Loren D. Nelson

Right ventricular end-diastolic volume index as a predictor of preload status in patients on positive end-expiratory pressure

OBJECTIVE To evaluate the clinical utility of right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery occlusion pressure (PAOP) as measures of preload status in patients with acute respiratory failure receiving treatment with positive end-expiratory pressure. DESIGN Prospective, cohort study. SETTING Surgical intensive care unit in a Level I trauma center/university hospital. PATIENTS Sixty-four critically ill surgical patients with acute respiratory failure. INTERVENTIONS All patients were treated for acute respiratory failure with titrated levels of positive end-expiratory pressure (PEEP) with the goal of increasing arterial oxygen saturation to > or =0.92, reducing FIO2 to <0.5, and reducing intrapulmonary shunt to < or =0.2. Serial determinations of RVEDVI, PAOP, and cardiac index (CI) were recorded. MEASUREMENTS AND MAIN RESULTS Two hundred-fifty sets of hemodynamic variables were measured in 64 patients. The level of PEEP ranged from 5 to 50 cm H2O (mean 12+/-9 [SD] cm H2O). At all levels of PEEP, CI correlated significantly better with RVEDVI than with PAOP. At levels of PEEP > or =15 cm H2O, CI was inversely correlated with PAOP, but remained positively correlated with RVEDVI. CONCLUSIONS CI correlates significantly better with RVEDVI than PAOP at all levels of PEEP up to 50 cm H2O. RVEDVI is a more reliable predictor of volume depletion and preload recruitable increases in CI, especially in patients receiving higher levels of PEEP where PAOP is difficult to interpret.

Gastric tonometry supplements information provided by systemic indicators of oxygen transport.

HYPOTHESIS Assessment of splanchnic perfusion by gastric intramucosal pH (pHi) adds to the information provided by systemic indicators of oxygen transport. SETTING University Hospital level I trauma center. DESIGN Prospective study in 20 critically ill trauma patients comparing pHi with base deficit, lactate, oxygen delivery, and oxygen consumption (indexed to body surface area), mixed venous oxygen saturation (Svo2), oxygen utilization coefficient, and arterial pH. All measurements were obtained at admission, 1, 2, 4, 8, 16, and 24 hours, or at death. MAIN OUTCOME MEASURES Correlation of pHi with the measured systemic variables, prediction of organ dysfunction, development of multiple organ dysfunction syndrome, and mortality. RESULTS There was a poor correlation between pHi and the systemic hemodynamic and oxygen transport variables. Patients with a low pHi (< 7.32) on admission who did not correct within the initial 24 hours had a higher mortality (50% vs. 0.0%, p = 0.03) and incidence of organ dysfunction (2.6 organs/patient vs. 0.62 organs/patient, p = 0.02) than those who did. Using logistic regression analysis, only pHi, base deficit, and Svo2 were significantly associated with mortality during the study period. At 24 hours, only pHi was different between patients who developed multiple organ dysfunction syndrome and those who did not. There was a threshold value for pHi (7.10) which identified those patients who would go on to develop multiple organ dysfunction syndrome. CONCLUSIONS Uncorrected splanchnic malperfusion is associated with a higher incidence of organ dysfunction and mortality. Gastric tonometry supplements information provided by systemic indicators of oxygen transport during resuscitation of critically ill trauma patients.

Percutaneous dilational tracheostomy: a comparison of single- versus multiple-dilator techniques.

Objective To compare the safety and efficacy of single- vs. multiple-dilator techniques in the performance of percutaneous dilational tracheostomy. Design Prospective randomized trial. Setting Intensive care units at a level 1 trauma center. Patients Fifty consecutive patients requiring tracheostomy for airway control or prolonged mechanical ventilatory support. Interventions Patients were randomized to receive a percutaneous dilational tracheostomy by either the single- or multiple-dilator technique described by Ciaglia. Measurements and Main Results Percutaneous dilational tracheostomy was performed using the single-dilator technique in 6:01 ± 3:03 mins and by the multiple-dilator technique in 10:01 ± 4:26 mins (p < .0006). There were no statistically significant differences in complication rates between the two techniques. No major complications occurred with either technique. Conclusion The single-dilator percutaneous tracheostomy technique is a safe, cost-effective, and more rapidly performed method for bedside tracheostomy in the intensive care unit.

Preload assessment in patients with an open abdomen.

BACKGROUND Intra-abdominal hypertension and abdominal compartment syndrome cause significant morbidity and mortality in surgical and trauma patients. Maintenance of intravascular preload and use of open abdomen techniques are essential. The accuracy of pulmonary artery occlusion pressure (PAOP) and central venous pressure (CVP) in patients with intra-abdominal hypertension has been questioned. METHODS Twenty surgical and trauma patients with intra-abdominal hypertension requiring open abdominal decompression were monitored using volumetric thermodilution pulmonary artery catheters. Hemodynamic, oxygenation, inspiratory, and intravesicular pressure measurements were collected prospectively. PAOP, CVP, and right ventricular end-diastolic volume index (RVEDVI) were compared as estimates of preload status. RESULTS Multiple regression analysis demonstrated that cardiac index correlated significantly better with RVEDVI (r = 0.69) than with PAOP (r = -0.27) or CVP (r = -0.28) during resuscitation after open abdominal decompression (p < 0.0001). CONCLUSION RVEDVI is superior to PAOP and CVP as an estimate of preload status in patients with an open abdomen.

Survival in patients with severe adult respiratory distress syndrome treated with high-level positive end-expiratory pressure.

OBJECTIVE To assess the mortality rate and complications in a population of surgical patients with severe adult respiratory distress syndrome (ARDS) treated with positive end-expiratory pressure (PEEP) of > 15 cm H2O in an attempt to reduce intrapulmonary shunt to approximately 0.20 and reduce FIO2 to < 0.50. DESIGN Retrospective review of patients treated by a standardized ventilatory support protocol at the time of their illness. SETTING A 24-bed surgical intensive care unit in a university medical center. PATIENTS All patients admitted to the surgical intensive care unit during a 34-month period who met the criteria for severe ARDS (Pao2 of < or = 70 torr [< or = 9.3 kPa] on an FIO2 of > or = 0.50, diffuse interstitial and/or alveolar infiltrates on chest radiograph, decreased lung compliance, no evidence of congestive heart failure, and a likely predisposing etiology) were evaluated. Patients treated with PEEP of > 15 cm H2O were selected for this review. INTERVENTIONS Patients were treated by a protocol to achieve oxygenation end points, which consisted of maintaining arterial oxyhemoglobin saturation (as determined by pulse oximetry of > or = 0.92), while reducing FIO2 to < 0.50 and decreasing intrapulmonary shunt fraction to < or = 0.20 by adding PEEP. With the exception of patients with suspected intracranial hypertension related to closed-head injury, low-rate intermittent mandatory ventilation was the primary mode of ventilation. Pressure-support ventilation was added, when needed, to improve patient comfort, enhance spontaneous tidal volume, or improve CO2 excretion. MEASUREMENTS AND MAIN RESULTS Eighty-six patients with severe ARDS were treated with a PEEP of > 15 cm H2O. Nineteen of these patients died early of severe closed-head injury or massive uncontrollable hemorrhage and were excluded from the evaluation. The remaining 67 patients had a mean Lung Injury Score of 3.3 during their treatment with high PEEP. Twenty (30%) of 67 patients died. Eight of the deaths occurred after decrease of ventilatory support and with acceptable blood gases. The other 12 patients who died had continued oxygenation deficits and received increased levels of ventilatory support at the time of death. Twenty-six (39%) of 67 patients had radiographic manifestations of barotrauma (pneumothorax, subcutaneous emphysema, etc.) related to their primary injuries or to complications related to central venous catheter placement. Seven (17%) of 41 patients developed clinical or radiographic signs of barotrauma while receiving high-level PEEP. The hemodynamic effects of increased airway pressure were managed with fluids and inotropic agents, when necessary, and did not limit the application of PEEP to reach the defined end point of treatment. CONCLUSIONS This subset of patients with severe ARDS treated with high-level PEEP had a mortality rate lower than those rates previously reported by other researchers using more conventional ventilatory support and resuscitation techniques. FIO2 may be significantly reduced and PaO2 may be maintained at acceptable values by decreasing intrapulmonary shunt fraction using high-level PEEP.

Use of recombinant human erythropoietin (r-HuEPO) in a Jehovah's Witness refusing transfusion of blood products: case report.

Recombinant human erythropoietin (r-HuEPO) administration to a Jehovahs witness refusing blood transfusions increased her nadir packed cell volume from 13% to 37% and reticulocyte count from 2% to 17.7%. R-HuEPO may provide an alternative safe and effective therapy in life-threatening anemia when blood transfusions are unacceptable to the patient.

Clinical outcomes after telemedicine intensive care unit implementation.

Objective: To examine clinical outcomes before and after implementation of a telemedicine program in the intensive care units of a five-hospital healthcare system. Design: Observational study with the baseline period of 1 yr before the start of a telemedicine intensive care unit program implementation at each of 5 hospitals. The post periods are 1, 2, and 3 yrs after telemedicine intensive care unit program implementation at each hospital. Setting: Ten adult intensive care units (114 beds) in five community hospitals in south Florida. A telemedicine intensive care unit program with remote 24/7 intensivist and critical care nurse electronic monitoring was implemented by a phased approach between December 2005 and July 2007. Measurements and Main Results: Records from 24,656 adult intensive care unit patients were analyzed. Hospital length of stay, intensive care unit length of stay, hospital mortality, and Case Mix Index were measured. Severity of illness using All Patient Refined-Diagnosis Related Groups scores was used as a covariate. From the baseline year to year 3 postimplementation, the severity-adjusted hospital length of stay was lowered from 11.86 days (95% confidence interval [CI] 11.55–12.21) to 10.16 days (95% CI 9.80−10.53; p < .001), severity-adjusted intensive care unit length of stay was lowered from 4.35 days (95% CI 4.22–4.49) to 3.80 days (95% CI 3.65–3.94; p < .001), and the relative risk of hospital mortality decreased to 0.77 (95% CI 0.69–0.87; p < .001). Conclusions: After 3 yrs of deployment of a telemedicine intensive care unit program, this retrospective observational study of mortality and length of stay outcomes included all cases admitted to an adult intensive care unit and found statistically significant decreases in severity-adjusted hospital length of stay of 14.2%, intensive care unit length of stay of 12.6%, and relative risk of hospital mortality of 23%, respectively, in a multihospital healthcare system.

Ventilatory response to high caloric loads in critically ill patients.

ObjectiveTo assess the effect of high caloric loads on CO2 metabolism and ventilation. DesignRetrospective, clinical review. SettingIntensive and special care units of a university medical center. PatientsA consecutive series of 78 intubated patients who underwent 129 metabolic measurements as part of their nutritional support. Measurements and Main ResultsA total of 129 measurements of oxygen consumption, CO2 production, respiratory quotient, energy expenditure, minute ventilation, alveolar ventilation, deadspace ventilation, Paco2, respiratory rates and volumes, and substrate intake were made in 78 critically ill patients to determine their response to caloric loads. Statistically significant differences in indexed CO2 production, exhaled minute ventilation, deadspace ventilation, and intermittent mandatory ventilation rate existed between groups of patients with respiratory quotient of >1 or respiratory quotient of >1. Total caloric and carbohydrate caloric intake were 21% greater in those patients with respiratory quotient of >1, but this was not a statistically significant difference (p = .51). There was no significant difference between the groups for indexed oxygen consumption, alveolar ventilation, Paco2, or measured energy expenditure. There was a correlation between carbohydrate caloric intake and CO2 production for the entire population (r2 = .31, p < .001), with the latter relationship statistically greater (p = .006) in the respiratory quotient of >1 group (r2 = .76, p < .001) relative to the respiratory quotient of >1 group (r2 = .20, p < .001). There was a correlation between carbohydrate caloric intake and alveolar ventilation (r2 = .19, p < .001) with no significant difference between the two groups. A correlation between CO2 production and exhaled minute ventilation (r2 = .25, p < .001) was present only in the respiratory quotient of > group while a strong correlation between CO2 production and alveolar ventilation was observed for the entire population (r2 = .47, p < .001) with no difference between groups. ConclusionsIncreased CO2 production, exhaled minute ventilation, and deadspace ventilation values in the overfed group and the lack of difference between alveolar ventilation, Paco2, and measured energy expenditure, along with correlations between CO2 production and alveolar ventilation suggest that carbohydrate loads increase CO2 production which drives alveolar ventilation, thus preventing hypercapnia. When alveolar ventilation does not increase (and Paco2 increases) or when the spontaneous breathing rate increases to augment alveolar ventilation, the clinical response of increasing mechanical ventilation may increase deadspace ventilation. (Crit Care Med 1994; 22:796–802)

Kinetic therapy in critically III patients: Combined results based on meta-analysis

Several investigators have independently studied kinetic therapy (KT) using continuous postural oscillation in medical, surgical, and neurologic intensive care units (ICUs). These studies were designed to determine if KT would reduce complications associated with immobilization of ICU patients and reduce costs by decreasing hospital stay. The results based on the six randomized studies varied with reports of significant and nonsignificant differences between KT tables (Roto Rest bed, KCI, San Antonio, TX) and conventional hospital beds. The inconsistencies could be due in part to insufficient sample sizes of each study, which ranged from 30 to 100 patients. The present report presents the results of meta-analysis, which tests the statistical significance of differences between treatment groups by combining six independent studies with a total sample size of 419 patients. The analysis indicates that the incidences of pneumonia and atelectasis were significantly reduced by KT tables (P < .002 and P < .03, respectively). The number of hours intubated and the length of ICU stay were also significant (P < .04 and P < .02, respectively). However, KT did not appear to have a statistically significant effect on adult respiratory distress syndrome, pressure ulcers, embolisms, mortality, or length of hospital stay.

Patient selection for iced versus room temperature injectate for thermodilution cardiac output determinations.

In 42 patients who required hemodynamic monitoring there was no statistically significant difference between mean cardiac output determined with iced vs. room temperature injectate. There was also no statistical difference in mean cardiac output values using iced vs. room temperature injectate when data were grouped according to body temperature, mean arterial pressure, and cardiac output. These results suggest that when cardiac output is measured by the methods described, the use of iced injectate is unnecessary in many critically ill patients.