Leopoldo Muniz da Silva

Emergence agitation in pediatric anesthesia: current features

OBJECTIVE Postoperative agitation in children is a well-documented clinical phenomenon with incidence ranging from 10% to 67%. There is no definitive explanation for this agitation. Possible causes include rapid awakening in unfamiliar settings, pain (wounds, sore throat, bladder distension, etc.), stress during induction, hypoxemia, airway obstruction, noisy environment, anesthesia duration, childs personality, premedication and type of anesthesia. The purpose of this paper is to discuss the possible causes of postoperative agitation in children, providing a foundation for better methods of identifying and preventing this problem. SOURCES MEDLINE and PubMed were searched using the following words: emergence, agitation, incidence, etiology, diagnosis, treatment, children, pediatric, anesthesia. SUMMARY OF THE FINDINGS This study includes a review of potential agitation trigger factors and a proposal for a standardized diagnostic score system, in addition to measures to improve prevention and treatment. CONCLUSION No single factor can identified as the cause of postoperative agitation, which should therefore be considered a syndrome made up of biological, pharmacological, psychological and social components, and which anesthesiologists and pediatric intensive care specialists should be prepared to identify, prevent and intervene appropriately as necessary.

Dexmedetomidine and S(+)-ketamine in ischemia and reperfusion injury in the rat kidney

PURPOSE To investigate blood creatinine and renal histology in rats anesthetized with S(+)-ketamine (keta) or dexmedetomidine (dex) and submitted to kidney ischemia/reperfusion injury (IRI). METHODS Under intraperitoneal (ip) S(+)-ketamine, 20 male Wistar rats were divided into two groups (n=10): maintenance with iv S(+)-ketamine or dex (keta and dex groups), and submitted to right (R) nephrectomy and left (L) renal artery clamping for 45 min. Blood creatinine was measured before ischemia (T1) and 48h after reperfusion (T2), when L nephrectomy was performed. Histological analysis was performed in all kidneys. RESULTS Blood creatinine was significantly higher at T2 in both groups, but dex group results were lower than those of keta group. Histological changes: between groups, R kidneys did not differ; there were significant high scores for vascular dilation: keta L kidneys; for vascular congestion, tubular dilation, and necrosis: L kidneys from both groups; for tubular degeneration: keta R kidneys. CONCLUSION S(+)-ketamine plus IRI were aggressive to rat kidneys, according to histological changes, and dexmedetomidine may have not totally protected the kidneys from these injuries, despite the better results of blood creatinine.

Prevention of renal ischemia/reperfusion injury in rats using acetylcysteine after anesthesia with isoflurane

PURPOSE To evaluate the effect of N-acetylcysteine, as a renoprotective agent, when administered early after anesthesia induction, against ischemia/reperfusion injury in rats anesthetized with isoflurane. METHODS Eighteen male Wistar rats weighing > 300 g were anesthetized with isoflurane. The internal jugular vein and the left carotid artery were dissected and cannulated. The animals were randomly divided into GAcetyl, receiving intravenous N-acetylcysteine, 300 mg/kg, and GIsot, isotonic saline. After 30 minutes, right nephrectomy was performed and the left renal artery was clamped during 45 minutes. The animals were sacrificed after 48 hours and blood samples were taken after anesthetic induction and upon sacrificing of the animals to evaluate blood creatinine. The kidneys were sent for histological analysis. RESULTS The variation in serum creatinine was 2.33 mg/dL ± 2.21 in GAcetyl and 4.38 mg/dL ± 2.13 in GIsot (p=0.074). Two animals presented intense tubular necrosis in GAcetyl, compared to 5 in GIsot. Only GAcetyl presented animals free of tubular necrosis (two) and tubular degeneration (one). CONCLUSION After renal ischemia/reperfusion, the rats which were given N-acetylcysteine presented less variation in serum creatinine and milder kidney injuries than the control group.

Renal histology and immunohistochemistry after acute hemorrhage in rats under sevoflurane and ketoprofen effect

PURPOSE To investigate the influence of intravenous nonselective cyclooxygenase inhibitor, ketoprofen (keto), on kidney histological changes and kidney cytokines, tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1), levels after hemorrhage of 30% of volemia (three times 10%, intervals of 10 min) in rats. METHODS Under sevoflurane (sevo) anesthesia, sevo and sevo+keto groups (10 rats each) were instrumented for Ringer solution (5 mL/kg/h) administration and mean arterial pressure (MAP) evaluation, plus keto (1.5mg/kg) administration in sevo+keto group in the beginning of anesthesia. Rectal temperature was continuously measured. The baseline data of temperature and MAP were collected at the first hemorrhage (T1), the third hemorrhage (T2) and 30 min after T2 (T3). Bilateral nephrectomy was achieved for histology and immunohistochemistry. RESULTS In both groups, temperature and MAP diminished from initial values. Hypothermia was greater in sevo group (p=0.0002). Tubular necrosis was more frequent in sevo group (p=0.02). The studied cytokines were equally present in the kidneys of both groups. CONCLUSION Ketoprofen was more protective to the rat kidney in condition of anesthesia with sevoflurane and hypovolemia, but it seems that TNF-α and IL-1 were not involved in that protection.

Parecoxib reduces renal injury in an ischemia/reperfusion model in rats

PURPOSE To evaluate the effect of parecoxib (an NSAID) on renal function by measuring plasma NGAL (serum neutrophil gelatinase-associated lipocalin) levels in an induced-ischemia rat model. METHODS Forty male Wistar rats were randomly assigned to one of four groups: Ischemia (I), Ischemia/parecoxib (IP), No-ischemia (NI), and No-ischemia/parecoxib (NIP). Body weight, mean arterial pressure, heart rate, body temperature, NGAL levels, and renal histology were compared across groups. RESULTS The Ischemia (I) group, which did not receive parecoxib, showed the highest NGAL levels (p=0.001), while the IP group, which received the medication, had NGAL levels similar to those of the non-ischemic (NI and NIP) groups. CONCLUSION Parecoxib resulted in renal protection in this experimental model.

Enzyme Biomarkers of Renal Tubular Injury in Arterial Surgery Patients

Objective: The aim of this study was to verify whether preoperative diabetes, hypertension, and renal function had any relationship with postoperative tubule function in patients submitted to anesthesia for arterial surgery. Methods: Prospective observational study. One hundred and forty-four patients submitted to anesthesia for arterial surgery enrolled consecutively and divided into four groups: G1 – diabetes and hypertension; G2 – diabetes; G3 – hypertension; and G4 – without hypertension or diabetes. Urine was obtained for laboratory analysis of urinary creatinine (Ucr), alkaline phosphatase (AP), γ-glutamyltransferase (γGT), and blood for cystatin C and creatinine before the surgery (M1) and 24 h after the surgery (M2). Results: Values of γGT, γGT/Ucr, and AP × γGT/Ucr increased at M2 in G4. Patients without renal function compromise (GFR ≥90 mL/min/1.73 m2) presented increased γGT/Ucr and AP × γGT/Ucr values at M2 and those with slightly compromised renal function (60–89 mL/min/1.73 m2) presented increased γGT values at M2. There was no correlation between deltaCystatin C and deltaAP, deltaγGT, deltaγGT/Ucr, deltaAP/Ucr, and deltaAP × γGT/Ucr. Conclusions: Diabetes, hypertension, and preoperative renal function seem to interfere in tubular enzymuria immediately after surgery in arteriopathic patients. However, when these markers do not increase in postoperative period, renal dysfunction cannot be discarded.

Total Spinal Anesthesia Failure: Have You Assessed the Sensory Anesthesia in Sacral Dermatomes?

Intrathecal local anesthetic maldistribution is a well-known cause of spinal anesthesia failure (SAF). This could potentially result in sensory blockade restricted to the sacral dermatomes. We sought to determine the overall incidence of SAF and the role of sacral dermatomes in differentiating between total and partial failures. Of the 3111 spinals prospectively examined, 194 (6.2%) were classified as failures. Of the 72 presumed total failures based on the initial assessment, evaluation of the sacral dermatomes revealed sensory blockade in 32 (44%; 95% confidence interval, 32.7%–56.6%). Sacral dermatome assessment after SAF may be important in safely guiding subsequent anesthetic management.

Bedside tests to predict laryngoscopic difficulty in pediatric patients

BACKGROUND AND OBJECTIVES Pediatric airway management is a priority during anesthesia, critical care and emergency medicine. The purpose of this study is to validate bedside tests that predict airway management difficulty in anesthetized children. METHODS Children under 12 years of age were recruited in a cross-sectional study to assess the value of some anthropometric measures as predictors of laryngoscopic difficulty. The patients were divided into three groups by age. Weight, height, neck circumference, BMI (body mass index), inter incisors distance thyromental distance, sternomental distance, frontal plane to chin distance (FPCD) and the Mallampati index were determined and were correlated with the CML (Cormack & Lehane classification). RESULTS The incidence of difficult laryngoscopy (CML 3 or 4) was 3.58%. Factors that were significantly associated with laryngoscopic difficulty included short inter incisors distance, high FPCD, thyromental distance, sternomental distance and the Mallampati index. The FPCD/weight index exhibited a higher area under the ROC curve than any other variable considered. CONCLUSIONS This study confirms that the FPCD and the FPCD/weight ratio are the most consistent predictors of laryngoscopic difficulty in pediatric patients. For patients over 6 months of age, the IID also correlated with laryngoscopic difficulty. For children who were capable of obeying simple orders, the Mallampati test correlated better with laryngoscopic difficulty than did the Mallampati test with phonation. Our results strongly suggest that skilled professionals should perform airway management in children, especially in patients with a high FPCD or a high FPCD/weight ratio.

Myocardial contractility impairment with racemic bupivacaine, non-racemic bupivacaine and ropivacaine. A comparative study

PURPOSE To study racemic bupivacaine, non-racemic bupivacaine and ropivacaine on myocardial contractility. METHODS Isolated Wistar papillary muscles were submitted to 50 and 100 mM racemic bupivacaine (B50 and B100), non-racemic bupivacaine (NR50 and NR100) and ropivacaine (R50 and R100) intoxication. Isometric contraction data were obtained in basal condition (0.2 Hz), after increasing the frequency of stimulation to 1.0 Hz and after 5, 10 and 15 min of local anesthetic intoxication. Data were analyzed as relative changes of variation. RESULTS Developed tension was higher with R100 than B100 at D1 (4.3 ± 41.1 vs -57.9 ± 48.1). Resting tension was altered with B50 (-10.6 ± 23.8 vs -4.7 ± 5.0) and R50 (-14.0 ± 20.5 vs -0.5 ± 7.1) between D1 and D3. Maximum rate of tension development was lower with B100 (-56.6 ± 38.0) than R50 (-6.3 ± 37.9) and R100 (-1.9 ± 37.2) in D1. B50, B100 and NR100 modified the maximum rate of tension decline from D1 through D2. Time to peak tension was changed with NR50 between D1 and D2. CONCLUSIONS Racemic bupivacaine depressed myocardial contractile force more than non-racemic bupivacaine and ropivacaine. Non-racemic and racemic bupivacaine caused myocardial relaxation impairment more than ropivacaine.

Effect of L-Arginine in the irrigation of preovulatory follicle and corpus luteum of young mares

The aim of this study was to analyze the follicle and oocytes morphometry from different follicular classes. The ovaries of 17 queens in anestrus were classified into three groups: Young (0–1 year), Adults (1–6 years) and Older (>6 years). The ovaries were fixed in paraformaldehyde 5%, embedding in paraffin and staining with haematoxylin-eosin. For morphological analysis the tissue sections were photographed by microscope (Olympus BX61) and classified as primordial, unilaminar primary, multilaminar primary, secondary and pre-ovulatory follicles. A total of 1039 follicles were measured and the parameters utilized were: diameter (lm), area (lm2) and perimeter (lm). The statistical used were ANOVA and the means were compared by Tukey test and medians using the Kruskal-Wallis test followed by Dunn’s multiple comparisons (p < 0.05). In young queens primordial follicles there were increased in the mean diameter, area and perimeter of follicle (45.16 lm, 1941 lm and 157.24 lm) and oocytes (40.55 lm, 1320.4 lm and 129.90 lm) when compared to adults (Follicles: 41.51 lm, 1652.4 lm e 145.56 lm and in oocytes: 37.57 lm, 1134.3 lm and 120.58 lm). A biphasic pattern of follicle and oocyte growth was observed through linear regression. Before antrum formation, follicle (x) and oocyte (y) size were positively and linearly correlated (y = 0.304x + 25.01, r = 0.72), although after antrum formation a negative correlation were found (y = 0.007x + 98.00, r = 0.00). The queen offers many benefits as a model of ovarian folliculogenesis, and may be useful in preserving of endangered animals. Acknowledgements: FAPESP for financial support.