Transfusion of 28-day-old leucoreduced or non-leucoreduced stored red blood cells induces an inflammatory response in healthy dogs.

BACKGROUND AND OBJECTIVES: Studies in mice suggest that rapid transfusions of red blood cells (RBCs), refrigerator stored for longer durations, induce a pro-inflammatory cytokine response. Studies in human neonates confirm these findings; however, to date, adult human studies have failed to replicate these findings. We used healthy research dogs to begin to examine the factors affecting the cytokine response to transfusion. MATERIALS AND METHODS: In a prospective study, healthy dogs were randomized for two autologous packed RBC transfusions after 7 (i.e. 'fresh') and 28 (i.e. 'old') days of storage, or after 28 and 7 days of storage, with or without prestorage leucoreduction (LR). RESULTS: No significant differences were observed between LR and non-LR transfusions for all circulating analytes measured following transfusion. A pro-inflammatory cytokine response, exemplified by monocyte chemoattractant protein-1, was observed 6 h after only old RBC transfusions, irrespective of infusion rate (P < 0·001). This response was accompanied by increased neutrophil counts (P < 0·001) and decreased platelet counts (P < 0·001). CONCLUSION: In healthy dogs, old RBC transfusions induce inflammation, which is unaffected by infusion rate.

The impact of expiration on particle deposition within the nasal cavity.

One of the most important functions of the nose is cleansing the inspired air. The aim of this study was to compare the intranasal deposition of particles during inspiration and expiration, applying different breathing manoeuvres. In nine subjects, the non-deposited particles during inhalation of an aerosol of starch particles were laser-optically detected by placing a suction probe transnasally in the anterior nasal segment. The particle deposition was measured during cyclical nose-in/nose-out (nose-only) and nose-in/mouth-out breathing. The deposited fraction was calculated in percentages. Active anterior rhinomanometry and acoustic rhinometry were performed. The mean deposited fraction in the anterior nasal segment was statistically significantly higher (P < 0.02) during nose-only breathing (46.0%) compared with nose-in/mouth-out breathing (33.0%). Our results suggest that intranasal particle deposition takes place during inspiration as well as during expiration. The period of expiration does not only seem to be important for water and heat recovery, but also for cleansing of the respiratory air.

Electrical analogs for monitoring vascular properties in artificial heart studies.

The problem of choosing parametric descriptions of the systemic vascular bed suitable for monitoring beat-to-beat changes in peripheral vascular properties is considered. Three simple models with two, three, and five elements are compared, essentially exploiting the Akaike information criterion combined with reasonable requirements for estimate accuracy. Analysis of pressure data, which are either simulated by the five-element model or measured on a mock circulatory system during abrupt changes in peripheral resistance, suggests guidelines for model selection. In particular, the five-element model exhibits very close adherence to physical reality by allowing for reflection, while the classical windkessel model provides the most reproducible estimates.

Tracking time-varying properties of the systemic vascular bed.

The problem of tracking changes in viscoelastic properties of the systemic arterial bed is considered and a recursive estimation procedure, belonging to the class of output-error algorithms with adjustable compensator, is developed and discussed. By means of computer simulations, suitable values are determined for the key design variable which controls the tradeoff between tracking ability and noise sensitivity of the algorithm. In this way, the algorithm allows on-line estimation of arterial compliance, peripheral resistance, and characteristic impedance on the basis of aortic pressure and flow signals. Furthermore, the results obtained from data numerically simulated, as well as measured on a mock circulatory system, demonstrate that the dominant arterial time-constant can be tracked by the algorithm using only measurements of the aortic pressure during diastole.

Pain center follow-up study of treated and untreated patients.

To investigate the outcome of patients treated in a multidisciplinary pain clinic, patients previously treated in the center and patients who had been eligible for, but did not desire such treatment, were contacted by phone. Their current life and pain status were assessed using a structured interview format. Fourteen individuals in each group agreed to participate in the study. The groups did not differ significantly on variables of sex, age, time since referral, marital status, premorbid income, and type of pain. Analysis of differences in discomfort level for the treated group revealed a 47% decrease from a mean of 7.02 to 3.67 (10-point scale). The telephone contact occurred approximately 2 1/2 years following initial referral. There were no statistical differences in current pain levels, number of pain-related visits to health professionals, pain-related expenses, employment status, disability status, history of pain-related litigation, use of medications, or frequency of pain-related surgeries since referral. Patients treated in the pain clinic were significantly more likely to use active, self-control strategies to manage pain than were individuals in the control group. Use of such strategies, however, was limited. The data suggest that outcome studies of pain patients should include control groups treated by other modalities or who receive no treatment; that maintenance of treatment goals is compromised by compliance problems; and that more comprehensive cost effectiveness studies of chronic pain treatment are needed.