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Biomedical subjects

H M Marsh

Publications and source records attributed to H M Marsh.

At least 37 records · Page 2Linked to original sources
PubMed1988

Nutritional assessment of intensive-care unit patients.

The decision about whether to institute aggressive nutritional support, with its attendant expense and potential morbidity, in critically ill patients remains controversial. We studied numerous commonly used variables for assessment of nutrition to identify critically ill patients at increased risk for the development of infection, for becoming ventilator dependent, and for mortality. We enrolled 111 patients in this study on their third day in the intensive-care unit (ICU). No attempt was made to influence nutritional support, nor was adequacy of such support studied. Although several measurements correlated with outcome, the serum albumin correlated with number of ICU days (r = -0.38; P less than 0.001), with the number of days on a ventilator, and with the number of hospital days. It was the only measurement that correlated with the development of both a new infection (P less than 0.05) and ventilator dependency (P = 0.002). Although the use of the serum albumin concentration in this setting has limitations, it is still the best, most commonly used measurement of nutrition available.

Adult↗
PubMed1988

Fundamental considerations in pacing of the diaphragm for chronic ventilatory insufficiency: a multi-center study.

Records were reviewed of 477 patients who had diaphragm pacemakers implanted for treatment of chronic hypoventilation. Three groups were established for comparison. (1) Center group: 165 patients operated on in six medical centers participating in a cooperative study; (2) Noncenter group, sufficient data available: 203 patients operated on by surgeons with experience limited to a few cases; (3) Nonstudy group, minimal data available: 109 patients operated on as in group 2; vital statistics only were contributed. The protocol for data gathering was comprised of 154 major variables. Basic data on age, sex, diagnosis and etiology were analyzed for homogenicity of data among the groups. A comprehensive analysis of the pacing methods, complication and results from the Center group yielded information on the early experience with diaphragm pacing important to its future application.

Diaphragm↗
PubMed1987

Pulmonary alveolar phospholipoproteinosis: experience with 34 cases and a review.

A retrospective review of Mayo Clinic records through 1983 revealed 84 patients (24 male and 10 female; mean age, 41 years) with the diagnosis of pulmonary alveolar phospholipoproteinosis. The major clinical features were dyspnea, cough, fever, and chest pain. Chest roentgenograms usually showed bilateral symmetric alveolar infiltrates, but asymmetric, unilateral, and chronic patchy patterns were also noted. Diagnosis was established by thoracotomy-lung biopsy in 26 patients. Histologic analysis revealed uniform filling of the alveoli by periodic acid-Schiff-positive material and maintenance of normal alveolar architecture. Electron microscopy showed enlarged alveolar macrophages with lamellar osmiophilic inclusions, dense granules, and myeloid bodies. Of the 21 patients who underwent therapeutic bronchoalveolar lavage, 13 had no recurrence of the disease during a mean follow-up of 8.8 years. In patients who underwent pulmonary function testing both before and after lavage, significant restrictive dysfunctions present before the procedure were alleviated afterward. Three deaths occurred among the 34 patients. Pulmonary alveolar phospholipoproteinosis may result from defective clearance of phospholipids by the alveolar macrophages, excessive production of phospholipids by type II pneumocytes, or both. It is likely a nonspecific response to a variety of injuries to the alveolar macrophage or type II pneumocyte or both, including exposure to certain dusts and chemicals and occurrence of hematologic diseases or infections. The uncommon occurrence of this disorder suggests individual susceptibility.

Adolescent↗
PubMed1986

Postprandial hyperglycemia in patients with noninsulin-dependent diabetes mellitus. Role of hepatic and extrahepatic tissues.

Patients with noninsulin-dependent diabetes mellitus (NIDDM) have both preprandial and postprandial hyperglycemia. To determine the mechanism responsible for the postprandial hyperglycemia, insulin secretion, insulin action, and the pattern of carbohydrate metabolism after glucose ingestion were assessed in patients with NIDDM and in matched nondiabetic subjects using the dual isotope and forearm catheterization techniques. Prior to meal ingestion, hepatic glucose release was increased (P less than 0.001) in the diabetic patients measured using [2-3H] or [3-3H] glucose. After meal ingestion, patients with NIDDM had excessive rates of systemic glucose entry (1,316 +/- 56 vs. 1,018 +/- 65 mg/kg X 7 h, P less than 0.01), primarily owing to a failure to suppress adequately endogenous glucose release (680 +/- 50 vs. 470 +/- 32 mg/kg X 7 h, P less than 0.01) from its high preprandial level. Despite impaired suppression of endogenous glucose production during a hyperinsulinemic glucose clamp (P less than 0.001) and decreased postprandial C-peptide response (P less than 0.05) in NIDDM, percent suppression of hepatic glucose release after oral glucose was comparable in the diabetic and nondiabetic subjects (45 +/- 3 vs. 39 +/- 2%). Although new glucose formation from meal-derived three-carbon precursors (53 +/- 3 vs. 40 +/- 7 mg/kg X 7 h, P less than 0.05) was greater in the diabetic patients, it accounted for only a minor part of this excessive postprandial hepatic glucose release. Postprandial hyperglycemia was exacerbated by the lack of an appropriate increase in glucose uptake whether measured isotopically or by forearm glucose uptake. Thus as has been proposed for fasting hyperglycemia, excessive hepatic glucose release and impaired glucose uptake are involved in the pathogenesis of postprandial hyperglycemia in patients with NIDDM.

C-Peptide↗
PubMed1986

Clinical outcome of respiratory failure in patients requiring prolonged (greater than 24 hours) mechanical ventilation.

Patients requiring prolonged (greater than 24 hours) mechanical ventilation have various conditions that result in respiratory failure. All patients requiring prolonged mechanical ventilation were subdivided into the following six groups: uncomplicated acute lung injury; respiratory failure complicated by multisystem failure; previous lung disease; trauma; other medical causes; and routine postoperative ventilation. During a one-year period, 327 patients required prolonged mechanical ventilation; acute lung injury and chronic obstructive pulmonary disease were the predominant conditions. Sepsis was both the major predisposing factor for and complication of acute lung injury. Mortality for patients with acute lung injury was 40 percent in the uncomplicated group and 81 percent in patients with acute lung injury complicated by multisystem failure. Acute respiratory failure in association with acute renal failure had a mortality of 89 percent. Number of organ systems involved also correlated with mortality. In patients with chronic obstructive pulmonary disease and pneumonitis or retained secretions, mortality was lower (30 percent), but a significant percentage of these patients (43 percent) became ventilator-dependent. Ventilator dependence did not significantly increase mortality during the course of respiratory failure.

Adult↗
PubMed1984

Calculation of mean airway pressure during mechanical ventilation in neonates.

Mean airway pressure (Paw) calculated by 4 methods was compared with measured Paw, using 833 observations on 16 infants requiring constant-flow, pressure-limited mechanical ventilation. Measured Paw was most accurately predicted by determining a waveform constant for each infant every 12 h, and then using the waveform constant in a general Paw equation for the ensuing 12 h. However, this method is impractical for clinical use. A square-waveform equation more accurately predicted Paw than did triangular or sine-like waveform equations. Because there was considerable interindividual variation in the accuracy of all methods, due to different individual respiratory waveforms and waveform constants, Paw should be measured and not calculated.

Humans↗
PubMed1984

Hemodynamic response to positive end-expiratory pressure following right atrium-pulmonary artery bypass (Fontan procedure).

Thirteen patients were studied in the early postoperative period to determine the hemodynamic response to increasing levels of positive end-expiratory pressure (PEEP) following right atrium-pulmonary artery bypass (Fontan procedure). Hemodynamic data and arterial oxygen and carbon dioxide tensions were measured without PEEP and with PEEP = 3, 6, 9, and 12 cm H2O. Cardiac index decreased progressively with increasing levels of PEEP compared to PEEP = 0 (cardiac index = 2.7 +/- 1.2 L/min/m2), and the decrease was significant at PEEP = 9 (cardiac index = 2.2 +/- 0.8 L/min/m2, p less than 0.05) and 12 cm H2O (cardiac index = 2.0 +/- 0.7 L/min/m2, p less than 0.05). Both arterial oxygen tension and pulmonary vascular resistance index increased significantly at all levels of PEEP studied compared to PEEP = 0. Significant positive trends were demonstrated for arterial oxygen tension and pulmonary vascular resistance index and a significant negative trend was shown for cardiac index with increasing PEEP. Heart rate, right atrial pressure, left atrial pressure, mean arterial blood pressure, and arterial carbon dioxide tension did not change significantly nor consistently with increasing PEEP. From these data it appears that PEEP is an effective means of raising arterial oxygen tension after right atrium-pulmonary artery bypass. A progressive fall in cardiac index occurs with increasing PEEP, and the fall becomes significant at PEEP greater than 6 cm H2O. The fall in cardiac index appears to be mediated by a significant rise in pulmonary vascular resistance index.

Adolescent↗
PubMed1983

Clinical implications of variation in total venoarterial shunt fraction calculated by different methods during severe acute respiratory failure.

Ventilation-perfusion imbalance is the major physiologic disturbance that produces hypoxemia in acute respiratory failure, and total venoarterial shunt fraction is frequently used as a measure of its severity. Ninety-one total venoarterial shunt fractions were calculated from 29 patients with severe acute respiratory failure. Four different methods were used for each estimation, only two of which considered the influence of cardiac output and tissue oxygen uptake. The differences among the results were statistically significant and rendered invalid those that were calculated independently of mixed venous oxygen values. Lack of uniformity of the methods that have been used for calculating shunts in respiratory failure makes it difficult to compare individual patients or groups of them from previous reports. Use of a standard method is desirable so that statistical evaluation of severity and response to treatment can be undertaken. Older data on which therapeutic decisions may be based can have misleading variability from those derived from currently accepted techniques and could appreciably influence patient care.

Acute Disease↗
PubMed1983

Outcome of anesthesia and surgery in hypothyroid patients.

We retrospectively examined the outcome of anesthesia and surgery in 59 hypothyroid patients and in 59 paired euthyroid matched controls. Hypothyroid patients had more preoperative risk factors but did not differ as a group from controls with regard to duration of surgery or anesthesia, lowest temperature and BP recorded during surgery, need for vasopressors, time to extubation, fluid and electrolyte imbalances, incidence of arrhythmias, pulmonary and myocardial infarction, sepsis, need for postoperative respiratory assistance, bleeding complications, or time to hospital dismissal. Analysis of subsets of hypothyroidism (thyroxine level, less than 1.0, less than 3.0, and greater than or equal to 3.0 micrograms/dL) also failed to disclose any significant differences compared with matched controls. Among patients with mild or moderate hypothyroidism, we found no evidence to justify deferring needed surgery until the hypothyroidism has been corrected.

Anesthesia↗
PubMed1982

Central neurogenic hyperventilation in an awake patient with brainstem astrocytoma.

A patient had the rare combination of central neurogenic hyperventilation (PaCO2 of 9 torr) and a normal level of consciousness for eight days. Morphine attenuated but never corrected the hyperventilation. Experimental effects of hypocapnia, which decreases both cerebral blood flow and metabolism in humans, are at odds with the normal mentation initially seen in this patient despite her marked and persistent hypocapnia. Death occurred after progressive brainstem dysfunction. Pathological study showed a well-differentiated astrocytoma involving primarily the medulla and pons, with scattered tumor foci throughout the entire neuraxis. Possible mechanisms for central neurogenic hyperventilation are discussed briefly in relation to the pathological findings and the observed response to morphine.

Arteries↗
PubMed1982

The hemodynamic response to dopamine and nitroprusside following right atrium-pulmonary artery bypass (Fontan procedure).

Cardiac output is critically dependent upon pulmonary vascular resistance after right atrium-pulmonary artery bypass (Fontan procedure), since there is no pulmonary ventricle in the circulation. Inotropic agents, including dopamine, may increase pulmonary vascular resistance and, therefore, might have an adverse effect on cardiac output. The present study determined the hemodynamic responses to dopamine and nitroprusside of 9 patients following right atrium-pulmonary artery bypass. Particular attention was given to effects on cardiac output (CI), pulmonary vascular resistance, and right atrial pressure (RAP). Baseline hemodynamic data were measured without drugs, with dopamine at 7.5 micrograms/kg/min, with sodium nitroprusside up to 5.0 micrograms/kg/min, and with a combination of dopamine, 7.5 micrograms/kg/min, and sodium nitroprusside, 1.0 micrograms/kg/min. Right and left atrial pressures (LAP), mean arterial blood pressure (BP), heart rate (HR), and CI were measured. Stroke volume index and pulmonary arteriolar resistance index were calculated. The increase in CI from baseline (1.98 +/- 0.86 liters per minute) was significant for infusions of dopamine (2.75 +/- 1.05, p less than 0.001), sodium nitroprusside (2.57 +/- 0.78, p less than 0.001), and both drugs (2.74 +/- 0.84, p less than 0.001). The increased CI was achieved primarily by a significant increase in HR with dopamine and by an increase in stroke volume index with sodium nitroprusside. With a similar increment in CI, the RAP was significantly decreased from baseline (21 +/- 4 torr) with sodium nitroprusside (15 +/- 3, p less than 0.001) but was unchanged with dopamine. Pulmonary arteriolar resistance index decreased significantly from baseline (375 +/- 230 dynes sec cm-5/m2) with sodium nitroprusside (169 +/- 132, p less than 0.001), and, interestingly, with dopamine as well (273 +/- 165, p less than 0.05). Both dopamine and sodium nitroprusside in these dosages have favorable effects on CI and pulmonary arteriolar resistance index in patients after right atrium-pulmonary artery bypass. Whenever feasible, sodium nitroprusside is preferred for increasing CI after such a bypass procedure, since lower RAP decreases the severity of fluid retention, ascites, and chest tube drainage.

Adolescent↗
PubMed1982

Continuous monitoring of mixed venous oxygen saturation in critically ill patients.

A new pulmonary artery balloon flow-directed catheter combines a fiberoptic photometric system for continuous display of mixed venous blood oxygen saturation (SvO2) with the capacity for hemodynamic measurements including thermodilution cardiac output estimation. This oximetry system was studied to determine its accuracy, reliability, and usefulness in the surgical intensive care unit (ICU). Twenty-two catheters were tested, but only 17 were successfully placed in 16 patients. There were technical problems associated with 10 catheters and on six occasions these necessitated the use of another catheter. The catheter values for SvO2 were closely related (r = 0.9516) to those obtained from a laboratory Co-oximeter. Continuous monitoring of SvO2 is accurate and valuable as a warning system for deterioration in cardiopulmonary function and as an indicator of the effects of various therapeutic maneuvers in critically ill patients.

Catheterization↗
PubMed1981

Infection of pulmonary artery catheters in critically ill patients.

Bacteriologic cultures were performed on the tips of pulmonary artery catheters removed from 153 critically ill patients, who had required pulmonary artery catheterization for management of hypovolemic or septicemic shock or for hemodynamic monitoring during mechanical ventilation with positive end-expiratory pressure. Positive results were obtained in 29 (19%) of the cases. Infection of indwelling pulmonary artery catheters may result from contamination during placement or removal or from transient or persistent bacteremia. Colonization was probable in 17 cases, and contamination in 12. There were no instances of sepsis definitely attributable to the catheter. Positive catheter-tip culture was associated significantly with known presence of a focus of infection before catheter insertion and with periods exceeding four days that the catheter remained in place.

Bacteria↗
PubMed1981

Respiratory timing and depth of breathing in dogs anesthetized with halothane or enflurane.

Tidal volume (VT) and inspiratory (TI) and expiratory (TE) times were measured during enflurane and halothane anesthesia in 12 prone dogs before and after bilateral vagotomy. "Elastic" loading or airway occlusion was used to obtain a VT-to-TI relationship in each state and to examine the rate of change in airway pressure. VT, TI, and TE were significantly (P less than 0.05) larger during enflurane than during halothane anesthesia, both before and after bilateral vagotomy. Before vagotomy, the rate of change in airway pressure during airway occlusion was similar for the two agents, as was an index of impedance of the respiratory system (Z'rs). Thus the difference in maximal pressure generated and in VT was most likely due to the difference in TI. Before vagotomy, TI increased as VT decreased with loading during enflurane but not halothane anesthesia, demonstrating a different effect of the two agents on the phasic vagal inspiratory inhibitory mechanism. After bilateral vagotomy, TI was unaltered during elastic loading with both agents but was still significantly longer during enflurane than halothane anesthesia. Thus it was concluded that TI was longer in the enfluraneanesthetized dogs than in the halothane-anesthetized dogs because of a different effect of these two agents on the bulbopontine "pacemaker" mechanism and not because of different effects on the phasic vagal inspiratory inhibitory mechanism.

Anesthesia↗