The effects of shivering on oxygen consumption and carbon dioxide production in patients rewarming from hypothermic cardiopulmonary bypass

Abstract

Oxygen consumption (r carbon dioxide production ('(/C02). end-t~dat carbon dioxide partial pressure (PETC02), mixed venous oxygen saturation (S;'02) and haemodynamic variables were recorded every 30 rain for four hours in 1_5 patients recovering from hypothermic cardiopulmonary bypass (CPBFollowing hypothermic cardiopulmonary bypass (CPB), patients usually arrive in the Intensive Care Unit (ICU) with a nasopharyngeal temperature (NPT) of 34-36 ' C. t Sladen et al. showed that over the subsequent 8 hr patients rewarm to normothermia, with the maximal rate of rewarrning occurring 2-4 hr after admission to the ICU.2 During this period of very rapid rewarming, marked changes have been suggested in both metabolic rate and myocardial work) '4 Increases in 02 consumption (VO2) and carbon dioxide production ('i/CO2) are undesirable in post-CPB patients because they lead to increases in heart rate (HR), mean arterial pressure (MAP) and rate pressure product (RPP) s causing an increase in myocardial oxygen consumption.6 Moreover, if the extent of these metabolic changes is not recognized then both respiratory and metabolic acidosis may occur. The present study was designed to determine the extent of these metabolic changes and their haemodynamic consequences during the first four hours after CPB. We also wished to determine the effects of shivering on these variables, if these effects are significant and how best to follow their trend. MethodsFifteen patients scheduled for elective cardiac surgery were studied. Patients with symptomatic peripheral vas- CAN J ANAESTH 1988 ; 35:4 / pp332-7

Metabolic Impact of Shivering During Therapeutic Temperature Modulation

“…The clinical consequences of shivering can include increased tissue ischemia, which has been associated with increased morbidity in postoperative patients who have undergone cardiac surgery. 25 We have shown that shivering during therapeutic normothermia is associated with lower Glasgow Coma Scale scores in neurocritical care patients, which most likely reflects the sedation required to adequately treat shivering. 15 The ability to titrate antishivering therapy with short-acting opioids or other sedative agents to a BSAS score of 1 might provide allow clinicians to eliminate harmful levels shivering without oversedating.…”

Diagnosis, prevention and treatment of accidental and perioperative hypothermia

“…Consequently, mild perioperative hypothermia lengthens postoperative recovery -even when temperature is not a criterion for transfer [74] . Shivering occurs postoperatively in 40 % of unwarmed patients [56] and is correlated with adrenergic activation [29] and discomfort [69,100] .…”

A Prospective, Observational Clinical Trial of Fever Reduction to Reduce Systemic Oxygen Consumption in the Setting of Acute Brain Injury

“…The association of fever reduction with reduction of systemic oxygen consumption, however, is challenged by the variability of responses from prior clinical studies [16,21,22]. The work by Manthous et al showed a significant reduction of systemic VO2 with fever reduction in the setting of hypoxemic, hypercapneic, or shock-related respiratory failure [16].…”