Normal saline instillation before suctioning: helpful or harmful? A review of the literature

This research utilization paper reviews the body of published literature on the practice of normal saline instillation before endotracheal suctioning of mechanically ventilated adult patients. Although normal saline instillation before suctioning is a common clinical practice, the research literature does not demonstrate any physiologic benefit to this procedure. Moreover, normal saline instillation may decrease oxygen saturation values (via pulse oximetry) after suctioning. The relevant research studies have been inconsistent and inconclusive because of limitations in sample size and research methodology. Further research studies using larger, more diverse samples, adhering strictly to recommended guidelines for endotracheal suctioning, and examining additional physiologic parameters of oxygenation are necessary. In addition, long-term outcomes of normal saline instillation such as respiratory infection and complications, as well as atelectasis, should be evaluated. Until scientific data can be presented to support the physiologic benefit of this practice, normal saline instillation should be discontinued as a routine or standard practice.

Normal saline instillation before suctioning: helpful or harmful? A review of the literature

This research utilization paper reviews the body of published literature on the practice of normal saline instillation before endotracheal suctioning of mechanically ventilated adult patients. Although normal saline instillation before suctioning is a common clinical practice, the research literature does not demonstrate any physiologic benefit to this procedure. Moreover, normal saline instillation may decrease oxygen saturation values (via pulse oximetry) after suctioning. The relevant research studies have been inconsistent and inconclusive because of limitations in sample size and research methodology. Further research studies using larger, more diverse samples, adhering strictly to recommended guidelines for endotracheal suctioning, and examining additional physiologic parameters of oxygenation are necessary. In addition, long-term outcomes of normal saline instillation such as respiratory infection and complications, as well as atelectasis, should be evaluated. Until scientific data can be presented to support the physiologic benefit of this practice, normal saline instillation should be discontinued as a routine or standard practice.

Delayed tissue-plasminogen activator therapy in a rabbit model of thromboembolic stroke

This study investigated the efficacy and safety of delayed therapy with tissue-plasminogen activator (t-PA) in a rabbit model of thromboembolic stroke. The t-PA therapy was started 3, 4, or 5 hours after autologous clot embolization. New Zealand rabbits were randomized to receive a 2-hour intravenous infusion of either t-PA (6.3 mg/kg) or a saline solution (0.9% saline) after an autologous clot had embolized the anterior cerebral circulation. Regional cerebral blood flow (rCBF), intracranial pressure (ICP), and infarct size were measured to determine the effects of the delayed administration of the t-PA after intracranial embolization. Additionally, the following physiological parameters were monitored throughout the protocol: mean arterial pressure, hematocrit, arterial blood gases, glucose, and core and brain temperatures. All animals were studied for 4 hours after the administration of the t-PA or control solution; thus, the duration of each experiment was 7, 8, or 9 hours after autologous clot embolization. In control animals, brain infarct size and final ICP values were directly related to the length of time studied after clot embolization; among control animals, the largest infarct size and greatest rise in ICP were seen 9 hours after embolization.(ABSTRACT TRUNCATED AT 250 WORDS)

Social support, quality of life, immune function, and health in persons living with HIV

The purpose of this study was to examine the relationship between social support and quality of life in individuals with HIV. Using a descriptive, correlational design, data were collected from 50 HIV-positive individuals who were: (a) participants in support groups at a behavioral medicine unit, (b) inpatient or respite care patients with HIV, or (c) respondents to advertisements at AIDS service organizations. Instruments used for data collection were the Personal Resource Questionnaire 85-Part 2 (Weinert, 1987), measuring perceived social support, and the Quality of Life Index (QLI) (Ferrans & Powers, 1985), measuring the sense of well-being in life including the satisfaction with and importance of life domains with four subscales: health and functioning, socioeconomic, psychological/spiritual, and family. The results of the study indicated that social support was significantly correlated with quality of life (r = 0.81, p < 0.0001). Further, HIV status (asymptomatic HIV, symptomatic HIV, AIDS) was significantly related to quality of life (p < 0.01). However, HIV status was not significantly related to social support. No significant relationship was found between CD4 counts and HIV status, CD4 counts and social support, or CD4 counts and perceived health status. However, CD4 counts were significantly correlated with scores on the QLI. The findings of the study indicate that social support and quality of life are significantly intercorrelated and that higher CD4 counts are related to quality of life in this sample of persons living with HIV. Further areas for research include evaluation of quality of life over the span of HIV disease and interventions aimed at enhancing or maintaining quality of life in persons across the spectrum of HIV disease.

TGF-beta 1 post-treatment in a rabbit model of cerebral ischaemia

Transforming growth factor-beta 1 (TGF-beta 1), suggested in some studies to suppress astrocyte and neutrophil function, has also reduced ischaemic brain injury when administered immediately prior to clot embolization in models of thromboembolic stroke. The effect of TGF-beta 1 as a post-treatment paradigm was investigated in a rabbit model of thromboembolic stroke. Following clot embolization, regional cerebral blood flow fell to < 10 cc 100 g-1 min-1 in all animals. TGF-beta 1 (10 micrograms) or vehicle (n = 5 each group) was infused via the contralateral carotid artery. TGF-beta 1 administration resulted in a rapid and selective reduction in the peripheral neutrophil count as compared to a significant (p < 0.05) increase in control values (2336 +/- 817 vs 4320 +/- 928 neutrophils mm3, mean +/- SEM). Neutrophil aggregation was increased within 30 min of TGF-beta 1 infusion when compared to control (2.07 +/- 0.70 vs 1.09 +/- 0.17 ohms, p < 0.05); neutrophil chemiluminescence, an index of the oxygen respiratory burst was not significantly affected by TGF-beta 1 administration. No difference in platelet counts or aggregation was noted. There was no significant difference between the two groups regarding brain infarct size (47.5 +/- 10.9 vs 56.5 +/- 10.4, n = 4, TGF-beta vs control, mean +/- SEM), intracranial pressure, or brain excitatory amino acid levels (aspartate and glutamate) within ischaemic regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of triphenyltetrazolium dye with light microscopic evaluation in a rabbit model of acute cerebral ischaemia

The present study was performed to compare brain infarct size assessment by routine histology (haematoxylin and eosin) and by 2,3,5-triphenyltetrazolium chloride staining techniques. New Zealand white rabbits were subjected to autologous clot embolization to the anterior circulation of the brain. After a study period of 7-8 h the brains were harvested and serially sectioned in the coronal plane. Brain slices were then immersed in a 1% triphenyltetrazolium chloride dye. Following visualization of the infarcted region, the brains were immediately placed in 10% formalin and later prepared for histologic evaluation by routine haematoxylin and eosin. The two methods were compared for their ability to estimate infarct size by an independent observer. There was excellent correlation between the two methodologies; infarct sizes of 57.4 +/- 5.0% versus 55.9 +/- 5.4% (mean +/- SEM, p < 0.007, r = 0.73, n = 12; expressed as percentage of the hemisphere infarcted) were noted for light microscopic evaluation versus triphenyltetrazolium chloride staining, respectively. It is concluded that triphenyltetrazolium chloride staining is an acceptable method for delineating brain infarct size in this rabbit model of thromboembolic stroke. The relative ease of infarct size determination with this technique suggests its more widespread use in similar models.

Tissue plasminogen activator: comparison of dose and route of administration in a rabbit model of thromboembolic stroke

The thrombolytic activity of tissue plasminogen activator was evaluated in a rabbit model of thromboembolic stroke using both various concentrations (3, 5, and 10 mg/kg; 20% bolus with the remaining 80% given over 30 min.) and routes of administration (intravenous versus regional intra-arterial). An autologous tin-tagged clot was embolized to the brain via the carotid artery. Tissue plasminogen activator was then given at the doses and routes noted (n = 3 in all groups). Thrombolytic activity was followed by serial x-rays of the tin-laden clot over a four-hour period. The brains were then removed and subjected to gross inspection. Only the intravenous dose of 5 mg/kg tissue plasminogen activator produced greater than 50% clot lysis in all animals. Doses of t-PA higher (10 mg/kg) or lower (3 mg/kg) than this were less effective in producing thrombolysis, demonstrating greater than 50% clot lysis in only one animal of each group. We conclude that in this model of thromboembolic stroke the intravenous administration of tissue plasminogen activator is more effective than intra-arterial, and that the optimal dose is in the range of 5 mg/kg.

Tumor necrosis factor and cardiac function

The direct effect of tumor necrosis factor (TNF), a product of activated macrophages, on myocardial performance was determined using an isolated papillary muscle technique and a modified Langendorff preparation. Papillary muscle was obtained from male adult rats 4-5 hours after they received either 100 ng/kg TNF (group A), or 100 micrograms/kg TNF (group B) or saline (control). Group B animals exhibited significantly greater peak tension development and velocity of contraction compared with controls (p less than 0.05). In group A animals these variables were not significantly different from those of the controls (p greater than 0.05). Electrophysiologic measurements revealed a significant decrease in resting membrane potential in both group A and group B animals compared with the controls (p less than 0.05). Whole hearts perfused with serum from animals treated with TNF 18-22 hours earlier exhibited significant impairment of contractility, decreased rate of systolic pressure development, and decreased rate of relaxation compared with the controls (p less than 0.05). Coronary flow and myocardial water content were similar for both groups of perfused hearts. These data suggest that tumor necrosis factor stimulates an early beneficial effect on myocardial function, which 18-22 hours later is associated with impairment of myocardial performance. This effect appears to be serum transferable.