Hemodynamic effects of levobupivacaine after pediatric caudal anesthesia evaluated by transesophageal doppler

Background: The aim of this study is to determine if there are significant differences in hemodynamic effects between combined general‐regional anesthesia using levobupivacaine 0.25% 2 ml·kg^?1 via the caudal route in comparison with balanced general anesthesia using continuous infusion of remifentanil in young children undergoing genitourinary surgery. Patients and methods: 62 ASA I‐II pediatric patients (12 female, 50 male) aged 6 months to 7 years undergoing genitourinary surgery were included in the study. Patients were randomly allocated into one of two groups of 31 patients each. Group Caud received caudal blockade with levobupivacaine 0.25% 2 mg·kg^?1 in combined general‐regional anesthesia and Group Gen received balanced general anesthesia with remifentanil. The noninvasive hemodynamic parameters were measured in each group 5 min after induction of general anesthesia or caudal block (Tcaud), after further 5 min coincident with skin incision (Tsi), 10 min after skin incision (T10i), at the end of surgical procedure (Tend). The time between Tcaud and Tsi was 10 min and the measurements during the interval time T10i‐Tend were performed every 15 min according to the duration of surgical procedures. Results: There was a decrease in all measured hemodynamic parameters at skin incision. The decreases occurred in both groups with those in the caudal group occurring at skin incision and those in the balanced anesthesia group occurring at 10 min after skin incision. These variations showed no significant differences for any of the stated outcomes; neither between the groups at each time point nor in the caudal in comparison with baseline measurements. Conclusions: Using transesophageal Doppler no differences in hemodynamic parameters could be detected between balanced general anesthesia with either caudal levobupivacaine or remifentanil infusion. Both techniques showed good hemodynamic stability with only minor changes from baseline over time which are unlikely to be of clinical significance except possibly in patients with preexisting cardiovascular compromise. Other studies with noninvasive monitoring in a larger population are required to better understand the consequences of caudal blockade on CO and on regional blood flow in infants.     

Effect of Propofol, Sevoflurane and Desflurane on systemic redox balance

We studied the effects of Propofol, Desflurane, and Sevoflurane on the systemic redox balance in patients undergoing laparohysterectomy. We measured blood concentration of glutathione (GSH), plasma antioxidant capacity (Trolox Equivalent Antioxidant Capacity-TEAC), and lipid peroxidation products (malondialdehyde (aMDA) and 4-hydroxynonenal (aHNE) protein adducts). Sixty patients were randomly placed into three groups of twenty people each. In Group P anesthesia was induced with Propofol 2 mg/kg and maintained with 12-10-8 mg/kg/min; in Groups S and D anesthesia was induced with 3 mg/kg Sodium Thiopental and maintained with 2 percent Sevoflurane and 6 percent Desflurane, respectively. Blood samples were collected prior to induction (T0 bas), 60min and 24h postoperatively (T1 60 and T2 24 h). In Group P, GSH increased on T1 60 and returned to baseline on T24h, while TEAC remained unmodified; in Groups S, GSH and TEAC decreased on T1 60 in Group D, on T1 60 there was a slight decrease of GSH and TEAC. The levels of aMDA slightly decreased throughout the study periods in Group P, increased in Group D, and remained stable in Group S. Propofol showed antioxidant properties, while Sevoflurane and Desflurane seemed to shift the redox balance towards oxidation, yet without inducing overt oxidative damage.     

Posterior endoscopic discectomy (and other procedures)

Percutaneous approaches to lumbar discectomy were somewhat controversial, because of their limited indications. They have not proven to be as effective as standard open lumbar disc surgery, because of longer operating times and some technical problems in addressing all the different aspects of lumbar disc herniations. New percutaneous posterior procedures for lumbar disc disease have been described in the last few years, but the MicroEndoscopic Discectomy (MED) introduced by Foley and Smith in 1997 seems to be the most promising one. MED, and METR’x which evolved from it, . allow the surgeon to address not only contained lumbar disc herniations, but also free-fragment disc pathology and symptomatic lateral recess stenosis secondary to bony hypertrophy. The surgical technique is summarized and some preliminary clinical results of a prospective multicenter study with 13 months’ mean follow-up are presented.     

Physiological effects of a lung-recruiting strategy applied during one-lung ventilation

Background: One‐lung ventilation (OLV) affects respiratory mechanics and ventilation/perfusion matching, reducing functional residual capacity of the ventilated lung. While the application of a lung‐recruiting manoeuvre (RM) on the ventilated lung has been shown to improve oxygenation, data regarding the impact of RM on respiratory mechanics are not available. Methods: Thirteen patients undergoing lung resection in lateral decubitus were studied. During OLV, a lung‐recruiting strategy consisting in a RM lasting 1 min followed by the application of positive end‐expiratory pressure 5 cmH₂O was applied to the ventilated lung. Haemodynamics, gas exchange and respiratory mechanics parameters were recorded on two‐lung ventilation (TLV_baseline), OLV before and 20 min after the RM (OLV_pre‐RM, OLV_post‐RM, respectively) and TLV_end. Haemodynamics parameters were also recorded during the RM. Results: The PaO₂/FiO₂ ratio was 358±126 on TLV_baseline; it decreased to 235±113 on OLV_pre‐RM (P<0.01) increased to 351±120 on OLV_post‐RM (P<0.01 vs. OLV_pre‐RM), and remain stable thereafter. During the RM, CI decreased from 3.04±0.7 l/m² OLV_pre‐RM to 2.4±0.6 l/m² (P<0.05), and returned to baseline on OLV_post‐RM (3.1±0.7 l/m², NS vs. OLV_pre‐RM). The RM resulted in alveolar recruitment and caused a significant decrease in static elastance of the dependent lung (16.6±8.9 cmH₂O/ml OLV_post‐RM vs. 22.3±8.1 cmH₂O/ml OLV_pre‐RM) (P<0.01). Conclusions: During OLV in lateral decubitus for thoracic surgery, application to the dependent lung a recruiting strategy significantly recruits the dependent lung, improving arterial oxygenation and respiratory mechanics until the end of surgery. However, the transient haemodynamic derangement occurring during the RM should be taken into account.     

Hemodynamic and respiratory changes during hip and knee arthroplasty. An echocardiographic study

BACKGROUND: The "bone cement implantation syndrome" is a rare but severe complication observed especially during the insertion of cemented prostheses in hip and knee replacement surgery. Several mechanisms are involved: effects of methylmethacrilate, embolism of fat, air and bone marrow, and release of tissue thromboplastin during acetabular and femoral reaming. Aim of this study was to detect embolic events, right heart impairment, hemodynamic and respiratory changes during hip and knee replacement surgery. METHODS: Design: Prospective study, between February-May 2001. Environment: Orthopedic Operative room. PATIENTS: Twenty-one patients who underwent total hip or knee arthroplasty under general anesthesia. Patients were divided in methylmethacrylate cemented prostheses groups (CEM, n=10) and totally uncemented prostheses (NON CEM, n=11). Data collection: Standard anesthesia monitoring and omniplane TEE were performed. TEE probe was positioned in order to obtain "inflow-outflow" views of right heart. Measurements were obtained after anesthesia induction (T1), during femoral realing (T2) at prostheses insertion (T3), and at the end of surgery (T4). RESULTS: Hemodynamic and respiratory parameters measured in different phases of surgical procedures were not different within groups and between groups. Fourtheen patients had TEE evidence of emboli, and the phenomenon was more evident in CEM group (Z= -347; p<0.001). During prostheses insertion, a slight, not significant increase in right ventricular dimensions was observed in both groups, without any right ventricular wall kinetic abnormality. No difference was observed between groups. No adverse cardiac or cerebrovascular events in intra- and postoperatory period were observed. CONCLUSIONS: In normal patients total hip or knee arthroplasty is associated with embolic phenomena, without any significant change in systemic and right heart hemodynamics. Insertion of cemented prostheses does not modify hemodynamic profile. It remains to be elucidated if the occurrence of emboli has a critical role in patients with cardiorespiratory disease.     

Micro opioid receptor A118G polymorphism and post-operative pain: opioids' effects on heterozygous patients

The single-nucleotide-polymorphism (SNP) 118A>G in the micro-1 opioid receptor gene (OPRM1) is associated with a decrease in the analgesic effects of opioids. The aim of this study is to assess whether 118A >G polymorphism could influence the analgesic response to opioid-based postoperative pain (POP) therapy. The study consisted of two parts: section alpha, observational, included 199 subjects undergoing scheduled surgical procedures with pain management standardized on surgery invasiveness and on expected level of postoperative pain; section beta, randomized, included 41 women undergoing scheduled caesarean delivery with continuous intra-operative epidural anesthesia and post-operative analgesia (CEA). In both sections, POP was measured over 48 h (T6h-T24h-T48h) by the visual analogue scale (VAS). In section beta we also tested the responsiveness of hypothalamic-pituitary-adrenal axis (HPA) expressed by cortisol levels. In section alpha, with cluster analysis, subjects were analyzed according to their genotype: a group (no. 1) of 34 patients reporting VAS score >3 at every time lapse was identified and included only A118G carriers, while wild-type (A118A - absence of 118A>G polymorphism) patients were unevenly distributed between those with cluster no. 2 (VAS score <3 at every study steps) and those with cluster no. 3 (VAS score progressively reducing from T6h). In section beta, A118G carriers receiving epidural sufentanil had the lowest VAS scores at T24h; also in these patients, cortisol levels remained more stable, with a mild decrease at T6h. This study shows that the OPRM1 118A>G polymorphism affects postoperative pain response in heterozygous patients: they have a different postoperative pain response than patients with wild-type genes, which may affect the efficacy of the analgesic therapy.