摘要:

We examined the cerebral blood flow response to alterations in perfusion pressure mediated through decreases in mean arterial pressure, increases in cerebrospinal fluid (CSF) pressure, and increases in jugular venous (JV) pressure in 42 pentobarbital anesthetized dogs. Each of these three pressures was independently controlled. Cerebral perfusion pressure was defined as mean arterial pressure minus JV or CSF pressure, depending on which was greater. Mean hemispheric blood flow was measured with the radiolabeled microsphere technique. Despite 30-mm Hg reductions in mean arterial pressure or increases in CSF or JV pressure, CBF did not change as long as the perfusion pressure remained greater than approximately 60 mm Hg. However, whenever perfusion pressure was reduced to an average of 48 mm Hg, cerebral blood flow decreased 27% to 33%. These results demonstrate the capacity of the cerebral vascular bed to respond similarly to changes in the perfusion pressure gradient obtained by decreasing mean arterial pressure, increasing JV pressure or increasing CSF pressure, and thereby support the above definition of cerebral perfusion pressure.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Twenty-eight cynomolgus monkeys had an autologous subarachnoid blood clot placed in the basal cisternae via craniectomy. Twenty-three monkeys survived clot placement and five animals died within 24 h. An additional eight monkeys underwent sham procedures and six acted as anesthetic controls. Cardiopulmonary indices were measured before clot placement and 30 to 60 min thereafter, to determine if certain changes had prognostic value for immediate outcome.In the 24-h survivors, heart rate and arteriovenous oxygen content difference increased significantly (p< .05 and .01, respectively), while stroke index (SI) (p< .01), mean pulmonary artery pressure (p< .001), pulmonary artery wedge pressure (p< .001), and central venous pressure (p< .05) fell. In the 24-h nonsurvivors, cardiac index (CI) (p< .05) and SI (p< .01) fell to an even greater extent than in the survivors. There was a significant (p< .05) difference between the two groups for CI and SI. There were no significant differences in the sham-operated animals. In six control monkeys, neither heart rate nor CI significantly increased throughout 5 h of anesthesia.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Discrepancies between pulmonary artery wedge pressure (WP) and left atrial pressure (LAP) occur with pulmonary embolism. Theoretically, this discrepancy could be affected by the bronchial circulation or by the type of embolus. To test this in dogs, we determined the effects of embolism induced by glass beads and by air upon the WP with intact vs. ligated bronchial blood flow to the left lower lobe. For those animals receiving pulmonary air infusions, the pulmonary artery pressure, WP, and pulmonary vascular resistance showed significant (p< .05) elevations with no change in LAP. There were no changes in these values when the bronchial blood flow was interrupted. When glass beads (120 ±) were injected into the left lower lobe, the pulmonary artery pressure and pulmonary vascular resistance rose as in the air emboli groups (p< .05); however, WP remained at control values and approximated LAP. Obstructing the bronchial blood flow did not change this response. We conclude that the discrepancy between WP and LAP depends upon the type of embolus and is not affected by bronchial blood flow.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Many recent ventilators used in the ICU have a demand valve for intermittent gas flow. While demand systems conserve gas flow, they do not appear to be as well tolerated by patients as are continuous flow systems. Using a mechanical model to simulate a patient's spontaneous breathing efforts, we tested nine common ventilators in the intermittent mode. Their sensitivity varied from −2.0 to −0.2 cm H2O and the total delay time from 19 to 92 msec. The initial inspiratory resistance varied between 0.03 and 0.10 cm H2O/L min and initial flow was between 2.5 and 12.3 L/min. These values were often not supplied or not the same as those in the manufacturer's specifications.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

This study assessed the bacteriologic safety of room-temperature injectate used for cardiac output measurement in a surgical ICU, and compared its cost/benefit relationship to that of prefilled packaged syringes and a closed-loop injectate system. Ninety-five samples of injectate were obtained at four time intervals from staff-prepared syringes, and cultured for microbiologic growth. About 29% (27/95) of samples yielded bacterial growth, ranging from two colony-forming units to those too numerous to count. All positive samples contained skin flora, including coagulase-negative staphylococci and coryneforms. Additionally, five plates contained colonies of Gram-negative bacteria. Extended storage time increased the risk of contamination: 16.2% were contaminated within the first 24 h, whereas 45% were contaminated when stored for more than 72 h. Switching to a closed injectate system significantly (p< .001) decreased the incidence of contamination by 1.2%, and also allowed a cost savings of $1.52/patient.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The role which beta-endorphin plays in the pathogenesis of hemorrhagic hypotension is controversial. In the present experiment, 20 ml/kg of blood was bled from ten healthy male baboons (Papio anubis) over 60 min and then retransfused over the next 30 min. We found that the mean plasma beta-endorphin level increased 109% above baseline (p< .05) within 15 min after starting hemorrhage, and rapidly returned to a baseline concentration with retransfusion. We conclude that in a primate species, circulating endogenous opioid peptide concentrations increase rapidly in response to sublethal hemorrhagic hypotension and normalize with restoration of the baseline intravascular volume. These findings support the concept that endogenous opioid peptides may mediate the hypotension of shock states.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

Available data on the characteristics of infections in different types of ICUs are limited. Between May and July 1984, overall infections rates of patients in the ICUs and in the general wards at the Detroit Receiving Hospital were 19.2% and 9.8%, respectively (p< .001). Specific infection rates (number of infections/100 admissions in each unit) were 35.2% for surgical unit, 29.8% for burn unit, 13.9% for medical unit, and 6.6% for coronary unit. Of the total number of patients admitted, only 1.9% patients in the coronary unit became infected while 10.9% to 13.6% in the other three units acquired infection. There were more infections per patient in the surgical unit than in the others.Device-related infections involving the urinary and respiratory tracts were the most common. Predominant pathogens isolated in order of frequency wereEsche-richia coli, Pseudomonas aeruginosa, Klebsiella pneu-moniae, andStaphylococcus aureus.Death rates among the infected patients were high; of those infected, nine patients (75%) of 12 in the surgical unit and ten (91%) of 11 in the medical unit died. For those who died, the duration from ICU admission to infection was 2 to 22 days (mean 6.5) and length of survival after becoming infected was 2 to 50 days (mean 22). The mortality rates between the infected and uninfected patients in the medical, surgical, and burn units were significantly different (p< .0005). Awareness of patterns for nosocomial infection in different ICUs is of, value in the adoption of appropriate infection control policies within each unit.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

A 16-yr-old female suffering acute, rapidly progressive combined respiratory and cardiac failure that was unresponsive to conventional volume-cycled ventilation, was stabilized with the simultaneous short-term use of veno-venous membrane oxygenation and high-frequency jet ventilation. Percutaneousl) introduced cannulas afforded rapid vascular access for membrane oxygenation, minimal wound problems during the perfusion, and easy decannulation. This is the first reported combined use of high-frequency jet ventilation and extracorporeal membrane oxygenation, and the first reported percutaneous initiation of veno-venous bypass. The patient remained alive and well 4 months after therapy.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

We treated two pediatric patients suffering respiratory failure associated with status asthmaticus. Neither patient responded to maximal bronchodilatory therapy and mechanical ventilation; however, continuous infusion of ketamine (1.0 to 2.5 mg/kg-h) immediately improved airway obstruction. Ketamine appears to increase catecholamine levels and directly relax bronchial smooth muscle. Except for increased secretions during the infusion, our patients showed no immediate or long-term sequelae from ketamine therapy. However, ketamine should only be used for asthmatics whose respiratory failure does not respond to conventional management and mechanical ventilation.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID

摘要:

The precise etiology of transient neurologic deficits at high altitude is unclear, particularly since the subjects are not investigated as they would be had the events occurred in an urban environment. This report describes two subjects who experienced transient ischemic attacks (TIAs) while ascending the northeast ridge route of Mt. Everest during the Ultima Thule Everest Expedition, and a third subject with TIAs during three separate high-altitude climbs. Possible etiologies and treatment for TIAs at high altitude are suggested.

ISSN:0090-3493    

出版商:OVID    

年代:1986

数据来源: OVID