Relationship of mortality to increasing oxygen delivery in patients > or = 50 years of age: a prospective, randomized trial.

OBJECTIVE: To investigate the relationship of mortality to early resuscitation using two levels of oxygen delivery (DO2) in critically ill surgical patients > or =50 yrs of age who were stratified into groups: age < or =75 yrs (age 50 to 75 yrs group); and age >75 yrs (age >75 yrs group). DESIGN: A prospective, randomized trial, continued from a previous project. SETTING: Surgical intensive care unit, university affiliated. PATIENTS: Consecutive patients, >50 yrs of age, unable to generate a DO2 of > or =600 mL/min/m2 with fluid resuscitation alone, with a diagnosis of systemic inflammatory response syndrome, sepsis, severe sepsis, septic shock, and/or acute respiratory distress syndrome. INTERVENTIONS: During the first 24 hrs of resuscitation, patients were randomized to receive fluids, blood transfusions, and vasoactive agents in order to achieve DO2 treatment goals of > or =600 mL/ min/m2 in the protocol group and 450 to 550 mL/min/m2 in the control group. MEASUREMENTS AND MAIN RESULTS: One hundred five patients completed the study. In patients aged 50 to 75 yrs, the mortality rate was 21% (9/43) in the protocol group and 52% (12/23) in the control group (p=.01, 95% confidence interval of -58% to -4%). In patients >75 yrs of age, the mortality rate was 57% (12/21) in the protocol group and 61% (11/18) in the control group. Oxygen extraction ratios (O2ER) and oxygen consumption values were significantly (p=.02) lower in the age >75 yrs group compared with the age 50 to 75 yrs group. CONCLUSIONS: Patients 50 to 75 yrs of age receiving a DO2 of > or =600 mL/min/m2 demonstrated a statistically significant (p=.01) improved survival rate over patients in the control group. Patients >75 yrs of age demonstrated no benefit from attempts to increase DO2 to >600 mL/min/m2, and they may have been overtreated as reflected by the lower O2ER values in this age group. Treating to an O2ER that reflects a balance between oxygen consumption and DO2 may be an alternative goal that allows individual titration.

Evaluation of a continuous cardiac output and mixed venous oxygen saturation catheter in critically ill surgical patients.

OBJECTIVE: To evaluate the agreement of continuous cardiac output and mixed venous oxygen saturation measurements, obtained with a modified pulmonary artery catheter, with those values obtained by standard intermittent bolus thermodilution and cooximetry. DESIGN: Prospective, clinical investigation. SETTING: A surgical intensive care unit in a tertiary referral center. PATIENTS: Twenty-one adult critically ill surgical patients, requiring pulmonary artery catheter monitoring. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A modified pulmonary artery catheter capable of continuous monitoring of cardiac output and mixed venous oxygen saturation was used with either an 8.5-Fr or a 9-Fr introducer. At random intervals, the continuous cardiac output measurement was compared with the cardiac output obtained using standard intermittent bolus thermodilution. The system was calibrated every 24 hrs for mixed venous oxygen saturation monitoring. Each saturation obtained by the laboratory cooximeter was compared with that value recorded using the catheter. Data points for 202 pairs of cardiac output (21 patients, 31 catheters) and 65 pairs of mixed venous oxygen saturation (20 patients, 28 catheters) were obtained. The bias and precision of the cardiac output data were 0.49 and 1.01 L/min, respectively. The agreement between the continuous and bolus values decreased as the cardiac output increased. Heart rate did not affect the agreement between the continuous and bolus techniques. The bias and precision of the mixed venous oxygen saturation data were -0.57% and 3.76%, respectively. The hematocrit did not affect the bias or precision of the venous saturation data over the hematocrit range observed (23.2% to 44.6%). Fewer catheter malfunctions were observed when the catheter was used with a 9-Fr introducer than with an 8.5-Fr introducer. CONCLUSIONS: The test catheter adequately measures continuous cardiac output and mixed venous oxygen saturation in the clinical setting. Because intermittent bolus thermodilution is not a true "gold standard" for cardiac output determination, new techniques compared with bolus thermodilution may fail to achieve accuracy expectations. A 9-Fr introducer is recommended, as fiberoptic damage may have occurred when the 8.5-Fr introducer was used.

The relationship of oxygen consumption measured by indirect calorimetry to oxygen delivery in critically ill patients.

OBJECTIVE: The existence of oxygen supply dependency, defined as oxygen consumption (VO2) limited by oxygen delivery (DO2), is still questioned. This study examined the relationship between VO2 and DO2 in two groups of critically ill surgical patients 50 years and older in the first 24 hours of resuscitation after pulmonary artery catheter insertion. Group 1 patients had systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, septic shock, and adult respiratory distress syndrome (ARDS). Group 2 patients had hemorrhagic shock. METHODOLOGY: Study methodology included (1) augmenting DO2 with fluids, blood, and vasopressors, (2) measuring VO2 by indirect calorimetry to avoid the problem of mathematical coupling with DO2 calculation, and (3) analyzing data during steady states of temperature, sedation, paralyzing agents, and vasopressors. RESULTS: Six to 18 measurements collected on all study patients during a period within the first 24 hours were analyzed using a linear regression analysis. Statistical significance was set at p < or = 0.05. Seven of nine patients in group 1 demonstrated positive, statistically significant relationships between VO2 and DO2. Of six patients in group 2, one patient demonstrated a positive, significant relationship of VO2 and DO2, three demonstrated inverse relationships, and two patients did not show a DO2/VO2 relationship. Supply dependency did not exist in all patients but was present in seven out of nine patients with systemic inflammatory response syndrome, sepsis, severe sepsis, septic shock, and adult respiratory distress syndrome in the first 24 hours of treatment.

Clinical and financial outcomes of lateral rotation low air-loss therapy in patients in the intensive care unit.

OBJECTIVE: To determine the clinical impact and cost-effectiveness of two lateral rotation low air-loss therapy beds and their supporting protocols in the treatment of critically ill patients. DESIGN: Retrospective-cohort (2:1 design) study consisting of chart reviews of patients on two types of lateral rotation low air-loss therapy and their protocols from January 1992 through July 1993. SETTING: Three intensive care units (ICUs) (30 medical and surgical beds) in a 506-bed community hospital. PATIENTS: Fifty-six critically ill patients admitted to the ICU and prescribed lateral rotation therapy. Patients treated on both beds were excluded from the study. MEASUREMENTS: Data were collected on age, sex, Acute Physiology and Chronic Health Evaluation II score, Therapeutic Intervention Scoring System on admission to the ICU, and the time interval (number of days) from ICU admission until placement on a specialty bed (Lag Time). Outcome measurements included presence of pneumonia, adult respiratory distress syndrome, and multiorgan system dysfunction during the ICU stay, and the number of intubation days, ICU hours, hospital length of stay, and mortality during hospitalization. RESULTS: Statistically significant differences in group outcomes were found as follows: (1) pneumonia (p = 0.001), (2) adult respiratory distress syndrome (p = 0.002), (3) hospital length of stay (p = 0.04), and (4) hospital costs (p = 0.0001). CONCLUSIONS: In this study, patients treated by a prevention protocol with the Restcue beds (Support Systems International, Inc., Charleston, S.C.) had better clinical and financial outcomes than patients treated on Biodyne beds (Kinetic Concepts, Inc., San Antonio, Texas) with a more restricted, cost-conscious protocol aimed primarily at patients who have or who are at a higher risk for severe pneumonia, presence of septic shock, or adult respiratory distress syndrome.

Frequency of mortality and myocardial infarction during maximizing oxygen delivery: a prospective, randomized trial.

OBJECTIVES: To determine the frequency of myocardial infarction and mortality during treatment that increased oxygen delivery (DO2) to > or = 600 mL/min/m2. To define the characteristics of patients achieving a high DO2 without inotropes in order to guide future studies. DESIGN: A prospective, randomized, controlled trial. SETTING: Two surgical intensive care units at The Queen's Medical Center in the University of Hawaii Surgical Residency Program. PATIENTS: Eighty-nine surgical patients (> or = 18 yrs of age), who were admitted to a surgical intensive care unit and who required pulmonary artery catheter monitoring, were selected for the study. Diagnoses included sepsis, septic shock, adult respiratory distress syndrome, or hypovolemic shock. Patients facing imminent death were excluded from the study. INTERVENTIONS: The treatment group received fluid boluses, blood products, and inotropes, as needed, to achieve a DO2 of > or = 600 mL/min/m2 in the first 24 hrs. Using the same interventions, we treated the control group to reach a DO2 of 450 to 550 mL/min/m2. MEASUREMENTS AND MAIN RESULTS: Hemodynamic measurements were obtained every 4 hrs until the pulmonary artery catheter was removed. DO2 and oxygen consumption were calculated by standard formulas. Serial creatine kinase myocardial fraction and electrocardiograms were documented for the first 48 hrs after study entry and for any new onset of arrhythmia or increasing hemodynamic instability. The patients who generated a high DO2 (> or = 600 mL/min/m2) with only preload treatment were reflective of patients with better cardiac reserve and low mortality rates. These patients, from both treatment and control groups, were excluded in the final analysis. The treatment group who received inotropes to achieve the high DO2 had a 14% mortality rate. Those patients who failed to achieve the high DO2 had a 67% mortality rate, and the control group who achieved a normal DO2 had a 62% mortality rate (p = .005). The frequency of myocardial infarction after study entry was 5.6% (five of 89 patients). This rate was not higher among the groups who received inotropes. Logistic regression analysis showed that age of > or = 50 yrs could be used to classify patients as not self-generating, with an 83% chance of being correct. CONCLUSIONS: The group that required catecholamines to achieve a DO2 of > or = 600 mL/min/m2 had a lower mortality rate, with no increase in the frequency of myocardial infarction. Future prospective, controlled trials examining select groups of patients (age > or = 50 yrs) may demonstrate a difference between control and treatment groups by eliminating the majority of patients who generate the high DO2 with only preload augmentation.

Effect of maximizing oxygen delivery on morbidity and mortality rates in critically ill patients: a prospective, randomized, controlled study.

OBJECTIVE: To determine the effects of optimizing oxygen delivery (DO2) to "supranormal" levels on morbidity and mortality in patients with sepsis, septic shock, and adult respiratory distress syndrome. DESIGN: A prospective, randomized, controlled trial. SETTING: A 16-bed surgical intensive care unit (ICU) and 14-bed mixed medical/surgical ICU in two separate hospitals in the University of Hawaii Surgical and Internal Medicine Residency programs. PATIENTS: During a 1-yr period, 67 patients who had pulmonary artery catheters and who met the criteria for sepsis or septic shock, adult respiratory distress syndrome, or hypovolemic shock were enrolled in the study. Patients admitted to the ICU who were < 18 yrs old, or with a do-not-resuscitate order, or those patients who faced imminent death (< 24 hrs), such as those patients with uncontrollable hemorrhage or brain death, were excluded from the study. INTERVENTIONS: Patients were randomized into treatment and control groups. The treatment group was assigned a therapeutic DO2 indexed (DO2I) goal of > 600 mL/min/m2. Interventions to attain this goal included fluid boluses, administration of blood products, and the use of inotropes. The control group was not assigned to a specific therapeutic goal other than "normal" values of DO2I of 450 to 550 mL/min/m2. Every attempt was made to reach the therapeutic goals within the first 24 hrs after entry into the study. Hemodynamic measurements were obtained on study patients every 4 hrs until the end of the study. The severity of illness was evaluated using the Therapeutic Intervention Scoring System, and the Acute Physiology and Chronic Health Evaluation II scoring system. MEASUREMENTS AND MAIN RESULTS: There were 32 patients in the control group and 35 patients in the treatment group. The groups were similar in age, sex, number of organ dysfunctions, Acute Physiology and Chronic Health Evaluation II and Therapeutic Intervention scores. There were no statistical differences between the two groups in mortality, development of organ failure, ICU days, and hospital days. Upon analysis, it became apparent that the patients comprised clinically distinct subgroups, including: a) a treatment group who achieved supranormal DO2I; b) a control group with normal DO2I; c) a treatment group who failed to reach target DO2I; d) a control group who self-generated to high DO2I values; and e) a small number of patients who could not even reach a normal DO2I of 450 mL/min/m2. These subgroups were found to be similar and matched. The mortality rate was significantly lower for patients in groups who reached supranormal values of DO2I whether treated or self-generated as compared with patients who reached normal DO2I values (14% vs. 56%, p = .01). CONCLUSIONS: Although there was no statistically significant difference in the control vs. treatment groups, subgroup analysis demonstrated a strong, significant difference between patients with supranormal values of oxygen transport vs. patients with normal levels of DO2. Supranormal values of DO2I, whether self-generated or as a result of treatment, resulted in a statistically significant decrease in mortality rate. This study adds to the weight of evidence that current standard of care of treating critically ill patients to normal DO2I should be reconsidered, and that maximizing to high DO2I might be a more appropriate therapeutic end-point.

Report of a hidden case of overfeeding.

Nutritional support is essential to the care of the critically ill patient, but complications of overfeeding can occur. Precise metabolic measurement by indirect calorimetry can detect problems of nutrition and allow adjustment in caloric intake. This case study illustrates the complications of carbon dioxide retention and inability to wean from mechanical ventilation with subsequent prevention of further complications.