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Biomedical subjects

B P Krieger

Publications and source records attributed to B P Krieger.

At least 19 recordsLinked to original sources
PubMed2001

Diving: what to tell the patient with asthma and why?

Until a decade ago, divers with asthma were uniformly barred from diving with compressed air. This prohibition was based more on theoretical concerns for barotrauma than on actual data. Follow-up studies, although retrospective, do not support a ban on recreational or commercial diving for divers with stable asthma. These studies have noted that, despite the prohibition on diving, many divers with asthma have logged multiple dives without negative consequences. When those who have suffered diving-related barotrauma have undergone physiologic testing, measurements of small airways dysfunction (maximal mid-expiratory flow rates) have been lower than measurements for comparable divers who have never suffered diving accidents. Follow-up studies with long-term commercial divers have shown that a small percentage of individuals who have sufferred diving-related barotrauma also develop abnormal maximal mid-expiratory flow rates and even some airway hyperreactivity. These latter findings correlate with the changes that occur in chronic asthmatic patients, especially those who are not well treated. The decision as to whether an asthmatic patient should be allowed to dive rests on the individual's physiologic function, maturity, and insight into the consequences of poorly managed airway inflammation and bronchospasm.

Asthma↗
PubMed1999

Altitude-related pulmonary disorders.

The major physiologic stress encountered at high altitude is caused by the occurrence of hypobaric hypoxia. In this article, acute and chronic pulmonocardiac adaptation to altitude is reviewed, including possible genetic differences among highlanders from the Himalayan versus the Andean Mountains. The origin, symptoms, and treatment of acute mountain sickness and high altitude pulmonary edema are outlined. In addition, the prediction and prevention of pulmonary complications that may be encountered or exacerbated during commercial airflight are noticed.

Altitude↗
PubMed1998

CD4 lymphocyte counts and mortality in AIDS patients requiring mechanical ventilator support due to Pneumocystis carinii pneumonia.

OBJECTIVE: To evaluate CD4 counts as a predictor of mortality in AIDS patients with respiratory failure due to Pneumocystis carinii pneumonia (PCP). DESIGN: Retrospective chart review. SETTING: Urban university medical center. PATIENTS: Forty-eight patients admitted to the medical ICU from January 1993 to August 1996 with diagnosis of HIV/AIDS, PCP, CD4 count <200 cells per cubic millimeter, who required mechanical ventilation for respiratory failure. INTERVENTIONS: Medical records were reviewed and age, CD4 count, lactate dehydrogenase, room air (RA) PaO2, coinfections, and day of admission to day of intubation (DOA-DOI) data were recorded. RESULTS: All 48 patients (12 women and 36 men) were treated with corticosteroids and IV trimethoprim-sulfamethoxazole. Age ranged from 21 to 65 years; CD4, 1 to 180, RA PaO2, 27 to 93 mm Hg; and DOA-DOI, 0 to 20 days. Mortality varied significantly depending on CD4 counts: CD4 0 to 10 (100%); CD4 11 to 50 (88%); CD4 51 to 100 (50%); and CD4 >100 (25%). There were no significant difference in mortality between the groups with DOA-DOI <5 days (82%) vs >5 days (80%) or between the groups with PaO2 <60 mm Hg (85%) vs PaO2 >60 mm Hg (73%). CONCLUSION: Even though overall mortality was 81%, the mortality rate was significantly different among the four groups. Most striking was the progressive increase in mortality as CD4 cells decreased from >100 (25% mortality) to <10 (100% mortality). Survivors had significantly higher CD4 cell counts than those who died. The CD4 cell count within 2 weeks of admission has significant prognostic value and may be helpful when counseling patients, families, and healthcare surrogates in end-of-life decision making.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Serial measurements of the rapid-shallow-breathing index as a predictor of weaning outcome in elderly medical patients.

STUDY OBJECTIVES: To determine the usefulness of serial measurements of the rapid-shallow-breathing index (f/VT) as a predictor for successfully weaning elderly medical patients from mechanical ventilator support using a threshold value (< or =130) derived specifically for this population. DESIGN: Prospective observational study using parameters suggested from retrospective analysis. SETTING: Medical ICUs of a university-affiliated private teaching hospital. PATIENTS: Using data obtained from a retrospective analysis of 10 medical patients > or =70 years old who had failed weaning, 49 additional medical patients older than 70 years were studied prospectively. INTERVENTIONS: Standard weaning parameters were determined using a hand-held spirometer. Respiratory rate (f, breaths/min) and tidal volume (VT, liters) were measured at the beginning of a spontaneous breathing trial and hourly thereafter for up to 5 h using the same hand-held spirometer. MEASUREMENTS AND RESULTS: Retrospective analysis showed that the published threshold value for f/VT (< or =105) had poor predictability for weaning success when measured at the beginning of the weaning trial. In the 9 of 10 patients who failed to wean in the retrospective review, the f/VT increased to > 130 as the trial progressed over 2 to 3 h. Using an f/VT < or =130 as the threshold value for prospectively predicting successful weaning, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value increased from 84%, 92%, 57%, 87%, and 67%, respectively, when measured at the beginning of the weaning trial to 92%, 93%, 89%, 97%, and 80%, respectively, when measured 3 h later. The area under the receiver operating characteristic curve for f/VT also improved from 0.81 to 0.93. CONCLUSIONS: Serial measurements of the rapid-shallow-breathing index in medical elderly patients during a period of spontaneous breathing can accurately predict the ability to be successfully weaned from mechanical ventilator support.

Aged↗
PubMed1994

Respiratory failure in the elderly.

Elderly patients are predisposed to respiratory failure because of physiological changes that occur with the aging process. These changes result in a loss of pulmonocardiac reserve and the relatively frequent need for mechanical ventilatory support. The management and weaning of elderly patients from mechanical ventilatory support is different from strategies used for younger patients. By focusing on the physiological changes that occur in the elderly, this article explains why the elderly experience more complications and higher mortality than younger patients with respiratory failure. It also suggests management strategies that incorporate newer insights into ventilatory and respiratory muscle failure.

Age Factors↗
PubMed1991

Noninvasive measurement of central venous pressure by neck inductive plethysmography.

Bedside estimation of the height at which the internal jugular veins collapse, referenced to a standard hemodynamic location, theoretically reflects central venous pressure. This method has never been demonstrated as accurate when compared to invasive CVP measurements because of the great clinical skills and time required to visually identify the internal jugular venous waveform. Since the principles of the bedside method are sound, we utilized them in conjunction with the neck inductive plethysmograph, a device which has the capability of recording internal jugular venous and carotid arterial waveforms. The respiratory distortion of these vascular waveforms was eliminated by employing a digital bandpass filter, making it easy to identify the venous and arterial waveforms on the videoscreen of a personal computer. The upper torso was positioned while observing the videoscreen until the vascular waveform was seen as a mixed arteriovenous waveform, signifying intermittent internal jugular venous collapse. The height of the internal jugular vein above the phlebostatic axis was obtained by external measurement and recorded as CVPni in cm H2O. In 43 patients, 86 percent of CVPni (NIP) values fell within 20 percent CVPi (invasive catheter measurements) over a range of CVP from 0 to 19 cm H2O. In an additional seven patients, CVPi was greater than the height that the upper torso could be elevated and an arterial waveform could not be obtained. Here, CVPni was recorded as the value at least exceeding the value measured. In two other patients, obstruction of an internal jugular vein gave spuriously low values of CVPni. Our study indicates that this new neck inductive plethysmographic method is accurate compared to invasive catheter measurements of CVP and should serve as a safe, noninvasive alternative in situations where such measurements are required.

Adult↗
PubMed1991

Thoracocardiography. Part 1: Noninvasive measurement of changes in stroke volume comparisons to thermodilution.

The thoracocardiograph (TCG) is a new noninvasive monitoring device that measures cardiac oscillations transmitted to the external surface of the thorax. It consists of 2.5 cm in height, elastic inductive plethysmographic transducers placed transversely in the proximity of the xiphoid process to provide changes in cross-sectional area on a transverse plane across the minor ventricular axis. Cardiac oscillations synchronous with each heart beat are extracted from the respiratory signal during breathing with an ensemble-averaging technique using the electrocardiograph as a trigger pulse. The average cardiac waveform at locations near the xiphoid process in normal humans has the appearance of a ventricular volume curve. The latter is also found in the majority of patients with heart disease although in some, outward (dyskinetic) rather than inward motion during systole occurs at one or more locations of the TCG transducers. As in echocardiography, such findings are consistent with ischemic or scarred myocardium invalidating computation of changes in stroke volume from such sites. In anesthetized dogs and critically ill patients with normal ventricular wall motion, changes in TCG derived ventricular volume waveform amplitudes agreed well with changes of thermodilution estimates of stroke volume during atrial pacing and fluid loading in the dogs on the one hand and with application of extrinsic positive end-expiratory pressure (PEEP) in patients on the other hand. Thoracocardiography has the potential for noninvasive, continuous monitoring of stroke volume and cardiac output as well as for detection of ischemic or scarred myocardium.

Aged↗
PubMed1991

Thoracocardiography. Part 2: Noninvasive measurement of changes in stroke volume; comparisons to impedance cardiograph.

The thoracocardiograph (TCG) displays cardiac oscillations transmitted to the external surface of the thorax through inductive plethysmographic transducers placed transversely around the thorax near or about the xiphoid process. Such signals, with the appearance of ventricular volume curves, were used to compute changes of stroke volume (SV) and cardiac output (CO) in normal subjects. Their values were compared with changes of SV and CO measured with the impedance cardiograph (IC). Increases of SV and CO were produced with subcutaneous terbutaline and there was excellent agreement between TCG and IC values, best from TCG transducers placed at the xiphoid process and 3 cm caudal to it, although TCG locations 6 cm caudad and 3 cm cephalad to the xiphoid were also satisfactory. Since the site 3 cm caudad to the xiphoid process is known to anatomically transect solely a segment of the left ventricle, it was designated the TCG-Reference location. Both TCG and IC derived SV were not altered during postural shifts about a horizontal axis. Neither TCG nor IC showed the expected large decreases of SV from supine posture to head-up tilt. With baseline TCG and IC measurements in 60 degrees head-up tilt. MAST suit application increased CO measured with TCG but not with IC. Neither TCG nor IC revealed alteration of CO with nasal CPAP up to 10 cm H2O despite a rise in functional residual capacity (FRC) level of 870 ml. This investigation indicates that TCG has promise as a near continuous, noninvasive monitor of SV and CO in normal subjects if postural axis is fixed and does not require highly trained personnel or labor-intensiveness for its operation.

Adult↗
PubMed1990

One year's experience with a noninvasively monitored intermediate care unit for pulmonary patients.

Many studies have shown that selected cardiac patients can be safely and economically cared for in intermediate care units rather than intensive care units. However, there are only limited data concerning intermediate care units for pulmonary patients. We prospectively followed up all Medicare patients from May 5, 1987, through May 4, 1988, who were admitted to a pulmonary noninvasive monitoring unit. Ninety-four patients were admitted 104 times; 33 required mechanical ventilatory support for an average of 26 days. The overall cost savings were greater than $173,000, while high-quality medical care was maintained. We conclude that a noninvasive monitoring unit can be effectively used as an alternative to the intensive care unit for selected pulmonary patients.

Aged↗
PubMed1990

Disseminated strongyloidiasis in AIDS and non-AIDS immunocompromised hosts: diagnosis by sputum and bronchoalveolar lavage.

In conclusion, disseminated strongyloidiasis is a fatal disease that commonly affects the lungs. The disease should be suspected in an immunocompromised host who came from an area endemic for S stercoralis even years before the onset of symptoms or in patients with unexplained gram-negative bacteremia or meningitis. Treatment should be started promptly and should be maintained for a long time.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Pleural pressure changes in dogs measured from suprasternal fossa movements.

Movements of the suprasternal fossa during spontaneous breathing monitored with the surface inductive plethysmograph (SIP) have been shown to reflect changes of intrapleural pressure in conscious humans. Calibration of this device in anesthetized intubated dogs was accomplished by adjusting the electrical gain of its analog waveform to be equivalent to changes of airway pressure during inspiratory efforts against an occluded airway. This procedure, denoted the occlusion test, was also used to identify the site of esophageal balloon catheter placement for its recording of intrapleural pressure deflections. The validity of SIP-derived estimates of inspiratory and expiratory pulmonary resistances and lung compliance was established by finding close agreement with measurements obtained with intraesophageal pressure changes during 1) unimpeded spontaneous breathing, 2) inspiratory resistive loading, 3) bronchoprovocation with aerosolized carbachol, 4) mechanical ventilatory modalities, and 5) induced pulmonary edema. Therefore, movements of the suprasternal fossa with respiration can be reliably transformed into quantitative or semiquantitative changes of intrapleural pressure in anesthetized intubated dogs during major alterations of pulmonary mechanics.

Airway Resistance↗
PubMed1990

Right upper lobectomy twenty years after left pneumonectomy. Preoperative evaluation and follow-up.

Quantitative perfusion lung scanning coupled with spirometry and balloon occlusion of the pulmonary artery supplying the lung to be resected have been used to predict the potential operability of patients being considered for pneumonectomy. These techniques were adapted for the lobar level prior to performing a right upper lobectomy in a 59-year-old man who had undergone a left pneumonectomy 20 years previously. This case demonstrates how physiologic reserve can be predicted in patients who require sequential pulmonary resection.

Carcinoma, Bronchogenic↗
PubMed1989

Evaluation of conventional criteria for predicting successful weaning from mechanical ventilatory support in elderly patients.

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 greater than or equal to 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 (less than or equal to 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.

Aged↗
PubMed1989

End-tidal carbon dioxide in critically ill patients during changes in mechanical ventilation.

Values of end-tidal CO2 (PETCO2) approximate PaCO2 in spontaneous breathing normal subjects and in stable patients receiving mechanical ventilatory support (MVS). Because marked inequality of ventilation/perfusion ratios in critically ill patients might affect this correlation, we assessed changes of PETCO2 in predicting changes in PaCO2 (delta PaCO2) and changes in minute ventilation (delta Ve) in this patient population. Twenty consecutive intubated patients 38 to 89 yr of age (mean, 70 yr) with respiratory failure while receiving MVS with indwelling arterial lines were studied. Settings on the mechanical ventilator were varied for frequency and tidal volume, and after a minimum of 5 to 10 min equilibration, PaCO2 and PETCO2 were measured. Vt and Ve were recorded from the digital indicator of the pneumotachygraph within the mechanical ventilator and corrected for compression volume in the respirator circuit. A total of 116 simultaneous measurements were performed. PETCO2 correlated well with PaCO2 (r = 0.78, p less than 0.001). The 95% confidence interval for the mean difference in PaCO2-PETCO2 was 4.0 +/- 0.97 mm Hg. However, delta PETCO2 (measured from baseline) did not correlate as well with delta PaCO2 (r = 0.58, p = less than 0.001). In four patients, the trend in their PETCO2 during changes in mechanical ventilation were in the opposite direction from the trend in their PaCO2. Thus, many critically ill patients, who cannto be preidentified, have an inconstant PaCO2-PETCO2 gradient with changes of ventilation. Utilization of PETCO2 as a noninvasive monitoring substitute for trends in PaCO2 in critically ill patients may be misleading despite establishing an initial PaCO2-PETCO2 relationship.

Adult↗
PubMed1989

Determination of auto-PEEP during spontaneous and controlled ventilation by monitoring changes in end-expiratory thoracic gas volume.

Auto-PEEP, or PEEPi, occurs when alveolar pressure fails to decrease to zero at the end of exhalation. While PEEPi can be measured in paralyzed or apneic patients by occlusion of the ventilator expiratory valve at end-exhalation (PEEPi-OC), this may not be possible in patients with spontaneous respiratory efforts. When adjusting the ventilator PEEP valve, FRC increases only after PEEPi has been exceeded. In both mechanically ventilated and spontaneously breathing patients, changes in FRC are mirrored by changes in end-expiratory TGV as measured with RIP set in the DC mode. We compared PEEPi as measured by RIP to PEEPi-OC in 20 patients receiving mechanical ventilator support. Noninvasive measurement of changes in end-expiratory TGV by RIP is a convenient alternative method to estimate PEEPi in both controlled, assisted, and spontaneously ventilating patients.

Adult↗
PubMed1989

New modes of palliative therapy for patients with lung cancer--a review.

Although our ability to cure nonsmall cell carcinoma of the lung has not changed appreciably over the past decade, newer modalities have provided improved palliative therapy. This article briefly reviews various forms of laser therapy and endobronchial irradiation (brachytherapy). The combination of these techniques appears to offer the promise of safely palliating patients who otherwise would rapidly succumb to local effects of their tumor.

Carcinoma, Non-Small-Cell Lung↗
PubMed1988

Initial experience with a central respiratory monitoring unit as a cost-saving alternative to the intensive care unit for Medicare patients who require long-term ventilator support.

The cost of delivering health care to Medicare patients in intensive care units (ICU), especially those on long-term ventilator support, has become a major financial burden to American hospitals. We established a central station, respiratory, noninvasive monitoring unit (NIMU) on a cardiac telemetry floor where nurse to patient ratio was 1:4 to 1:6 as a cost-effective alternative to the ICU which has a ratio of 1:2. During the first five months of operation, 55 patients were admitted to this unit, of which 11 were long-term ventilator Medicare patients. Seven of these 11 patients were successfully weaned and discharged from the hospital. Overall, a minimum of $21,724 was saved over five months by shifting these long-term ventilator patients from the ICU to the NIMU while quality of medical care remained or exceeded accepted standards. We conclude that alternative health care delivery systems such as the NIMU need to be investigated as safe, cost-reducing substitutes for selected ICU patients to prevent loss of quality medical care in the financial backlash of the present Medicare prospective payment schedule.

Aged↗