Thoracic sympathetic block reduces respiratory system compliance

Abstract

ORIGINAL ARTICLE INTRODUCTIONAdequate postoperative analgesia is considered to be a major key for reducing pul monary morbidity and improving the outcome. l-3 Thoracic epidural anesthesia (TEA) has been proposed as a reliable analgesic method following thoracic surgery.3 Most of these benefi ts, however, relate to the postoperative or to the so-called perioperative period. Some case reports have suggested that sympathetic block secon dary to thoracic or spinal anesthesia might cause impaired intraoperative ventilation by increasing airway resistance and bronchial reactivity. 4,5 A similar controversy surrounds some aspects of respiratory mechanics in anesthetized humans. Although previous studies have demonstrated that systemic local anesthetic secondary to TEA does not alter airway resistance in humans, and even attenuates bronchial hyperreactivity, 6,7 the effects of thoracic sympathetic block on respiratory mechanics, particularly on its compliance, have been poorly explained.Pressure-volume curves are a feasible method for studying respiratory system mechanics, and the use of a low-fl ow infl ation technique has been established as a reliable and quick method for obtaining these curves. 8,9 The remaining doubts are whether the advantageous postoperative effects of TEA begin intraoperatively, and whether these benefi ts outweigh the undesirable intraoperative effects of thoracic sympathetic block. OBJECTIVETo evaluate the effects of intraoperative thoracic sympathetic block on the elastic, viscoelastic and resistive properties of the respiratory system and its components (chest wall and pulmonary parenchyma), through analysis of pressure-volume curves obtained under quasi-static conditions. METHODS Patient selection Patient selectionPatients requiring pulmonary segmental resection, pulmonary lobectomy, pulmonary biopsy or mediastinal nodular resection were eligible for the study. Those classifi ed on the American Society of Anesthesiologists (ASA) scale as having a physical status score of 3 or higher were excluded, as were those presenting with moderate or severe obstructive respiratory disease, or any degree of restrictive respiratory disease, as diagnosed by spirometry and/or clinical signs. Written informed consent was obtained from each patient, and the study was approved by the hospital's Ethics Committee.Patients were randomly assigned to one of two anesthetic solutions that were injected into the epidural space: 15 ml of 0.5% bupivacaine plus epinephrine 1:200,000 and 2 mg morphine chlorohydrate (bupivacaine group), or 15 ml 0.9% NaCl plus epinephrine 1:200,000 and 2 mg morphine chlorohydrate (placebo group). Randomization and blindness were achieved by having an anesthesiologist who was not involved in the study make the draw for the two solutions by means of a randomization table that identifi ed the patients. Anesthesia AnesthesiaAll patients were administered epidural and general anesthesia. They were premedicated with 10 mg of diazepam orally the night before surgery and 0.1 mg/kg of ...

Use of invasive placebos in research on local anaesthetic interventions

“…The literature search identified 452 potentially eligible RCTs. After the abstracts were reviewed, 69 trial reports were retrieved in full to confirm that they met the inclusion criteria and 10 trial reports [14–23] were excluded for various reasons (Fig. 1).…”

Optimizing Perioperative Ventilation Support with Adequate Settings of Positive End-Expiratory Pressure

“…In the past three decades, a multitude of physicians and scientists dedicated themselves to identify the best PEEP levels for patients under surgeries (Beiderlinden et al, 2003, Berendes et al, 1996, Bensenor et al, 2007, as well as patients with variable diseases, such as ALI or ARDS (Badet et al, 2009, Huh et al, 2009, morbid obesity (Bohm et al, 2009, Erlandsson et al, 2006, chronic obstructive pulmonary disease (COPD) (Glerant et al, 2005, Mancebo et al, 2000, brain-injury (Shapiro andMarshall, 1978, Huynh et al, 2002), including infants (Greenough et al, 1992, Dimitriou et al, 1999. Although different terminologies and endpoints for optimizing PEEP were used (Villar, 2005), most of the approaches tried to obtain the best oxygenation while minimizing VILI as outcome.…”

Front Lines of Thoracic Surgery

“…In the past three decades, a multitude of physicians and scientists dedicated themselves to identify the best PEEP levels for patients under surgeries (Beiderlinden et al, 2003, Berendes et al, 1996, Bensenor et al, 2007, as well as patients with variable diseases, such as ALI or ARDS (Badet et al, 2009, morbid obesity (Bohm et al, 2009, Erlandsson et al, 2006, chronic obstructive pulmonary disease (COPD) (Glerant et al, 2005, Mancebo et al, 2000, brain-injury Marshall, 1978, Huynh et al, 2002), including infants (Greenough et al, 1992, Dimitriou et al, 1999. Although different terminologies and endpoints for optimizing PEEP were used (Villar, 2005), most of the approaches tried to obtain the best oxygenation while minimizing VILI as outcome.…”