Artigo recomendado: Thoracic sympathetic block reduces respiratory system compliance

Fábio Ely Martins Benseñor, Joaquim Edson Vieira, José Otávio Costa Auler Júnior (Anesthesia Department, Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil)

Sao Paulo Med J. 2007;125(1):9-14

CONTEXT AND OBJECTIVE

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

DESIGN AND SETTING

Randomized, doubleblind 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, fl ows 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. Student’s 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.

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