摘要:

Unlike the systemic circulation, the pulmonary vasculature constricts in response to hypoxia to divert blood flow to better-ventilated segments. The site of this response, the hypoxic pulmonary vasoconstriction, has been reported as precapillary in numerous experimental models of isolated animal lungs.In the present study, the response of intact chest dog and human lungs to hypoxia and hypoxemia, respectively, was also precapillary vasoconstriction. In dogs, hypoxia in the ipsilateral lung attenuated the normal vertical blood flow gradient. Contralateral hypoxia did not alter pulmonary regional blood flow, precapillary (Ra), postcapillary, or total pulmonary vascular resistance.In patients, an elevated alveolar-arterial oxygen pressure gradient of 50 to 150 torr resulted in significantly increased Ra. Further hypoxemia did not increase this response. In addition, the effective pulmonary capillary pressure did not bear a constant relationship to the pulmonary artery occlusion or wedge pressure (WP). Therefore, in patients in respiratory failure, WP does not reliably estimate hydrostatic pressure at the pulmonary capillaries.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

To assess whether the accepted weaning parameters (derived from middle-aged patients) are helpful in determining discontinuation of mechanical ventilatory support (MVS) in elderly patients, we retrospectively reviewed records of 269 patients > 70 yr who were weaned from MVS from January, 1984 through June, 1985 at one institution. Parameters studied included spontaneous respiratory rate, tidal volume, minute ventilation, maximal inspiratory pressure (MIP), pH, Paco2, Pao2, and Pao2/Fio2. Two hundred forty-one patients (mean age 80 yr) were successfully weaned while 28 patients (mean age 80 yr) required reinstitution of MVS within 48 h. MIP and pH were statistically lower in the unsuccessfully weaned group, although the mean absolute differences were small (‐32 vs. −38 cm H2O and 7.42 vs. 7.44 cm H2O, respectively). All parameters had good positive predictive values but poor negative predictive values (⩽22%) and only marginal diagnostic accuracy (58% to 86%). We conclude that strict adherence to previously published weaning parameters may not be applicable in deciding when to discontinue MVS in elderly patients.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

A meta-analysis was performed of 15 randomized studies on the prophylaxis with cimetidine and/or antacids of upper GI bleeding acquired in the ICU. There were eight comparisons of a group receiving cimetidine with a control group, nine comparisons of a group receiving antacids with a control group, and ten comparisons of a group receiving cimetidine with a group receiving antacids. The incidence of upper GI bleeding ranged from 3.4% to 52.7% among 866 control patients who received either a placebo or no prophylaxis. In five of eight comparisons, cimetidine was significantly more effective than no treatment or a placebo to prevent occult and overt upper GI bleeding; the typical odds ratio was 0.32 (95% confidence interval 0.21 to 0.49). In six of nine comparisons, antacids were significantly more effective than no treatment or a placebo; the typical odds ratio was 0.12 (0.08 to 0.19). Finally, antacids were significantly more effective than cimetidine in two of ten comparisons; the typical odds ratio was 1.61 (0.97 to 2.65). However, weaknesses in the study designs, heterogeneity of treatment effects, the lack of strength of the accumulated evidence, and the fact that no utility has been shown in terms of reducing morbidity (shock, need for transfusion) or mortality, prevent any definitive conclusion in regard to compulsory use of upper GI bleeding prophylaxis for ICU patients.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Decreased hepatic clearance of exogenous sodium lactate has previously been demonstrated in patients with hepatic dysfunction. The purpose of this study was to obtain a more precise understanding of the rate of metabolic normalization or decrease of endogenously produced lactate in patients with hepatic cirrhosis. The differential kinetics of lactate metabolism are of clinical interest.Male volunteer patients with hepatic cirrhosis (n = 7), who had survived acute hospitalization, were compared to healthy age-matched males with normal liver function (n = 7). After arterial cannulation, bicycle ergometry was performed at a workload of 25 watts (W); the load was increased by increments of 25 W at 2-min intervals to maximum aerobic capacity. Lactate was measured in arterial blood before, at 4-min intervals during, and on a minimum of 11 occasions in the 30 to 70 min after exercise. The time interval during which lactate declined linearly to half its maximal concentration (Lt50) was graphically computed. The Lt50 was 34.8 ± 4.5 min (mean ± SEM) in the experimental group and 14.1 ± 1.3 min in the control subjects (p< .005). Lactate disappears from the bloodstream almost three times more slowly in patients with hepatic cirrhosis. The implication for interpretation of changes in lactate during circulatory shock in the presence of liver dysfunction is addressed.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

We studied the hemodynamic effects of acute alterations in Paco2in ten ventilator-dependent children after open heart surgery. Despite end-tidal CO: monitoring, five children inadvertently developed Paco2> 50 torr during the study. Increasing and decreasing Paco2in these children resulted in significant parallel changes in cardiac index (CI), oxygen delivery, physiologic shunt, mean pulmonary pressure, and right ventricular stroke work index, and inverse changes in systemic vascular resistance index (p< .01). No significant hemodynamic changes were observed with alterations in Paco2in children whose Paco2remained < 50 torr. These findings are partly related to significantly larger reductions in Paco2which occurred in the hypercarbic children compared to the others (25 vs. 12 torr;p< .001). Heart rate, mean arterial BP, and venous filling pressures did not change significantly in either group.We conclude that mean alterations in Paco2< 12 torr (range 28 to 50) have no significant effect on CI in children after open heart surgery. However, moderate hypercarbia and its correction to a mean Paco2of 30 torr are associated with significant effects on central hemodynamics. Moreover, no significant changes in the commonly monitored physiologic variables were observed despite large variations in Paco2.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

We studied the hemodynamic effect of a single dose of the new direct-acting vasodilator, flosequinan, in ten patients with severe acute-onset heart failure complicating acute myocardial infarction (MI) resistant to high iv doses of diuretics, nitrates, and dobutamine.Flosequinan was added to conventional therapy at 3.8 ± 0.5 days after infarction in the form of a single 100-mg oral dose. Hemodynamic measurements were performed every hour for 4 h after administration, without any other drug being added. The nitrate infusion rate was kept constant. Flosequinan produced hemodynamic improvement in this group. The effect peaked at 1 to 2 h and remained at this level at 4 h. Pulmonary capillary wedge pressure decreased from 27.2 ± 5.4 to 16.4 ± 3.0 mm Hg, and cardiac output increased from 3.5 ± 03 to 4.1 ± 0.4 L/min (p< .001 for both). Cardiac index, stroke index, and left ventricular stroke work index were significantly increased. Pulmonary arterial and right atrial pressures, and systemic and pulmonary vascular resistances were also significantly reduced. Heart rate was not significantly altered. Mean systemic arterial pressure was slightly reduced. Flosequinan administration was not associated with symptomatic hypotension, cardiac arrhythmias, or other adverse events, and the hemodynamic effect was not related to the pretreatment serum sodium concentration.We conclude that flosequinan is effective in producing acute hemodynamic improvement in patients with heart failure complicating acute MI resistant to conventional therapy.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

A total of 77 consecutive patients submitted to mechanical ventilation (MV) for > 48 h in a respiratory ICU (RICU) were studied to investigate the incidence, etiology, and consequences of ventilator-associated pneumonia. Eighteen (23%) patients developed a bacterial pneumonia after 5.6 ± 1.0 days (mean ± SEM; range 2 to 17) of MV. Three additional cases were demonstrated at autopsy, raising the incidence to 27%. Overall, the mean duration of MV increased from 9.7 ± 0.9 to 32.2 ± 5.1 days (p< .0001) when pneumonia developed. A longer period of hospital stay before RICU admission and the presence of chronic obstructive pulmonary disease were significant characteristics of patients with pneumonia when compared to patients without nosocomial pulmonary infection. One or more etiological agents were identified in 14 patients from the pneumonia group by means of a highly specific technique (protected brush catheter, transthoracic needle aspiration, pleura) fluid, and/or blood cultures). The predominant pathogens isolated were Gram-negative bacilli (Acinetobactersp. andPseudomonassp.). Half of the cases were polymicrobial. Compared to other series, our results may reflect with more accuracy the actual incidence of nosocomial pneumonia in mechanically ventilated patients, since we used highly accurate techniques along with autopsy findings which allowed us to confirm or discard the diagnosis of bacterial pneumonia.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Paranasal sinusitis is reported as a complication of prolonged nasal intubation and the source of sepsis in adult intensive care patients. In surgical neonates with congenital malformations, prolonged intubation with a nasotracheal (NT) or NG tube is often necessary, but sinusitis with complicating sepsis is seldom reported. Sinus x-rays may confirm the diagnosis; in infancy, prolonged nasal intubation delays the pneumatization of the sinuses and the mastoids, resulting in additional diagnostic problems. In a 1-yr period, we saw three patients with multiple septic episodes in which the source of sepsis was undetectable. Despite the absence of clinical symptoms and radiologic evidence of sinusitis or mastoiditis, surgical drainage revealed pus and led to the disappearance of septic episodes and ear, nose, and throat problems.There is an association between prolonged NT and NG intubation, and sinusitis or mastoiditis as an unrecognized source of sepsis in young infants. Absence of radiologic evidence of sinusitis or mastoiditis causes pitfalls in diagnosis and is related to delayed pneumatization of the sinuses and the mastoid in prolonged nasal intubation in young infants.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Three patients had immeasurable serum creatinine concentrations using a colorimetric method while receiving high doses of furosemide. The present study shows that enzymatic methods of measuring the serum creatinine concentration should be used in patients receiving high doses of furosemide.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID

摘要:

Water and electrolyte content influences the rheology of respiratory mucus. Nasal secretions can be obtained from almost all patients and may be regarded as a possibly useful model of the electrolyte composition of lower airway secretions that are difficult to collect in most patients.Na, K, and Cl were determined from nasal secretions in 35 ICU patients. We studied the relationship of those values to the patients' water and salt states. Our study indicates that: a) lower K and Cl levels and higher Na levels than those found in plasma are common to both nasal and bronchial secretions; b) variations of electrolyte levels in nasal secretions are interrelated; c) patients with lower values of free-water clearance show lower Na and higher Cl levels in nasal secretions, possibly due to increased epithelial transport; d) the amount of K in nasal secretions appears correlated with its urinary fractional excretion (this could be explained by the variations in intracellular K levels); and e) in hyperchloremic patients, plasma/secretion differences of Na are decreased, possibly due to decreased epithelial transport.

ISSN:0090-3493    

出版商:OVID    

年代:1989

数据来源: OVID