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R C McIntyre

Publications and source records attributed to R C McIntyre.

85 records · Page 5Linked to original sources
PubMed1994

Cardiopulmonary effects of permissive hypercapnia in the management of adult respiratory distress syndrome.

BACKGROUND: Despite numerous advances, the mortality from adult respiratory distress syndrome (ARDS) remains high. Traditional ventilator management in ARDS has been to maintain normal PaCO2 by positive pressure ventilation (PPV). However, high levels of PPV may worsen the lung injury by alveolar overdistension. Permissive hypercapnia (PHC) has been proposed as an alternative method of ventilation, but hypercapnia may affect the hemodynamics of a hyperdynamic, critically ill patient. The purpose of this study was to determine the effect of PHC on ventilator requirement, arterial oxygenation, and hemodynamic performance in patients with severe ARDS. METHODS: Ten men and 5 women with established ARDS (mean Murray lung injury score 3.42 +/- 0.1) were prospectively studied using an established protocol when the static pulmonary plateau pressure (Pplat) exceeded 40 cm H2O. The initial tidal volume (V(t)) was decreased to achieve a Pplat < 40 cm H2O or to a lower limit of 5 cc/kg. Arterial blood gas and hemodynamic data were obtained serially. RESULTS: The V(t) was reduced from 9.9 +/- 0.5 mL/kg to 7.7 +/- 0.5 mL/kg at 24 hours, p < 0.05. This reduction of V(t) produced a decrease in minute ventilation (Ve: 18.0 +/- 1.6 to 11.9 +/- 0.7 L/min, p < 0.05), peak airway pressure (PAP: 55 +/- 2 vs 45 +/- 3 cm H2O, p < 0.05), and Pplat (Pplat 45.4 +/- 1.5 vs. 36.7 +/- 1.9) at 24 hours. The PaCO2 rose from 37.9 +/- 1.3 to 56.7 +/- 3.0 mm Hg (p < 0.05), and the pH decreased from 7.41 +/- 0 to 7.31 +/- 0 (p < 0.05) at 24 hours. There were no significant changes in mean airway pressure, static compliance, arterial oxygenation, pulmonary vascular resistance, systemic vascular resistance, cardiac index, or systemic oxygen delivery and consumption. CONCLUSIONS: Permissive hypercapnia by V(t) reduction: (1) decreased Ve, PAP, and Pplat without a change in mean airway pressure, static compliance or arterial oxygenation; (2) caused a mild partially compensated acidosis; and (3) does not adversely affect pulmonary vascular resistance, systemic vascular resistance, cardiac index, or systemic oxygen delivery and consumption.

Adolescent↗
PubMed1994

Adenosine A1-receptor mechanisms antagonize beta-adrenergic pulmonary vasodilation in hypoxia.

Hypoxic pulmonary vasoconstriction is refractory to beta-adrenergic receptor (beta-AR)-mediated pulmonary vasodilation. We hypothesized that hypoxic pulmonary arteries release adenosine (Ado) that antagonizes beta-AR-mediated pulmonary vasodilation. Using isolated rat pulmonary artery rings, we investigated 1) the effect of hypoxia and exogenous Ado on beta-AR-mediated pulmonary vasodilation, 2) the intracellular site of dysfunctional beta-AR-mediated pulmonary vasodilation in hypoxia, and 3) the Ado receptor subtype responsible for dysfunction of beta-AR-mediated pulmonary vasodilation. Hypoxia attenuated normal beta-AR-mediated pulmonary vasodilation to isoproterenol (97.5 +/- 0.8 vs. 71.5 +/- 2.3%, P < 0.01). In contrast, forskolin induced the same vasorelaxation in hypoxic pulmonary rings as controls (P = 0.09). Incubation of normoxic rings with Ado attenuated the vasorelaxation response induced by beta-AR stimulation (71.5 +/- 5.9%, P < 0.01), similar to the effect observed in hypoxia. Both nonspecific Ado receptor blockade (8-sulfophenyl-theophylline) and specific A1-receptor blockade (8-cyclopentyl-1,3-dimethylxanthine) restored the vasorelaxation response of hypoxic rings induced by beta-AR stimulation (93.3 +/- 2.3 and 92.2 +/- 2.8%, P < 0.01). The effects of hypoxia and Ado were reproduced by a specific A1 agonist (2-chloro-N6-cyclopentyladenosine), demonstrating impaired vasorelaxation induced by beta-AR stimulation in normoxia (70.6 +/- 4.5%, P < 0.01). From these data, we conclude that hypoxia antagonizes beta-AR-mediated pulmonary vasodilation via an Ado A1-receptor mechanism.

Adenosine↗
PubMed1994

Update on laparoscopic ultrasonography.

Ultrasonography has many clinical applications and can be done with both extra- and intracorporeal techniques. Miniaturization of ultrasound transducers has opened the way for intracorporeal use of ultrasound at laparoscopy. The principles of ultrasonography are presented. Laparoscopic intracorporeal ultrasound (LICU) has proven to be useful in the differential diagnosis of liver tumours. In one series, 75 of 85 patients had positive identification of a suspected liver tumour with laparoscopic ultrasound examination. LICU has also been useful for delineation of hepatobiliary anatomy during laparoscopic cholecystectomy in both animal models and patients having cholecystectomy. LICU may detect useful anatomic information prior to dissection of the cystic duct and is accurate in detecting common bile duct stones. LICU may also be useful in the preoperative staging of pancreatic malignancy. Laparoscopic intracorporeal ultrasound may find practical application in other areas as experience evolves.

Animals↗
PubMed1994

The pediatric diaphragm in acute gastric volvulus.

Acute gastric volvulus occurred in nine infants and one older child during the past 19 years; all patients had an associated left diaphragmatic anomaly. There were seven examples of eventration of the diaphragm, two of giant hiatal hernia and one Bochdalek hernia. Nine of the ten patients presented with vomiting and one with acute respiratory distress. The gastric volvulus was mesenteroaxial in eight patients and organoaxial in two. Operative treatment consisted of repair of the diaphragmatic anomaly and gastric fixation in eight patients. Gastric fixation alone was performed in one patient. A single patient died preoperatively and had gastric necrosis at postmortem examination. Of the nine patients treated operatively, all remain alive and well without recurrence. Acute gastric volvulus should be considered in any infant presenting with unexplained vomiting in association with a left diaphragm anomaly, and once diagnosed, immediate operation is mandatory.

Acute Disease↗
PubMed1993

Pelvic fracture geometry predicts risk of life-threatening hemorrhage in children.

Recent studies have concluded that pelvic fractures in children, unlike those in adults, are not a source of life-threatening hemorrhage. Our study hypothesis was that major bleeding occurs in children with pelvic fractures, and fracture geometry allows early identification of patients at risk for severe hemorrhage. Fifty-seven (5.5%) of 1044 pediatric trauma patients sustained pelvic fractures. The majority of injuries were from motor vehicle crashes (n = 21, 36.8%) and auto-pedestrian collisions (n = 18, 31.6%). Twenty-three children (40.4%) had unilateral anterior fractures (type I), seven (12.2%) had unilateral posterior fractures (type II), 23 (40.4%) had unilateral anterior and posterior fractures (type III), and four (7%) had bilateral anterior and posterior (type IV) fractures. Eighteen children (32.6%) required blood transfusions during the initial 48 hours (mean, 59 mL/kg). Skeletal fixation was applied in ten patients (17.5%), and it controlled bleeding in six (60%). Pelvic angiography identified arterial hemorrhage in three of four patients, and embolization controlled bleeding in all cases. The only death in the series (mortality, 1.7%) was from multisystem trauma. Age, sex, Injury Severity Score, Revised Trauma Score, mechanism of injury, and pelvic fracture geometry were evaluated as risk factors predictive of hemorrhage employing multiple logistic regression. Only pelvic fracture geometry independently identified patients at increased risk of major bleeding. We conclude that pelvic fracture geometry identifies a subset of pediatric trauma patients at high risk for life-threatening hemorrhage and urge a prompt multispecialty approach to these patients.

Accidents, Traffic↗
PubMed1993

Comparison of video thoracoscopic lung biopsy to open lung biopsy in the diagnosis of interstitial lung disease.

BACKGROUND: Up to one third of patients with interstitial lung disease will require a lung biopsy for diagnosis. Open lung biopsy is generally accepted as the most reliable method of biopsy and tissue diagnosis. The purpose of this study was to compare the efficacy and safety of video thoracoscopic lung biopsy, a minimally invasive technique, with open lung biopsy in the diagnosis of interstitial lung disease. METHODS: From December 1990 to January 1992, 43 patients were referred for diagnostic lung biopsy. Twenty-two consecutive patients undergoing video thoracoscopic lung biopsy (VTLB) over a 6-month period were retrospectively studied and compared with 21 consecutive patients who had undergone open lung biopsy (OLB) in the preceding 6-month period. RESULTS: VTLB (46 +/- 4 minutes) did not add to operative time when compared with OLB (38 +/- 3 min, p = 0.09). The same number of biopsies per patient were performed (VTLB, 1.9 +/- 0.1; OLB, 2.0 +/- 0.1; p = 0.48), the same amount of tissue was obtained per biopsy (VTLB, 6.69 +/- 0.82 cm3; OLB, 5.78 +/- 0.54 cm3; p = 0.36), and the diagnostic accuracy of each method was comparable (VTLB, 95 percent; OLB, 100 percent). However, patients undergoing VTLB demonstrated a significant reduction in length of pleural drainage (1.36 +/- 0.25 days) and hospital stay (2.57 +/- 0.46 days) relative to patients undergoing OLB (3.20 +/- 0.34 days, 5.71 +/- 0.63 days; p < 0.05). Complications occurred in 2/22 VTLB patients (9 percent, 0 deaths) and 4/21 OLB patients (19 percent, 1 death). CONCLUSIONS: When compared with OLB, VTLB does the following: (1) provides equivalent specimen volume; (2) achieves equal diagnostic accuracy; (3) does not add to operative time or complications; and (4) reduces the time necessary for pleural drainage and length of hospital stay. Our findings suggest that VTLB is an effective and safe alternative to OLB in the diagnosis of interstitial lung disease.

Adult↗
PubMed1993

Cold ischemia and reperfusion each produce pulmonary vasomotor dysfunction in the transplanted lung.

Pulmonary vascular resistance is significantly increased in the transplanted lung. We hypothesized that the ischemic or reperfusion injuries incurred by the transplanted lung may produce pulmonary vasomotor dysfunction, which in turn may produce increased pulmonary vascular resistance. In a dog model of autologous lung transplantation, the purpose of this study was to examine the following mechanisms of pulmonary vasomotor control and to relate each of them to cold ischemia and to reperfusion: (1) endothelium-dependent cyclic guanosine monophosphate-mediated vasorelaxation (response to acetylcholine 10(-6) mol/L), (2) endothelium-independent cyclic guanosine monophosphate-mediated vasorelaxation (response to sodium nitroprusside 10(-6) mol/L), and beta-adrenergic cyclic adenosine monophosphate-mediated vasorelaxation (response to isoproterenol 10(-6) mol/L). Autologous right lung transplantation was performed in five dogs. At each of three times, two third-order pulmonary arteries were dissected from each transplanted lung and studied: control (immediately after harvest), cold ischemia (3 hours in 4 degrees C saline solution), and cold ischemia plus reperfusion (1 hour after lung reimplantation). The vasorelaxing effects of acetylcholine, sodium nitroprusside, and isoproterenol were studied in isolated pulmonary arterial rings, suspended on fine wire tensiometers in individual organ chambers. Statistical analysis was by analysis of variance. Results demonstrated significant dysfunction of beta-adrenergic cyclic adenosine monophosphate-mediated relaxation after cold ischemia alone, and this dysfunction was exacerbated by reperfusion. Endothelium-dependent cyclic guanosine monophosphate-mediated relaxation was not impaired by cold ischemia alone but was significantly impaired by reperfusion. Endothelium-independent cyclic guanosine monophosphate-mediated relaxation was not impaired by cold ischemia or reperfusion. We conclude that cold ischemia and reperfusion each produce different patterns of pulmonary vasomotor dysfunction. Cumulatively, such dysfunction may contribute to increased pulmonary vascular resistance in the transplanted lung.

Animals↗
PubMed1992

A comparison of outcome and cost of open vs. laparoscopic cholecystectomy.

One hundred elective completed laparoscopic cholecystectomies performed during the period July 1990 to June 1991 were prospectively analyzed for age, sex, and the study variables. A control group of 100 age- and sex-matched patients undergoing elective open cholecystectomy in the year prior to the advent of laparoscopic cholecystectomy was retrospectively analyzed. Both groups were comparable with regard to height, weight, severity of disease, and co-morbidity. The mean operative time for the laparoscopic cholecystectomy group was 107 min vs. 72 min for the open cholecystectomy group. Other significant differences included the use of cholangiography (24% vs. 93%), placement of drains (4% vs. 27%), and morbidity (3% vs. 7%). There was no mortality in either group. The mean length of hospital stay was 1.6 days for the laparoscopic cholecystectomy group vs. 4.8 days in the open cholecystectomy group. The resultant difference in hospital charges to the patient favored laparoscopic cholecystectomy with a mean charge of $6471 vs. $8896 for the open cholecystectomy group. The results of this study support the conclusions that laparoscopic cholecystectomy is a safe and effective alternative to open cholecystectomy and results in a significantly shorter hospital stay with considerable cost savings.

Adult↗
PubMed1992

The fifth sound.

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Child↗
PubMed1979

Modes of transmission of cholera in a newly infected population on an atoll: implications for control measures.

To determine the modes of transmission in a cholera epidemic in a newly infected population on an atoll, two studies were conducted, in which persons with cholera were individually matched, by age and sex, with neighbourhood controls. Among the first recognised cases, cholera was associated with frequent (daily or weekly) consumption of raw lagoon fish that had been salted and partially dried. Vibrio cholerae was isolated from the lagoon, which was contaminated by human wastes. During the declining phase of the epidemic, cholera was associated with consumption of raw clams, salt-fish, sardines, and other fish from the lagoon. When seafood from enclosed bodies of faecally contaminated water is frequently eaten raw, imported V. cholerae can become established and can be extremely difficult to eradicate.

Adolescent↗
PubMedDate not supplied

Laparoscopy-guided intracorporeal ultrasound accurately delineates hepatobiliary anatomy.

UNLABELLED: The purpose of this study was to develop a technique and assess the ability of a laparoscopic ultrasound probe to delineate biliary antomy and to determine the presence or absence of duct stones. METHODS: Five pigs had ultrasonography of biliary structures and liver at laparoscopy followed by cholangiograms and anatomical dissection. Five patients had ultrasonography of the biliary tract at laparoscopic cholecystectomy. RESULTS: All animals had adequate visualization of important hepatobiliary structure, and an optimal method of accessing these structures at laparoscopy was established. Patients had ultrasonography which used methods developed in the animal trial. All had adequate visualization of the entire common bile duct confirmed by cholangiography. Limitations in demonstrating the relationship of the cystic duct to the common duct were technical and can be corrected. CONCLUSION: Laparoscopic ultrasonography has significant potential for delineation of biliary anatomy and determination of presence or absence of duct calculi. Clinical implementation could minimize the risk of iatrogenic duct injury and the need for operative cholangiography.

Animals↗