Search PubMed⌕ Search

Biomedical subjects

M R Pinsky

Publications and source records attributed to M R Pinsky.

At least 109 records · Page 6Linked to original sources
PubMed1994

Effect of inhaled nitric oxide on pulmonary hemodynamics after acute lung injury in dogs.

Increased pulmonary vascular resistance (PVR) and mismatch in ventilation-to-perfusion ratio characterize acute lung injury (ALI). Pulmonary arterial pressure (Ppa) decreases when nitric oxide (NO) is inhaled during hypoxic pulmonary vasoconstriction (HPV); thus NO inhalation may reduce PVR and improve gas exchange in ALI. We studied the hemodynamic and gas exchange effects of NO inhalation during HPV and then ALI in eight anesthetized open-chest mechanically ventilated dogs. Right atrial pressure, Ppa, and left ventricular and arterial pressures were measured, and cardiac output was estimated by an aortic flow probe. Shunt and dead space were also estimated. The effect of 5-min exposures to 0, 17, 28, 47, and 0 ppm inhaled NO was recorded during hyperoxia, hypoxia, and oleic acid-induced ALI. During ALI, partial beta-adrenergic blockade (propranolol, 0.15 mg/kg i.v.) was induced and 74 ppm NO was inhaled. Nitrosylhemoglobin (NO-Hb) and methemoglobin (MetHb) levels were measured. During hyperoxia, NO inhalation had no measurable effects. Hypoxia increased Ppa (from 19.8 +/- 6.1 to 28.3 +/- 8.7 mmHg, P < 0.01) and calculated PVR (from 437 +/- 139 to 720 +/- 264 dyn.s.cm-5, P < 0.01), both of which decreased with 17 ppm NO. ALI decreased arterial PO2 and increased airway pressure, shunt, and dead space ventilation. Ppa (19.8 +/- 6.1 vs. 23.4 +/- 7.7 mmHg) and PVR (437 +/- 139 vs. 695 +/- 359 dyn.s.cm-5, P < 0.05) were greater during ALI than during hyperoxia. No inhalation had no measureable effect during ALI before or after beta-adrenergic blockade. MetHb remained low, and NO-Hb was unmeasurable. Bolus infusion of nitroglycerin (15 micrograms) induced an immediate decrease in Ppa and PVR during ALI.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1994

Assessment of the immediate effects of cardiopulmonary bypass on left ventricular performance by on-line pressure-area relations.

BACKGROUND: Pressure-volume relations have been established as useful measures of left ventricular (LV) performance. Application of these methods to the intraoperative setting have been limited because of difficulties acquiring LV volume data. Transesophageal echocardiographic automated border detection can measure LV cross-sectional area as an index of volume, which can be coupled with pressure data to construct pressure-area loops on-line. The purpose of this study was to evaluate intraoperative LV performance in patients undergoing coronary bypass surgery before and immediately after cardiopulmonary bypass using on-line pressure-area relations. METHODS AND RESULTS: Studies were attempted in 13 consecutive patients. Simultaneous measures of LV cross-sectional area, LV pressure, and electromagnetic flow probe-derived aortic flow recorded on a computer work station interfaced with the ultrasound system. Pressure-area loops were compared with simultaneous pressure-volume loops constructed from pressure and flow data during inferior vena caval occlusions before and after bypass. Pressure-volume calculations (end-systolic elastance, maximal elastance, and preload-recruitable stroke work) were then applied to pressure-area loops with area substituted for volume data. Changes in stroke force from pressure-area loops were closely correlated with changes in estimates of stroke work from pressure-volume loops for individual patients before bypass (r = .99 +/- .03, SEE = 5 +/- 2%, n = 10) and after bypass (r = .96 +/- .05, SEE = 5 +/- 2%, n = 9). Pressure-area estimates of end-systolic elastance, maximal elastance, and preload-recruitable stroke force decreased significantly from before to after cardiopulmonary bypass in the 7 patients with paired data sets. Load-dependent measures of LV function (stroke volume, cardiac output, and fractional area change) were unchanged after surgery in these same patients. CONCLUSIONS: Intraoperative pressure-area loops may be acquired and displayed on-line using transesophageal echocardiographic automated border detection and readily analyzed in a manner similar to pressure-volume loops. LV performance was depressed immediately after cardiopulmonary bypass compared with before. On-line pressure-area relations may be clinically useful to assess LV performance in patients undergoing cardiac surgery in whom load and contractility may be expected to vary rapidly.

Aged↗
PubMed1994

Clinical studies on cytokines in sepsis: role of serum cytokines in the development of multiple-systems organ failure.

The universal finding of a persistently elevated serum TNF level after 12 h in patients who go on to develop MSOF and die suggests that factors other than peak intensity of intravascular proinflammatory response determine survival. The persistence of elevated levels of TNF in the serum of patients who progress to MSOF suggests an aetiological relationship between continual activation of the immune response and remote organ dysfunction in critically ill patients.

Critical Illness↗
PubMed1994

Heart-lung interactions during positive-pressure ventilation.

Artificial ventilation using intermittent positive airway pressure is the mainstay support of patients in respiratory failure. By maintaining alveolar ventilation and alveolar stability, positive airway pressure can sustain respiratory gas exchange between the lungs and circulation, thereby supporting pulmonary homeostasis in patients who would otherwise be unable to maintain oxygen transfer and CO2 elimination. However, positive-pressure ventilation (PPV) also results in complex cardiovascular interactions. More often than not, these interactions impede blood flow through ventilated lungs and reduce global cardiac output. Although arterial oxygen content is adequately sustained because oxygen delivery is equal to the product of arterial oxygen content and cardiac output, global oxygen delivery may be reduced by PPV because of a decrease in cardiac output. Because a primary function of the cardiovascular-respiratory system is to deliver sufficient amounts of oxygen to meet systemic metabolic demands, measurement of arterial blood gases alone in monitoring ventilatory support is inadequate in assessing the cardiopulmonary effects of PPV. Clear understanding of cardiopulmonary interactions associated with mechanical ventilation is required in the rational management of critically ill ventilator-dependent patients. The hemodynamic effects of mechanical ventilation are complex and cannot be explained in terms of the interactions of single hemodynamic processes and cardiac function. However, when considered in this manner, such interactions can be understood more easily. In most patients it is usually clear which process is dominant, permitting adjustments in overall therapy in order to optimize care. This review identifies these interactions and demonstrates which are dominant in specific clinical scenarios.

Animals↗
PubMed1993

On-line estimation of changes in left ventricular stroke volume by transesophageal echocardiographic automated border detection in patients undergoing coronary artery bypass grafting.

Echocardiographic automated border detection can determine the interface between blood and myocardial tissue and calculate left ventricular (LV) cavity area in real-time. The objective was to determine if on-line measurements of LV cavity area by transesophageal automated border detection could be used to determine beat-to-beat changes in stroke volume in humans. Studies were attempted on 9 consecutive patients, aged 66 +/- 8 years, undergoing coronary bypass surgery. Stroke volume was measured by electromagnetic flow from the ascending aorta, and LV cavity area was measured at the midventricular short-axis level. Simultaneous area and flow data were recorded on a computer workstation through a customized interface with the ultrasound system. Recordings were performed during baseline apnea and rapid alterations induced by inferior vena caval occlusions before and after cardiopulmonary bypass. Measurements of stroke area (maximal area-minimal area) were correlated with stroke volume for matched beats. Data were available for analysis on 8 of 9 patients before and on 5 patients after cardiopulmonary bypass for 644 beats. Stroke area was closely correlated with stroke volume both before (mean R = 0.94 +/- 0.03, SEE = 0.33 +/- 0.12 cm2) and after (mean R = 0.92 +/- 0.05, SEE = 0.59 +/- 0.81 cm2) cardiopulmonary bypass. The slopes of these stroke area-stroke volume relations were quite reproducible from before to after cardiopulmonary bypass in the same patient but varied between individual patients. Transesophageal automated border detection has potential for on-line estimation of changes in stroke volume in selected patients.

Aged↗
PubMed1993

On-line estimation of stroke volume by means of echocardiographic automated border detection in the canine left ventricle.

Echocardiographic automated border detection (ABD) is a new on-line technique that can determine the interface between blood and myocardial tissue and calculate left ventricular (LV) cavity area in real time. The objective of this study was to determine whether ABD measurements of the LV cavity area could be used to estimate LV stroke volume at basal conditions and during large changes in LV stroke volume induced by inferior vena caval occlusions in an open-chest canine model. Seven dogs had LV stroke volume measured by electromagnetic flow from the ascending aorta with epicardial recordings of ABD echocardiographic area at the midventricular short-axis level. Simultaneous beats of stroke volume were recorded along with ABD echo area during baseline apnea and during IVC occlusions. Neither ABD echo stroke area nor stroke volume varied significantly during apnea baseline. Changes in stroke area were closely correlated with changes in stroke volume for 540 matched beats from 24 IVC occlusions: R = 0.93, standard error of the estimate = 5%, y = 0.92x + 0.4 (p < 0.001). Echocardiographic ABD appears to be a promising new on-line method of determining rapid alterations in LV stroke volume; it also has potential applications to multiple investigational and clinical settings.

Animals↗
PubMed1993

Postreperfusion syndrome: hypotension after reperfusion of the transplanted liver.

Sixty-nine patients undergoing liver transplantation were evaluated to elucidate the relationship between hypotension and physiological changes seen on reperfusion of the grafted liver. Measured variables included hemodynamic profiles, core temperature, serum potassium, ionized calcium levels, arterial blood-gas tensions, and acid-base state. Measurements were taken 60 minutes after skin incision (baseline), 5 minutes before reperfusion, and 30 seconds and 5 minutes after reperfusion. On the basis of changes in mean arterial pressure (MAP) patients were divided in two groups. Group 1 (n = 49) maintained MAP greater than 70% and group 2 (n = 20) had MAP less than 70% of the baseline value for at least 1 minute within 5 minutes after reperfusion. On reperfusion, changes common to both groups were 27% increase in cardiac filling pressures, 23% base deficit, and 30% serum potassium level and a decrease of 16% in cardiac output and 9% in temperature. Compared with group 1, group 2 had greater decrease in systemic vascular resistance (SVR) (1097 +/- 868 and 741 +/- 399 dyn.s-1. cm-5, respectively, P < .05) and higher potassium level (4.5 +/- 0.8 and 5.3 +/- 0.8 mmol/L, P < .05). Collectively in both groups, there was no correlation between MAP and physiological variables; however, there was a poor correlation with SVR (r = .32, P < .01). Reperfusion hypotension seen in group 2 patients correlated only with a decrease in systemic vascular resistance (r = .5, P < .05). Acute hyperkalemia, hypothermia, and acidosis do not appear to be major causes of reperfusion hypotension.

Adult↗
PubMed1993

Effect of the pericardium on systolic ventricular interdependence in the dog.

Systolic ventricular interdependence, whereby changes in left ventricular (LV) ejection alter right ventricular (RV) ejection, has been described. It is unclear, however, whether this interaction is influenced by pericardial volume constraint or by myocardial mechanical coupling. We hypothesized that if mechanical coupling were the primary factor determining systolic ventricular interdependence then it should be unaltered by the presence or absence of an intact pericardium, but affected by changes in LV end-systolic volume. We tested this hypothesis by observing the changes in RV stroke volume (SVrv) and peak systolic pressure (PSPrv) during a single LV isovolumic contraction under conditions of normal or increased (1.3 x normal) RV end-diastolic volume with and without an intact pericardium. In 10 anesthetized, open-chested dogs SVrv was derived from the integrated pulmonary arterial flow probe signal and RV ejection fraction (EFrv) was derived from the thermodilution plateau method and a rapidly responsive thermistor in the pulmonary artery. Right ventricular end-diastolic volume was considered to be the ratio of SVrv to EFrv. Left ventricular isovolumic contraction increased SVrv and PSPrv during all conditions (P < .01). However, PSPrv increased more when the pericardium was intact (P < .05). These data suggest that LV ejection can enhance SVrv and that this interaction is not appreciably altered by volume loading or the presence of an intact pericardium. Pericardial interactions may alter PSPrv but do not affect SVrv.

Animals↗
PubMed1993

Right ventricular function during orthotopic liver transplantation.

Right ventricular (RV) function was assessed in 20 patients undergoing orthotopic liver transplantation to determine its role in the hemodynamic instability frequently seen during this procedure. A modified pulmonary artery catheter equipped with a fast response thermistor was used to determine RV ejection fraction (EFrv), allowing for calculation of RV end-diastolic volume index (EDVIrv, as the ratio of stroke index [SI] to EFrv) and RV end-systolic volume index (ESVIrv, as the difference between EDVIrv and SI). The above hemodynamic measures were taken during dissection for hepatectomy (stage I), during the anhepatic stage (stage II), and after reperfusion of the grafted liver, the neohepatic stage (stage III). No patient had pulmonary hypertension during the study interval. No correlation was observed between right atrial pressure (Pra) and EDVIrv, indicating that Pra is a less reliable clinical indicator of RV preload. RV function appeared to be well preserved throughout the procedure, as indicated by a relatively constant and supranormal EFrv, although a small and probably clinically unimportant decrease in EFrv was observed during the anhepatic stage (0.52, 0.50, and 0.55 during stages I, II, and III, respectively). There was a strong correlation between SI and EDVIrv for pooled data over a wide range of EDVIrv (60-185 mL.m-2). Although unstable central blood temperature precluded the determination of EFrv within the first 5 min after reperfusion, RV function was unaltered otherwise during uncomplicated orthotopic liver transplantation using venovenous bypass, indicating that orthotopic liver transplantation per se is not associated with significant RV dysfunction.

Adult↗
PubMed1993

Serum cytokine levels in human septic shock. Relation to multiple-system organ failure and mortality.

PURPOSE: Cytokines have been associated with the development of sepsis and diffuse tissue injury following septic or endotoxic challenges in humans. Furthermore, relative organ-system dysfunction, not specific organ dysfunction, appears to predict outcome from critical illness. We hypothesized that persistence of inflammatory cytokines within the circulation, reflecting a generalized systemic inflammatory response, is associated with multiple-system organ failure (MSOF) and death from critical illness. In addition, since hepatic function is central to host-defense homeostasis, we further reasoned that critically ill patients with hepatic cirrhosis would have an increased incidence of MSOF and death following sepsis associated with a persistence of cytokines in the blood. PATIENTS AND METHODS: We measured serum levels of tumor necrosis factor (TNF), interleukin (IL) 1, IL-2, IL-6, and interferon gamma (IFG) serially for the first 48 h following the onset of hypotension (systolic blood pressure < 90 mm Hg) thought likely to be due to sepsis in all patients presenting to one ICU. These data were correlated with initial severity of shock and retrospective determination of septic or nonseptic origin, preexistent hepatic cirrhosis, subsequent development of MSOF, and outcome. RESULTS: Fifty-three specific episodes of shock in 52 patients were recorded (35 septic and 18 nonseptic episodes). Mortality was higher in septic patients (41 vs 17 percent, p < 0.01), as was the development of MSOF (29 vs 6 percent, p < 0.001), incidence of cirrhosis (21 vs 0 percent, p < 0.01), and TNF levels over the study interval (p < 0.01). Nonseptic patients also had an initial elevation in TNF over 48-h levels (p < 0.05) that were higher than serum levels reported for normal subjects (chi 2, p < 0.05). There was no relation between peak TNF level and outcome. Sixty-seven percent of the cirrhotic patients had development of MSOF and died, while only 30 percent of the noncirrhotic patients had development of MSOF or died (p < 0.05). The TNF and IL-6 levels in patients who had MSOF or who died were both elevated and did not decrease over time independent of presence or absence of sepsis (p < 0.01). Similarly, IL-6 levels after 12 h were higher in cirrhotic patients than in noncirrhotic septic patients (p < 0.05). No elevation in IL-1, IL-2, or IFG was seen in any patient subpopulation. CONCLUSIONS: TNF and IL-6 serum levels are higher in septic than in nonseptic shock, but the persistence of TNF and IL-6 in the serum rather than peak levels of cytokines predicts a poor outcome in patients with shock.

Cytokines↗
PubMed1992

Outcome of intensive care of the "oldest-old" critically ill patients.

OBJECTIVE: To determine the short-term and long-term outcome of critically ill "oldest-old" (greater than or equal to 85 yrs) patients. DESIGN: Retrospective chart review and follow-up telephone interview. SETTING: ICUs at a tertiary care hospital. METHODS: The medical records of all patients greater than or equal to 85 yrs of age admitted to the ICUs during 1988 were reviewed. Demographic information, severity of illness, major interventions, mortality rate, and hospital charges were examined. A follow-up telephone interview was conducted to determine the quality of life and mortality rate after discharge. RESULTS: Of 34 patients greater than or equal to 85 yrs of age admitted to the ICU, 21 (62%) survived to discharge from the hospital, and 13 (62%) of these 21 patients were discharged to home. Mean +/- SD hospital charges were $34,738 +/- 34,366. Seventeen of the 21 patients were contacted for long-term follow-up, and ten of these patients were alive at a mean follow-up time of 18 +/- 10 months (range 1 to 32). Eight of the ten patients described their quality of life as fair or good. CONCLUSION: These findings suggest that age alone may be an inappropriate criterion for allocation of ICU resources.

Aged↗
PubMed1992

Continuous monitoring of right ventricular volume changes using a conductance catheter in the rabbit.

To assess the reliability of conductance (G) catheter for evaluating right ventricular (RV) volume changes, a miniature (3.5F) six-electrode catheter was developed and tested in 11 New Zealand rabbit hearts. In five animals the heart was excised; in six it was left in the thorax. RV conductance was recorded while the RV was filled with blood in 0.25-ml steps at different left ventricular (LV) volumes. Linear correlation of measured conductance vs. reference volumes was computed. RV conductance was highly correlated with reference volume [correlation coefficient (r) ranging from 0.991 to 0.999]. Slope of regression lines was not significantly affected by LV volume variations in 1-ml steps or by acute conductance changes of structures surrounding the heart, whereas the intercept was affected only by the 0- to 1-ml LV volume change. In four rabbits, RV conductance changes during a cardiac cycle [stroke volume- (SV) G] were compared in vivo with electromagnetic flow probe-derived estimates of SV (SVem) as stroke volume was varied by graded inferior vena caval occlusion. SV-G correlated well with SVem (r ranging from 0.92 to 0.96). This correlation persisted after the thorax was filled with saline; however, significant differences were found in individual slopes (P < 0.001). These results show that the conductance catheter has a potential to reliably monitor in vivo relative RV volume changes in small-animal hearts.

Anesthesia↗
PubMed1992

Effect of positive end-expiratory pressure on right ventricular function in humans.

The effect of positive end-expiratory pressure (PEEP) on right ventricular (RV) function in humans is complex. Previous studies have been limited in their interpretation by not defining either pericardial pressure (Ppc) or RV volumes. Accordingly, we measured RV volumes and pressures and Ppc as PEEP was increased from zero to 15 cm H2O in 12 patients after thoracotomy, using a pulmonary arterial catheter equipped with a rapid responding thermistor that allowed measurement of RV ejection fraction (ef), while Ppc was measured via a pericardial balloon catheter. RV end-diastolic volume (EDV) was estimated as the ratio of stroke volume (SV) to RVef, whereas RV end-systolic volume (ESV) was estimated as RV EDV-SV. Right atrial pressure (Pra) was defined as end-diastolic pressure, and pulmonary arterial pressures (Ppa), both peak and mean, were used as end-systolic pressures. PEEP increased Ppc, Pra, and lung compliance (Cl). Cardiac output also decreased but not significantly. Neither mean nor peak systolic Ppa, nor RVef was significantly altered by PEEP. There was no relation between either RV filling pressure (Pra-Ppc) and EDV or the change in RV filling pressure and EDV, although EDV varied significantly as PEEP varied for individuals (p less than 0.05). Similarly, there was no relation between Ppa and ESV when either mean or peak Ppa values relative to Ppc were used. The relations between EDV and both SV and RVef were weak (r = 0.54 and 0.55, respectively). RVef varied inversely with ESV (r = -0.77), although it showed no relation to transmural peak Ppa (r = 0.28).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Effects of a closed tracheal suction system on ventilatory and cardiovascular parameters.

OBJECTIVE: To determine whether patients ventilated in the assist-control mode experienced a change in oxygenation, respiratory rate, inspiratory:expiratory ratio, heart rate, blood pressure or acid-base balance when suctioned with a closed tracheal suction system. DESIGN: A quasi-experimental, within-subject, repeated-measures design was used. SUBJECTS: 18 patients ventilated on a fraction of inspired oxygen of 0.47 +/- 0.17 and 2.3 +/- 5.0 cm H2O positive end-expiratory pressure. INTERVENTIONS: Two suction passes were performed, with measurements at baseline, immediately after the first suction pass, immediately before the second suction pass, immediately after the second suction pass, 2 minutes after the second suction pass and 5 minutes after the second suction pass. No hyperoxygenation was used. RESULTS: Significant differences were seen over time for arterial oxygen saturation, respiratory rate and inspiratory:expiratory ratio. Arterial oxygen saturation decreased to less than 90% in four subjects (range 88% to 89%), with a maximum fall of 9%. No significant differences were seen for heart rate, blood pressure, partial pressure of carbon dioxide, bicarbonate, time to nadir (lowest arterial oxygen saturation) or recovery time. CONCLUSIONS: Subjects ventilated in the assist-control mode and suctioned with a closed tracheal suction system did not experience significant changes in cardiovascular or acid-base parameters when suctioned without hyperoxygenation. Although most subjects did not become desaturated, four subjects experienced desaturation at one or more intervals. To prevent desaturation, hyperoxygenation should be used before and after suctioning with a closed tracheal suction system.

Aged↗
PubMed1992

Cardiovascular response in canine endotoxic shock: effect of ibuprofen pretreatment.

Ibuprofen pretreatment increases arterial pressure and reduces mortality in endotoxic dogs. The increase in arterial pressure may be caused by increases in arterial resistance, arterial sphincter tone, or both. Thus it is not clear if ibuprofen pretreatment prevents the hemodynamic effects of endotoxemia or merely masks such effects by producing concomitant increases in arterial resistance. Accordingly, this study was performed to determine the effects of ibuprofen pretreatment on arterial pressure-flow relations and other measures of cardiovascular function in a canine model of endotoxic shock. In 19 pentobarbital-anesthetized and splenectomized, closed-chest dogs, biventricular stroke volumes were measured with electromagnetic flow probes, and intrathoracic vascular and pleural pressures were measured with catheters. Instantaneous venous return curves (see Pinsky MR, J Appl Physiol 56:765, 1984) were generated during positive-pressure ventilation, and steady-state arterial pressure-flow relations, left ventricular function, peripheral vascular compliance, oxygen consumption/oxygen delivery ratio, and arterial blood lactate levels were measured during two sequential volume loading and removal (20 ml/kg) sequences. All but two dogs received a bolus infusion of Escherichia coli endotoxin (2 mg/kg) between the two fluid challenge runs. Eleven of the 17 endotoxic dogs also received ibuprofen (15 mg/kg) immediately before the initial fluid challenge. Ibuprofen pretreatment abolished all hemodynamic effects of endotoxin, whereas in the untreated group endotoxin caused decreases in calculated arterial outflow pressure and in peripheral vascular capacitance. Oxygen consumption remained constant despite changes in oxygen delivery in the nonendotoxic dogs and in the ibuprofen-pretreated dogs, whereas oxygen consumption covaried with oxygen delivery in the endotoxic dogs not pretreated with ibuprofen. Arterial lactate levels were higher after endotoxin infusion (2.1 +/- 0.5 to 3.1 +/- 0.6 mmol/liter; P less than 0.05 pre- to postvolume) but were not different between treatment groups. These data suggest that ibuprofen alters many, but not all, of the hemodynamic effects of endotoxin infusion in the dog.

Acidosis↗