Systemic PaO2 Oscillations Cause Mild Brain Injury in a Pig Model.

OBJECTIVE: Systemic PaO2 oscillations occur during cyclic recruitment and derecruitment of atelectasis in acute respiratory failure and might harm brain tissue integrity. DESIGN: Controlled animal study. SETTING: University research laboratory. SUBJECTS: Adult anesthetized pigs. INTERVENTIONS: Pigs were randomized to a control group (anesthesia and extracorporeal circulation for 20 hr with constant PaO2, n = 10) or an oscillation group (anesthesia and extracorporeal circulation for 20 hr with artificial PaO2 oscillations [3 cycles min⁻¹], n = 10). Five additional animals served as native group (n = 5). MEASUREMENTS AND MAIN RESULTS: Outcome following exposure to artificial PaO2 oscillations compared with constant PaO2 levels was measured using 1) immunohistochemistry, 2) real-time polymerase chain reaction for inflammatory markers, 3) receptor autoradiography, and 4) transcriptome analysis in the hippocampus. Our study shows that PaO2 oscillations are transmitted to brain tissue as detected by novel ultrarapid oxygen sensing technology. PaO2 oscillations cause significant decrease in NISSL-stained neurons (p < 0.05) and induce inflammation (p < 0.05) in the hippocampus and a shift of the balance of hippocampal neurotransmitter receptor densities toward inhibition (p < 0.05). A pathway analysis suggests that cerebral immune and acute-phase response may play a role in mediating PaO2 oscillation-induced brain injury. CONCLUSIONS: Artificial PaO2 oscillations cause mild brain injury mediated by inflammatory pathways. Although artificial PaO2 oscillations and endogenous PaO2 oscillations in lung-diseased patients have different origins, it is likely that they share the same noxious effect on the brain. Therefore, PaO2 oscillations might represent a newly detected pathway potentially contributing to the crosstalk between acute lung and remote brain injury.

Pharmacological interventions and concepts of fast-track perioperative medical care for enhanced recovery programs.

BACKGROUND: Improving perioperative efficiency and tightly maintaining the patient's homeostasis in order to improve rehabilitation and well-being are key factors in the increasing popularity of fast-track recovery programs. Although the pharmacological contribution should not be overestimated, the use of up-to-date pharmacological agents with predictable duration of action and minimal side effects is mandatory to allow for a fast and gentle recovery process. METHODS: A literature review of about 160 peer-reviewed publications provides the basis for this review of pharmacological interventions for optimizing recovery following anesthesia. RESULTS: The choice of anesthetic technique and pharmacological agents should be tailored to the needs of the patient as well as the type of procedure being performed as fast-track surgery. The universally applicable goals valid for every class of intervention are that they should be easy to use, have minimal side effects, maintain homeostasis, allow for a predictable on- and offset, and give minimal impairment of recovery and function. CONCLUSIONS: The pivotal role played by the anesthesiologist in facilitating the recovery process following surgical procedures has assumed increased importance in the concept of enhanced recovery programs. Although the interdisciplinary approach common to all parties involved (surgeons, anesthesiologists, nurses, physiotherapists) is the true enabler of fast-track surgery, the choice of anesthetic drugs and concomitant medication can all influence the ability to fast-track patients after surgery and should therefore considered mandatory in fast-track programs.