Charles J. Hinds

Elevation of Systemic Oxygen Delivery in the Treatment of Critically Ill Patients

BACKGROUND Elevation of systemic oxygen delivery and consumption has been associated with an improved outcome in critically ill patients. We conducted a randomized trial to determine whether boosting oxygen delivery by infusing the inotropic agent dobutamine would improve the outcome in a diverse group of such patients. METHODS On the basis of previously published recommendations, we established the following goals: a cardiac index above 4.5 liters per minute per square meter of body-surface area, oxygen delivery above 600 ml per minute per square meter, and oxygen consumption above 170 ml per minute per square meter. If these goals were not achieved with volume expansion alone, patients were randomly assigned to a treatment or control group. The treatment group received intravenous dobutamine (5 to 200 micrograms per kilogram of body weight per minute) until all three goals had been achieved. Dobutamine was administered to the control group only if the cardiac index was below 2.8 liters per minute per square meter. RESULTS A total of 109 patients were studied. In nine patients the therapeutic goals were achieved with volume expansion alone; all nine patients survived to leave the hospital. Fifty patients were randomly assigned to the treatment group, and 50 to the control group. During treatment, there were no differences between the two groups in mean arterial pressure or oxygen consumption, despite a significantly higher cardiac index and level of oxygen delivery in the treatment group (P < 0.05). Although the predicted risk of death during hospitalization was 34 percent for both groups, the in-hospital mortality was lower in the control group (34 percent) than in the treatment group (54 percent) (P = 0.04; 95 percent confidence interval, 0.9 to 39.1 percent). CONCLUSIONS The use of dobutamine to boost the cardiac index and systemic oxygen delivery failed to improve the outcome in this heterogeneous group of critically ill patients. Contrary to what might have been expected, our results suggest that in some cases aggressive efforts to increase oxygen consumption may have been detrimental.

Increased Mortality Associated with Growth Hormone Treatment in Critically Ill Adults

BACKGROUND The administration of growth hormone can attenuate the catabolic response to injury, surgery, and sepsis. However, the effect of high doses of growth hormone on the length of stay in intensive care and in the hospital, the duration of mechanical ventilation, and the outcome in critically ill adults who are hospitalized for long periods is not known. METHODS We carried out two prospective, multicenter, double-blind, randomized, placebo-controlled trials in parallel involving 247 Finnish patients and 285 patients in other European countries who had been in an intensive care unit for 5 to 7 days and who were expected to require intensive care for at least 10 days. The patients had had cardiac surgery, abdominal surgery, multiple trauma, or acute respiratory failure. The patients received either growth hormone (mean [+/-SD] daily dose, 0.10 +/- 0.02 mg per kilogram of body weight) or placebo until discharge from intensive care or for a maximum of 21 days. RESULTS The in-hospital mortality rate was higher in the patients who received growth hormone than in those who did not (P<0.001 for both studies). In the Finnish study, the mortality rate was 39 percent in the growth hormone group, as compared with 20 percent in the placebo group. The respective rates in the multinational study were 44 percent and 18 percent. The relative risk of death for patients receiving growth hormone was 1.9 (95 percent confidence interval, 1.3 to 2.9) in the Finnish study and 2.4 (95 percent confidence interval, 1.6 to 3.5) in the multinational study. Among the survivors, the length of stay in intensive care and in the hospital and the duration of mechanical ventilation were prolonged in the growth hormone group. CONCLUSIONS In patients with prolonged critical illness, high doses of growth hormone are associated with increased morbidity and mortality.

Challenges in end-of-life care in the ICU

The jurors identified numerous problems with end of life in the ICU including variability in practice, inadequate predictive models for death, elusive knowledge of patient preferences, poor communication between staff and surrogates, insufficient or absent training of health-care providers, the use of imprecise and insensitive terminology, and incomplete documentation in the medical records. The jury strongly recommends that research be conducted to improve end-of-life care. The jury advocates a “shared” approach to end-of-life decision-making involving the caregiver team and patient surrogates. Respect for patient autonomy and the intention to honour decisions to decline unwanted treatments should be conveyed to the family. The process is one of negotiation, and the outcome will be determined by the personalities and beliefs of the participants. Ultimately, it is the attending physician’s responsibility, as leader of the health-care team, to decide on the reasonableness of the planned action. In the event of conflict, the ICU team may agree to continue support for a predetermined time. Most conflicts can be resolved. If the conflict persists, however, an ethics consultation may be helpful. Nurses must be involved in the process. The patient must be assured of a pain-free death. The jury of the Consensus Conference subscribes to the moral and legal principles that prohibit administering treatments specifically designed to hasten death. The patient must be given sufficient analgesia to alleviate pain and distress; if such analgesia hastens death, this “double effect” should not detract from the primary aim to ensure comfort.

Effect of a perioperative, cardiac output-guided hemodynamic therapy algorithm on outcomes following major gastrointestinal surgery: a randomized clinical trial and systematic review

IMPORTANCE Small trials suggest that postoperative outcomes may be improved by the use of cardiac output monitoring to guide administration of intravenous fluid and inotropic drugs as part of a hemodynamic therapy algorithm. OBJECTIVE To evaluate the clinical effectiveness of a perioperative, cardiac output-guided hemodynamic therapy algorithm. DESIGN, SETTING, AND PARTICIPANTS OPTIMISE was a pragmatic, multicenter, randomized, observer-blinded trial of 734 high-risk patients aged 50 years or older undergoing major gastrointestinal surgery at 17 acute care hospitals in the United Kingdom. An updated systematic review and meta-analysis were also conducted including randomized trials published from 1966 to February 2014. INTERVENTIONS Patients were randomly assigned to a cardiac output-guided hemodynamic therapy algorithm for intravenous fluid and inotrope (dopexamine) infusion during and 6 hours following surgery (n=368) or to usual care (n=366). MAIN OUTCOMES AND MEASURES The primary outcome was a composite of predefined 30-day moderate or major complications and mortality. Secondary outcomes were morbidity on day 7; infection, critical care-free days, and all-cause mortality at 30 days; all-cause mortality at 180 days; and length of hospital stay. RESULTS Baseline patient characteristics, clinical care, and volumes of intravenous fluid were similar between groups. Care was nonadherent to the allocated treatment for less than 10% of patients in each group. The primary outcome occurred in 36.6% of intervention and 43.4% of usual care participants (relative risk [RR], 0.84 [95% CI, 0.71-1.01]; absolute risk reduction, 6.8% [95% CI, -0.3% to 13.9%]; P = .07). There was no significant difference between groups for any secondary outcomes. Five intervention patients (1.4%) experienced cardiovascular serious adverse events within 24 hours compared with none in the usual care group. Findings of the meta-analysis of 38 trials, including data from this study, suggest that the intervention is associated with fewer complications (intervention, 488/1548 [31.5%] vs control, 614/1476 [41.6%]; RR, 0.77 [95% CI, 0.71-0.83]) and a nonsignificant reduction in hospital, 28-day, or 30-day mortality (intervention, 159/3215 deaths [4.9%] vs control, 206/3160 deaths [6.5%]; RR, 0.82 [95% CI, 0.67-1.01]) and mortality at longest follow-up (intervention, 267/3215 deaths [8.3%] vs control, 327/3160 deaths [10.3%]; RR, 0.86 [95% CI, 0.74-1.00]). CONCLUSIONS AND RELEVANCE In a randomized trial of high-risk patients undergoing major gastrointestinal surgery, use of a cardiac output-guided hemodynamic therapy algorithm compared with usual care did not reduce a composite outcome of complications and 30-day mortality. However, inclusion of these data in an updated meta-analysis indicates that the intervention was associated with a reduction in complication rates. TRIAL REGISTRATION isrctn.org Identifier: ISRCTN04386758.

Persistent neuromuscular and neurophysiologic abnormalities in long-term survivors of prolonged critical illness

ObjectiveTo establish the prevalence, clinical characteristics, and electrophysiologic features of residual neuromuscular dysfunction after prolonged critical illness. DesignProspective follow-up study of survivors of prolonged critical illness. SettingA university hospital and two district general hospitals in the UK. PatientsThe study occurred for a period of 5 yrs. All patients during that time who were in the intensive care unit for >28 days were entered in the study. Measurements and Main ResultsAt follow-up, length of intensive care unit and hospital stay, duration of mechanical ventilation and admission Acute Physiology and Chronic Health Evaluation II score were recorded from the case notes. A clinical history was obtained, a Barthel Index disability score was calculated, and a full neurologic examination was performed. Nerve conduction studies, needle electromyography, single-fiber electromyography and thermal thresholds were performed. A total of 195 patients were identified. There were 86 survivors, of whom 47 could be contacted and 22 consented to be studied. The median time from intensive care unit discharge to follow-up was 43 months (range, 12–57 months). All gave a clear history of severe weakness and functional impairment after hospital discharge and, in all, recovery was prolonged. Motor or sensory deficits were present on clinical examination in 59% of the patients studied. Common peroneal nerve palsy was present in two patients. A total of 21 of 22 (95%) patients had electromyographic evidence of chronic partial denervation at follow-up, findings indicative of a preceding axonal neuropathy. The single-fiber electromyographic studies were also consistent with a preceding motor neuropathy. ConclusionSevere weakness requiring prolonged rehabilitation and abnormal clinical neurologic findings are extremely common in survivors of protracted critical illness. Neurophysiologic evidence of chronic partial denervation of muscle consistent with previous critical illness polyneuropathy is almost invariable and can be found up to 5 yrs after intensive care unit discharge in >90% of these long-stay patients. Evidence of myopathy is unusual. These findings have important implications for the management and rehabilitation of intensive care survivors.

The effect of increasing doses of norepinephrine on tissue oxygenation and microvascular flow in patients with septic shock

Objective:To investigate the effect of escalating doses of norepinephrine, aimed at achieving incremental increases in mean arterial pressure (MAP), on microvascular flow and tissue oxygenation in patients with septic shock. Design:Single-center interventional study. Setting:University hospital intensive care unit. Patients:Sixteen patients with established septic shock. Interventions:The norepinephrine dose was escalated to achieve incremental increases in the MAP from 60 to 70, 80, and 90 mm Hg. Measurements and Main Results:In addition to routine clinical measurements, cardiac output was determined using lithium dilution and arterial waveform analysis, cutaneous tissue Pto2 was measured using a Clark electrode, cutaneous red blood cell flux was assessed using laser Doppler flowmetry, and sublingual microvascular flow was evaluated using sidestream darkfield imaging. The mean (sd) norepinephrine dose increased from 0.18 (0.18) &mgr;g·kg−1·min−1 at 60 mm Hg to 0.41 (0.26) &mgr;g·kg−1·min−1 at 90 mm Hg (p < 0.0001). During this period, global oxygen delivery increased from 487 (418–642) to 662 (498–829) mL·min−1·m−2 (p < 0.01), cutaneous Pto2 increased from 44 (11) to 54 (13) mm Hg (p < 0.0001) and cutaneous microvascular red blood cell flux increased from 26.1 (16.2–41.9) to 33.3 (20.3–46.7) perfusion units (p < 0.05). No changes in sublingual microvascular flow index, vessel density, the proportion of perfused vessels, perfused vessel density, or heterogeneity index were identified by sidestream darkfield imaging. Conclusions:In patients with septic shock, targeting higher MAP by increasing the dose of norepinephrine resulted in an increase in global oxygen delivery, cutaneous microvascular flow, and tissue oxygenation. There were no changes in preexisting abnormalities of sublingual microvascular flow. Further research is required to clarify the optimal end points for vasopressor therapy in patients with septic shock.

Critical illness is associated with low circulating concentrations of insulin-like growth factors-i and -ii, alterations in insulin-like growth factor binding proteins, and induction of an insulin-like growth factor binding protein 3 protease

OBJECTIVES To describe the sequential changes in the circulating concentrations of insulin-like growth factor-I, insulin-like growth factor-II, and insulin-like growth factor binding proteins in critically ill patients. To determine whether critical illness is associated with induction of a specific protease directed against insulin-like growth factor binding protein 3 and to relate these changes to outcome. DESIGN Prospective, descriptive study. SETTING Intensive care unit (ICU) of a university hospital. PATIENTS Eighteen heterogeneous critically ill patients, requiring ventilatory support. INTERVENTIONS Serial daily blood samples were collected until death or discharge from the ICU. In five patients, samples were also obtained on the ward before discharge from the hospital. MEASUREMENTS AND MAIN RESULTS Serum concentrations of insulin-like growth factor-I, insulin-like growth factor-II, and insulin-like growth factor binding proteins 1, 2, and 3 were measured by radioimmunoassay. After 5 days, insulin-like growth factor binding protein 3 concentrations were measured on alternate days. Alterations in binding of insulin-like growth factor-I to insulin-like growth factor binding protein 3 and the presence of protease activity directed against insulin-like growth factor binding protein 3 were investigated by Western ligand blotting. Circulating concentrations of insulin-like growth factor-I and insulin-like growth factor-II were low and remained low throughout the 7-day study period. Insulin-like growth factor binding protein 1 concentrations were initially increased to within the fasting range, but subsequently decreased. There was considerable variability in insulin-like growth factor binding protein 2 concentrations, but generally, concentrations were at the upper end of the normal range throughout. Insulin-like growth factor binding protein 3 concentrations were consistently low and Western ligand blotting at the nadir of the insulin-like growth factor-I concentration demonstrated the presence of a protease directed against insulin-like growth factor binding protein 3. The last recorded concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein 3 were higher in survivors than in nonsurvivors (p < .05). Two patients were also studied for a prolonged period. In one patient, a survivor, insulin-like growth factor-I and insulin-like growth factor binding protein 3 were low initially, but later increased in association with recovery and cessation of protease activity over a period of 33 days. In another patient, a nonsurvivor, insulin-like growth factor-I and insulin-like growth factor binding protein 3 remained low and protease activity persisted until the patient died 38 days after admission to the ICU. CONCLUSIONS Critical illness is associated with low circulating concentrations of insulin-like growth factor-I, insulin-like growth factor-II, and insulin-like growth factor binding protein 3 and these low values are associated with induction of protease activity specifically directed against insulin-like growth factor binding protein 3. In survivors, recovery is associated with increasing insulin-like growth factor-I and insulin-like growth factor binding protein 3 concentrations and cessation of protease activity. The therapeutic effects of exogenous growth factors are likely to be influenced by these changes.

Low Serum Mannose-Binding Lectin Level Increases the Risk of Death due to Pneumococcal Infection

Abstract Background. Previous studies have shown associations between low mannose-binding lectin (MBL) level or variant MBL2 genotype and sepsis susceptibility. However, MBL deficiency has not been rigorously defined, and associations with sepsis outcomes have not been subjected to multivariable analysis. Methods. We reanalyzed MBL results in a large cohort with use of individual data from 4 studies involving a total of 1642 healthy control subjects and systematically defined a reliable deficiency cutoff. Subsequently, data were reassessed to extend previous MBL and sepsis associations, with adjustment for known outcome predictors. We reanalyzed individual data from 675 patients from 5 adult studies and 1 pediatric study of MBL and severe bacterial infection. Results. XA/O and O/O MBL2 genotypes had the lowest median MBL concentrations. Receiver operating characteristic analysis revealed that an MBL cutoff value of 0.5 ≪g/mL was a reliable predictor of low-producing MBL2 genotypes (sensitivity, 82%; specificity, 82%; negative predictive value, 98%). MBL deficiency was associated with increased likelihood of death among patients with severe bacterial infection (odds ratio, 2.11; 95% confidence interval, 1.30–3.43). In intensive care unit–based studies, there was a trend toward increased risk of death among MBL-deficient patients (odds ratio, 1.58; 95% confidence interval, 0.90–2.77) after adjustment for Acute Physiology and Chronic Health Enquiry II score. The risk of death was increased among MBL-deficient patients with Streptococcus pneumoniae infection (odds ratio, 5.62; 95% confidence interval, 1.27–24.92) after adjustment for bacteremia, comorbidities, and age. Conclusions. We defined a serum level for MBL deficiency that can be used with confidence in future studies of MBL disease associations. The risk of death was increased among MBL-deficient patients with severe pneumococcal infection, highlighting the pathogenic significance of this innate immune defence protein.

Patterns of neurophysiological abnormality in prolonged critical illness.

ObjectiveTo describe the various patterns of neurophysiological abnormalities which may complicate prolonged critical illness and identify possible aetiological factors.DesignProspective case series of neurophysiological studies, severity of illness scores, organ failures, drug therapy and hospital outcome. Some patients also had muscle biopsies.SettingGeneral intensive care unit (ICU) in a University Hospital. Patients: Forty-four patients requiring intensive care unit stay of more than 7 days. The median age was 60 (range 27–84 years), APACHE II score 19 (range 8–33), organ failures 3 (range 1–6), and mortality was 23%.ResultsSeven patients had normal neurophysiology (group I), 4 had a predominantly sensory axonal neuropathy (group II), 11 had motor syndromes characterised by markedly reduced compound muscle action potentials and sensory action potentials in the normal range (group III) and 19 had combinations of motor and sensory abnormalities (group IV). Three patients had abnormal studies but could not be classified into the above groups (group V). All patients had normal nerve conduction velocities. Electromyography revealed evidence of denervation in five patients in group III and five in group IV. There was no obvious relationship between the pattern of neurophysiological abnormality and the APACHE II score, organ failure score, the presence of sepsis or the administration of muscle relaxants and steroids. A wide range of histological abnormalities was seen in the 24 patients who had a muscle biopsy; there was no clear relationship between these changes and the neurophysiological abnormalities, although histologically normal muscle was only found in patients with normal neurophysiology. Only three of the eight patients from group III in whom muscle biopsy was performed had histological changes compatible with myopathy.ConclusionsNeurophysiological abnormalities complicating critical illness can be broadly divided into three types — sensory abnormalities alone, a pure motor syndrome and a mixed motor and sensory disturbance. The motor syndrome could be explained by an abnormality in the most distal portion of the motor axon, at the neuromuscular junction or the motor end plate and, in some cases, by inexcitable muscle membranes or extreme loss of muscle bulk. The mixed motor and sensory disturbance which is characteristic of ‘critical illness polyneuropathy’ could be explained by a combination of the pure motor syndrome and the mild sensory neuropathy. More precise identification of the various neurophysiological abnormalities and aetiological factors may lead to further insights into the causes of neuromuscular weakness in the critically ill and ultimately to measures for their prevention and treatment.

Selective inhibition of the activity of inducible nitric oxide synthase prevents the circulatory failure, but not the organ injury/dysfunction, caused by endotoxin

ABSTRACT Inhibitors of nitric oxide synthase (NOS) attenuate the circulatory failure caused by endotoxin, but the role of NO in the development of multiple organ dysfunction and the relative contribution of NO produced by endothelial NOS and inducible NOS (iNOS) to organ injury remains unclear. Here we report for the first time that 1400W, a novel and highly selective inhibitor of iNOS activity, attenuates the delayed hypotension as well as the rise in the plasma levels of nitrite/nitrate caused by endotoxin in the rat. Inhibition of iNOS activity with 1400W administered either before or 2 h after endotoxin injection did not, however, attenuate the hepatocellular injury, renal dysfunction, or pancreatic injury in this model. Similarly, administration of another selective inhibitor of iNOS activity, L-NIL, 2 h after endotoxin injection abolished the rise in nitrite/nitrate and attenuated the delayed hypotension caused by endotoxin, but failed to ameliorate organ injury. Thus, selective inhibition of iNOS activity with 1400W attenuates the circulatory failure induced by endotoxin in the rat, but fails to influence the degree of organ injury/dysfunction.