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Biomedical subjects

M H Sanders

Publications and source records attributed to M H Sanders.

At least 37 records · Page 2Linked to original sources
PubMed1993

Adequacy of prescribing positive airway pressure therapy by mask for sleep apnea on the basis of a partial-night trial.

We tested the hypothesis that a prescription for positive-pressure therapy (including pressure level, patient-device interface, and positive-pressure modality, e.g., CPAP or BiPAP) for obstructive sleep apnea (OSA) can be developed on the same night as the polysomnographic (PSG) diagnosis is made. Fifty consecutive patients with OSA in whom a partial-night PSG diagnosis was made (PSGD) underwent a therapeutic trial of positive-pressure therapy during the remainder of the night (PSG-PPP). The average apnea index during PSGD was 54.96 +/- 36.3 (mean +/- SD). On a subsequent full-night PSG (PSG-PPF), the prescription was tested. Thirty-one of the 50 patients were satisfactorily treated with CPAP, without variation of the interface during both PSG-PPP and PSG-PPF. In these patients the average pressure prescription while receiving PSG-PPF was statistically higher than during PSG-PPP (11.77 +/- 3.6 versus 10.56 +/- 3.6 cm H2O, respectively, p = 0.002). In 14 of these 31 patients (45%) some alteration in pressure requirement was necessary during PSG-PPF. Eleven patients required 2.5 cm H2O higher pressure and three patients required 5 cm H2O higher pressure during PSG-PPF than during PSG-PPP. There was a change of interface across the two therapeutic trials in 15 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1993

Significance and treatment of nonapneic snoring.

Snoring has been associated with an increased risk of vascular morbidity and mortality and with the complaint of excessive daytime sleepiness. Much of this risk may be attributable to concomitant sleep apnea or hypopnea. Recent work suggests that in certain individuals, snoring without apnea or hypopnea can lead to sleep disruption. This appears to be due to augmented ventilatory effort in response to an increased "internal" resistive load that results in repetitive arousals from sleep. This condition has been termed the upper airway resistance syndrome (UARS). Identification of load-related arousals in patients with the UARS may require the addition of esophageal pressure monitoring to the diagnostic polysomnogram. Nasal continuous positive airway pressure (CPAP) effectively eliminates snoring, hypopnea and apnea and therefore may be useful in treating this form of sleep-disordered breathing. The diagnostic criteria and indications, if any, for chronic treatment of these nonapneic snorers with nasal CPAP as well as long term compliance remain to be determined.

Adult↗
PubMed1992

Physiologic implications of adding small amounts of carbon dioxide to the gas mixture during inhalation of xenon.

In addition to being a physiologically active tracer of CBF, xenon (Xe) in subanesthetic concentrations produces a relatively mild lowering of carbon dioxide (CO2) in the blood and elevation of transcranial Doppler (TCD) velocity. The addition of small concentrations of CO2 (0.4-1.2%) to the inhaled mixture produced no measurable effect on end tidal (P(et)) CO2 or TCD velocity. Cerebral blood flow (CBF) alterations induced by Xe are minimized by allowing P(et)CO2 to fall, permitting quantitative measurement of CBF by the Xe/CT CBF method.

Administration, Inhalation↗
PubMed1991

The effect of obliterative bronchiolitis on breathing pattern during exercise in recipients of heart-lung transplants.

The more rapid and shallow ventilation pattern seen during exercise in patients with obstructive and/or restrictive lung disease has been attributed by some investigators to the effects of vagal afferents from intrapulmonary receptors. Recipients of heart-lung transplants (HLTR) offer a unique opportunity to test this hypothesis since they have denervated lungs and may develop obliterative bronchiolitis after organ rejection. We thus compared the ventilation responses to incremental bicycle ergometry of five HLTR with relatively normal pulmonary function (HLTR-N) and four with bronchiolitis obliterans (HLTR-O). We compared the slopes of the linear portion of the tidal volume versus inspired minute ventilation relationship of both groups. The rate of rise of tidal volume (VT) (slope of VT versus VI) was greater in HLTR-N (0.31 +/- 0.004) than in HLTR-O (0.023 +/- 0.007) (p less than 0.05). This corresponded to a slower increase in respiratory rate (RR) (slope of RR versus Vl/cm) in HLTR-N (0.055 +/- 0.005) than in HLTR-O (0.083 +/- 0.019) (p less than 0.01). Furthermore, values for VT, inspiratory time (TI), and duty cycle (TI/Ttot) measured during exercise at the VT break point were all significantly lower in the HLTR-O than in HLTR-N. We also evaluated the ability of HLTR with lung disease to regulate their ultimate level of ventilation during maximal exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Diagnosis of sleep-disordered breathing by half-night polysomnography.

We hypothesized that sleep-disordered breathing (SDB), defined by the apnea index (AI), the apnea + hypopnea index (A + H/I), or the desaturation event frequency (number of desaturations greater than 5%/h slept) (DEF), could be diagnosed after less than full-night polysomnography (PSG). Forty-eight consecutive full-night PSG sessions were evaluated by separately analyzing the first half (PSG-1/2) and the total (PSG-T) sleep time: 134.42 +/- 35.7 and 277.15 +/- 56.5 min (mean +/- SD), respectively. PSG-1/2 and PSG-T were not different with respect to AI. The DEF was statistically but not clinically higher during PSG-1/2 (41.72 +/- 41 versus 37.95 +/- 35.8, p = 0.04). Sensitivities, specificities, and predictive values of each PSG-1/2 parameter were determined by comparing the values with those measured during PSG-T, using cutoff frequencies of both 5 and 10 events/h slept to define SDB. At a cutoff frequency of 10, sensitivities and positive predictive values were high for all PSG-1/2 parameters (range, 94.6 to 96.9%). The specificities of the DEF and AI during PSG-1/2 were also high (93.75 and 95%, respectively), but the negative predictive value of the DEF was substantially better (93.75 versus 83.3%). With SDB defined by 5 events/h slept, there also were high sensitivities (87.9 to 93%), positive predictive values (93.6 to 100%), and specificities (86.7 to 100%) for all parameters. Negative predictive values, however, were substantially reduced (62.5 to 76.5%). We conclude that PSG during 2 h of sleep is an appropriate method for evaluating SDB.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗
PubMed1990

Inductance plethysmography measurement of CPAP-induced changes in end-expiratory lung volume.

The respiratory inductance plethysmograph (RIP) has recently gained popularity in both the research and clinical arenas for measuring tidal volume (VT) and changes in functional residual capacity (delta FRC). It is important however, to define the likelihood that individual RIP measurements of VT and delta FRC would be acceptably accurate (+/- 10%) for clinical and investigational purposes in spontaneously breathing individuals on continuous positive airway pressure (CPAP). Additionally, RIP accuracy has not been compared in these regards after calibration by two commonly employed techniques, the least squares (LSQ) and the quantitative diagnostic calibration (QDC) methods. We compared RIP with pneumotachographic (PTH) measurements of delta FRC and VT during spontaneous mouth breathing on 0-10 cmH2O CPAP. Comparisons were made after RIP calibration with both the LSQ (6 subjects) and QDC (7 subjects) methods. Measurements of delta FRC by RIPLSQ and RIPQDC were highly correlated with PTH measurements (r = 0.94 +/- 0.04 and r = 0.98 +/- 0.01 (SE), respectively). However, only an average of 30% of RIPQDC determinations per subject and 31.4% of RIPLSQ determinations per subject were accurate to +/- 10% of PTH values. An average of 55.2% (QDC) and 68.8% (LSQ) of VT determinations per subject were accurate to +/- 10% of PTH values. We conclude that in normal subjects, over a large number of determinations, RIP values for delta FRC and VT at elevated end-expiratory lung volume correlate well with PTH values. However, regardless of whether QDC or LSQ calibration is used, only about one-third of individual RIP determinations of delta FRC and one-half of two-thirds of VT measurements will be sufficiently accurate for clinical and investigational use.

Functional Residual Capacity↗
PubMed1990

Polysomnography early after uvulopalatopharyngoplasty as a predictor of late postoperative results.

We performed nocturnal diagnostic polysomnography (PSG 1), PSG early after UPPP on the second to the fifth postoperative night (PSG 2) and PSG late after UPPP (PSG 3) six or more weeks after surgery, on 15 male patients with obstructive sleep-disordered breathing. On PSG 1, the A + H/I for the group was 66.6 +/- 8.8 (mean +/- SE). During non-REM sleep the A + H/I on PSG 3 (29 +/- 10) was lower than it was on PSG 2 (54.3 +/- 11.3) (p = 0.004) and lower than that on PSG 1 (70.8 +/- 10.3) (p = 0.003). Similarly, during non-REM sleep, the AI on PSG 3 (16.1 +/- 7.4) was less than that on PSG 2 (39.1 +/- 10.4) (p = 0.003) and less than that on PSG 1 (41.7 +/- 9.6) (p = 0.015). In the eight patients in whom REM sleep was recorded on all three PSGs, there was no difference with respect to A + H/I or AI. The nadir of SaO2 during non-REM sleep was higher during PSG 3 than during PSG 1 (p = 0.002), but not different from that on PSG 2. There were no differences among the three studies with respect to REM-related nadirs of SaO2; however, there was a good deal of interindividual variability across the three PSGs. In general, individuals with satisfactory amelioration of sleep-disordered breathing on PSG 2 demonstrated similar improvement on PSG 3. Patients who did not have a substantial improvement in the early postoperative period often had improvement on PSG 3, but there was a good deal of interindividual variability in this regard. We conclude that PSG within a few days following UPPP is warranted in patients with obstructive sleep-disordered breathing to determine if there has been worsening of upper airway function or oxygenation (or both) during sleep in the early postoperative period. A satisfactory result early after UPPP suggests that a late postoperative PSG is unnecessary, with savings in cost and the convenience.

Adult↗
PubMed1990

Obstructive sleep apnea treated by independently adjusted inspiratory and expiratory positive airway pressures via nasal mask. Physiologic and clinical implications.

Treatment of obstructive sleep apnea with nasal continuous positive airway pressure mandates simultaneous increases of both inspiratory and expiratory positive airway pressures to eliminate apneas as well as nonapneic oxyhemoglobin desaturation events. We hypothesized that the forces acting to collapse the upper airway during inspiration and expiration are of different magnitudes and that obstructive sleep-disordered breathing events (including apneas, hypopneas and nonapneic desaturation events) could be eliminated at lower levels of EPAP than IPAP. To test these hypotheses, a device was built that allows the independent adjustment of EPAP and IPAP (nasal BiPAP). Our data support the hypotheses that expiratory phase events are important in the pathogenesis of OSA and that there are differences in the magnitudes of the forces destabilizing the upper airway during inspiration and expiration. Finally, applying these concepts, we have shown that by using a device that permits independent adjustment of EPAP and IPAP, obstructive sleep-disordered breathing can be eliminated at lower levels of expiratory airway pressure compared with conventional nasal CPAP therapy. This may reduce the adverse effects associated with nasal CPAP therapy and improve long-term therapeutic compliance.

Algorithms↗
PubMed1989

Chronotropic effects of progressive hypoxia and hypercapnia.

The effects of acute, progressive isocapnic hypoxia and hyperoxic hypercapnia on heart rate (HR) were determined in 13 normal individuals. In all subjects there was an inverse linear relationship between hemoglobin oxygen saturation and HR. For the group, the HR (mean +/- SE) increased from 72 +/- 2 to 89.5 +/- 3 beats/min representing a 25% increase. During progressive hypercapnia, the HR increased from 72 +/- 2 to 75 +/- 2 beats/min, representing only a 4% increase. In contrast to the HR response to hypoxia, there was a heterogeneous HR response to hypercapnia, with most subjects having a mild increase in HR, but some showing no response and a few exhibiting a decrease in HR. We conclude that although there is a significant tachycardic response to isocapnic hypoxia, the tachycardic response to hyperoxic hypercapnia is small and clinically insignificant. In addition, while there is uniformly a tachycardic response to isocapnic hypoxia, there is a considerable interindividual variability of the HR response to hyperoxic hypercapnia.

Adult↗
PubMed1989

Ventilation and breathing pattern during progressive hypercapnia and hypoxia after human heart-lung transplantation.

The effects of human pulmonary denervation on the ventilatory responses to progressive hyperoxic hypercapnia and isocapnic hypoxia as well as the effect on resting breathing pattern were evaluated in nine female heart-lung transplant (H-LT) recipients. The results were compared to those obtained from 10 normal women of comparable age and stature. Testing was performed 2 to 37 months after H-LT (median, 7.5 months). Cardiac function was normal in all H-LT recipients. None of the patients had spirometric evidence of airway obstruction, while six had a restrictive pattern with forced vital capacities less than 80% of predicted values. Resting minute ventilation (VE), tidal volume (VT), and ventilatory drive (VT/TI) in the H-LT recipients were not significantly different from those of the normal subjects. Inspiratory time (TI), however, was significantly shorter in the H-LT patients (1.64 +/- 0.2 versus 2.09 +/- 0.13 s, p = 0.035), and resting breathing frequency (F) tended to be greater in the H-LT recipients (16.27 +/- 2.04 versus 12.82 +/- 0.53 breaths/min, p = 0.052). The overall ventilatory response to hypercapnia was reduced after H-LT (0.91 +/- 0.17 versus 1.5 +/- 0.27 L/min/mm Hg CO2, p less than 0.043), as was the F response (0.2 +/- 0.09 versus 0.65 +/- 0.13 breaths/min/mm Hg CO2, p less than 0.01). The VT and VT/TI responses to hypercapnia did not differ between the H-LT recipients and normal subjects. There were no significant differences between the two groups with respect to the responses to progressive hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Breathing during wakefulness and sleep after human heart-lung transplantation.

To study the effects of pulmonary denervation on breathing during sleep, sleep studies were conducted on seven heart-lung transplant recipients (H-LT) and a comparable number of sex-matched normal subjects of similar age. Four of the H-LT patients had a restrictive pattern on spirometry. The time since transplantation ranged from 45 to 1,102 days. There were no significant differences between the groups with respect to total sleep time or distribution of sleep stages. There were no significant differences between the H-LT recipients and normal subjects with respect to baseline awake oxyhemoglobin saturation (SaO2) or the nadirs of SaO2 during REM and non-REM sleep, the absolute number and frequency (number per hour of sleep) of apneas, hypopneas, desaturation events, both over the whole night of study or separately during non-REM and REM sleep. Across wakefulness and all sleep stages, the H-LT patients tended to have shorter total respiratory cycle times (Ttot) (p = 0.052) and more rapid breathing frequency (F) than the normal subjects. This was associated with significantly shorter inspiratory times (Tl) (p less than 0.001) and smaller duty cycles (Tl/Ttot) (p less than 0.005) in the H-LT recipients. During non-REM and REM sleep, F tended to be higher in the H-LT recipients with pulmonary restriction than in the nonrestricted patients. There were no significant differences between the H-LT recipients and the normal subjects with regard to the periodicity of breathing, either in terms of timing parameters or breath amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Evidence of an altered pattern of breathing during exercise in recipients of heart-lung transplants.

Recipients of heart-lung transplants represent an unusual opportunity to study the regulation of ventilation, because the neural pathways between the lungs and the central nervous system are disrupted in these patients. We compared the ventilation response in seven recipients of heart-lung transplants who had normal pulmonary function and seven recipients of heart transplants, all of whom performed incremental bicycle ergometry. The level of ventilation in recipients of heart-lung transplants was similar to that in heart-transplant recipients for equivalent levels of carbon dioxide production. Arterial pH and partial pressure of carbon dioxide at maximal exercise were normal and not significantly different in the two groups, also suggesting that levels of ventilation were appropriate in both groups. However, the rate of the rise in respiratory rate for increasing levels of ventilation was significantly lower in recipients of heart-lung transplants than in heart-transplant recipients, and the initial increase in tidal volume was more rapid in the former group than in the latter. Thus, recipients of heart-lung transplants have an appropriate level of ventilation during exercise as the result of a disproportionate increase in tidal volume at a reduced respiratory rate. We speculate that intrapulmonary receptors are important in regulating the pattern, but not the absolute level, of ventilation during exercise.

Acid-Base Equilibrium↗
PubMed1988

The acute effects of uvulopalatopharyngoplasty on breathing during sleep in sleep apnea patients.

Uvulopalatopharyngoplasty (UPPP) is frequently employed in the treatment of obstructive sleep apnea (OSA). Despite anecdotal reports of early post-UPPP deaths and the recommendation by some authors to perform a prophylactic tracheotomy for selected patients at the time of UPPP, there has been no systematic examination of breathing during sleep in the early post-UPPP period. In order to evaluate the early postoperative risk and the need for prophylactic tracheotomy in UPPP patients, we conducted polysomnograms (PSGs) on eight obese OSA patients on the second post-UPPP night and on another obese OSA patient on the fifth night after surgery. Postoperatively during wakefulness there was a significant increase in the alveolar-arterial oxygen gradient (p less than 0.05); in three individuals, the PaO2 was sufficiently reduced to warrant supplemental oxygen. For the group of nine patients there were no differences between the pre- and post-UPPP apnea index (AI), hypopnea index (HI), or apnea plus hypopnea index during non-rapid eye movement sleep. In individual patients, the pattern of sleep-disordered breathing events was variably altered, but there was a reciprocal relationship between the changes in AI and HI (r = 0.75; p less than 0.02). The duration of apnea in non-rapid eye movement sleep was shorter in four patients and unchanged in five patients postoperatively. Although the mean nadir of hemoglobin saturation was unchanged before and after UPPP, one patient desaturated to dramatically low levels in association with several excessively prolonged apneas post-UPPP. Desaturation was probably minimized in the three patients receiving supplemental oxygen. There were no serious adverse effects resulting directly from sleep-disordered breathing or nocturnal hemoglobin oxygen desaturation following UPPP. Our data suggest that performing a tracheotomy in a nonselective fashion in OSA patients undergoing UPPP is not warranted. In lieu of this, these individuals should be carefully monitored following surgery. In addition, patients with severe OSA and/or moderate-to-severe nocturnal hemoglobin oxygen desaturation should be considered for early postoperative PSGs as should those individuals who are more hypoxemic while awake following surgery. Patients who require supplemental oxygen postoperatively should also be studied to ensure adequate oxygenation and to monitor for acute, oxygen-related prolongation of apnea.

Adult↗
PubMed1987

Abnormal ventilatory chemosensitivity and congenital myopathy.

Abnormal ventilatory function is common in patients with neuromuscular disorders. This report describes depressed ventilatory response to both hypoxia and hypercapnia, as well as arterial oxygen desaturation during sleep in a family with congenital myopathy. The index patient also had an abnormal ventilatory response to metabolic acid loading. There was clinical evidence of proximal muscle weakness, and a muscle biopsy specimen was consistent with myopathy. The reduction in ventilatory drive, however, could not be explained solely by ventilatory muscle weakness. This report describes a distinct familial syndrome of congenital myopathy and abnormal ventilatory response to hypercapnia and hypoxia. All affected family members had unique facial features, proximal muscle weakness, and impaired ventilatory responses. The combination of impaired ventilatory drive and reduced ventilatory muscle strength leaves patients particularly vulnerable, and heightened awareness of this association is important in the treatment of these patients.

Adult↗
PubMed1986

Breathing during sleep immediately after uvulopalatopharyngoplasty.

Uvulopalatopharyngoplasty (UPPP) has been acclaimed in the treatment of obstructive sleep apnea (OSA). Evaluation of the effect of UPPP has usually been done 6 to 8 weeks postoperatively. Recently, a patient died suddenly at home of unknown causes 48 hours following UPPP. Autopsy evaluation demonstrated no evidence of hemorrhage, aspiration, or airway edema; however, it caused us to reassess our postoperative program. Three obese patients (192%, 162% and 157% of ideal body weight) with OSA underwent polysomnography on the second postoperative night. The mean duration of the postoperative apneas was not significantly different; however, the nadir SaO2 during apnea in one patient was significantly lower postoperatively. Those individuals with awake hypercapnia nad hypoxemia who had significant sleep associated hemoglobin unsaturation preoperatively may be at greatest risk. These observations indicate that careful postoperative monitoring is warranted in this group of patients.

Adult↗
PubMed1986

Nutritional intervention in malnourished patients with emphysema.

We have previously reported the association of significant malnutrition with pulmonary emphysema and noted that the degree of malnutrition correlated with some measures of pulmonary function. The purpose of this study was to examine the energy requirements of malnourished patients with emphysema and acute effects of nutritional repletion on indices of pulmonary function and nutrition. We studied 6 malnourished patients with emphysema during a 3-wk admission to a clinical research unit. Initially, patients were allowed access to standard food sources ad libitum. Subsequently, if caloric goals were not met, nutritional supplementation was given orally. All patients receiving the ad libitum diet ingested calories in excess of their maintenance energy requirements. All patients increased their body weight (p less than 0.001) and percent ideal body weight (p less than 0.001). Anthropometric nutritional parameters showed a small but significant improvement (p less than 0.05). Although there was no significant change in spirometric results, lung volumes or DLCO after 3 wk maximal inspiratory mouth and transdiaphragmatic pressures increased (p less than 0.005). Peripheral skeletal muscle strength as measured by handgrip also improved (p less than 0.001). We conclude that inability to ingest an adequate number of calories was not the cause of weight loss in these patients. We also found that when given sufficient calories in excess of their needs, patients gain weight. Weight gain and improvement in anthropometric measurements are accompanied by significant improvement in ventilatory and peripheral muscle strength.

Aged↗
PubMed1986

Patient compliance with nasal CPAP therapy for sleep apnea.

Continuous positive airway pressure via the nasal route (nasal CPAP) is effective in reducing the frequency of occlusive and mixed patterns of sleep apnea. Little is known about long-term patient compliance with this therapeutic modality, however. In order to evaluate this, questionnaires were mailed to 24 sleep apnea patients who had received a nasal CPAP system for nightly use. Patients were requested not to sign the questionnaire. At the time of mailing, the patients had possessed their nasal CPAP equipment for 10.3 +/- 8 months (mean +/- SD). Twenty patients (83 percent) responded to the questionnaire. Sixteen responders used nasal CPAP during all nightly sleep time, and two used it for all but one and 2.5 hours of nightly sleep time, respectively. One individual used it on alternate nights, and one patient did not use it all. Thus, 17 of 20 (85 percent) responders were compliant. Including information about the four nonresponders, obtained by means other than questionnaire, 18 of 24 (75 percent) patients were compliant with therapy. All but two patients were obese at the time sleep apnea was diagnosed. Only 50 percent of questionnaire responders reported weight loss after receiving nasal CPAP, and these individuals were frequent nasal CPAP users. The most common complaints were mask discomfort (14 responders) and nasal dryness and congestion (13 responders). We conclude that long-term home nasal CPAP is a viable therapy that is conscientiously applied and well-tolerated by most sleep apnea patients.

Adolescent↗