Correction: Evaluating Mechanisms of Postoperative Delirium and Cognitive Dysfunction Following Elective Spine Surgery in Elderly Patients (CONFESS): Protocol for a Prospective Observational Trial.

[This corrects the article DOI: 10.2196/15488.].

Evaluating Mechanisms of Postoperative Delirium and Cognitive Dysfunction Following Elective Spine Surgery in Elderly Patients (CONFESS): Protocol for a Prospective Observational Trial.

Background: Elderly people are at particular high risk for postoperative delirium (POD) following spine surgery, which is associated with longer hospital stays, higher costs, risk for delayed complications, long-term care dependency, and cognitive dysfunction (POCD). It is insufficiently understood which mechanisms and risk factors contribute to the development of POD and POCD following these major but plannable surgeries.

Objective: This study aims to identify modifiable risk factors in spine surgery.

Anemia tolerance during normo-, hypo-, and hypervolemia.

Background: Restrictive intraoperative fluid management has been demonstrated to improve outcome of visceral and lung surgery in several studies. However, subsequent hypovolemia (HOV) may be accompanied by a decrease of anemia tolerance, resulting in increased transfusion needs. We therefore investigated the effect of volume status on anemia tolerance.

Influence of clonidine induced sympathicolysis on anaemia tolerance in anaesthetized pigs.

Background: Clonidine effectively decreases perioperative mortality by reducing sympathetic tone. However, application of clonidine might also restrict anaemia tolerance due to impairment of compensatory mechanisms. Therefore, the influence of clonidine induced, short-term sympathicolysis on anaemia tolerance was assessed in anaesthetized pigs.

Determination of organ-specific anemia tolerance.

Objective: Utilization of anemia tolerance reduces the need for and risks of perioperative transfusion. Recent publications indicate that the critical limit for oxygen supply might not be the same for each organ system. Therefore, we investigated the effects of acute dilutional anemia on heart, brain, kidneys, liver, small intestine, and skeletal muscle to quantify organ-specific tolerance of different levels of acute anemic hypoxia.

Hyperoxia reversibly alters oxygen consumption and metabolism.

Aim: Ventilation with pure oxygen (hyperoxic ventilation: HV) is thought to decrease whole body oxygen consumption (VO(2)). However, the validity and impact of this phenomenon remain ambiguous; until now, under hyperoxic conditions, VO(2) has only been determined by the reverse Fick principle, a method with inherent methodological problems. The goal of this study was to determine changes of VO(2), carbon dioxide production (VCO(2)), and the respiratory quotient (RQ) during normoxic and hyperoxic ventilation, using a metabolic monitor.

The choice of the intravenous fluid influences the tolerance of acute normovolemic anemia in anesthetized domestic pigs.

Introduction: The correction of hypovolemia with acellular fluids results in acute normovolemic anemia. Whether the choice of the infusion fluid has an impact on the maintenance of oxygen (O₂) supply during acute normovolemic anemia has not been investigated so far.

Methods: Thirty-six anesthetized and mechanically ventilated pigs were hemodiluted to their physiological limit of anemia tolerance, reflected by the individual critical hemoglobin concentration (Hbcrit).

Neuromuscular blockade with rocuronium bromide increases the tolerance of acute normovolemic anemia in anesthetized pigs.

Background: The patient's individual anemia tolerance is pivotal when blood transfusions become necessary, but are not feasible for some reason. To date, the effects of neuromuscular blockade (NMB) on anemia tolerance have not been investigated.

Methods: 14 anesthetized and mechanically ventilated pigs were randomly assigned to the Roc group (3.

Effects of alterations of inspiratory oxygen fractions on heart rate variability.

Background: Changes in heart rate variability (HRV) during anaesthesia depend on multiple influences such as hypnosis, analgesia, surgical stress, and interacting drugs. Several recent studies have aimed to establish HRV-based monitoring tools to measure perioperative stress or anaesthetic depth. Although hyperoxic ventilation (HV) is known to alter autonomic cardiovascular regulation, there have been no studies investigating its influence on time- and frequency-domain analysis during general anaesthesia.

Changes in heart rate variability across different degrees of acute dilutional anemia.

Background: We investigated changes in heart rate variability (HRV) across different degrees of acute dilutional anemia (hemoglobin [Hb]=9, 7, 5, 4, and 3 g/dL) in a pig model.

Methods: Twelve anesthetized mechanically ventilated pigs of either gender (mean body weight 27.5±5.

Effects of hyperoxic ventilation on 6-h survival at the critical haemoglobin concentration aggravated by experimentally induced tachycardia in anaesthetized pigs.

Aim: Administration of 100% oxygen [hyperoxic ventilation (HV)] has been proven to ameliorate oxygen transport, tissue oxygenation and survival in different models of extreme normovolemic and hypovolemic anaemia. However, up to date, it is unknown whether HV is also able to improve outcome of extreme anaemia if myocardial oxygen consumption is contemporaneously increased by tachycardia. Therefore, we investigated the influence of HV on the 6-h survival rate during extreme anaemia and aggravated by experimentally induced tachycardia in a prospective, randomized study in a pig model of critical anaemia.

Hyperoxic ventilation improves survival in pigs during endotoxaemia at the critical hemoglobin concentration.

Aim Of The Study: Recently it has been demonstrated that short term hyperoxic ventilation (HV) can improve glucose metabolism, reduce pulmonary and hepatic apoptosis, and improve gastrointestinal perfusion during acute sepsis. However, it is unknown whether additional O(2) improves survival. Therefore we investigated the effects of increased plasma O(2) on survival during extreme anaemia and concomitant endotoxaemia in order to quantify the efficacy of HV.

Low hemoglobin levels during normovolemia are associated with electrocardiographic changes in pigs.

We studied whether low hemoglobin concentrations during normovolemia change the myocardial electrical current (electrocardiogram) in a pig model. Normovolemic anemia was achieved by stepwise replacing blood with colloids (hydroxyethyl starch 6%). We measured the length of the PQ-, QT-, QTc, and the ST interval as well as the amplitude of the Q wave and T wave at hemoglobin concentrations of 9.

Improved short-term survival with polyethylene glycol modified hemoglobin liposomes in critical normovolemic anemia.

Objective: To investigate the efficacy of a polyethylene glycol (PEG) modified formulation of liposome-encapsulated hemoglobin (LEH) as an oxygen-carrying blood substitute in the treatment of critical normovolemic anemia.

Design And Setting: Prospective, controlled, randomized experimental study in a university research facility.

Subjects: 14 anesthetized and mechanically ventilated beagle dogs.

[Tolerance to perioperative anemia. Mechanisms, influencing factors and limits].

The expected cost explosion in transfusion medicine increases the socio-economic significance of specific institutional transfusion programs. In this context the estimated use of the patient's physiologic tolerance represents an integral part of any blood conservation concept. The present article summarizes the mechanisms, influencing factors and limits of this natural tolerance to anemia and deduces the indication for perioperative red blood cell transfusion.

Norepinephrine increases tolerance to acute anemia.

Objective: Extreme anemia threatens myocardial oxygen supply by 1) a decline of arterial oxygen content and 2) by a decline of mean aortic pressure (MAP) and thus coronary perfusion pressure. Standard treatment of low arterial oxygen content includes ventilation with pure oxygen and the transfusion of red blood cells. However, it is unknown whether the stabilization of MAP and coronary perfusion pressure with norepinephrine as the sole therapeutic modality may also increase tolerance to extreme anemia and thus improve outcome.

[Tolerance to perioperative anemia. Mechanisms, influencing factors and limits].

The expected cost explosion in transfusion medicine increases the socio-economic significance of specific institutional transfusion programs. In this context the estimated use of the patient's physiologic tolerance represents an integral part of any blood conservation concept. The present article summarizes the mechanisms, influencing factors and limits of this natural tolerance to anemia and deduces the indication for perioperative red blood cell transfusion.

[Tolerance to perioperative anemia. Mechanisms, influencing factors and limits].

The expected cost explosion in transfusion medicine (increasing imbalance between donors and potential recipients, treatment of transfusion-associated complications) increases the socio-economic significance of specific institutional transfusion programs. In this context the estimated use of the patient's physiologic tolerance to anemia enables 1) the tolerance of larger blood losses (loss of "diluted blood"), 2) the onset of transfusion to the time after surgical control of bleeding to be delayed and 3) the perioperative collection of autologous red blood cells. The present review article summarizes the mechanisms, influencing factors and limits of this natural tolerance to anemia and deduces the indication for perioperative red blood cell transfusion.

Hyperoxic ventilation increases the tolerance of acute normovolemic anemia in anesthetized pigs.

Objective: To investigate the impact of prophylactic hyperoxic ventilation with Fio2 0.6 on the physiologic limit of acute normovolemic anemia.

Design: Prospective, controlled, randomized experimental study.