In an intensive care unit population, the incidence of central venous catheter infection and colonization is low overall and, clinically and statistically, is not different at all three sites when optimal insertion sites are selected, experienced operators insert the catheters, strict sterile technique is present, and trained intensive care unit nursing staff perform catheter care.

To determine whether blood hemoglobin concentration ([Hb]) could be measured noninvasively as the ratio of pulsatile changes in attenuation (absorbance plus scatter) of light (D) across a body part to changes in light path length (l), we measured transmission of near-infrared light (905 +/- 10 nm) through a finger, using a modified pulse oximeter, and simultaneously monitored fingertip diameter, using a sonomicrometer. In 25 subjects with [Hb] ranging from 3.1 to 18.2 gm/dl, and with normal oxygenation, average D/l ratio over 30-60 s correlated strongly with [Hb] measured by Coulter counter (r = 0.84, p << 0.001), though with considerable scatter, with absolute value of differences averaging 17% of the mean. Using 12 gm/dl and 0.75 mm(-1) as the lower limits of normal for [Hb] and D/l, respectively, two of nine normals had low (D/l) (78% specificity), and only one of 16 anemic subjects had borderline normal (D/l) (94%-100% sensitivity). The positive predictive value of a low (D/l) was 88% and the negative predictive value was 87.5%. With further development, this technique may reduce the need for phlebotomy, thereby reducing risks and costs and improving the experience of being a patient.

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T he article in this issue by Dimick et al 1 about total parenteral nutrition (TPN) and infections associated with use of central venous catheters addresses a major concern in critical care medicine. In day-to-day practice, certain intervention-related complications are inevitable. As our understanding in general improves, we find many other factors that contribute to complications. Dimick et al indicate that with proper care, infection related to central venous catheters used for TPN is avoidable.As critical care medicine continues to advance, outcomes improve and interventions previously considered high risk become safer. Two vital components of critical care are the use of central venous catheters and TPN. The most severely ill patients often require both for survival and recovery. In the intensive care unit, gastrointestinal dysfunction associated with multiorgan failure and shock or with abdominal surgery is not uncommon. Nutrition cannot be compromised. 2 However, when TPN is suggested for a patient, the risk of infectious complications, especially infection related to use of central venous catheters, is often thought greater than potential benefits.Why is this risk so often weighed with greater importance than are other clinical factors? Does this concern have merit, or is it simply an overreaction? Catheter-related infection is potentially devastating. Such infections greatly increase morbidity, mortality, 3,4 and length of stay. 5 Pittet and Wenzel 4 reported an odds ratio for death of 20.45 (95% CI, 18.9-22.1) for patients with catheter-related infection. Thus, the concern is understandable because of the potential consequences.A decade ago, Kudsk et al 6 compared the prevalence of septic complications in a group of severely ill trauma patients who received either TPN or enteral feeding. The group given TPN had significantly higher prevalences of pneumonia (31% vs 11.8%; P¬ <¬ .02), intra-abdominal abscess (13.3% vs 1.9%; P¬ <¬ .04) and catheter sepsis (13.3% vs 1.9%; P¬ <¬ .04). Other investigators 7 reported similar data. The large difference in rates between patients given TPN and those given enteral feedings makes it difficult to argue a lack of association between TPN and infectious complications.The question yet to be answered about TPN is, despite the inherent infectious risks, can infectious complications be avoided? Dimick et al 1 have begun to answer this question. Now that a decade has passed, the research of Dimick et al and that of other investigators has improved safety for interventions commonly used in critically ill patients.The earlier studies on TPN were performed without glucose control. Recently, van den Berghe et al 8 reported that tight glucose control decreased mortality significantly (8.0% with conventional treatment vs 4.6% with tight glucose control, P¬ <¬ .04). Were the increases in infectious complications in the earlier reports a direct result of poorly controlled hyperglycemia? If euglycemia had been achieved, would the differences in infectious rates found by Kudsk et al ...

The use of inferior vena cava (IVC) filter for massive pulmonary emboli (PE) with cardiopulmonary instability has not been clinically studied. We present a case series of six such patients who received an IVC filter with anticoagulation rather than thrombolysis because of high risk of bleeding. Acute pulmonary embolectomy was considered, but was not possible for a variety of individual clinical situations. These six hospitalized patients prospectively followed during their admission. They were triaged to three medical intensive care units (ICUs) and one surgical ICU in three university teaching hospitals. One patient was transferred from another institution. All six patients had severe hypoxia and tenuous cardiopulmonary status. All required high inspiratory oxygen and hemodynamic support; two required mechanical ventilation and vasopressors. An IVC filter was placed emergently and anticoagulation was started immediately All six patients had resolution of pulmonary thromboemboli (PTE) on anticoagulation while the IVC filter prevented further PE. All six patients were discharged home in their pre-critical illness state. None ofthe patients suffered complications from this therapy and had excellent resolution ofcardiopulmonary collapse. The IVC filter placement prevented further major embolic events while the PTE resolved with anticoagulation. An IVC filter should be considered as an adjunct to anticoagulation therapy for those patients with massive PE and cardiopulmonary instability who are not candidates for thrombolysis, and acute pulmonary embolectomy is not readily available or is of very high risk.

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