Sepsis and Catecholamine Support are the Major Risk Factors for Critical Illness Polyneuropathy after Open Heart Surgery[1]

Background: Critical illness polyneuropathy (CIP) remains a problem after open heart surgery. Recently, we reported about a retrospectively performed study pointing out that sepsis, the application of higher amounts of catecholamines and intervention such as chronic venovenous hemodiafiltration may be involved in the onset of CIP. A prospectively performed study is presented in order to evaluate the significance of risk factors initially after open heart surgery. Methods: From June 1997 until September 1998, patients undergoing open heart surgery and being ventilated beyond 3 days were prospectively enrolled in the study and underwent a standard protocol of electromyographic investigation in order to determine CIP. Several items were recorded: amount of catecholamines, serum levels of urea, creatinine, albumine, and glucose. The duration of sepsis and chronic venovenous hemodiafiltration were reevaluated. Additionally the age, the left ventricular enddiastolic pressure prior to the operation, the time of ICU stay and the time of ventilatory support were compared. Results: Within the observation period, 37 adult patients could be enrolled in the study, whereas 12 patients did develop CIP and 7 patients did not. Patients developing CIP required significantly different amounts of epinephrine (0.17 ± 0.02 vs. 0.09 ± 0.01 mg/kg/day, p < 0.05, t-test) higher amounts of norepinephrine (0.06 ± 0.02 vs. 0.02 ± 0.01 mg/kg/day, p < 0.05, t-test), and lesser dosages of dobutamine (2.2 ± 0.5 vs. 4.9 ± 0.7, p < 0.05, t-test). After cardiac surgery, the plasma levels of urea was initially significantly elevated in patients developing CIP (127.4 ± 10.5 vs 97.3 ± 18.5, p < 0.05, t-test) Patients suffering from CIP stayed significantly longer in the ICU (40.3 ± 11.7 vs. 19.6 ± 11.3 days, p < 0.05 t-test) with an extended time of ventilator support. (769.6 ± 205.0 vs 295.0 ± 134.0 hours, p < 0.05, t-test). Patients of the CIP group were suffering significant longer from sepsis than patients without CIP. Conclusions: Sepsis and catecholamine support and an increased level of urea were associated with the development of CIP. The prevention of sepsis and a modulation of the catecholamine support in order to improve microcirculatory flow may reduce the onset of CIP in patients undergoing open heart surgery.

Key words:

Critical illness polyneuropathy - - Cardiac surgery - - Microcirculation - - Sepsis - - Catecholamine support - - Microcirculatory flow

1 This work was presented in part at the 28^th Annual Meeting of the German Society for Thoracic and Cardiovascular Surgery, Dresden, February 24 to 27, 1999

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1 This work was presented in part at the 28^th Annual Meeting of the German Society for Thoracic and Cardiovascular Surgery, Dresden, February 24 to 27, 1999