High central venous pressure is associated with prolonged mechanical ventilation and increased mortality after lung transplantation.

BACKGROUND: Poor oxygenation might occur in transplanted lungs as a result of reperfusion injury and lack of lymphatic drainage. Low central venous and pulmonary capillary wedge pressures are advocated to reduce pulmonary edema and maximize oxygenation but might adversely affect cardiac index, circulation, and renal function. METHODS: Histories, intensive care unit charts, and donor data on 118 lung transplantations performed between 1999 and 2002 were retrospectively assessed. Multiple logistic regression analysis was performed on donor, recipient, operative, and intensive care unit parameters to determine the relationship of filling pressure (central venous and pulmonary capillary wedge pressures) to prolonged mechanical ventilation and outcome. The mean central venous pressure was used to divide patients into high and low central venous pressure groups, which were then compared to determine differences in outcome and complication rates. RESULTS: A high central venous pressure was found to be associated with prolonged mechanical ventilation (odds ratio, 1.57; 95% confidence interval, 1.13-2.20; P = .008). After removing the effect of poor myocardial function by excluding patients with low cardiac index (< 2.2 L x min -1 x m(-2) ) and high inotrope requirement (> 10 microg/min), central venous pressure remained associated with prolonged mechanical ventilation (odds ratio, 2.31; 95% confidence interval, 1.31-4.07; P = .004). Duration of ventilation (P < .001), intensive care unit mortality (P = .02), hospital mortality (P = .09), and 2-month mortality (P = .02) were higher in patients with central venous pressures of greater than 7 mm Hg. There was no evidence of complications caused by hypovolemia in the low (< or = 7 mm Hg) central venous pressure group, who had lower inotrope requirements (P = .02) and lower creatinine levels (P = .013). Conclusions A high central venous pressure was associated with adverse outcomes after lung transplantation.

Prospective randomized trial to assess caloric and protein needs of critically Ill, anuric, ventilated patients requiring continuous renal replacement therapy.

OBJECTIVES: We measured the energy and protein needs in 50 sequential, critically ill, ventilated patients requiring continuous renal replacement therapy (CRRT) for renal failure by using indirect calorimetry and three sequential isocaloric protein-feeding regimes of 1.5, 2.0, and 2.5 g. kg(-1). d(-1). We also assessed the compliance of actual feeding with target feeding and correlated the predictive energy requirements of the formulae with the actual energy expenditure (EE) measured by indirect calorimetry. We also determined whether these feeding regimes affected patient outcome. METHODS: The energy and protein needs of 50 consecutive, critically ill patients (31 male; age 53.3 +/- 17.4 y; Acute Physiology and Chronic Health Evaluation (APACHE II) score: 26.0 +/- 8.0; Acute Physiology and Chronic Health Evaluation score predicted risk of death: 50.0 +/- 25.0%) were assessed by using indirect calorimetry and ultrafiltrate nitrogen loss. Entry into this study was on commencement of CRRT. To eliminate any beneficial effect from the passage of time on nitrogen balance, 10 of the 50 patients were randomized to receive 2.0 g. kg(-1). d(-1) throughout the study, and the others received an escalating isocaloric feeding regime (1.5, 2.0, and 2.5 g. kg(-1). d(-1)) at 48-h intervals. Enteral feeding was preferred, but if this was not tolerated or unable to meet target, it was supplemented or replaced by a continuous infusion of total parenteral nutrition. Energy was given to meet caloric requirements as predicted by the Schofield equation corrected by stress factors or based on the metabolic cart readings of EE and was kept constant for all patients throughout the trial. Patients were stabilized on each feeding regime for at least 24 h before samples of dialysate were taken for nitrogen analysis at 8-h intervals on the second day. CRRT was performed by using a blood pump with a blood flow of 100 to 175 mL/min. Dialysate was pumped in and out counter-currently to the blood flow at 2 L/h. A biocompatible polyacrylonitrile hemofilter was used in all cases. RESULTS: EE was 2153 +/- 380 cal/d and increased by 56 +/- 24 cal/d (P < 0.0001) throughout the 6-d study period to 2431 +/- 498 cal/d. At study entry, the mean predicted (Schofield) caloric requirement was 2101 +/- 410. Patients received 99% of the predicted energy requirements. However, the mean EE was 11% higher at 2336 +/- 482 calories. This difference was not uniform. If the predicted caloric requirement was less than 2500, the EE exceeded the predicted by an average of 19%. If the predicted caloric requirement was greater than 2500, the EE on average was 6% less than predicted. This relation was significant (P = 0.025) and has not been described previously. Nitrogen balance was inversely related to EE (P = 0.05), positively related to protein intake (P = 0.0075), and more likely to be attained with protein intakes larger than 2 g. kg(-1). d(-1) (P = 0.0001). Nitrogen balance became positive in trial patients over time but were negative in control patients over time (P = 0.0001). Nitrogen balance was directly associated with hospital outcome (P = 0.03) and intensive care unit outcome (P = 0.02). For every 1-g/d increase in nitrogen balance, the probability of survival increased by 21% (P = 0.03; odds ratio, 1.211; 95% confidence limits, 1.017,1.443). Further, although enterally and parenterally fed patients had lower mortalities than predicted, the presence of enteral feeding, even after adjusting for predicted risk of death, had a statistically significant benefit to patient outcome (P = 0.04). CONCLUSIONS: This study found that a metabolic cart can improve the accuracy of energy provision and that a protein intake of 2.5 g. kg(-1). d(-1) in these patients increases the likelihood of achieving a positive nitrogen balance and improving survival. Enteral feeding is preferable, but if this is not possible or does not achieve the target, then it should be supplemented by parenteral feeding.

Impact of increasing parenteral protein loads on amino acid levels and balance in critically ill anuric patients on continuous renal replacement therapy.

OBJECTIVES: We wanted to establish optimum protein and glucose intakes during total parenteral nutrition by using a constant caloric but changing protein intake in critically ill, ventilated, anuric patients on continuous renal replacement therapy and measuring amino acid and glucose losses across the hemofilter. METHODS: Eleven consecutive, critically ill patients (eight male, age, 43.5 +/- 21.8 y; Acute Physiology and Chronic Health Evaluation II score, 20.5 +/- 7.0; Acute Physiology and Chronic Health Evaluation risk of death: 36.5% +/- 23.0 and 6 +/- 1 impaired organ systems) entered this study. Patients were fed by continuous infusion of a total parenteral mixture consisting of Synthamin (a mixture of essential and non-essential amino acids), 50% dextrose, and intralipid (long-chain triglycerides) to meet caloric requirements as predicted by Schofield's equation corrected by stress factors. The amount of protein infused was varied (1 to 2.5 g. kg(-1). d(-1)) by increments of 0.25 g. kg(-1). d(-1). Patients were stabilized on each feeding regimen for at least 24 h before paired samples of blood and dialysate were taken for amino acid and glucose measurements. Continuous renal replacement therapy was performed by using a blood pump with a blood flow of 100 to 175 mL/min. Dialysate was pumped in and out counter-currently to the blood flow at 2 L/h. A biocompatible polyacrylonitrile hemofilter was used in all cases. RESULTS: With protein intakes below 2.5 g. kg(-1). d(-1), blood levels of 14% to 57% of the measured amino acids were below the lower limits of the normal range. At 2.5 g. kg(-1). d(-1), all measured amino acids were within the normal range. Amino acid balance became more positive as protein input increased (P = 0.0001). Glucose and amino acid losses were dependent on blood concentration. Overall, 17% (range, 13% to 24%) of infused amino acids and 4% of infused glucose were lost in the dialysate. CONCLUSIONS: This study of critically ill, ventilated, anuric patients on continuous renal replacement therapy suggested that increases in protein and glucose are required to account for the increased losses across the hemofilter. A protein intake of 2.5 g. kg(-1). d(-1) appeared to optimize nitrogen balance and correct amino acid deficiencies.

Evidence-based medicine in intensive care.

The life-threatening nature of critical illness, requiring simultaneous, multiple interventions, makes it difficult, if not impossible, to study the effects of any one treatment. It is often not possible to conduct trials in critically ill patients, as they can not give informed consent. Some high quality, prospective studies have influenced clinical practice in intensive care, but others with lower grades of evidence have led to some controversy. In intensive care, clinical practice is still influenced by a combination of theory, experience and evidence.

Successful extracorporeal life support in a case of severe flecainide intoxication.

OBJECTIVE: To show the effectiveness of emergency extracorporeal membrane oxygenation (ECMO) in treating severe, life-threatening flecainide intoxication. DESIGN: Case report. SETTING: Intensive care unit in a quaternary care center. PATIENT: A patient with electromechanical dissociation after severe flecainide acetate overdose. INTERVENTION: ECMO. CASE REPORT: A 30-yr-old male with a history of depression presented after a severe flecainide overdose with plasma concentrations exceeding 20 times the upper boundary of the therapeutic range. At presentation, the patient was in refractory cardiocirculatory collapse and was successfully resuscitated with ECMO. Twenty-six hours later, extracorporeal support could be discontinued and the patient made a full recovery. CONCLUSION: In patients with severe but potentially reversible cardiac dysfunction attributable to flecainide intoxication, ECMO can maintain cardiac output and vital organ perfusion while allowing time for drug redistribution, metabolism, and clearance.

Percutaneous tracheostomy in critically ill patients: a prospective, randomized comparison of two techniques.

OBJECTIVE: To prospectively compare two commonly used methods for percutaneous dilational tracheostomy (PDT) in critically ill patients. DESIGN: Prospective, randomized, clinical trial. SETTING: Trauma and general intensive care units of a university tertiary teaching hospital, which is also a level 1 trauma center. PATIENTS: One hundred critically ill patients with an indication for PDT. INTERVENTIONS: PDT with the Ciaglia technique using the Ciaglia PDT introducer set and the Griggs technique using a Griggs PDT kit and guidewire dilating forceps. MEASUREMENTS AND MAIN RESULTS: Surgical time, difficulties, and surgical and anesthesia complications were measured at 0-2 hrs, 24 hrs, and 7 days postprocedure. Groups were well matched, and there were no differences between the two methods in surgical time or in anesthesia complications. Major bleeding complications were 4.4 times more frequent with the Griggs PDT kit. With the Ciaglia PDT kit, both intraoperative and at 2 and 24 hrs, surgical complications were less common (p = .023) and the procedure was more often completed without expert assistance (p = .013). Tracheostomy bleeding was not associated with either anticoagulant therapy or an abnormal clotting profile. Multivariate analysis identified the predictors of PDT complications as the Griggs PDT kit (p = .027) and the Acute Physiology and Chronic Health Evaluation (APACHE) II score (p = .041). The significant predictors of time required to complete PDT were the APACHE II score (p = .041), a less experienced operator (p = .0001), and a female patient (p = .013). CONCLUSIONS: Patients experiencing PDT with the Ciaglia PDT kit had a lower surgical complication rate (2% vs. 25%), less operative and postoperative bleeding, and less overall technical difficulties than did patients undergoing PDT with the Griggs PDT kit. Ciaglia PDT is, therefore, the preferred technique for percutaneous tracheostomy in critically ill patients.

Pyroglutamic acidemia: a cause of high anion gap metabolic acidosis.

OBJECTIVE: To report four cases of pyroglutamic acidemia in adults causing clinically significant acidosis. DATA SOURCES: Patients admitted to the intensive care units of the Alfred Hospital (a quaternary referral center) and Geelong Hospital (a major regional center) with an unexplained high anion gap acidosis. CONCLUSIONS: Pyroglutamic acidemia (5-oxoprolinemia) is a rare cause of high anion gap metabolic acidosis that should be suspected in patients presenting with sepsis, hepatic, and/or renal dysfunction who are receiving drugs such as acetaminophen, flucloxacillin, and vigabatrin after the more common causes of a high anion gap acidosis have been excluded. Should pyroglutamic aciduria be present, known precipitants should be ceased, infection should be managed aggressively, and supportive management should be instituted.

Hyperbaric or normobaric oxygen for acute carbon monoxide poisoning: a randomised controlled clinical trial.

OBJECTIVE: To assess neurological sequelae in patients with all grades of carbon monoxide (CO) poisoning after treatment with hyperbaric oxygen (HBO) and normobaric oxygen (NBO). DESIGN: Randomised controlled double-blind trial, including an extended series of neuropsychological tests and sham treatments in a multiplace hyperbaric chamber for patients treated with NBO. SETTING: The multiplace hyperbaric chamber at the Alfred Hospital, a university-attached quarternary referral centre in Melbourne providing the only hyperbaric service in the State of Victoria. PATIENTS: All patients referred with CO poisoning between 1 September 1993 and 30 December 1995, irrespective of severity of poisoning. Pregnant women, children, burns victims and those refusing consent were excluded. INTERVENTION: Daily 100-minute treatments with 100% oxygen in a hyperbaric chamber--60 minutes at 2.8 atmospheres absolute for the HBO group and at 1.0 atmosphere absolute for the NBO group--for three days (or for six days for patients who were clinically abnormal or had poor neuropsychological outcome after three treatments). Both groups received continuous high flow oxygen between treatments. MAIN OUTCOME MEASURES: Neuropsychological performance at completion of treatment, and at one month where possible. RESULTS: More patients in the HBO group required additional treatments (28% v. 15%, P = 0.01 for all patients; 35% v. 13%, P = 0.001 for severely poisoned patients). HBO patients had a worse outcome in the learning test at completion of treatment (P = 0.01 for all patients; P = 0.005 for severely poisoned patients) and a greater number of abnormal test results at completion of treatment (P = 0.02 for all patients; P = 0.008 for severely poisoned patients). A greater percentage of severely poisoned patients in the HBO group had a poor outcome at completion of treatment (P = 0.03). Delayed neurological sequelae were restricted to HBO patients (P = 0.03). No outcome measure was worse in the NBO group. CONCLUSION: In this trial, in which both groups received high doses of oxygen, HBO therapy did not benefit, and may have worsened, the outcome. We cannot recommend its use in CO poisoning.

Optimal assessment of cervical spine trauma in critically ill patients: a prospective evaluation.

There is no uniformly accepted protocol for the radiological assessment of the cervical spine in critically ill trauma patients. The Alfred Trauma Centre receives about 40% of Victorian patients with major trauma. A protocol was developed for cervical spine evaluation, comprising three plain X-rays and a swimmer's view added when necessary to visualize C7-T1, CT and/or MRI for abnormal regions, and functional (flexion/extension) X-rays to exclude cervical spine instability due to soft tissue trauma. Functional X-rays were performed "actively" in conscious patients and "passively" in unconscious patients. One hundred consecutive patients were prospectively evaluated and 91 survived to complete data collection. Six (6.6%) had unstable cervical spine injuries--five detected with plain X-rays and one (1.1%) detected only with passive functional X-rays. Static cervical X-rays cost $93.00 per patient. Functional cervical X-rays added $42.00 per patient and were uncomplicated. Collar complications were common when collars remained on for more than 72 hours. This low detection rate is clinically important because of the enormous potential social and economic costs of missed unstable cervical spine fractures.

The evolution of the intensivist: from health care provider to economic rationalist and ethicist.

In contrast to many open intensive care units (ICUs) in the United State, where "parent" units (sometimes with few intensive care skills) admit and manage their own patients, Australia has closed units in which the intensivist has primary control of patient care while the patient remains in the ICU. This difference is important because in Australia, by virtue of having control of the ICU, the intensivist can be made responsible not only for patients care, but for resource allocation and financial constraint. Australian intensivists are called upon daily to make difficult decisions about who will be admitted, prematurely discharged or transferred from ICUs, and when treatment will be restricted or withdrawn.

Use of a measurement of pulmonary hyperinflation to control the level of mechanical ventilation in patients with acute severe asthma.

Mechanical ventilation causes significant morbidity and mortality in patients with severe asthma. Hypoventilation may reduce this morbidity and mortality, but indicators to guide the degree of hypoventilation are unclear. We used a measure of pulmonary hyperinflation to assess the degree of airflow obstruction and to guide the extent and duration of hypoventilation. Ten patients who required mechanical ventilation for acute severe asthma were studied. All were sedated, paralyzed, and given an initial minute ventilation (VE) of 200 ml/kg/min. End-inspiratory lung volume (VEI) above FRC was measured from the total exhaled gas volume during 40 to 60 s of apnea. VEI was used to regulate VE to a safe level (VEsafe), irrespective of PaCO2, by reducing the rate when VEI was > 20 ml/kg and increasing it when VEI was < 20 ml/kg. Each patient was weaned when VEsafe resulted in PaCO2 < or = 40 mm Hg (the weaning point). FRC was measured computer analysis of anterior and lateral chest radiographs taken at the end of apnea. Using the weaning point criterion, 2 patients (PaCO2 < 40 mm Hg) were weaned shortly after arrival. The remaining eight (initial PaCO2, 63 +/- 17 mm Hg) continued hypoventilation until the weaning point was reached (30 +/- 29 h). The weaning point was reached by the VE required for PaCO2 40 mm Hg decreasing concurrent with the VEsafe increasing. All but 1 patient were successfully weaned within 24 h of the weaning point.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk factors for morbidity in mechanically ventilated patients with acute severe asthma.

Acute severe asthma is associated with significant morbidity and mortality. We retrospectively quantified hypotension, pulmonary barotrauma, and cardiac arrhythmias in all patients with severe asthma admitted to the intensive care unit (ICU) and prospectively evaluated the predictive value of a measurement of dynamic hyperinflation (DHI) in those patients who required mechanical ventilation. In the first study, 88 ICU admissions for severe asthma over 5 yr (73 patients, 40 +/- 18 yr, 36 men, 37 women) were evaluated. Fifty-one admissions were mechanically ventilated, 29 were not, and 8 previously ventilated patients remained briefly intubated but were not ventilated in the ICU. Hypotension (18/88, 20%), pulmonary barotrauma (12/88, 14%), and arrhythmias (9/88, 10%) were entirely confined to patients who had been mechanically ventilated. There were no significant differences in ventilatory parameters, airway pressures, or blood gases between mechanically ventilated patients with and without complications. Two patients with previous severe hypoxic cerebral damage died from this complication after ICU discharge. In the second study, the end-inspiratory lung volume (VEI) (1) was compared with standard ventilatory parameters in 22 patients. There were no ICU deaths, but high incidences of pulmonary barotrauma (27%) and hypotension (41%) were found. Both minute ventilation (VE and VEI) were significantly higher in patients who developed complications (VE 13.7 +/- 3.0 versus 11.2 +/- 2.5 L/min, VEI 26.1 +/- 4.7 versus 20.0 +/- 7.4 ml/kg, p less than 0.05) but only VEI had a threshold value significantly predictive of complications. For VEI less than 1.4 L, 0/5 (0%) patients had complications; for VEI greater than or equal to 1.4 L, 11/17 (65%) had complications (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Myopathy in severe asthma.

Myopathy complicating the therapy of severe asthma has been recently described in several case reports. Twenty-five consecutive patients admitted to the intensive care unit (ICU) at this hospital for mechanical ventilation for severe asthma were studied for the incidence of creatine kinase (CK) enzyme rise and for the development of clinical myopathy. Pharmacologic therapy was standardized, every patient receiving corticosteroids and aminophylline intravenously and salbutamol both nebulized and intravenously. Twenty-two patients received muscle relaxant therapy with vecuronium. In 19 of 25 (76%) of patients there was elevation of CK levels to a median of 1,575 U/L (range, 66 to 7,430) occurring 3.6 +/- 1.5 days after admission. In nine patients there was clinically detectable myopathy. The presence of either myopathy or CK enzyme rise was associated with a significant prolongation of ventilation time. Arterial blood gas measurements on admission to the ICU revealed a pH (mean +/- SD) of 7.07 +/- 0.21, a PaCO2 of 87.2 +/- 32.7, and a PaO2 (with a high FIO2) of 129 +/- 97 mm Hg; however, no correlation was found between the severity of initial metabolic disturbance and the subsequent development of myopathy. There was no association between the type of corticosteroid administered and the subsequent development of myopathy. Patients with myopathy had received a significantly higher total dose of vecuronium when compared with those who did not develop myopathy (p < 0.001, Kruskal Wallis test). We have therefore found a surprisingly high incidence of CK enzyme rise and myopathy in this group of mechanically ventilated patients with severe asthma.(ABSTRACT TRUNCATED AT 250 WORDS)