Effects of high thoracic epidural anesthesia and local anesthetics on bronchial hyperreactivity

Retrosternal Block Use in the Treatment for Dyspnoea

We present a technique of retrosternal block for symptomatic treatment for dyspnoea of various aetiologies. In our experience with 20 patients, a retrosternal block using lignocaine improved symptoms within minutes. The block was easy to perform and was helpful when the patients’ symptoms were not relieved by conventional therapy. Prospective controlled studies are needed to further assess this simple and promising treatment.

From "awake" to "monitored anesthesia care" thoracic surgery: A 15 year evolution

Although general anesthesia still represents the standard when performing thoracic surgery, the interest toward alternative methods is increasing. These have evolved from the employ of just local or regional analgesia techniques in completely alert patients (awake thoracic surgery), to more complex protocols entailing conscious sedation and spontaneous ventilation. The main rationale of these methods is to prevent serious complications related to general anesthesia and selective ventilation, such as tracheobronchial injury, acute lung injury, and cardiovascular events. Trends toward shorter hospitalization and reduced overall costs have also been indicated in preliminary reports. Monitored anesthesia care in thoracic surgery can be successfully employed to manage diverse oncologic conditions, such as malignant pleural effusion, peripheral lung nodules, and mediastinal tumors. Main non-oncologic indications include pneumothorax, emphysema, pleural infections, and interstitial lung disease. Furthermore, as the familiarity with this surgical practice has increased, major operations are now being performed this way. Despite the absence of randomized controlled trials, there is preliminary evidence that monitored anesthesia care protocols in thoracic surgery may be beneficial in high-risk patients, with non-inferior efficacy when compared to standard operations under general anesthesia. Monitored anesthesia care in thoracic surgery should enter the armamentarium of modern thoracic surgeons, and adequate training should be scheduled in accredited residency programs.

The effect of thoracosopic thoracic sympathetomy on pulmonary function and bronchial hyperresponsiveness

BACKGROUND

Endoscopic thoracic sympathectic denervation (ESD) is a procedure used in primary hyperhidrosis and upper extremity ischemia. Bronchial tone is affected by the sympathetic and parasympathetic nervous systems and bronchial asthma is associated with an imbalance between them. The aim of this study was to evaluate the effects of ESD on pulmonary function and bronchial hyperresponsiveness (BHR).

PATIENTS AND METHODS

Fifty-eight patients with primary hyperhidrosis (n = 54) or upper limb ischemia (n = 4) were included. Spirometry and bronchial provocation test with methacholine was performed before and 4 weeks after ESD.

RESULTS

Forced expiratory volume in 1 second (FEV(1)) and forced vital capacity (FVC) were significantly decreased early after ESD (from 4.67 +/- 0.84 L and 4.36 +/- 0.85 L to 4.12 +/- 0.78 L and 3.84 +/- 0.82 L, respectively), although no patient complained of an aggravation of respiratory symptoms. Twelve patients (21%) had a positive response to methacholine provocation preoperatively, and all remained positive post surgery. The provocative concentration of methacholine, which brought about a 20% decrease in the FEV(1) in the patients, was not significantly changed after surgery (from 5.1 +/- 4.3 to 4.6 +/- 4.6). Of 46 patients who had a negative result for methacholine challenge preoperatively, 12 (26%) became positive after surgery. In terms of the level of sympathectomy, T3 sympathectomy significantly increased the ratio of patients exhibiting a positive response to methacholine (from 19% to 34%, respectively) (p < 0.005).

CONCLUSIONS

Thoracic sympathectomy can adversely affect lung function early after surgery, although the clinical significance is uncertain. It may also exert an influence on the development of bronchial hyperresponsiveness, especially when performed at the T3 level.

Thoracic sympathetic block reduces respiratory system compliance

CONTEXT AND OBJECTIVE

Thoracic epidural anesthesia (TEA) following thoracic surgery presents known analgesic and respiratory benefits. However, intraoperative thoracic sympathetic block may trigger airway hyperreactivity. This study weighed up these beneficial and undesirable effects on intraoperative respiratory mechanics.

DESIGN AND SETTING

Randomized, double-blind clinical study at a tertiary public hospital.

METHODS

Nineteen patients scheduled for partial lung resection were distributed using a random number table into groups receiving active TEA (15 ml 0.5% bupivacaine, n = 9) or placebo (15 ml 0.9% saline, n = 10) solutions that also contained 1:200,000 epinephrine and 2 mg morphine. Under general anesthesia, flows and airway and esophageal pressures were recorded. Pressure-volume curves, lower inflection points (LIP), resistance and compliance at 10 ml/kg tidal volume were established for respiratory system, chest wall and lungs. Students t test was performed, including confidence intervals (CI).

RESULTS

Bupivacaine rose 5 +/- 1 dermatomes upwards and 6 +/- 1 downwards. LIP was higher in the bupivacaine group (6.2 +/- 2.3 versus 3.6 +/- 0.6 cmH2O, p = 0.016, CI = -3.4 to -1.8). Respiratory system and lung compliance were higher in the placebo group (respectively 73.3 +/- 10.6 versus 51.9 +/- 15.5, p = 0.003, CI = 19.1 to 23.7; 127.2 +/- 31.7 versus 70.2 +/- 23.1 ml/cmH2O, p < 0.001, CI = 61 to 53). Resistance and chest wall compliance showed no difference.

CONCLUSION

TEA decreased respiratory system compliance by reducing its lung component. Resistance was unaffected. Under TEA, positive end-expiratory pressure and recruitment maneuvers are advisable.

[Strategies for perioperative sympatho-modulation]

Despite the growing evidence for the efficacy of different sympatho-modulatory therapies to lower perioperative cardiac morbidity and mortality, such therapeutic strategies are rather infrequently used in daily clinical practice. Most physicians involved in perioperative medicine are aware of the increasing literature related to this topic, but only few comply with current clinical practice guidelines even in the absence of contraindications. This review discusses possible explanations for this reluctance and again summarizes the basic and clinical principles of current sympatho-modulatory therapies including alpha(2)-agonism, beta-adrenergic antagonism, and regional anesthetic techniques in modern anesthetic practice. In addition, the emerging perioperative concept of a patient-tailored individualized pharmacotherapy based on "gene profiling", particularly the adrenergic polymorphisms, is discussed.

Non-analgetic effects of thoracic epidural anaesthesia

PURPOSE OF REVIEW

This review presents a brief overview of the non-analgetic effects of thoracic epidural anaesthesia. It covers the cardiac, pulmonary and gastrointestinal effects of thoracic epidural anaesthesia. The results of newer studies are of particular importance regarding mortality and major morbidity after thoracic epidural anaesthesia.

RECENT FINDINGS

The clinical effects of thoracic epidural anaesthesia are mainly attributed to a transient thoracic sympathetic block affecting different organs. Furthermore, local anaesthetic itself reabsorbed from the epidural space may contribute to the non-analgetic effects of thoracic epidural anaesthesia. Experimental studies have suggested that thoracic epidural anaesthesia may attenuate the perioperative stress response after major surgery. The possible beneficial mechanisms of action include an improvement of left ventricular function by direct anti-ischaemic effects, a reduction in cardiovascular complications, an advance on gastrointestinal function, and a reduction in pulmonary complications, as well as a positive impact on the coagulation system and the postoperative inflammatory response. However, it is questionable whether these effects of thoracic epidural anaesthesia may lead to an improved perioperative outcome after major surgery. Recent studies have suggested that, despite the superior quality of pain relief and better quality of life, thoracic epidural anaesthesia does not reduce mortality and major morbidity, especially after major abdominal and cardiac surgery.

SUMMARY

Despite this controversy, the numerous positive effects and advantages of thoracic epidural anaesthesia are the reasons for its increasing popularity. However, the advantages of thoracic epidural anaesthesia must be incorporated into a multimodal treatment management aimed at improving outcomes after surgery.

Continuous thoracic epidural anesthesia induces segmental sympathetic block in the awake rat

Thoracic epidural anesthesia (TEA) is used increasingly in critical care, especially for cardiac and intestinal sympathetic block. In this study we evaluated cardiorespiratory function and sympathetic activity in a new model of continuous TEA in awake rats. Thirteen rats received epidural saline control (CON) or bupivacaine 0.5% epidural infusion (EPI) at 15 microl/h for 2 h on day 1 and day 3. Mean arterial blood pressure, heart rate, respiration rate, arterial PCO2, and motor score were recorded at baseline and after 30, 60, 90, and 120 min. Skin temperature was measured at front paws, high-thoracic, mid-thoracic, and low-thoracic, hind paws, and the proximal and distal tail. Changes in sympathetic activity were assessed by skin temperature changes from baseline (DeltaT). In the EPI group, hemodynamics and respiration remained unchanged and only mild motor deficits occurred. DeltaT in thoracic segments was higher in the EPI than in the CON group (P <0.001 at all times at high-thoracic, mid-thoracic, and low-thoracic segments). Skin temperature decreased in the distal tail in the EPI group, e.g., after 90 min DeltaT=-0.86 +/- 0.25 degrees C (EPI) versus 0.4 +/- 0.12 degrees C (CON) (P <0.05 at 60, 90, and 120 min). DeltaT on day 3 was comparable to day 1. TEA induced stable segmental sympathetic block without cardiorespiratory and motor side effects in awake rats. This new technique may be applied in prolonged models of critical illness.