Biomedical subjects

P J Feustel

Publications and source records attributed to P J Feustel.

At least 19 recordsLinked to original sources

PubMed2003

Longitudinal outcome of Parkinson's disease patients with psychosis.

OBJECTIVES: To examine the long-term outcome of PD patients with psychosis requiring antipsychotic therapy; to explore predictors of mortality, nursing home placement, dementia, and persistent psychosis; and to compare outcomes of those with persistent psychosis vs those whose psychosis resolved. METHODS: Baseline data available from 59 patients enrolled in the PSYCLOPS (PSychosis and CLOzapine in PD Study) trial included age, age at onset of PD, duration of PD and psychosis, character of psychosis, medications, living setting, and scores for Mini-Mental State Examination (MMSE), Unified Parkinson's Disease Rating Scale, Hoehn and Yahr Scale, and Clinical Global Impression Scale. Longitudinal data were collected 26 months later regarding four outcomes: death, nursing home placement, diagnosis of dementia, and persistence of psychosis. Logistic regression was used to explore whether any baseline characteristics were associated with an increased likelihood of one of these outcomes. RESULTS: At baseline, 56% of patients had an MMSE score of <25, 12% were in a nursing home, 95% had hallucinations, and 60% had paranoia. On follow-up, 25% were dead, nursing home placement occurred in 42%, psychosis was persistent in 69%, and dementia was diagnosed in 68%. Select baseline characteristics predicted individual outcomes: Nursing home placement was associated with the presence of paranoia and older age; persistent psychosis was associated with younger age at onset of PD and longer disease duration; dementia was associated with older age at PD onset and lower initial MMSE score; no characteristics predicted death. Whether psychosis persisted or not had no significant effect on the development of the other three outcomes. The prevalence of hallucinations at follow-up was not different between groups currently receiving antipsychotics vs those on no treatment. CONCLUSIONS: Psychosis in PD requiring antipsychotic therapy is frequently associated with death, nursing home placement, development and progression of dementia, and persistence of psychosis. Still, it appears the prognosis has improved with atypical antipsychotic therapy based on the finding that 28% of NH patients died within 2 years compared with 100% in a previous study done prior to availability of this treatment.

Aged↗

PubMed2003

Influence of diagnostic and therapeutic doses on thyroid remnant ablation rates.

Radioiodine ablation of thyroid tissue after subtotal thyroidectomy has been shown to decrease recurrence in certain subsets of patients with well-differentiated thyroid cancer. In a substantial percentage of cases (20-30%), initial ablation of the thyroid remnant fails, necessitating a second treatment. The factors associated with ablation failure are not fully understood. In particular, it is not certain whether the use of doses higher than 3.70 GBq would result in any additional benefit, or whether there is a 'stunning' effect of the diagnostic dose of 131I on the subsequent ablation rate. A retrospective analysis was performed of all patients (n=389) with well-differentiated thyroid cancer treated at our institution between 1992 and 2001. Remnant ablation success was determined by a whole-body radioiodine scan. The following factors, thought to be associated with thyroid remnant ablation, were studied by logistic regression analysis: age, gender, tumour histology, stage, pre-therapy neck uptake of 131I, diagnostic dose, ablation dose, time between diagnostic and therapeutic dose (T1), time between therapeutic administration and the first follow-up whole-body scan (T2) and the thyroid-stimulating hormone (TSH) level measured at the time of therapy. Follow-up whole-body scans were available in 214 patients. We found no association with age, gender, histology, TSH level, neck uptake, diagnostic dose and successful ablation. The therapeutic dose was the only variable found to be associated with success (odds ratio, 1.96 per 1.85 GBq increment; 95% confidence interval, 1.11-3.46). Our results confirm the presence of a significant percentage of ablation failures (24.4%) despite the use of high ablative doses (3.70-7.40 GBq). Higher therapeutic doses are associated with higher rates of successful ablation, even when administered to patients with more advanced stages. Using our protocol, higher diagnostic doses were not associated with higher rates of ablation failure.

Adolescent↗

PubMed2003

Diuretic renogram clearance half-times in the diagnosis of obstructive uropathy: effect of age and previous surgery.

Diuretic renography with radiotracers has been used successfully to diagnose obstruction in patients with hydronephrosis. Controversy persists with regard to the best approach for the interpretation of renogram curves: visual analysis or a quantitative index, i.e. the clearance half-time. The latter is often reported to be in the intermediate or non-diagnostic range. It is important to measure the incidence of equivocal half-times in various subsets of patients with hydronephrosis in order to determine in which settings the measurement of this index may be clinically useful. We performed a retrospective study of diuretic renograms performed at our institution between 1997 and 2000 for the evaluation of suspected uretero-pelvic junction (UPJ) obstruction. Vigorous intravenous hydration, exceeding current guidelines, was employed in these patients. Three hundred and seventy-seven renogram curves in 205 patients were analysed. Patients were divided into three groups: >1 year of age; 20 min) or intermediate (half-time, 10-20 min). In patients >1 year of age, 37% of 101 renograms showed normal half-times before furosemide, 20% showed normal half-times after furosemide, 44% showed prolonged half-times and none (0%) showed an intermediate half-time. In patients </=1 year of age, there was a statistically significantly different distribution, with 48% of 64 renograms showing normal washout before furosemide, 16% showing normal clearance after furosemide, 19% showing abnormal half-times and 17% showing intermediate half-times. In 33 renograms from patients who had undergone corrective surgery, 49% had normal half-times, 24% had prolonged half-times and 27% had intermediate half-times. It can be concluded that, when using the selection criteria, hydration, acquisition and processing protocols and half-time definition employed in this study, the addition of a clearance measurement in patients older than 1 year with suspected UPJ disease enhances patient classification and may improve the diagnostic confidence. There was a significantly higher incidence of intermediate half-times in patients with native disease aged <1 year than in those >1 year. Caution is advised when interpreting this finding in this age group. The measurement of washout was less useful in patients who had undergone a corrective procedure, because of the high rate of 'indeterminate' and 'abnormal' values in spite of successful surgery. Vigorous intravenous hydration, exceeding current standards, may have contributed to the lower incidence of intermediate half-times than reported previously.

Adolescent↗

PubMed2001

Preoperative risk assessment for gastrostomy tube placement in head and neck cancer patients.

BACKGROUND: The presentation and definitive surgical treatment of head and neck malignancies have varying impact on postoperative recovery and return of swallowing function, which heretofore has not been well defined. METHODS: We performed a retrospective chart review of 142 patients who underwent extirpative surgery for head and neck cancer. RESULTS: Factors significantly associated with the need for long-term postoperative nutritional support (p < .05) included heavy alcohol use, tongue base involvement and surgery, pharyngectomy, composite resection, reconstruction with a myocutaneous flap, radiation therapy, tumor size, and moderately-to-poorly differentiated histology. Heavy alcohol users were at an absolute risk for gastrostomy tube dependence; patients who underwent radiation therapy, flap reconstruction, tongue base resection, and pharyngectomy were at a two to sevenfold increased risk for gastrostomy tube dependence, respectively. CONCLUSIONS: High-risk patients based on these criteria should receive a feeding gastrostomy at the time of their initial surgical therapy.

Aged↗

PubMed2001

Tamoxifen inhibits nitrotyrosine formation after reversible middle cerebral artery occlusion in the rat.

Tamoxifen (TAM), a widely used non-steroidal anti-estrogen, has recently been shown to be neuroprotective in a rat model of reversible middle cerebral artery occlusion (rMCAo). Tamoxifen has several potential mechanisms of action including inhibition of the release of excitatory amino acids (EAA) and nitric oxide synthase (NOS) activity. The question addressed in this study was whether TAM reduces ischemia-induced production of nitrotyrosine, considered as a footprint of the product of nitric oxide and superoxide, peroxynitrite. In rat brain, 2 h rMCAo produced a time-dependent increase in nitrotyrosine content in the cerebral cortex, as measured by Western blot analysis. Compared with vehicle, TAM significantly reduced nitrotyrosine levels in the ischemic cortex at 24 h. The neuronal (n)NOS inhibitor, 7-nitroindazole also tended to reduce nitrotyrosine, but this reduction was not statistically significant. Immunostaining for nitrotyrosine was seen in cortical neurons in the MCA territory and this immunostaining was reduced by TAM. In vitro, TAM and the calmodulin inhibitor trifluoperazine inhibited, with similar EC(50) values, the activity of recombinant nNOS as well as NOS activity in brain homogenates, measured by conversion of [(3)H]arginine to [(3)H]citrulline. There was marginal inhibition of recombinant inducible (i)NOS activity up to 100 microM TAM. These data suggest that TAM is an effective inhibitor of Ca(2+)/calmodulin-dependent NOS and the derived peroxynitrite production in transient focal cerebral ischemia and this may be one mechanism for its neuroprotective effect following rMCAo.

Animals↗

PubMed2001

Outcome of adolescent trauma admitted to an adult surgical intensive care unit versus a pediatric intensive care unit.

BACKGROUND: Institutional protocol designates the adult trauma service as the primary manager of all adolescent traumas (age 14-18 years) unless admission to the pediatric intensive care unit (PICU) occurs. In the PICU, primary care becomes the responsibility of the pediatric intensivist, with trauma service as a consultant. The purpose of this study was to identify differences in the management of adolescent trauma between the pediatric intensivist in the PICU, and the adult trauma team in the surgical intensive care unit (SICU). METHODS: From January 1993 to January 1998, the medical records of all adolescent trauma patients requiring intensive care unit (ICU) management were reviewed. Depending on bed availability, patients younger than 16 were admitted to the PICU, and those 16 or older to the SICU. Demographic data obtained were age, sex, race, mechanism of injury, length of stay (LOS), ICU length of stay, days on mechanical ventilation, intubation, tracheotomy, intracranial pressure monitor, and Swan-Ganz catheter placement. Home discharge, rehabilitation placement, and death were recorded. Morbidity was measured using Injury Severity Score methodology, Pediatric Trauma Score, and Pediatric Risk of Mortality. RESULTS: One hundred nine completed records were reviewed (SICU, n = 58; PICU, n = 51). There was no statistical difference in sex, race, mechanism of injury, ICU LOS, tracheotomy, and intracranial pressure monitor placements. There was no difference in morbidity, as measured by Injury Severity Score, Pediatric Trauma Score, and Pediatric Risk of Mortality score or in outcome measurements (death, rehabilitation placement). SICU patients were older (SICU, 16.9 +/- 1.0 years; PICU, 15.4 +/- 1.0 years; p < or = 0.1 Mann-Whitney U test), more likely to be intubated (SICU, n = 42; PICU, n = 24; p < or = 0.05 Fisher's exact test), more likely to have pulmonary artery catheter placement (SICU, n = 7; PICU, n = 0), and had longer LOS (SICU, 12.2 +/- 10.6; PICU, 9.8 +/- 14.1; p < or = 0.03 Mann-Whitney U test). CONCLUSION: Adolescent trauma patients admitted to the PICU were less likely to be intubated or have a Swan-Ganz catheter placed. They had decreased LOS and days of mechanical ventilation. There was no difference in outcome measurements.

Adolescent↗

PubMed2000

Acute treatment with tamoxifen reduces ischemic damage following middle cerebral artery occlusion.

Inhibitors of cell-swelling-activated anion channels, including the antiestrogenic compound tamoxifen (TAM), have been shown to attenuate the increase in excitatory amino acids (EAA) during ischemia. Since TAM enters the CNS we tested whether it provides protection from damage due to reversible middle cerebral artery occlusion (rMCAo) in rats. TAM (5 mg/kg, i.v.) infused 25 min before ischemia, potently reduced the total volume of the infarct from 328 +/- 34 mm3 to 41 +/- 21 mm3, a reduction of 87%, as measured by TTC staining. It was equally effective when infused starting at 1 h after reperfusion, i.e. 3 h after initiation of rMCAo. Protection of neurons was also found histologically. TAM had no effect on CBF as measured by hydrogen clearance. This appears to be the first report of a marked neuroprotective effect of TAM. Further studies are needed to determine whether its effects are due to inhibition of EAA release and/or other potential neuroprotective sites of action.

Animals↗

PubMed2000

Comparison of power-assisted adenoidectomy vs adenoid curette adenoidectomy.

OBJECTIVE: To compare the safety and efficacy of power-assisted adenoidectomy (PAA) vs adenoid curette adenoidectomy (ACA). DESIGN: A prospective randomized study. SETTING: Children's hospital of a tertiary care medical center. PATIENTS: Ninety patients (aged 1-13 years) underwent PAA, and 87 patients (aged 1-12 years) underwent ACA. MAIN OUTCOME MEASURES: The parameters evaluated were operative time, blood loss, completeness and depth of resection, injuries to surrounding structures, short- and long-term complications, surgeon satisfaction with the procedure, and parents' assessment of the patient's postoperative recovery period. RESULTS: The PAA was 20% faster (P<.001) and had 27% less blood loss (P<.001) than the ACA. It provided a more complete resection(P<.001) and better control of the depth of resection (P<.05). Surgeon satisfaction was greater with PAA (P<.001). There was no difference in the recovery period or parent satisfaction. One patient in the PAA group returned to the operating room for control of postoperative bleeding, and 1 child in the ACA group returned to the hospital for postoperative dehydration. CONCLUSION: The PAA provides a faster, dryer, more complete, and more surgically satisfying resection than the ACA.

Adenoidectomy↗

PubMed1999

Scintigraphic detection of breast cancer xenografts with Tc-99m natural and recombinant human alpha-fetoprotein.

Because adenocarcinoma of the breast expresses receptors for alpha-fetoprotein (AFP), we studied Tc-99m AFP as a radiopharmaceutical to detect breast cancer. The biodistribution of Tc-99m radiolabeled natural human AFP (full length) and recombinant domain III (DIII) of human AFP was compared to Tc-99m sestamibi and Tl-201 in a murine model of human breast cancer. Estrogen receptor positive (MCF7, T-47D) and estrogen receptor negative (MDA-MB-231, BT-20) human breast cancer xenografts were grown subcutaneously in the lateral thorax region of immunosuppressed mice (ICR SCID). Quantitative comparisons of percent-injected dose per gram of tissue (%ID/gram) and tumor to thigh ratio (T/Th) were performed at 0-60 minutes and at 24 hours following injection. For most tumors, T/Th for AFP and DIII was significantly greater than T/Th for Tc-99m sestamibi and Tl-201. In all breast cancers (BT-20, MCF7, MDA-MB-231, T-47D), Tc-99m AFP T/Th increased from 60 minutes to 24 hours, suggesting good tumor retention of this radiopharmaceutical. DIII and AFP had significantly higher %ID/gram than either Tl-201 or Tc-99m sestamibi when considered across all tumor types at both 60 minutes and 24 hours. The data suggests that localization of Tc-99m AFP in human breast cancer xenografts is initially rapid, increases with time, and is superior to Tc-99m sestamibi and Tl-201. Given its high uptake by breast cancer cells, its low non-tumor localization and its rapid renal excretion, these Tc-99m AFP preparations may be useful agents to detect human breast carcinoma.

Animals↗

PubMed1999

Inhibition of ischemia-induced glutamate release in rat striatum by dihydrokinate and an anion channel blocker.

BACKGROUND AND PURPOSE: Increased activation of excitatory amino acid (EAA) receptors is considered a major cause of neuronal damage. Possible sources and mechanisms of ischemia-induced EAA release were investigated pharmacologically with microdialysis probes placed bilaterally in rat striatum. METHODS: Forebrain ischemia was induced by bilateral carotid artery occlusion and controlled hypotension in halothane-anesthetized rats. During 30 minutes of ischemia, microdialysate concentrations of glutamate and aspartate were measured in the presence of a nontransportable blocker of the astrocytic glutamate transporter GLT-1, dihydrokinate (DHK), or an anion channel blocker, 4,4'-dinitrostilben-2,2'-disulfonic acid (DNDS), administered separately or together through the dialysis probe. RESULTS: In control striata during ischemia, glutamate and aspartate concentrations increased 44+/-13 (mean+/-SEM) times and 19+/-5 times baseline, respectively, and returned to baseline values on reperfusion. DHK (1 mmol/L in perfusate; n=8) significantly attenuated EAA increases compared with control (glutamate peak, 9. 6+/-1.7 versus control, 15.4+/-2.6 pmol/ microL). EAA levels were similarly decreased by 10 mmol/L DHK. DNDS (1 mmol/L; n=5) also suppressed EAA peak increases (glutamate peak, 5.8+/-1.1 versus control, 10.1+/-0.7 pmol/ microL). At a higher concentration, DNDS (10 mmol/L; n=7) further reduced glutamate and aspartate release and also inhibited ischemia-induced taurine release. Together, 1 mmol/L DHK and 10 mmol/L DNDS (n=5) inhibited 83% of EAA release (glutamate peak, 2.7+/-0.7 versus control, 10.9+/-1.2 pmol/ microL). CONCLUSIONS: These findings support the hypothesis that both cell swelling-induced release of EAAs and reversal of the astrocytic glutamate transporter are contributors to the ischemia-induced increases of extracellular EAAs in the striatum as measured by microdialysis.

ATP-Binding Cassette Transporters↗

PubMed1999

Workforce demand for neurosurgeons in the United States of America: a 13-year retrospective study.

OBJECT: The workforce demand for neurosurgeons was quantified by a review and an analysis of journal recruitment advertisements published over the past 13 years. METHODS: A retrospective analysis of recruitment advertisements from July 1985 through June 1998 was performed by examining issues of the Journal of Neurosurgery and Neurosurgery. Advertisement information that appeared in each journal during the last 3 years was collected from alternating months (July to May); information that appeared prior to that time was collected from alternating recruitment years back to 1985. The authors examined the following workforce parameters: practice venue, subspecialization, and practice size. They found no significant decrease in neurosurgical recruitment advertisements. There was an average of 102.7+/-22.4 (standard deviation) advertised positions per year during the most recent 3 years compared with 92.6+/-17.9 advertised positions per year during the preceding decade. Similarly, there has been no decline in advertised positions either in academic (33+/-6.1/year for the most recent 3 years compared with 32.8+/-5.9/year for 1985-1995) or private practice (69.7+/-21.6/year for the most recent 3 years compared with 59.8+/-13.4/year for 1985-1995). A shift in demand toward subspecialty neurosurgery was observed. During the past 3 years, 31.2+/-5.9% of advertised positions called for subspecialty expertise, compared with 18.5+/-2.8% for the preceding decade (p < 0.05). The largest number of subspecialty advertisements designated positions for spine and pediatric neurosurgeons. Private practice advertisements increasingly sought to add neurosurgeons to group practices. CONCLUSIONS: Contrary to previous reports and a prevailing myth, our data show no decrease in workforce demand for neurosurgeons in the United States over the past 3 years compared with the prior decade. A shift toward subspecialist recruitment, particularly for spine neurosurgeons, has been demonstrated in both academic and private practice venues.

Academic Medical Centers↗

PubMed1998

Clinical comparison of tardive and idiopathic cervical dystonia.

It has been suggested that tardive cervical dystonia may be clinically indistinguishable from the idiopathic form and that the diagnosis rests solely on documenting an exposure to dopamine antagonist medications. To investigate this, we performed a retrospective evaluation of patient records on 102 patients with idiopathic and 20 patients with tardive cervical dystonia seen in our Movement Disorder Clinic over the past 8 years. Several clinical and demographic variables were compared and a number of differences were observed. The presence of extracervical involvement, retrocollis, and spasmodic head movements were individually found to be predictive of tardive cervical dystonia. Torticollis, laterocollis, and trick maneuvers were predictive of idiopathic cervical dystonia. Head tremor (42.2%) and family history of dystonia (9.8%) were present only in the idiopathic group. Cervical muscle hypertrophy was significantly more common in the idiopathic group (100% versus 75%). No difference was found between the two groups in their response to treatment with botulinum toxin A. These results indicate that clinical differences between idiopathic and tardive cervical dystonia exist. These differences may help to distinguish them in the clinical setting, improve diagnostic accuracy, and support the existence of a causal relationship between exposure to dopamine antagonist medications and chronic dystonia.

Adult↗

PubMed1995

Orbital fractures in children.

OBJECTIVE: To determine if the pattern of orbital fractures may be influenced by the changing craniofacial ratio of the growing child, as the orbit is the boundary between the face and the cranium. DESIGN: Retrospective case series of 40 patients between the ages of 1 year and 16 years with orbital fractures. SETTING: The Albany (NY) Medical Center Hospital, a tertiary level 1 trauma center. OUTCOME MEASURES: The sex, age, site, and mechanism of injury, associated injury, and treatment methods for children admitted to the Albany Medical Center Hospital with orbital fractures between July 1986 and June 1992. RESULTS: Fourteen children had fractures of the orbital roof, 10 children had fractures of the orbital floor, 14 children had mixed fractures, and two children had fractures of the medial wall. The mean age (4.8 +/- 3.3 years) of the 14 patients with roof fractures was significantly less than the mean age (12.0 +/- 4.2 years) of the 26 children with other orbital fractures. Logistic regression demonstrated that the age at which the probability of lower orbital fractures exceeds the probability of orbital roof fractures is 7.1 +/- 1.0 years. Orbital roof fractures had a significantly greater likelihood of associated neurocranial injuries. The need for surgical repair was significantly lower among children with roof fractures as well as among children 7 years of age and younger. CONCLUSIONS: Orbital roof fractures are a type of skull fracture that occur primarily in younger children as a consequence of the proportionally larger cranium and the lack of frontal sinus pneumatization. Lower orbital fractures are a type of facial fracture that occur primarily in older children as a consequence of the increased vulnerability of the face due to growth and the pneumatization of the paranasal sinuses.

Adolescent↗

PubMed1995

Effect of hemorrhagic shock and reperfusion on the respiratory quotient in swine.

OBJECTIVES: Respiratory quotient, the ratio of CO2 production to oxygen consumption (VO2), is principally affected by the fuel source used for aerobic metabolism. Since the respiratory quotient, VO2, and CO2 production cannot be directly measured easily, indirect calorimetry is commonly used to determine the value of these variables at the airway level (i.e., airway respiratory quotient, airway VO2, and airway CO2 production). However, under nonsteady-state conditions, a variety of phenomena can alter the relationship between true metabolic activity and measurements determined by indirect calorimetry. During exercise, for example, airway respiratory quotient increases as anaerobic threshold is reached because of the disproportionate increase in airway CO2 production that results from the CO2 liberated through the buffering of excess hydrogen ions by bicarbonate. We hypothesized that hemorrhage and reinfusion might change airway respiratory quotient in a consistent manner as shock is produced and reversed. DESIGN: Prospective laboratory study. SETTING: University animal laboratory. SUBJECTS: Eight pigs (25 +/- 2 [SD] kg), anesthetized with fentanyl and relaxed with pancuronium bromide, and mechanically ventilated on room air. INTERVENTIONS: The animals were sequentially hemorrhaged and then autotransfused while metabolic and hemodynamic measurements were obtained, using continuous indirect calorimetry and continuous applications of the Fick principle. Hemoglobin, arterial lactate concentration, and blood gases for calibration were measured serially. Analysis of variance was used to compare various periods in time. MEASUREMENTS AND MAIN RESULTS: Between baseline and peak hemorrhage, and between peak hemorrhage and postreinfusion, all of the following variables changed significantly (p < .05): airway VO2 (baseline 6.4 +/- 0.9 mL/min/kg, peak hemorrhage 3.9 +/- 0.6 mL/min/kg, postreinfusion 7.0 +/- 1.4 mL/min/kg); airway CO2 production (baseline 5.5 +/- 0.9 mL/min/kg, peak hemorrhage 4.5 +/- 0.9 mL/min/kg, postreinfusion 6.0 +/- 1.4 mL/min/kg); airway respiratory quotient (baseline 0.87 +/- 0.07, peak hemorrhage 1.16 +/- 0.07, postreinfusion 0.87 +/- 0.05); lactate concentration (baseline 2.4 +/- 1.2 mmol/L, peak hemorrhage 6.7 +/- 1.9 mmol/L, postreinfusion 5.1 +/- 2.0 mmol/L); and delta PCO2 (venous PCO2-PaCO2) (baseline 4.5 +/- 3.6 torr [0.6 +/- 0.5 kPa], peak hemorrhage 12.1 +/- 5.3 torr [1.6 +/- 0.7 kPa], postreinfusion 2.7 +/- 2.7 torr [0.4 +/- 0.4 kPa]). CONCLUSIONS: Airway respiratory quotient increases in hemorrhagic shock and decreases again as shock is reversed during reinfusion. This phenomenon appears related to the buffering of excess of hydrogen ion during hemorrhagic shock.

Animals↗

PubMed1995

Cerebral blood flow and blood volume in response to O2 and CO2 changes in normal humans.

Changes in cerebral blood volume (CBV) after head injury may be an important determinant of intracranial pressure (ICP). To determine the normal response of CBV to hypoxemia, hypercapnia, and hypocapnia, eight normal subjects (5 males and 3 females; ages 25 to 43) were studied under these conditions. Cerebral blood volume was measured using an external collimated gamma detector to determine 99m-Tc-labeled red blood cell (RBC) activity in the intracranial vascular pool, and cerebral blood flow (CBF) was determined by internal carotid artery duplex scanning. Hypocapnia (Paco2 = 26.0 +/- 1.7 mm Hg, mean +/- SE) was achieved by hyperventilation, hypercapnia (Paco2 = 47.8 +/- 1.5 mm Hg) was achieved by inhalation of 6% CO2, and hypoxemia (Pao2 = 38.1 +/- 1.1 mm Hg, O2 saturation = 76.7 +/- 2.0%) was achieved by inhalation of 10% O2. Changes in CBF and CBV were determined by comparing the values in each condition to the immediately preceding period of normoxia and normocapnia. For conditions of hypocapnia, hypercapnia, and hypoxemia, the percentage of change in CBV was: -7.2 +/- 0.01, 12.8 +/- 0.01, and 5.2 +/- 0.03, respectively. The simultaneous percentage of change in CBF for the same conditions was -30.7 +/- 4.0, 29.5 +/- 9.2, and 18.4 +/- 6.9, respectively. For all conditions, changes in CBF were greater than changes in CBV; however, this was most pronounced during hypocapnia induced by hyperventilation. Because the change in CBV reflects the potential change in ICP in response to treatment, therapeutic hyperventilation may impair CBF to a greater degree than it reduces ICP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Effect of hyperventilation, mannitol, and ventriculostomy drainage on cerebral blood flow after head injury.

Therapies to lower intracranial pressure (ICP) after traumatic brain injury (TBI) include hyperventilation (HV), intravenous mannitol (IM), and cerebrospinal fluid drainage from a ventriculostomy (DV). To determine the effects of these therapies on cerebral blood flow (CBF), fiberoptic oximetry was used to measure jugular venous O2 saturation (SjvO2) as an index of the CBF to cerebral metabolic rate for O2 (CMRO2) ratio after IM (25 g IV for more than 5 min), DV (3 min), or HV (increase respiratory rate by 4) therapy for elevated ICP. Assuming CMRO2 is constant, changes in SjvO2 reflect changes in CBF. Continuous measurements of SjvO2, ICP, blood pressure, arterial O2 saturation, and end-tidal CO2 were obtained in 22 patients with a Glasgow Coma Scale score of 5.3 +/- 0.4 (mean +/- SD) in the first 5 days after TBI. Therapy was initiated a total of 196 times when ICP was > 15 mm Hg for > 5 minutes, and measurements made at 20 minutes after treatment were compared with those made just before. After DV, ICP fell in 90% of the observations by 8.6 +/- 0.7 mm Hg (mean +/- SEM, n = 119); after IM, ICP fell in 90% of the observations by 7.4 +/- 0.7 mm Hg (n = 43); and after HV, ICP fell in 88% of the observations by 6.3 +/- 1.2 mm Hg (n = 14). In patients where ICP fell, SjvO2 increased by 2.49 +/- 0.7% saturation (from 68.0 +/- 1.3%) with IM, but only by 0.39 +/- 0.4% saturation (from 67.2 +/- 0.9%) with DV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Effects of ethanol on respiratory function in traumatic brain injury.

It has been observed that traumatic brain injury (TBI) increases the susceptibility of the brain to subsequent hypoxia, and prolonged apnea occurs in ethanol (EtOH)-treated animals following brain injury. This investigation tests the hypothesis that EtOH suppresses ventilation and hypercapnic respiratory drive following TBI. Immature pigs were anesthetized with halothane and received a 2 to 3 atm fluid-percussion brain injury. Respiratory parameters, including tidal volume, frequency, ventilation (VE), and arterial blood gases were measured on 100% O2 and on 5% to 6% inspired CO2 in O2 prior to and at 10, 60, 120, and 180 minutes after TBI. Hypercapnic response sensitivity (S) was measured as the change in VE per mm Hg increase in PaCO2. Intracranial pressure, mean arterial blood pressure, heart rate, brain temperature, glucose, and EtOH levels were also monitored. Three groups were studied: the first group of six received EtOH (3.5 gm/kg, intragastrically) without brain injury; the second group of six received TBI without EtOH; the third group of eight received EtOH and TBI. Ethanol levels were 121 +/- 13 (standard error of the mean) mg/dl in the EtOH/TBI group (136 +/- 25 in the EtOH group) at the time of injury, and 175 +/- 12 mg/dl in the EtOH/TBI group (200 +/- 20 mg/dl in the EtOH group) at 120 minutes after injury. The EtOH/TBI animals had significantly lower VE and S, and higher PaCO2 following brain injury (p < 0.05, repeated-measures analysis of variance). No significant differences were identified between groups for pH, PaCO2, intracranial pressure, heart rate, brain temperature, or glucose levels. Ethanol intoxication leads to significant impairment of respiratory control following traumatic brain injury and may contribute to brain injury in intoxicated trauma victims.

Alcoholic Intoxication↗

PubMed1994

Feasibility of continuous oxygen delivery and cardiac output measurement by application of the Fick principle.

Continuous mixed venous oxygen saturation (SVO2) measurements from fiberoptic pulmonary artery catheters, arterial oxygen saturation (SaO2) measurements from pulse oximetry, and minute-by-minute oxygen consumption (VO2) measurements from indirect calorimetry can be used for near-continuous estimation of cardiac output (Qt) and oxygen delivery (DO2) by application of the Fick Principle. Assumptions required for calculation of blood oxygen contents include constant hemoglobin concentration (Hgb) and constant or negligible physically dissolved oxygen. First, the influence of these assumptions on continuous Qt and DO2 determinations was tested. Unmeasured changes in Hgb resulted in substantial error in calculated Qt, whereas calculated DO2 was minimally affected. Both Qt and DO2 were little altered by errors in PaO2 or PVO2. Second, the effects of SVO2, SaO2, and VO2 measurement errors on Qt and DO2 calculations under normal and extreme conditions were quantified. Relative errors in SVO2 were increased by a factor of 4.2 in Qt estimations and by a factor of 3.2 in DO2 measurements under normal conditions. These factors increased with increasing SVO2, and thus, Qt and DO2 became increasingly unreliable as oxygen extraction fell. Third, we compared continuous measurements of Qt and DO2 with intermittent measurements made by thermodilution cardiac output and blood sampling, and found correlation coefficients of 0.85 for Qt and 0.89 for DO2. Fourth, common measurement errors in VO2 and DO2 calculated in this way were found to bias regressions between VO2 and DO2, and this bias could be minimized only if the DO2 range were high and SVO2 were low.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗