart rate variability (HRV) would correlate. METHODS: We calculated maternal and children's HRVs and analyzed the relationship between the two. A total of 24 pairs of mother and child were analyzed. Maternal and children's HRVs were recorded from the night before the child's surgery to the arrival to the operation room. RESULTS: The ratios of low-frequency components (LF) to high-frequency components (HF) (LF/HF ratio) of children's and maternal HRVs obtained during the immediate pre-operative period (06:00-08:00 hours) showed a significantly, positive correlation, but no correlation was found for the LF/HF ratios obtained during the pre-operative night. CONCLUSION: The LF/HF ratios of HRV immediately before surgery in children and mothers showed a significant positive correlation.

Intra-operative natural sound decreases salivary amylase activity of patients undergoing inguinal hernia repair under epidural anesthesia.

BACKGROUND: The perioperative period is psychologically as well as physically stressful for patients. Although music and sound are known to reduce patients' psychological stress, a few previous studies showed an objective outcome of music. The aim of the present study was to evaluate the relaxing effect of music during epidural anesthesia, using patients' salivary amylase activity. METHODS: Thirty-two American Society of Anesthesiologists (ASA) I or II patients presenting for inguinal hernia repair under epidural anesthesia were randomly assigned to listen to sounds of a soft wind and a twitter (S group) or to have no sounds (N group). Patients' salivary amylase activity was evaluated on arrival to the operating room and at wound closure. RESULTS: Intra-operative music significantly decreased salivary amylase activity at wound closure in the S group and the activity at wound closure of the S group was significantly smaller than that of the N group. CONCLUSION: Intra-operative natural sound significantly decreased salivary amylase activity of patients undergoing inguinal hernia repair under epidural anesthesia.

Transcutaneous electrical nerve stimulation at the PC-5 and PC-6 acupoints reduced the severity of hypotension after spinal anaesthesia in patients undergoing Caesarean section.

BACKGROUND: Despite prophylactic measures, hypotension remains a common side-effect of spinal anaesthesia for parturients. Electroacupuncture at the Neiguan (PC-6) and Jianshi (PC-5) points influences haemodynamics. We thus hypothesized that transcutaneous electrical nerve stimulation (TENS) at traditionally used acupuncture points would reduce the severity of hypotension after spinal anaesthesia in patients undergoing Caesarean section. METHODS: After obtaining approval from the local ethics committee and written informed patient consent, 36 singleton parturients undergoing Caesarean section under spinal anaesthesia were randomized into three groups. The control group received no treatment, and the acupoint and non-acupoint groups received TENS at the PC-5 and PC-6 points of both arms and non-acupoints of both shoulders, respectively. RESULTS: The median (range) of the lowest recorded systolic blood pressure was significantly higher in the acupoint group compared with the other groups and that of the non-acupoint group was higher than that of the control group [control, 70 (68-82) mm Hg; acupoint, 94 (84-109) mm Hg; non-acupoint, 81 (70-92) mm Hg: P<0.001]. Significantly more parturients in the control and non-acupoint groups experienced hypotension [control, 10 (83%); acupoint, 4 (33%); non-acupoint, 10 (83%): P=0.013]. More ephedrine was required to maintain arterial blood pressure in the control and non-acupoint groups. CONCLUSIONS: TENS on the traditional acupuncture points reduced the severity and incidence of hypotension after spinal anaesthesia in parturients.

Induction and emergence behavior of children undergoing general anesthesia correlates with maternal salivary amylase activity before the anesthesia.

BACKGROUND: The parents of the children who undergo surgery experience stress during the pre-anesthetic period. Such stress influences the mental status of their children, thereby inducing their pre-anesthetic anxiety and problematic behavior at emergence. Recently, measurement of salivary biomarkers was evaluated as stress biomarkers. Especially, alpha-amylase is utilized as an excellent index for psychological stress. In the present study, we tested whether salivary amylase activity of mothers before the surgery of their children correlates with the peri-operative children's behaviors. METHODS: A total of 22 pairs of mothers and children were analyzed. Maternal salivary amylase activity was evaluated at the entrance of the operation room. The children underwent minor plastic surgery under general anesthesia, and induction and emergence behaviors were assessed. RESULTS: The higher the maternal salivary amylase activity, the severer the children's induction anxiety (r(s)=-0.667, n=22, P<0.0001), and the higher the maternal amylase activity, the severer the children's emergence agitation (r(s)=0.705, n=22, P<0.0001). CONCLUSION: Induction and emergence behaviors of children undergoing general anesthesia significantly correlated with their respective maternal salivary amylase activity during the pre-anesthetic period.

Parental presence during induction enhances the effect of oral midazolam on emergence behavior of children undergoing general anesthesia.

BACKGROUND: Pre-anesthetic anxiety and emergence agitation are major challenges for anesthesiologists in pediatric anesthesia. Thus, sedative premedication and parental presence during induction of anesthesia (PPIA) are used to treat pre-anesthetic anxiety in children. The aim of the present study was to test if a combination of mother presence and midazolam premedication is effective for improving emergence condition in children undergoing general anesthesia. METHODS: Sixty children were allocated to one of three groups: a sedative group (0.5 mg/kg oral midazolam), a PPIA group or a sedative and PPIA group. When anesthesia was induced with 7% sevoflurane in 100% oxygen, qualities of mask induction were rated. Anesthesia was maintained with sevoflurane (1.5-2.5%) in 60% oxygen and intravenous fentanyl 4 microg/kg. During emergence from anesthesia, the score of the child's emergence behavior was rated. RESULTS: The children in the midazolam group showed a better quality of mask induction compared with those in the PPIA group, the addition of parental presence to oral midazolam did not provide additional improvement of mask induction. In contrast, the children in the midazolam + PPIA group were less agitated than those in the other groups at emergence from anesthesia. CONCLUSION: Parental presence during induction of anesthesia enhanced the effect of oral midazolam on emergence behavior of children undergoing general anesthesia.

The effect of intrathecal fentanyl added to hyperbaric bupivacaine on maternal respiratory function during Cesarean section.

BACKGROUND: Subarachnoid blockade with local anesthetics induces respiratory depression. Although the addition of fentanyl to bupivacaine has become popular in subarachnoid blockade for Cesarean section, there is no information on the effect of intrathecal fentanyl on maternal spirometric respiratory function in parturients undergoing Cesarean section. METHODS: We tested the effect of the addition of intrathecal fentanyl to hyperbaric bupivacaine on maternal spirometric performance in 40 consenting parturients undergoing Cesarean section. The parturients were randomized into two groups: those receiving 2.0 ml of hyperbaric bupivacaine 0.5% and 0.4 ml of saline intrathecally and those receiving 2.0 ml of hyperbaric bupivacaine and 0.4 ml of fentanyl (20 microg) intrathecally. We performed spirometry on arriving at the operation room and 15 min after subarachnoid blockade. RESULTS: Subarachnoid blockade with bupivacaine significantly decreased the peak expiratory flow rate, but did not induce significant changes in vital capacity and forced vital capacity. The addition of intrathecal fentanyl to bupivacaine improved the quality of subarachnoid blockade, but did not lead to a deterioration in respiratory function compared with intrathecal bupivacaine alone. CONCLUSIONS: The addition of intrathecal fentanyl to hyperbaric bupivacaine did not lead to a deterioration in maternal spirometric respiratory function in parturients undergoing Cesarean section.

Intra-articular injection of warmed lidocaine improves intraoperative anaesthetic and postoperative analgesic conditions.

BACKGROUND: Although local anaesthesia for knee arthroscopy is a well-documented procedure, arthroscopy under local anaesthesia is often interrupted because of intolerable discomfort and pain. Warming local anaesthetic solutions may increase its anaesthetic effect. We tested whether intra-articular injection of warmed lidocaine solution could improve intraoperative anaesthetic and postoperative analgesic conditions. METHODS: Patients in the warmed group received 20 ml warmed (40 degrees C) lidocaine 1% intra-articularly 20 min before surgery. The patients in the control group received 20 ml room-temperature (25 degrees C) lidocaine 1% intra-articularly 20 min before surgery. During surgery, the patients reported pain on a visual analogue scale (VAS). RESULTS: The median VAS pain score was 1.5 (range, 0.0-3.0) in the warmed lidocaine group and 5.0 (4.0-8.0) in the control group (P<0.001). The median intra- and postoperative analgesic requirements in the control group were significantly greater than that in the warmed group. CONCLUSION: Warmed lidocaine injected intra-articularly provides improved intraoperative anaesthetic and postoperative analgesic conditions for patients undergoing knee arthroscopy.

Comparison of a combination of midazolam and diazepam and midazolam alone as oral premedication on preanesthetic and emergence condition in children.

BACKGROUND: Preanesthetic anxiety and emergence agitation are major challenges for anesthesiologists in pediatric anesthesia. Thus, midazolam has been used as premedication for children. However, midazolam alone is not effective for emergence agitation. The present study tested the effect of a combination of midazolam and diazepam on the preanesthetic condition and emergence behavior in children. METHODS: Forty-two children were allocated to one of three groups: the NoPre group received no premedication; the Mi group received midazolam 0.5 mg kg(-1) orally; and the Mi + Di group received midazolam 0.25 mg kg(-1) and diazepam 0.25 mg kg(-1) orally. When anesthesia was induced with 7% sevoflurane in 100% oxygen, qualities of mask induction and sedation were rated. Anesthesia was maintained with sevoflurane (3-5%) in 100% oxygen. During emergence from anesthesia, the score of the child's emergence behavior was rated. RESULTS: Children in the Mi and Mi + Di groups were more sedated than those in the NoPre group. A combination of midazolam and diazepam provided a better quality of mask induction, when compared with no premedication. Also, the children in the Mi + Di group were less agitated than those in the other groups during the emergence. CONCLUSION: Children in the Mi + Di group were significantly more sedated at induction of anesthesia and less agitated during emergence from anesthesia.

Pre-anesthetic presence of an injured dam influences pups' locomotor behavior during emergence from anesthesia in rats.

BACKGROUND: Pre-anesthetic mother-infant interaction is an important factor for smooth emergence of pediatric anesthesia. In many mammalian species, disruptions of the mother-infant relationship cause psychological and behavioral changes. This study was to investigate whether or not pre-anesthetic presence of an injured dam has an impact on locomotor behavior of rat pups. METHODS: We used a video-tracking system to test the effects of pre-anesthetic relations between pups and their dams on pups' locomotor behavior during emergence from general anesthesia, in 40 3-week-old Sprague-Dawley male rats. Pups were divided into two groups: pups housed with a dam (n = 20) and those housed with an injured dam (n = 20). Pups were anesthetized with 1.2% halothane for 30 min. At emergence, we recorded their locomotor behavior for 15 min. RESULTS: Pre-anesthetic manipulation to dams significantly increased the distance traveled by pups. However, the manipulation did not cause any difference in the maximum velocity. CONCLUSION: Pre-anesthetic presence of an injured dam influenced pups' locomotor behavior at emergence from anesthesia.

Preoperative stellate ganglion blockade prevents tourniquet-induced hypertension during general anesthesia.

BACKGROUND: Prolonged and excessive inflation of pneumatic tourniquets leads to a hyperdynamic circulatory response. Sympathomimetic activity is an important factor in tourniquet-induced hypertension. Stellate ganglion block specifically blunts sympathetic efferent nerves and prevents hypertension induced by sympathomimetic stimulation. The present study was performed to investigate the effects of stellate ganglion block (SGB) on arterial pressure and heart rate during prolonged tourniquet use under general anesthesia. METHODS: Twenty patients scheduled for knee arthroscopy were either treated with 10 ml of 1% lidocaine for SGB (SGB group; n = 10), or intramuscular injection (IM group; n = 10) before tourniquet inflation. Comparisons of systolic and diastolic arterial pressure and heart rate were made before and after the induction of anesthesia, 10 min after the lidocaine treatment, every 5 min during the first 60 min after tourniquet inflation, and immediately before and 5 min following deflation. The maximum values of the circulatory variables were compared. RESULTS: Tourniquet inflation caused increases in the circulatory variables in both groups. Systolic arterial pressure in the SGB group was significantly lower than that in the IM group after 55 min of tourniquet inflation. Diastolic arterial pressure also was significantly lower in the SGB group immediately before the deflation. The maximum values of the three hemodynamic variables were significantly lower in the SGB group. Arterial pressure significantly decreased after tourniquet deflation in the IM group. CONCLUSION: Ipsilateral SGB attenuated the hyperdynamic response mediated by prolonged tourniquet inflation during knee arthroscopy.

Pre-anesthetic maternal separation increases pups' locomotor behavior during emergence from anesthesia in rats.

BACKGROUND: Problematic behavior at emergence from anesthesia in children, partly linked with maternal separation, is a major problem in pediatric anesthesia. In humans, as well as in many other mammalian species, such separation causes psychological and behavioral changes. This study was to investigate whether or not pre-anesthetic maternal separation has a similar effect on rat pups. METHODS: This study was conducted on 66 3-week-old Sprague-Dawley male rats. The rats were divided into two groups; pups housed with a dam (n = 33) and those housed without (n = 33). Pups were anesthetized with 1.2% halothane for 30 min. Afterwards we recorded their locomotor behavior at emergence from general anesthesia using a video tracking system. RESULTS: Pre-anesthetic maternal separation significantly increased the maximum velocity and the distance traveled by pups at the emergence. CONCLUSION: Pre-anesthetic maternal separation influenced pups' locomotive behavior at emergence.