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Biomedical subjects

M S Dahn

Publications and source records attributed to M S Dahn.

At least 37 records · Page 2Linked to original sources
PubMed1990

Hepatic parenchymal oxygen tension following injury and sepsis.

Hepatic blood flow and splanchnic oxygen consumption were measured in 16 injured (n = 6) or septic (n = 10) patients and compared with values in 16 normal volunteers. Sepsis and injury appeared to stimulate an increase in blood flow and oxygen utilization, with the highest levels observed in the septic group. Patients with sepsis exhibited a 72% and 60% increase in hepatic blood flow and splanchnic oxygen consumption, respectively, compared with normal volunteers. Application of these data to the Krogh-Erlang tissue model indicates that despite an increase in oxygen delivery to the splanchnic bed during sepsis, it becomes more sensitive to hypoxic/ischemic events compared with other patient groups. This is indicated by a reduced centrilobular and increased critical oxygen tension. The major factor responsible for this is the regional hypermetabolism present in sepsis. This analysis emphasizes the critical importance of maintaining oxygen transport in critically ill patients with sepsis.

Humans↗
PubMed1990

Renal functional response to dopamine during and after arteriography in patients with chronic renal insufficiency.

The potential renal vasodilatory effect of dopamine in improving renal function after arteriography was studied. Sixty patients with preexisting renal insufficiency were prospectively randomized into two groups. Patients in the treated group (n = 30) received an infusion of dopamine for 12 hours starting at the beginning of arteriography. Patients who received placebo infusion with arteriography (n = 30) served as controls. The study was conducted in two different time intervals. In the first interval, serum creatinine levels and 12-hour creatinine clearance values were obtained before and immediately after arteriography in 12 patients in the dopamine group and 13 patients in the control group. In the second interval, the same variables were measured before arteriography and for 3 consecutive days after arteriography in 18 patients in the dopamine group and 17 patients in the control group. Serum creatinine levels became significantly elevated in the control group on the 1st day and remained so on the 3rd day after arteriography, whereas the dopamine group did not show significant elevation of these levels. Creatinine clearance decreased in the control group on the 1st day, but this deterioration was not sustained on the 3rd day. In the dopamine group, there was no deterioration in creatinine clearance on either day, and mean effective renal plasma flow during and after arteriography was greater.

Aged↗
PubMed1990

Hepatic blood flow and splanchnic oxygen consumption measurements in clinical sepsis.

In an effort to characterize the hemodynamic response of the liver to sepsis, hepatic blood flow (HBF) was measured in 10 normal volunteers and compared with that of 9 patients with sepsis. Flow was determined according to two different indicators and three methods of analysis including indocyanine green dye clearance (HBFICG), galactose clearance (GC), and galactose clearance with splanchnic galactose gradient measurement (HBFGG). For normal subjects, these three analytic methods provided essentially identical results (HBFICG = 0.74 +/- 0.18, GC = 0.72 +/- 0.14, and HBFGG = 0.76 +/- 0.16 L/min-m2). With hepatic venous sampling, HBF in patients with sepsis was significantly higher than normal levels (HBFICG = 1.28 +/- 0.50 and HBFGG = 1.17 +/- 0.52 L/min-m2) (p less than 0.025), but HBF by the GC technique (0.89 +/- 0.41 L/min-m2), which uses peripheral venous sampling, was not significantly increased because of reduced splanchnic galactose extraction, which appears to be characteristic of sepsis. Thus HBF estimates based on peripheral venous sampling must be interpreted with caution in view of the reduced extraction fraction in sepsis. HBF in clinical sepsis tends to increase in response to this inflammatory stress.

Galactose↗
PubMed1989

Management of multiple enterocutaneous fistulas.

Enterocutaneous fistulas present a difficult management problem in the intensive care unit. Although some patients require surgical intervention for fistula control, key elements to good clinical management include mechanical control and vigorous nutritional support. This approach includes eradication of malnutrition, support of the hypercatabolic state, and maintenance or replacement of protein loss from fistula drainage. Good mechanical control involves integument protection and a mechanism of drainage collection. The patient we describe taxed the ingenuity and creativity of all those concerned with his care. Modification of a previously described technique to protect surrounding skin and collect fistula output served as a simple and inexpensive approach to eliminate infection potential, improve the patient's comfort, and decrease the nursing time that would have been required for frequent, complex dressing changes.

Aged↗
PubMed1989

Hemodynamic benefits of verapamil after aortic reconstruction.

Because of the high incidence of coronary artery disease (CAD) in patients undergoing aortic surgery, and because myocardial oxygen consumption is proportional to blood pressure x heart rate (HR) (pressure-rate product), it is important to prevent increases in these parameters postoperatively. The effect of verapamil, a calcium channel antagonist, on these parameters was evaluated in 30 patients undergoing abdominal aortic reconstruction. Postoperatively HR increased 27% in 19 patients without CAD and 47% in 11 patients with CAD. Pressure-rate product (blood pressure x HR) increased 17% and 31% in these two groups, respectively. Verapamil was able to reduce postoperative HR by 3% in patients without CAD and by 13% in patients with CAD. Verapamil reduced pressure-rate product 8% and 18%, respectively, in the two groups. These reductions were statistically significant in patients with CAD and occurred without reductions in cardiac output or left ventricular ejection fraction. Thus the postoperative increases in myocardial oxygen demand appeared to be primarily related to increased HR after aortic surgery, and these were reduced by verapamil without impairing blood flow or cardiac function.

Aged↗
PubMed1988

Insulinlike growth factor 1 production is inhibited in human sepsis.

We studied the response of 14 normal volunteers and five septic patients to a 48-hour course of exogenous biosynthetic human growth hormone (hGH) or placebo. Six normal controls (group 1) received saline, eight normal controls received hGH (group 2), and five septic patients also received biosynthetic hGH (group 3). Urinary urea excretion declined, and splanchnic amino acid uptake was maintained only in group 2 subjects. Septic patients exhibited changes in amino acid and urea dynamics comparable to those of subjects receiving placebo. Insulinlike growth factor 1 (IGF-1) production and plasma concentrations increased in group 2 in a fashion corresponding to the changes in nitrogen exchange, whereas septic patients exhibited no change in IGF-1 level. Therefore, in this septic patient group, exogenous hGH was ineffective in attenuating nitrogen losses and stimulating IGF-1 production. This supports the hypothesis that IGF-1 is a mediator of the anabolic effect of hGH.

Adult↗
PubMed1988

Central mixed and splanchnic venous oxygen saturation monitoring.

Central mixed venous oxygen saturation (SvO2) monitoring in critically ill patients to estimate adequacy of peripheral perfusion is gaining increasing popularity. However, a number of unexpected responses, one of which is marked depression of regional (splanchnic) venous oxygen saturation which may coexist with normal or high SvO2, makes interpretation of this parameter difficult. The SvO2 and hepatic venous oxygen saturation levels in seven injured (postoperative) and 15 septic patients were measured. No substantial differences between central and hepatic venous oxygen saturation was noted in nonseptic patients, however, septic subjects exhibited a normal SvO2 of 70.5% +/- 8.7% at a time when the hepatic venous saturation was 55.6% +/- 14.4% which is a significant (p less than 0.05) reduction. This reduced oxygen saturation was noted to arise from an increased regional metabolic rate rather than reduced perfusion. Nevertheless, we conclude that a flow limited regional oxygen consumption may potentially exist despite the presence of a normal SvO2 in certain patient subgroups such as septic subjects. Therefore, a normal SvO2 should not be considered as sole criteria to insure optimal oxygen delivery in critically ill patients.

Aged↗
PubMed1988

Altered T-lymphocyte subsets in severe sepsis.

To investigate the immune response of surgical patients to injury and sepsis, we measured total lymphocyte counts and T-cell subsets in five nonseptic and 17 septic subjects. Total lymphocyte and T-cell levels declined to similar degrees following injury or sepsis and did not appear to be of value as prognostic indicators. However, analysis of T-cell subsets in septic patients indicated that survivors exhibited normal T-cell subpopulations as well as helper to suppressor cell ratios. Nonsurvivors generally exhibited a selective depression of helper (OKT4) T-cells and the resultant degree of helper to suppressor ratio decline was directly related to mortality. A helper to suppressor ratio (OKT4/T8) below 0.6 was uniformly associated with a fatal outcome. Finally, a small subgroup of septic nonsurviving patients exhibited a selective depression of suppressor (OKT8) lymphocytes which also appeared to carry an unfavorable prognosis. These data indicate that T-lymphocyte subpopulation analysis is a useful predictor of hospital course.

Adult↗
PubMed1988

Patient-controlled analgesia versus intermittent analgesia dosing.

Actively involving the patient in his or her own pain management by using patient-controlled analgesia (PCA) during the postoperative period is a concept recently introduced. This method allows self-administration of small, frequent doses of an analgesic agent to maintain a state of constant pain control. We studied the relative efficacy of PCA compared with intermittent analgesic dosing in 16 male patients requiring posterolateral thoracotomy. Eight patients received intermittent doses of buprenorphine hydrochloride (0.3 mg intramuscularly every 3 to 6 hours), and eight patients were allowed to self-activate a PCA device according to a designed protocol. In the patients using PCA, a significant reduction in the postoperative pulmonary complication rate, as evidenced by radiographic findings, was noted. In addition, significantly less medication was used and postoperative fever was substantially reduced in the PCA group. We believe PCA to be a safe, effective, and beneficial pain management modality that deserves attention in the postoperative period.

Aged↗
PubMed1987

Insulin production following injury and sepsis.

It is known that alterations in insulin metabolism following injury and infection result in depression of insulin levels and the development of insulin resistance. In order to further study insulin during septic and traumatic stress, we estimated insulin production in control (Group 1, n = 6), postoperative (Group 2, n = 5), and postoperative-septic (Group 3, n = 8) human subjects by measuring the 24-hour urinary C-peptide excretion. In addition, basal and peak glucose and insulin levels in response to a standard (0.5 gm/kg) intravenous glucose stimulus were measured immediately thereafter to determine if insulin levels reflected insulin production. Basal insulin for Groups 1, 2, and 3 (16 +/- 8.4, 10 +/- 3.4, 9.5 +/- 4.4 microU/ml +/- SD, respectively) were not substantially different. Peak insulin response to glucose infusion declined from Groups 1 to 3 (51 +/- 14, 42.4 +/- 31, 20.4 +/- 6.8 microU/ml, respectively) with Group 3 exhibiting a significantly decreased mean peak level compared to the other groups. Corresponding C-peptide excretion rates increased from Groups 1 to 3 (28.3 +/- 15.3, 63.7 +/- 27.6, 121.3 +/- 95.2 micrograms/day, respectively) with Group 3 exhibiting a significantly (p less than 0.05) higher level than Group 1. These data suggest that low insulin levels which may be evident in injured or septic patients not in shock reflect increased clearance and not decreased production.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Cardiopulmonary complications after major surgery: a role for epidural analgesia?

Improvement in postoperative pulmonary mechanics with epidural analgesia has been described. Data on the hemodynamic effects of this technique are absent from the surgical literature. To provide such data we have evaluated two groups of patients undergoing aortic reconstruction: group I (n = 25), general anesthesia and group II (n = 6), general anesthesia with adjunctive epidural analgesia. The groups were comparable preoperatively as judged by the incidence of cardiac history, preoperative ejection fraction, and measured hemodynamic parameters. Postoperatively there were no significant differences in the pressure-related parameters; however, rate-related factors including heart rate and double product were significantly decreased in group II with no reduction in cardiac index. Postoperative increases in total body oxygen consumption were also markedly attenuated by epidural analgesia. Epidural analgesia reduces the hemodynamic demands on the heart after major surgery and is a useful adjunct, especially in patients with coronary artery disease.

Aged↗
PubMed1987

Splanchnic and total body oxygen consumption differences in septic and injured patients.

The splanchnic and total body oxygen exchange and flow dynamics for injured patients (n = 7) and patients with sepsis and stable vital signs (n = 12) were studied. All patients were judged to be in the hyperdynamic phase of the stress response. In both patient groups 27% to 28% of the cardiac index was directed to the splanchnic circulation. However, in sepsis the splanchnic region consumed a significantly larger fraction (p less than 0.05) of the total body oxygen (43.8%) compared with that consumed in injury (30.2%). After injury, the regional splanchnic flow and oxygen consumption appeared to be well matched whereas in sepsis, a disproportionately higher oxygen consumption is found, which must be supplied by increasing blood oxygen extraction. This regional hypermetabolism of the splanchnic area probably results from the increased metabolic demand imposed by the various synthetic processes of this region. In addition, it is proposed that excessive discrepancy between splanchnic flow and oxygen demand may precipitate regional ischemia.

Aged↗
PubMed1986

Common iliac to femoral bypass. An alternative in the high risk patient.

Eighteen patients presenting with atherosclerotic iliac occlusive disease have been treated with ileofemoral bypass grafting over the preceding 66 months. All patients were treated for limb salvage. The risk factors of this patient population were judged to be excessive for the performance of aortofemoral bypass grafting. The accumulated patency for this approach at 5 years was 84.6 per cent with a mean follow-up duration of 29.1 months. Based on these results, this approach appears to be an excellent inflow procedure for patients considered unsuitable for conventional aortofemoral reconstruction.

Aged↗
PubMed1985

The relationship of insulin production to glucose metabolism in severe sepsis.

Basal glucose metabolism was evaluated in eight stable, infected patients by measuring hepatic glucose production rates in relation to stress endocrine profile and by comparing these data to five injured, noninfected patients. All patients exhibited normal total-body oxygen consumptions and cardiac indices. Fasting basal insulin values were similar in both groups (6 microU/cc) despite a significantly higher plasma glucose level in septic patients (106 +/- 14 mg/dL) compared to nonseptic patients (88 +/- 10 mg/dL). Septic patients exhibited splanchnic glucose production and calculated glucose clearance rates, 53% and 34% higher, than injured nonseptic patients, respectively. In addition, septic patients exhibited a decreased pancreatic insulin secretory response to an intravenous glucose tolerance test as evidenced by a significantly depressed peak insulin value (17 microU/cc) relative to injured patients (77 microU/cc). These findings indicate that insulin suppression is evident in sepsis even in the absence of shock and suggest that sepsis-related basal hyperglycemia does not appear to be associated with peripheral insulin resistance.

Aged↗
PubMed1985

An assessment of the variability of early scalp-components of the somatosensory evoked response in uncomplicated, unshunted carotid endarterectomy.

Although many publications deal with the usefulness of the SER in CEAs, the criteria of calling a SER abnormal during a CEA are largely arbitrary. One way to define the limits of normalcy for SERs during the CEA will be to analyze the SER tracings obtained during unshunted and uncomplicated (intra- and postoperative) CEAs. In 23 such CEAs (10 right, 13 left; clamptime 10-23 mins.), data analysis at the ipsilateral parietal electrode, on stimulation of the contralateral median nerve (square pulse -5.1/sec, 10-30 V, 200 microseconds; bandpass-30-3000 Hz trials-500 stimuli), revealed that (1) latency fluctuations of the N20 (21.4 msec) were narrowest, being less than 1.5 msec different during and after clamping compared to the preclamp latency in all 23 CEAs, whereas those of P25 (27.4 msec) and N35 (38.5 msec) were greater than 2.0 msec different from the preclamp latency in 3 and 8 CEAs respectively, and (2) the amplitudes of N20, P25 and N35 measured from the preceding peak of opposite polarity, fell to less than 75% of the preclamp value on 3, 4 and 7 CEAs respectively. It is concluded that N20 was the most stable of the first three short-latency components in the SER and should perhaps be most relied upon to predict abnormality of the SER during CEAs.

Brain Ischemia↗
PubMed1985

Management of aortofemoral graft failure.

A simplified technique of patch angioplasty is demonstrated for the reconstruction of the failed distal aortofemoral anastomosis. The salient features of this technique include performance of the angioplasty without disconnecting the original anastomosis and reutilization of the existing suture line in order to avoid late formation of a pseudoaneurysm.

Blood Vessel Prosthesis↗
PubMed1985

The significance of hypoalbuminemia following injury and infection.

Serum albumin and absolute hepatic albumin synthetic rates were measured in ten seriously ill injured and septic patients using the (14C) carbonate technique. Although it is commonly believed that serum albumin levels (SAL) reflect hepatic function and visceral protein status in hospitalized patients, no relationship was found between these two measured parameters in this patient population. A depressed mean serum albumin level of 1.98 +/- 0.50 gm/dl (range: 1.25-2.69 gm/dl) was associated with a supranormal mean albumin synthetic rate of 215 +/- 121 mg/kg/day (range: 21-447 mg/kg/d). No significant mean SAL and albumin synthetic rate differences were noted between injured nonseptic and septic patient populations. Since albumin synthesis was elevated in most of these stressed patients these findings support the view that extravascular protein redistribution and/or increased peripheral catabolism are the major factors responsible for hypoalbuminemia in critically ill patients.

Aged↗