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Biomedical subjects

M H Hines

Publications and source records attributed to M H Hines.

12 recordsLinked to original sources
PubMed2001

Comparison of autopsy, X-ray, and M.R.I. findings following a low speed impact to the shoulder.

The objectives of the study was to generate data useful to engineers improving crash test dummies and to physicians in anticipating low speed lateral impact injuries to the shoulder. Constant impact mass, distance and variable speeds were used to generate impact forces. Twelve unembalmed human cadavers were studied within 48 hours of death. Pre-test and Post-test physical, X-Ray, and Magnetic Resonance examinations were completed. X-Ray best identified bone injury, Magnetic Resonance intratendinous and intramuscular pathology and autopsy joint instability. Low speed (3.5-7.0 m/sec) impacts under these testing conditions frequently produce soft tissue and bone injuries. Sternoclavicular and acromioclavicular joint instabilities were found in 83% of the cadavers. The most frequent bone fractures were in the distal clavicle of 42% and labral or rotator cuff tears in 13% of the cadavers.

Accidents, Traffic↗
PubMed2000

Late follow-up after thoracoscopic ductal ligation.

Interventional catheterization and minimally invasive surgical techniques offer the real possibility of a reduction in cost and morbidity when compared with the traditional surgical approach to patent ductus arteriosus. Video-assisted thoracoscopic surgery may prove to be a superior technique because of its application to a wider range of patients needing ductal closure, a lower incidence of residual shunting, no evidence for recurrent shunting, and the absence of intravascular foreign bodies.

Adolescent↗
PubMed2000

Division of venous collateral after Glenn shunt by minimally invasive surgery.

An infant with cyanotic heart disease that was palliated with a bidirectional cavopulmonary shunt developed progressive cyanosis 3 months after the surgical procedure. A large hemizygous vein was found to be decompressing the bidirectional Glenn shunt from the left innominate vein and was ligated using video-assisted thoracoscopic surgery. The unusually rapid appearance of the shunt, and the excellent outcome associated with the video-assisted thoracoscopic surgery procedure are discussed.

Collateral Circulation↗
PubMed2000

Comparison of a prototype esophageal oximetry probe with two conventional digital pulse oximetry monitors in aortocoronary bypass patients.

OBJECTIVE: Pulse oximetry (SpO2) is the non-invasive standard for monitoring arterial oxygen saturation in patients undergoing anesthesia, but is subject to external interference by motion artifact, peripheral vasoconstriction, and low cardiac output. We hypothesized that oximetry signals could be acquired from the esophagus when peripheral pulse oximetry is unobtainable. Therefore, we tested an esophageal stethoscope which incorporates transverse oximetry photodetectors and emitters in patients undergoing coronary bypass surgery. METHODS: Immediately after induction of general anesthesia in 10 coronary artery bypass (CABG) patients, Criticare and Nellcor digital probes were positioned on the left hand, concurrent with placement of an esophageal SpO2 probe. A computer recorded 5,910 matched oximetry signals every 15 sec during an average of 2.5 hrs. All SpO2 measurements were before, and immediately after non-pulsatile, hypothermic cardiopulmonary bypass. Data represent the percentage (median value [range]) of the total monitored time that a SpO2 value was displayed. RESULTS: The Nellcor (99.8%, range 6.5-100%) and Criticare (99.7%, range 36.6-100%) acquired and displayed saturation signals more frequently (p = 0.003) than the esophageal monitor (75.3%, range 42.1-95.8%). The two standard digital oximeters had a mean difference of 0.9%, with a standard deviation of the differences of 0.9. The esophageal probe had a mean difference of -5.2% and -4.8%, with standard deviation of differences of 8.0 and 7.7 (compared to the Nellcor and Criticare monitors, respectively). A second-generation prototype shielded from electrocautery interference was tested in an additional 4 patients. The shielded prototype displayed signals more frequently (96.7%, range 68.4-100%) than the original esophageal prototype. CONCLUSIONS: Digital pulse oximetry failure is common in CABG patients, probably because of marginal cardiac output and peripheral vasoconstriction associated with hypothermia. Our study could not confirm that esophageal technology, which utilizes the esophagus as a site of transflectance oximetry, was superior to conventional digital pulse oximetry.

Adult↗
PubMed1998

Video-assisted thoracoscopic ligation of patent ductus arteriosus: safe and outpatient.

BACKGROUND: Minimally invasive techniques for interruption of patent ductus arteriosus have been reported, but are in use at only a few centers. We examined our series of patients who underwent thoracoscopic patent ductus arteriosus ligation. METHODS: We reviewed 59 consecutive patients, age 6 days to 50 years, weighing 640 g to 62 kg, who underwent video-assisted placement of a stainless steel clip across the patent ductus arteriosus. RESULTS: Thirty-eight nonneonates and 21 neonates (18 were < or =1,500 g) underwent video-assisted thoracic surgery for patent ductus arteriosus closure with intraoperative echocardiographic confirmation in nonneonates. There were no residual shunts, transfusions, chylothoraces, or significant pneumothoraces. Four were converted to thoracotomy, 3 for anatomic variances, and 1 for coagulopathy. Thirty-six of 38 nonneonate patients stayed less than 24 hours; 18 were discharged the evening of the operation. Two were admitted, one after thoracotomy, and one for a small mucosal intubation injury. No others required a chest tube. There were two recurrent nerve injuries. All neonates survived, and were extubated. CONCLUSIONS: Video-assisted thoracoscopic ductus closure is a safe, reliable technique and can be performed as an outpatient procedure in nonneonate patients.

Adolescent↗
PubMed1998

Continuous intrapulmonary distension with perfluorocarbon accelerates neonatal (but not adult) lung growth.

BACKGROUND/PURPOSE: We have previously demonstrated that experimental fetal tracheal ligation reverses the structural and physiological effects of pulmonary hypoplasia associated with congenital diaphragmatic hernia. The purpose of this study was to determine if lung growth could be similarly accelerated postnatally by continuous liquid-based intrapulmonary distension. METHODS: Ten neonatal lambs were divided into two experimental groups. Five neonatal animals underwent a right thoracotomy with isolation of the anterior superior segment of the right upper lobe. A pressure monitoring catheter was introduced and perfluorocarbon (PFC) was instilled into the segment. Animals were subjected to a 21-day distention period with continuous maintenance of 7 to 10 mm Hg intrabronchial pressure. Five other neonatal animals used as age- and weight-matched controls were killed immediately after distension with PFC to 7 to 10 mm Hg. To evaluate the effect of age on postnatal growth, identical procedures were performed on seven mature sheep. Four adult animals underwent a 21-day distension with PFC, and three animals were killed immediately after PFC distension. RESULTS: Neonatal animals who underwent distension showed a significant acceleration of lung growth based on right upper lobe volume to body weight ratio (P = .0019), total alveolar number (P = .003), and total alveolar surface area (P = .006), when compared with controls. Alveolar growth was attributed to an increased alveolar number rather than increased alveolar size based on a normal histological appearance, normal airspace fraction (P = NS), and normal alveolar numerical density (P = NS). In contrast, no significant differences in lung growth or maturation indices were present in adult animals. CONCLUSIONS: From this preliminary data we conclude: (1) Liquid-based airway distension does accelerate postnatal lung growth, (2) lung architecture remains normal during this period of accelerated growth, (3) adult sheep do not respond to liquid-based airway distension with lung growth, and (4) prolonged exposure to intrapulmonary PFC appears to be safe. We speculate that stretch is the stimulus for lung growth because there are no known growth factors present in PFC.

Animals↗
PubMed1998

Dobutamine antagonizes epinephrine's biochemical and cardiotonic effects: results of an in vitro model using human lymphocytes and a clinical study in patients recovering from cardiac surgery.

BACKGROUND: Patients may receive more than one positive inotropic drug to improve myocardial function and cardiac output, with the assumption that the effects of two drugs are additive. The authors hypothesized that combinations of dobutamine and epinephrine would produce additive biochemical and hemodynamic effects. METHODS: The study was performed in two parts. Phase 1 used human lymphocytes in an in vitro model of cyclic adenosine monophosphate (cAMP) generation in response to dobutamine (10(-8) to 10(-4) M) or epinephrine (10(-9) M to 10(-5) M), and dobutamine and epinephrine together. Phase 2 was a clinical study in patients after aortocoronary artery bypass in which isobolographic analysis compared the cardiotonic effects of dobutamine (1.25, 2.5, or 5 microg x kg(-1) x min(-1)) or epinephrine (10, 20, or 40 ng x kg(-l) x min(-1)), alone or in combination. RESULTS: In phase 1, dobutamine increased cAMP production 41%, whereas epinephrine increased cAMP concentration approximately 200%. However, when epinephrine (10(-6) M) and dobutamine were combined, dobutamine reduced cAMP production at concentrations between 10(-6) to 10(-4) M (P = 0.001). In patients, 1.25 to 5 microg x kg(-1) x min(-1) dobutamine increased the cardiac index (CI) 15-28%. Epinephrine also increased the CI with each increase in dose. However, combining epinephrine with the two larger doses of dobutamine (2.5 and 5microg x kg(-1) x mi(-1)) did not increase the CI beyond that achieved with epinephrine and the lowest dose of dobutamine (1.25 microg x kg(-1) x min(-1)). In addition, the isobolographic analysis for equieffective concentrations of dobutamine and epinephrine suggests subadditive effects. CONCLUSIONS: Dobutamine inhibits epinephrine-induced production of cAMP in human lymphocytes and appears to be subadditive by clinical and isobolographic analyses of the cardiotonic effects. These findings suggest that combinations of dobutamine and epinephrine may be less than additive.

Adrenergic Agonists↗
PubMed1996

Depression of cardiac function after deep hypothermic circulatory arrest in deeply anesthetized neonatal lambs.

Cardiac dysfunction is common after neonatal cardiac operations. Previous in vivo studies in neonatal animal models however, have failed to demonstrate decreased left ventricular function after ischemia and reperfusion. Cardiac dysfunction may have been masked in these studies by increased endogenous catecholamine levels associated with the use of light halothane anesthesia. Currently, neonatal cardiac operations are often performed with deep opiate anesthesia, which suppresses catecholamine surges and may affect functional recovery. We therefore examined the recovery of left ventricular function after ischemia and reperfusion in neonatal lambs anesthetized with high-dose fentanyl citrate (450 micrograms/kg administered intravenously). Seven intact neonatal lambs with open-chest preparation were instrumented with left atrial and left ventricular pressure transducers, left ventricular dimension crystals, and a flow transducer. The lambs were cooled (< 18 degrees C) on cardiopulmonary bypass (22 +/- 6 minutes), exposed to deep hypothermic circulatory arrest (46 +/- 1 minutes), and rewarmed on cardiopulmonary bypass (30 +/- 10 minutes). Catecholamine levels and indexes of left ventricular function were determined before (baseline) and 30, 60, 120, 180, and 240 minutes after termination of cardiopulmonary bypass. Levels of epinephrine, norepinephrine, and dopamine were unchanged from baseline values. Left ventricular contractility (slope of end-systolic pressure-volume relationship) was depressed from baseline value (31.7 +/- 9.3 mm Hg/ml) at 30 minutes (15.7 +/- 6.4 mm Hg/ml) and 240 minutes (22.7 +/- 6.4 mm Hg/ml) but unchanged between 60 and 180 minutes. Left ventricular relaxation (time constant of isovolumic relaxation) was prolonged from baseline value (19.0 +/- 3.0 msec) at 30 minutes (31.4 +/- 10.0 msec) and 240 minutes (22.1 +/- 2.8 msec) but unchanged between 60 and 180 minutes. Afterload (left ventricular end-systolic meridional wall stress) was decreased at 30, 60, and 240 minutes. Indexes of global cardiac function (cardiac output, stroke volume), preload (end-diastolic volume), and left ventricular compliance (elastic constant of end-diastolic pressure-volume relationship) were unchanged from baseline values. In deeply anesthetized neonatal lambs exposed to ischemia and reperfusion, left ventricular contractility, relaxation, and afterload are markedly but transiently depressed early after reperfusion and mildly depressed late after reperfusion.

Animals↗
PubMed1991

Improved lung preservation with cold air storage.

Conventional topical slush cooling limits lung transport to 4 to 6 hours. For this canine study of an alternate air cooling system, 37 canine lungs were removed: 24 were placed in plastic bags, and inserted in a Transplanthermm container at core air temperatures (n = 6 lungs each) of (A) 4 degrees C, (B) 8 degrees C, (C) 12 degrees C, and (D) 20 degrees C; 6 were stored conventionally in ice slush (E); and 7 were transplanted immediately (F). After 8 hours, the stored lungs were transplanted and the contralateral pulmonary artery was ligated. Survival, arterial oxygen tension, and extravascular lung water were monitored at 15 minutes and every hour for 4 hours. Four-hour survival was 100% in groups A, B, and F; 83% in group C, 50% in group D, and 17% in group E. The mean arterial oxygen tension at 1 hour was lower in group E (6.4 +/- 2.4 kPa) than in group A (39.8 +/- 13.2 kPa) (p = 0.0002) or in group F (42.0 +/- 16.2 kPa) (p = 0.0035). Extravascular lung water in group E was higher at 15 minutes (15.44 +/- 5.63 mL/kg) than in group A (3.76 +/- 0.63 mL/kg) (p = 0.0001) and group F (4.69 +/- 1.65 mL/kg) (p = 0.003). Cold air storage appears to provide better lung preservation than hypothermic immersion in ice slush.

Air↗
PubMed1990

Modified retrograde intubation technique for rapid airway access.

To reverse accidental extubation in the burn patient, a guide-wire can be passed retrograde through the cricothyroid membrane, and a thin tube changer can be placed over the guide-wire and down through the edematous airway and vocal cords. An endotracheal tube can then be passed over the tube changer to rapidly regain airway access.

Burns↗
PubMed1983

Diffusion of Ca2+ and the quiescent response of sea urchin sperm flagella.

The starting and stopping transients observed in sea urchin sperm flagella in the presence of high Ca2+ are believed to begin with an influx of Ca2+ into the axoneme and to end, as indicated by resumption of normal beating, when the Ca2+ has been reduced to very low levels by an active extrusion process. If the influx and efflux processes were uniformly distributed along the length of the flagellum, it is not likely that the starting and stopping transients would occur as a well defined sequence of events that always proceeds from the proximal to the distal end. Theoretical analysis of the concentration profiles of Ca2+ expected if Ca2+ influx occurred along the length of the flagellum but efflux was restricted to the proximal end shows that the time required to reduce [Ca2+] in the distal portion of the flagellum would generally be longer than the observed recovery times. Localization of both the influx and efflux processes near the proximal end, however, yields concentration profiles consistent with observations on the duration of starting and stopping transients.

Animals↗