Biomedical subjects

J C Hendricks

Publications and source records attributed to J C Hendricks.

At least 19 recordsLinked to original sources

PubMed1996

Open versus stereotactic breast biopsy.

BACKGROUND: Stereotactic breast biopsy has been developed as a less invasive means of performing biopsy for mammographic abnormalities. METHODS: From July 1994 through June 1995, 103 women with mammographic abnormalities requiring biopsy were prospectively evaluated. RESULTS: Fifty-one women had open biopsy, and 52 women had stereotactic biopsy. The average age in both groups was 60 years. Pathology revealed malignancy in 12% of stereotactic biopsies and 13% of open biopsies. Complications occurred in 6% of the open biopsies and 4% of the stereotactic biopsies and were limited to hematomas or seromas. The average cost was $2400 for open biopsy and $650 for stereotactic biopsy (P < 0.01). One hundred and one patients returned for a follow-up mammogram within 6 months, and 1 patient in each group required a second biopsy, which revealed benign pathology. A Patient Satisfaction Survey revealed no significant differences in patient satisfaction between the two types of procedures. CONCLUSION: There were no differences between open and stereotactic biopsies in regards to diagnostic accuracy, complications, or patient satisfaction. A significant difference was noted in charges during the time frame of our study.

Biopsy, Needle↗

PubMed1996

Does upper airway muscle injury trigger a vicious cycle in obstructive sleep apnea? A hypothesis.

Recent studies have indicated that the level of neural activation of upper airway dilator muscles is abnormally elevated in patients with obstructive sleep apnea (OSA). This is presumed to represent an adaptive mechanism that partially compensates for the anatomically small upper airway found in individuals with OSA. We have reviewed evidence that pharyngeal dilator muscles undergo secondary changes in structure as a direct consequence of their increased activity level in OSA. These alterations have the potential to be both beneficial and harmful with respect to the maintenance of upper airway patency. We propose a model outlining the possible role of activity-induced upper airway muscle remodeling and injury in the pathogenesis of OSA, and discuss potential implications for treatment of the disease.

Humans↗

PubMed1996

Modafinil decreases hypersomnolence in the English bulldog, a natural animal model of sleep-disordered breathing.

The English bulldog is a natural model of sleep-disordered breathing (SDB). This condition is marked by 1) hypersomnolence and 2) disordered breathing episodes that are most frequent and severe during rapid eye movement (REM) sleep. Modafinil has been found to increase arousal levels in animals and decrease excessive daytime sleepiness in humans. Therefore, in this study we focused mainly on the effects of the drug on total sleep time and sleep latency and secondarily assessed its effect on REM SDB. Five English bulldogs were implanted with subcutaneous electroencephalographic/electrooculographic (EEG/EOG) electrodes and instrumented with respiratory oscillation belts to measure abdominal and rib cage movements and an ear oximeter to measure saturation. The dogs were studied for approximately 8 hours each subsequent day on two consecutive days. On the first day, they received the vehicle dimethyl sulfoxide (DMSO) i.v. as a control. On the following day they received 10 mg/kg body weight of modafinil i.v. dissolved in the DMSO vehicle. Our findings indicate that modafinil significantly alleviates hypersomnolence (p < 0.05) in the bulldog, as evidenced by dramatically decreased mean total sleep time (from a control value of 50.5% to 8.3% with the drug) and increased mean sleep latency (from a control value of 71.0 minutes to a value of 346.6 minutes with the drug). We obtained limited data on the effect of modafinil on SDB because the drug either greatly diminished or entirely eradicated REM sleep in all five dogs.

Animals↗

PubMed1996

Quantitative magnetic resonance imaging of upper airways musculature in an animal model of sleep apnea.

Electromyographic studies of patients with sleep apnea and of the English bulldog, an animal model of sleep apnea, indicate that there is increase activity of the airways dilator muscles. The muscles, when biopsied, show both adaptation and muscle injury. In this study we have utilized quantitative magnetic resonance imaging to characterize changes in the upper airway musculature of the bulldog in vivo. The imaging procedure utilized provided a quantitative measurement of the T2 relaxation times of airway muscle (geniohyoid, sternohyoid, sternothyroid, thyropharyngeus, and hyopharyngeus) and nonairway muscles spatially localized to submillimeter-resolution levels. Quantitative differences between the medians and distributions of T2 relaxation times of airway vs. nonairway muscles were demonstrated. These differences were related to the degree of sleep-disordered breathing. The changes observed are compatible with the hypothesis that there is both increased edema and fibrosis in upper airway muscle in sleep apnea.

Animals↗

PubMed1996

The effects of serotonin antagonists in an animal model of sleep-disordered breathing.

Recent studies have shown excitatory effects of serotonin on upper airway motoneurons. This excitatory effect is normally present and arises from cells in the caudal raphe nuclei. The firing of these serotonergic neurons is reduced during sleep. To determine the importance of serotonin in the maintenance of patient airways and normal respiration in waking in obstructive sleep apnea, we studied the effects of two serotonin antagonists on upper airway dilator muscle activity, diaphragm activity, Sao2, and upper airway cross-sectional area in an animal model of sleep-disordered breathing, the English bulldog. Systemic administration of both antagonists resulted in significant reductions in the peak amplitudes of upper airway muscle respiratory bursts (range, 39 to 62% suppression; p < 0.05). Lesser reductions in diaphragm activity were noted (range, 10 to 33% suppression; p < 0.05). Oxyhemoglobin saturations also fell (p < 0.05), coinciding with suppressions in upper airway muscle activity. With reductions in dilator muscle activity, upper airway cross-sectional areas, as measured with cine CT, showed significant inspiratory collapse. These results support the hypothesis that serotonin is important in the maintenance of patent upper airways in obstructive sleep apnea.

Animals↗

PubMed1995

Noncardiogenic pulmonary edema in dogs and cats: 26 cases (1987-1993)

Medical records of 23 dogs and 3 cats treated for noncardiogenic pulmonary edema (NPE) resulting from airway obstruction (n = 8), cranial trauma (7), electric shock (7), or seizures (4) between 1987 and 1993 were reviewed. There were 18 purebred dogs, 5 mixed-breed dogs, 2 domestic shorthair cats, and 1 Siamese. Sixteen animals were male, and 10 were female. All but 7 were less than 1 year old. Time between the inciting incident and onset of respiratory tract signs ranged from minutes to several hours. Respiratory distress was the primary clinical sign for all animals with NPE resulting from airway obstruction, cranial trauma, or seizures, and for 2 of the 7 animals with NPE resulting from electric shock. The only consistent clinicopathologic abnormality was hyperglycemia, which was detected in 12 animals. Arterial blood gas partial pressures were measured in 11 animals; 10 were hypoxemic. On thoracic radiographs, the predominant pattern of pulmonary infiltration was alveolar. Symmetry of involvement, which was assessed by examining dorsoventral or ventrodorsal radiographic projections, could be determined for 23 animals. In 18, involvement was asymmetric, and in 13 of those 18, the right side was predominantly involved. On lateral radiographic projections, the caudodorsal quadrant of the lung field was involved primarily or as part of a diffuse distribution in all but 1 animal. Generally, animals with NPE resulting from airway obstruction had the greatest degree of radiographic involvement, followed in decreasing order, by animals with NPE resulting from cranial trauma, animals with NPE resulting from seizures, and animals with NPE resulting from electric shock. Overall, 9 animals died.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Transanal excision of rectal carcinoma.

Twenty-two men and 16 women with a mean age of 67 years were treated for rectal carcinoma by transanal excision. Patients presented with rectal bleeding (63%), change in bowel habits (11%), rectal pain (4%), or were asymptomatic and discovered on screening proctosigmoidoscopy (22%). The tumors were located from the anal verge to 8 cm proximally and ranged in size from 1 to 4 cm. Pathologic findings included adenocarcinoma (92%), squamous cell carcinoma (4%), and cloacogenic carcinoma (4%). Postoperative hospitalization averaged two days (0 to 29 days). One patient died of a perioperative myocardial infarction for an operative mortality of 3 per cent. Morbidity was 7 per cent and included urinary retention and pneumonia. Postoperative radiation therapy was administered to 11 patients with either undifferentiated tumors or invasion into the muscularis propria. Follow-up in these 38 patients averaged 30 months. One patient died of metastatic carcinoma, and two patients developed local recurrence that was treated successfully by a low anterior resection or abdominoperineal resection. Transanal excision of rectal carcinoma can be performed in properly selected patients with good overall survival and local control.

Adenocarcinoma↗

PubMed1994

Use of positive-pressure ventilation in dogs and cats: 41 cases (1990-1992).

Intermittent positive-pressure ventilation (PPV) is an invasive means of respiratory support that is indicated in animals with central and peripheral neuromuscular disease, as well as in those with primary disorders of the lung parenchyma. We reviewed the medical records of 34 dogs and 7 cats treated with PPV. The animals could be allotted to 2 groups; group 1 (21/41) had primary failure of ventilation attributable to neuromuscular disease or airway obstruction, and group 2 (20/41) had primary pulmonary parenchymal disease. Mean inspiratory time was 1.02 +/- 0.2 seconds (range, 0.6 to 1.5 seconds). Mean inspiratory flow was 26.9 +/- 18.5 L/min (range, 7 to 87 L/min), and was positively correlated with body weight (R = 0.57). Mean set respiratory rate was 19.6 +/- 10 breaths/min (range, 5 to 60 breaths/min), with mean tidal volume of 15.5 +/- 6.2 ml/kg of body weight. Positive end-expiratory pressure (PEEP) was required in 14 of 20 dogs in group 2. Mean peak airway pressure in group 1 was 21.6 +/- 6.3 cm of H2O, whereas in group 2 it was 32.9 +/- 12.5 cm of H2O. The higher peak airway pressure in group-2 dogs reflected poor lung compliance and the use of PEEP in dogs with parenchymal lung disease. Mean duration of PPV was 28.2 +/- 29.4 hours (range, 2 to 137 hours). The overall survival rate was 39% (16/41).(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Obstruction↗

PubMed1994

A prospective randomized trial comparing open versus laparoscopic appendectomy.

OBJECTIVE: The authors determined whether there was an advantage to laparoscopic appendectomy when compared with open appendectomy. SUMMARY/BACKGROUND DATA: The advantages of laparoscopic appendectomy versus open appendectomy were questioned because the recovery from open appendectomy is brief. METHODS: From January 15, 1992 through January 15, 1993, 75 patients older than 9 years were entered into a study randomizing the choice of operation to either the open or the laparoscopic technique. Statistical comparisons were performed using the Wilcoxon test. RESULTS: Thirty-seven patients were assigned to the open appendectomy group and 38 patients were assigned to the laparoscopic appendectomy group. Two patients were converted intraoperatively from laparoscopic appendectomies to open procedures. Thirty-one patients (81%) in the open group had acute appendicitis, as did 32 patients (84%) in the laparoscopic group. Mean duration of surgery was 65 minutes for open appendectomy and 87 minutes for laparoscopic appendectomy (p < 0.001). There were no statistically significant differences in length of hospitalization, interval until resumption of a regular diet, or morbidity. Duration of both parenteral and oral analgesic use favored laparoscopic appendectomy (2.0 days versus 1.2 days, and 8.0 days versus 5.4 days, p < 0.05). All patients were instructed to return to full activities by 2 weeks postoperatively. This occurred at an average of 25 days for the open appendectomy group versus 14 days for the laparoscopic appendectomy group (p < 0.001). CONCLUSIONS: Patients who underwent laparoscopic appendectomies have a shorter duration of analgesic use and return to full activities sooner postoperatively when compared with patients who underwent open appendectomies. The authors consider laparoscopic appendectomy to be the procedure of choice in patients with acute appendicitis.

Acute Disease↗

PubMed1994

Pharyngeal myopathy of loaded upper airway in dogs with sleep apnea.

Recent work indicates that upper airway dilator muscles of individuals with obstructive sleep apnea syndrome (OSAS) demonstrate an increased level of activity during wakefulness compared with normal subjects. In addition, massive bursts of pharyngeal dilator activity are associated with the termination of upper airway occlusive events during sleep. This complex pattern of altered pharyngeal dilator activation is also observed in the English bulldog, an animal model of OSAS. In the present study, it was hypothesized that such alterations in activity level might lead to changes in the structure of pharyngeal muscles in the bulldog. Full-thickness biopsies were obtained from two pharyngeal dilator muscles, the sternohyoid (SH) and geniohyoid, as well as a limb muscle, the anterior tibialis, in bulldogs (n = 5) and control dogs (n = 7). Immunohistochemical analysis of myosin heavy chain expression revealed an increased contribution of fast type II myosin heavy-chain fibers to SH in bulldogs. The bulldog SH also demonstrated increased connective tissue content compared with control dogs, consistent with the presence of fibrosis. Both pharyngeal dilators in the bulldog exhibited an elevated proportion of morphologically abnormal fibers indicative of ongoing or prior injury. No differences in any of the above parameters were seen between bulldogs and control dogs in the anterior tibialis limb muscle. We conclude that the chronic load and altered pattern of usage imposed on the upper airway dilators in OSAS lead to myopathic changes that may ultimately impair the ability of these muscles to maintain pharyngeal patency.

Airway Obstruction↗

PubMed1993

A pulmonary rehabilitation program for patients with asthma and mild chronic obstructive pulmonary diseases (COPD).

The effects of a pulmonary rehabilitation program on 44 patients with chronic obstructive pulmonary disease (COPD) were compared to a control group. The treated group was admitted to the program for a period of three months. The program consisted of several parts, such as physical training, health education, and psychological and social matters. Before participation, the patients were thoroughly examined and provided with optimal medical treatment. Both groups were assessed by means of biometrical tests and questionnaires for a period of 2 years. The rehabilitation group improved significantly in endurance, psychological parameters, and consumption of medical care. Working days increased and their way of life became more active. Smoking habits and body fat percentage decreased. Bronchial hyperreactivity, need for pulmonary drugs, and coughing and sputum production did not improve in the rehabilitation group compared to the control group. Airway obstruction, expressed as forced expiratory volume in one second, and complaints of dyspnea, allergy and hyperreactivity scores on questionnaires improved only in the short term (< 1 year), but did not improve significantly in the long term. This study shows that pulmonary rehabilitation can result in improvements in patients with asthma or COPD who have many complaints despite the fact that their pulmonary function is not severely disturbed.

Adult↗

PubMed1993

Laparoscopic-assisted bowel surgery.

The use of laparoscopic surgical techniques is now being applied to a variety of operations traditionally performed in an open fashion. Twenty patients underwent laparoscopic-guided large and small bowel surgery at our institution from March 1991 to April 1992. The indications for surgery included polyps, obstruction, bleeding, and perforation, and pathologic diagnoses included benign polyps, lipomas, inflammatory bowel disease, perforation of a jejunal diverticulum, colonic arteriovenous malformations, and adenocarcinoma. Mobilization of the colon, ligation of the mesentery, and closure of the mesenteric defect were performed using the laparoscopic equipment. One trocar site was enlarged to 3 cm to deliver the bowel through the abdominal wall. All anastomoses were hand-sewn. Postoperative hospitalization ranged from 2 to 31 days (median, five days). No mortality was noted, and morbidity was 20 percent. We conclude that laparoscopic-guided bowel surgery is technically feasible and should translate into shorter hospitalization and less patient discomfort.

Aged↗

PubMed1993

Combined laparoscopic and endoscopic management of cholelithiasis and choledocholithiasis.

With the advent of laparoscopic cholecystectomy, optimal management of common duct stones remains controversial. Seven hundred six patients underwent laparoscopic cholecystectomy in our institution from January 1990 through January 1992. From this group of patients, 50 were identified as having clinical or radiographic evidence of common duct stones. Thirty-one patients demonstrated preoperative risk factors for common duct stones and underwent preoperative endoscopic retrograde cholangiopancreatography (ERCP). The risk factors included jaundice (19%), pancreatitis (23%), elevated liver function tests (52%), and ultrasound evidence of choledocholithiasis (6%). Preoperative ERCP was performed in 94% of patients. There were two failures due to periampullary diverticula. Common duct stones were identified in 18 patients (62%) and successfully removed by endoscopic sphincterotomy in all of these patients. Nineteen patients were found to have unsuspected common duct stones on intraoperative cholangiography. Eighteen patients (95%) underwent successful ERCP and endoscopic sphincterotomy with stone extraction. Overall, major morbidity was 2% and included one patient who experienced endoscopic sphincteroplasty. The three endoscopic failures were managed by open common duct exploration, laparoscopic duct exploration, and combined laparoscopic and open common duct exploration. We conclude that combined laparoscopic and endoscopic therapy is a viable option for the management of cholelithiasis with choledocholithiasis.

Cholangiopancreatography, Endoscopic Retrograde↗

PubMed1993

Effects of acute sleep deprivation on control of the diaphragm during REM sleep in cats.

Recently, investigators demonstrated that acute sleep deprivation in healthy subjects results in significant periodic decrements in ventilation during recovery rapid-eye-movement (REM) sleep. The neural bases of such phenomena are unknown. The decrements in ventilation coincide with REM sleep-associated phasic activities, such as bursts of eye movements. The purpose of this study was to determine the effects of acute sleep deprivation on control of diaphragm activity during recovery REM sleep. In chronically implanted, naturally sleeping, unrestrained cats, we recorded the electroencephalogram, electrooculogram, pontogeniculooccipital waves, neck and diaphragmatic electromyograms, and the computed moving average of the diaphragm. Acute sleep deprivation resulted in an increase in REM sleep-associated phasic alterations in diaphragmatic control during recovery REM sleep. There was an increase in the percentage of bursts during recovery REM sleep with reduced inspiratory drive. Acute sleep deprivation resulted in a substantial increase in the number of brief pauses (fractionations) in diaphragmatic activity during recovery REM sleep. Respiratory timing was also affected by sleep deprivation, with a reduced expiratory time resulting in an increased duty cycle ratio. There was a significant increase in the percentage of bursts with decremented peak amplitude of the moving average of the diaphragm, a measure that correlates with tidal volume. Despite significant increases in respiratory-related phasic alterations, there were no parallel increases in excitatory phenomena, i.e., eye movements or pontogeniculooccipital waves. These results imply that respiratory control mechanisms in REM sleep are sensitive to the effects of prior sleep deprivation.

Animals↗

PubMed1993

Upper airway dilating muscle hyperactivity during non-rapid eye movement sleep in English bulldogs.

Sleep-disordered breathing (SDB) is seen during rapid eye movement (REM) sleep in English bulldogs, but it is absent during non-REM sleep. The SDB during REM sleep is associated with changes in neural drive to the diaphragm (DIA) and to an upper airway dilator, the sternohyoid (SH). In the present study, the EMG activity of the DIA was recorded in unrestrained, naturally sleeping, English bulldogs (n = 6) and in control dogs (n = 5). The EMG of the SH was recorded in five of these bulldogs and in four of the control dogs. The activity of the DIA was similar in the two groups of dogs throughout sleep, with the normal increased variability and altered recruitment patterns during REM sleep in all dogs. However, in the presence of the narrowed upper airway of bulldogs, the pattern of the upper airway dilator was dramatically different. In bulldogs, SH activity was virtually always related to inspiration (96 to 100% of breaths during both waking and non-REM sleep). In contrast, SH activity showed inspiratory-related increases in only a minority of breaths during non-REM sleep (32%) in control dogs (p < 0.05). Furthermore, SH drive, as measured by the plateau amplitude, fell during REM sleep in bulldogs, whereas it increased in control dogs (p < 0.05). In control dogs without SDB, we found that central respiratory drive to the SH was highest but variable during waking and minimal during non-REM sleep and that it fluctuated with phasic events during REM sleep. In bulldogs, however, high levels of SH activity occurred during waking and throughout non-REM sleep, apparently preventing SDB in these states. Episodic decreases in SH drive were observed during REM, and they were associated with SDB. These data support the proposition that compensatory pharyngeal dilator hyperactivity is necessary to maintain airway patency and normal breathing in bulldogs, a canine breed with an anatomically compromised upper airway.

Animals↗

PubMed1993

Safety and efficacy of total thyroidectomy for differentiated thyroid carcinoma: a 20-year review.

Controversy continues to exist regarding the optimal extent of resection for differentiated thyroid carcinoma (DTC). Subtotal thyroidectomy has been advocated by some authors in expectation of lower complication rates, while others advocate total thyroidectomy to achieve better cure rates. To examine this issue, the medical records of 124 patients who underwent total thyroidectomy for DTC were retrospectively reviewed. Total thyroidectomy was the initial procedure in 115 patients, while nine patients had complete thyroidectomy following some type of subtotal resection. Concomitant procedures were performed in 47 patients. Ninety papillary, 20 mixed papillary-follicular variant, one Hürthle cell type, and 13 follicular carcinomas were performed. Tumors were bilateral or multicentric in 40 patients, with metastases present in one-third of patients at the same time of initial operation. Permanent hypoparathyroidism developed in two patients, and permanent ipsilateral recurrent laryngeal nerve palsy occurred in one patient, for an overall significant complication rate of 2.4 per cent. Tumor recurrence was noted at a mean of 19 months postoperatively in 14 patients. Ninety-six patients received adjuvant postoperative radioiodine therapy to ablate residual functioning thyroid tissue or suspected metastases. We conclude that total thyroidectomy as treatment for differentiated thyroid carcinoma carries a low rate of morbidity, treats occult contralateral disease, and should facilitate radioiodine scanning and ablation of residual functioning thyroid tissue or metastatic disease.

Adenocarcinoma↗

PubMed1992

Brachycephalic airway syndrome.

The range of clinical syndromes and the pathophysiology of respiratory disorders in brachycephalic animals are presented. The problem of deciding which patients require surgical management is reviewed in the light of recent studies and the author's clinical experience. Newer information from related disorders in humans suggests that serious problems can be subclinical and difficult to diagnose. The index of suspicion and guidelines for providing surgical relief to veterinary patients may need to undergo revision.

Airway Obstruction↗

PubMed1992

Arterial blood gas tensions in healthy aged dogs.

Twenty-four healthy dogs > 8 years old were recruited. In each instance, arterial blood gas tensions were analyzed. The alveolar-to-arterial oxygen gradient (P[A-a]O2) was calculated to assess adequacy of pulmonary gas exchange. Thoracic radiographs were evaluated to ensure lack of visible signs of pulmonary disease and that lung features were similar to those in aged dogs of previous reports. Unlike findings in aged human beings, arterial partial pressure of oxygen (PaO2) was not decreased in this group of aged dogs (mean +/- SD, 102.9 +/- 7.8 mm of Hg). Similarly, P(A-a)O2 also was not increased. The thoracic radiographic findings were consistent with those of previous reports of pulmonary changes in aged dogs. The extent of radiographic abnormalities and the PaO2 were not correlated.

Aging↗