Critical Care Scoring System--new concept based on hemodynamic data

Effect of a protective-ventilation strategy on mortality in the acute respiratory distress syndrome

BACKGROUND

In patients with the acute respiratory distress syndrome, massive alveolar collapse and cyclic lung reopening and overdistention during mechanical ventilation may perpetuate alveolar injury. We determined whether a ventilatory strategy designed to minimize such lung injuries could reduce not only pulmonary complications but also mortality at 28 days in patients with the acute respiratory distress syndrome.

METHODS

We randomly assigned 53 patients with early acute respiratory distress syndrome (including 28 described previously), all of whom were receiving identical hemodynamic and general support, to conventional or protective mechanical ventilation. Conventional ventilation was based on the strategy of maintaining the lowest positive end-expiratory pressure (PEEP) for acceptable oxygenation, with a tidal volume of 12 ml per kilogram of body weight and normal arterial carbon dioxide levels (35 to 38 mm Hg). Protective ventilation involved end-expiratory pressures above the lower inflection point on the static pressure-volume curve, a tidal volume of less than 6 ml per kilogram, driving pressures of less than 20 cm of water above the PEEP value, permissive hypercapnia, and preferential use of pressure-limited ventilatory modes.

RESULTS

After 28 days, 11 of 29 patients (38 percent) in the protective-ventilation group had died, as compared with 17 of 24 (71 percent) in the conventional-ventilation group (P<0.001). The rates of weaning from mechanical ventilation were 66 percent in the protective-ventilation group and 29 percent in the conventional-ventilation group (P=0.005): the rates of clinical barotrauma were 7 percent and 42 percent, respectively (P=0.02), despite the use of higher PEEP and mean airway pressures in the protective-ventilation group. The difference in survival to hospital discharge was not significant; 13 of 29 patients (45 percent) in the protective-ventilation group died in the hospital, as compared with 17 of 24 in the conventional-ventilation group (71 percent, P=0.37).

CONCLUSIONS

As compared with conventional ventilation, the protective strategy was associated with improved survival at 28 days, a higher rate of weaning from mechanical ventilation, and a lower rate of barotrauma in patients with the acute respiratory distress syndrome. Protective ventilation was not associated with a higher rate of survival to hospital discharge.

Temporal hemodynamic effects of permissive hypercapnia associated with ideal PEEP in ARDS

The associated use of permissive hypercapnia (PHY) and high PEEP levels (PEEP(IDEAL)) has been recently indicated as part of a lung-protective-approach (LPA) in acute respiratory distress syndrome (ARDS). However, the net hemodynamic effect produced by this association is not known. We analyzed the temporal hemodynamic effects of this combined strategy in 48 patients (mean age 34 +/- 13 yr) with ARDS, focusing on its immediate (after 1 h), early (first 36 h), and late (2nd-7th d) consequences. Twenty-five patients were submitted to LPA--with the combined use of permissive hypercapnia (PHY), VT < 6 ml/kg, distending pressures above PEEP < 20 cm H2O, and PEEP 2 cm H2O above the lower inflection point on the static inspiratory P-V curve (P(FLEX))- and 23 control patients were submitted to conventional mechanical ventilation. LPA was initiated at once, resulting in an immediate increase in heart rate (p = 0.0002), cardiac output (p = 0.0002), oxygen delivery (DO2l, p = 0.0003), and mixed venous Po2 (p = 0.0006), with a maintained systemic oxygen consumption (p = 0.52). The mean pulmonary arterial pressure markedly increased (mean increment 8.8 mm Hg; p < 0.0001), but the pulmonary vascular resistance did not change (p = 0.32). Cardiac filling pressures increased (p < 0.001) and the systemic vascular resistance fell (p = 0.003). All these alterations were progressively attenuated in the course of the first 36 h, despite persisting hypercapnia. Plasma lactate suffered a progressive decrement along the early period in LPA but not in control patients (p < 0.0001). No hemodynamic consequences of LPA were noticed in the late period and renal function was preserved. A multivariate analysis suggested that these acute hyperdynamic effects were related to respiratory acidosis, with no depressant effects ascribed to high PEEP levels. In contrast, high plateau pressures were associated with cardiovascular depression. Thus, as long as sufficiently low distending pressures are concomitantly applied, the sudden installation of PHY plus PEEP(IDEAL) induces a transitory hyperdynamic state and pulmonary hypertension without harmful consequences to this young ARDS population.

Effects of pentoxifylline on hemodynamics and oxygenation in septic and nonseptic patients

OBJECTIVE

To evaluate the effects of pentoxifylline on hemodynamics and systemic oxygenation in septic and nonseptic critically ill patients.

DESIGN

Prospective clinical investigation.

SETTING

Intensive care unit (ICU) of a university hospital.

PATIENTS

Nineteen critically ill patients were included in the study 1 to 4 days after their admission to the ICU. A systemic inflammatory response syndrome was present in 12 patients, fulfilling at least two of the American College of Chest Physicians/ Society of Critical Care Medicine Consensus Conference criteria. The other seven patients did not fulfill these criteria and were classified as nonseptic.

INTERVENTIONS

All patients were mechanically ventilated. The dosage of catecholamines was kept constant during the entire study period and at least during 15 mins before the start of the study. In both study groups, pulmonary and radial artery catheters were inserted and 5 mg/kg of pentoxifylline (diluted in 300 mL of physiologic saline) was intravenously administered over a period of 180 mins at a rate of 100 mL/hr.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic variables, oxygen transport (DO2), oxygen uptake (VO2), and oxygen extraction ratio were determined before pentoxifylline, after 2.5 mg/kg of pentoxifylline, after 5 mg/kg of pentoxifylline, and 60 mins after the termination of pentoxifylline. Repeated-measures analysis of variance and Mann-Whitney test were used for statistical analysis. At baseline, there were significant differences between the septic and the nonseptic groups in mean pulmonary arterial pressure (septic: 31 +/- 5 mm Hg; nonseptic: 26 +/- 7 mm Hg, p < .05), and pulmonary vascular resistance index (PVRI) (septic: 344 +/- 121 dyne.sec/ cm5.m2; nonseptic: 233 +/- 100 dyne.sec/cm5.m2, p < .05). In the septic group, significant increases in heart rate and cardiac index were observed. Systemic vascular resistance index and PVRI decreased. No significant changes in hemodynamic variables occurred in the nonseptic group. In both groups, DO2 and VO2 increased significantly, while oxygen extraction ratio remained unchanged.

CONCLUSIONS

The administration of pentoxifylline to septic patients results in a significant improvement in hemodynamic performance compared with critically ill nonseptic patients. The better hemodynamic state is accompanied by an increase in DO2 and VO2 with unchanged oxygen extraction ratio.

Does Acute Physiologic and Chronic Health Evaluation (APACHE II) scoring predict need for prolonged support after coronary revascularization?

Significant intensive care unit (ICU) resources are allocated to patients recovering from coronary artery bypass graft (CABG) procedures, suggesting that a system to identify patients at risk for prolonged ICU therapy would help to enhance the use of this resource. To test the hypothesis that post-CABG patients likely to require prolonged ICU stay could be identified at the time of admission using the Acute Physiologic and Chronic Health Evaluation (APACHE II) system for scoring the severity of illness, we retrospectively reviewed the length of ICU stay for all patients recovering from CABG procedures over 1 yr, comparing the APACHE II scores assigned to patients requiring the longest stay with scores for patients with the briefest stay to determine whether a difference in score corresponded with the difference in length of stay. All medical records were reviewed and the physiologic variables (n = 12) used to assess acute physiologic status were recorded. Perioperative therapeutic interventions having significant impact on the physiologic variables used to derive the APACHE II score also were recorded. The study group was defined as patients requiring ICU care lasting between 14 and 84 days (n = 20); a control group of 23 patients was randomly selected from 124 patients having an ICU stay of 48 h or less. The overall APACHE II scores, and the component scores used to derive the overall scores, were calculated for both groups and were compared. The mean APACHE II score for the study group was 23.5 compared with 13.2 (P < 0.001) for the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of indications for early discharge from the intensive care unit. Clinical efficacy assessment project: American College of Physicians

OBJECTIVE

To formulate recommendations for the development of early intensive care unit (ICU) discharge criteria for low-risk monitor patients.

DESIGN

Literature review of published reports over the period 1966 to 1991 pertaining to ICU discharge criteria.

PATIENTS

Studies identifying patients admitted to ICUs who could be characterized as low risk. Patient populations of interest included adults (> or = 18 years of age) with low-risk medical or mixed medical/surgical conditions; cardiac care unit and burn patients were excluded.

MEASUREMENTS AND MAIN RESULTS

Of 1,492 articles identified as being pertinent to ICU discharge, only 2 studies (by the same group of investigators) were found that distinguished low-risk populations among medical and mixed medical/surgical ICU patients. The physiologic component of the Acute Physiology and Chronic Health Evaluation (APACHE) was used in both of these studies to ascertain the degree of risk. No studies were found that compared outcomes of low-risk patients remaining in the ICU after 24 h with those transferred to other hospital locations.

CONCLUSIONS

Objective methods (such as APACHE III) should be used to identify low-risk patients at 24 h post-ICU admission. A multicenter study should be conducted to compare outcomes on patients identified as low risk who are randomly assigned to alternative hospital locations for treatment versus those assigned to continued ICU treatment until routine ICU discharge. Mortality and quality of life data should be used as outcome measures (prior to ICU admission and 6 months post-ICU discharge).