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Biomedical subjects

J C Hendricks

Publications and source records attributed to J C Hendricks.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1992

State-related changes in breathing. Are we missing sleep-disordered breathing syndromes in veterinary patients?

In recent decades, treatment of sleep disorders has developed rapidly. Prevalent and severe sleep disorders affecting respiration have been discovered in clinical sleep disorders centers. Although sleep studies are not currently, and may never become, a clinical tool for veterinarians, evidence from investigative work shows that dogs, at least, can suffer from "sleep-disordered breathing" syndromes similar to those affecting humans. The physiology and pathophysiology of sleep and breathing are strikingly similar in dogs and humans.

Airway Obstruction↗
PubMed1991

Open versus laparoscopic cholecystectomy. A comparison of postoperative pulmonary function.

Upper abdominal surgery is associated with characteristic changes in pulmonary function which increase the risk of lower lobe atelectasis. Sixteen patients undergoing open cholecystectomy and 20 patients undergoing laparoscopic cholecystectomy were prospectively evaluated by pulmonary function tests (forced vital capacity [FVC], forced expiratory volume [FEV-1], and forced expiratory flow [FEF] 25% to 75%) before operation and on the morning after surgery to determine if the laparoscopic technique lessens the pulmonary risk. Fraction of the baseline pulmonary function was calculated by dividing the postoperative pulmonary function by the preoperative pulmonary function and multiplying by 100%. Postoperative FVC measured 52% of preoperative function for open cholecystectomy and 73% for laparoscopic cholecystectomy (p = 0.002). Postoperative FEV-1 measured 53% of baseline function for open cholecystectomy and 72% for laparoscopic cholecystectomy (p = 0.006). Postoperative FEF 25% to 75% measured 53% for open cholecystectomy and 81% for laparoscopic cholecystectomy (p = 0.07). It is concluded that laparoscopic cholecystectomy offers improved pulmonary function compared to the open technique.

Adult↗
PubMed1991

Differential activation within costal diaphragm during rapid-eye-movement sleep in cats.

Simultaneous recordings of the diaphragmatic electromyogram (EMG) were made from two separate regions of the costal diaphragm in six normal cats. The diaphragmatic activities were always synchronous and the amplitudes and rates of rise were similar during slow-wave sleep. In contrast, during natural rapid-eye-movement (REM) sleep, different activity was often present in the two leads. These differences were in the time of onset and offset, as well as in the amplitude and spike patterns, and occurred in approximately 5-20% of the diaphragmatic bursts averaged over the entire REM sleep period. With respect to eye movement density, the rate of differential activation was higher during periods of high density (26%) than in the absence of eye movements (1%) in the four animals for which these data were available. Differential activation of portions of the costal diaphragm is apparently a normal event of REM sleep. This could result from descending state-specific phasic neuronal activity that bypasses the medullary respiratory generator. Differential activation of portions of the diaphragm could contribute to disordered ventilation during REM sleep.

Animals↗
PubMed1991

Phasic respiratory muscle patterns and sleep-disordered breathing during rapid eye movement sleep in the English bulldog.

Basic mechanisms of sleep-disordered breathing (SDB) during rapid-eye-movement sleep (REMS) have been little investigated, despite the fact that events are often more prolonged and SaO2 nadirs lower during REMS. We predicted that the mechanisms of SDB in REMS would be related to the normal phasic changes in respiratory control in that state, rather than to cyclic arousals or responses to hypoxia as postulated for non-REMS SDB. Recordings of the EMG of the diaphragm (DIA) and the sternohyoid (SH), an upper airway dilating muscle, were made in five English bulldogs during sleep. We found that, as predicted, SDB events were associated with phasic influences rather than with arousals or response to hypoxia. The onset of SDB was significantly related to suppression of drive to both the DIA (p less than 0.01) and the SH (p less than 0.01). The mean drive of the DIA was suppressed to 42% of normal and of the SH to 17% of normal; the suppression of the SH was significantly greater than that of the DIA (p less than 0.05). Events were associated with changes in respiratory muscle EMG patterns typical of phasic REMS (p less than 0.01 for each muscle). The occurrence and duration of events exhibited no clear pattern or relationship to arousal or SaO2. Rather, as would be expected of phenomena associated with phasic REMS, the onset and termination of events were unpredictable. The association of SDB in REMS with phasic REMS influences rather than arousal or hypoxia suggests new directions for therapeutic approaches.

Animals↗
PubMed1991

Static thoracic compliance as a measurement of pulmonary function in dogs.

Thoracic compliance measurements by use of readily available equipment were determined to be practical and safe in dogs. Twenty healthy dogs (age 1 to 16 years, weight 2.3 to 49.5 kg) were anesthesized for routine procedures such as dentistry or neutering. The animals were first hyperventilated to reduce pulmonary atelectasis, to check for leakage at the endotracheal tube cuff, and to induce mild hypocarbia, thus minimizing voluntary respiratory efforts. Total thoracic compliance measurements were calculated as the difference between exhaled volumes at static inspiratory pressures of 15 and 20 cm of H2O, divided by the pressure difference, and expressed as a function of body weight. The procedure was easy, took 5 to 10 minutes, and caused no recognizable ill effects in any of the dogs studied. Mean total thoracic compliance was 42.25 +/- 32 ml/cm of H2O. There was a significant correlation with weight, but no significant relationship was seen between compliance and age, or gender. The mean weight-adjusted total thoracic compliance was 1.85 +/- 0.56 ml/cm of H2O/kg. In studies in a small group of dogs with documented respiratory tract disease, 4 of 7 had a mean compliance greater than 2 SD below the normal range. Thus, this test may become part of the routine workup of any animal being anesthetized for procedures such as bronchoscopy to evaluate respiratory tract disease. Routine monitoring of animals on ventilators could provide early warning of complications such as pneumonia, pleural effusion, or pulmonary edema.

Animals↗
PubMed1990

Startle-evoked changes in diaphragmatic activity during wakefulness and sleep.

Tonic inhibition of some respiratory muscles occurs as part of the generalized muscle atonia of rapid-eye-movement sleep (REMS). A second type of inhibition of the diaphragm during REMS, fractionations, consists of brief pauses in the diaphragmatic electromyogram (DIA EMG) in association with phasic events. Because motor inhibition can occur as part of the startle response, and the brain is highly activated during REMS, we hypothesized that the neural basis of the fractionations might be activation of a startle network. To test this hypothesis, tone bursts (100 dB, 20-ms duration at 15-s intervals) were applied to cats at a fixed inspiratory level in the DIA moving average during REMS, non-rapid-eye-movement sleep (NREMS), and wakefulness. Parallel sham studies (no tone applied) were obtained for each state. The response of the DIA EMG was averaged over 100 ms by using the tone pulse as a trigger, and the following parameters of the DIA EMG were measured: latency to peak and/or nadir, increment or decrement in activity, and duration of peak and/or nadir. After a tone, all five animals studied displayed a profound suppression of DIA activity during REMS (latency to nadir 42.4 +/- 10.0 ms, duration of suppression 35.9 +/- 17.6 ms). Similarly, DIA activity was suppressed in all cats during NREMS (latency to nadir 40.9 +/- 13.3 ms, duration 23.9 +/- 13.4 ms). An excitatory response was observed in only two cats during NREMS and wakefulness. The similarity of startle-induced DIA EMG pauses to spontaneous fractionations of DIA activity during REMS suggests that the latter result from activation of a central startle system.

Acoustic Stimulation↗
PubMed1990

Effect of dorsolateral pontine lesions on diaphragmatic activity during REMS.

Muscle atonia is a feature of normal rapid-eye-movement sleep (REMS). The suppression of accessory respiratory muscle activity has been investigated and a role for sleep-disordered breathing hypothesized, but the suppression of diaphragmatic activity has rarely been considered. We hypothesized that the activity of the diaphragm was suppressed by an area of the dorsolateral pons during REMS. Lesions in this region have previously been shown to abolish the atonia of REMS. The diaphragmatic electromyogram (EMG) activity was analyzed in five naturally sleeping cats before and after pontine lesions leading to REMS without atonia. Although respiratory timing parameters were not altered by the lesion, the inspiratory rate of rise was significantly increased in all cats, and the brief pauses (40-100 ms) in the diaphragmatic EMG normally seen in REMS were virtually abolished. We conclude that the dorsolateral pons has a role in suppressing diaphragmatic activation during REMS. This suppression affects the average rate of rise of diaphragmatic activity and also leads to brief intermittent complete cessation of ongoing muscle activity. These decrements in diaphragm activity could jeopardize ventilation during REMS.

Animals↗
PubMed1989

Treatment of cataplexy in a dog with narcolepsy.

A 1-year-old female Rottweiler with a history of narcolepsy and cataplexy lost weight and became worse when given cholinergic agents and/or prednisolone over a 12-day period. The dog was then treated with imipramine HCl, and has been almost clinically normal for 2 years.

Animals↗
PubMed1989

Movement disorders during sleep in cats and dogs.

Spontaneous sleep movement disorders in 5 cats and 3 dogs were studied. Objective abnormalities during sleep were confirmed by electrographic or behavioral monitoring techniques in all animals. The cause of the disorder was CNS disease in 3 animals. A cause was not discovered in the other 5 animals, although at necropsy, 2 were found to have thyroid tumors. Many pharmacologic treatments were ineffectual, but trials with the benzodiazepine tranquilizer, clonazepam, suggested it will prove useful in controlling violent movements during rapid-eye-movement sleep.

Animals↗