Biomedical subjects
Publications and source records attributed to J R Mackenzie.
We describe the occurrence of a significant cosmetic blemish in the cheek of a young girl which was caused by extravasation of 'Lipiodol' from the lacrimal canaliculus. Erythema and swelling lasted for several months before resolving completely. This complication has not been reported in the English literature before.
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The purpose of this study was to investigate the influence of postnatal x-ray pelvimetry after caesarean section on the management of the subsequent pregnancy. The case records of 331 women delivered by casearean section in their first pregnancy were reviewed. By standard radiological criteria, the pelvis was considered to be inadequate in 248 (75%) of them and adequate in 83 (25%). Of the women with a radiologically inadequate pelvis, 172 underwent an elective caesarean section. Seventy-six were allowed vaginal delivery: 51 of these women delivered vaginally and 25 required an emergency caesarean section. Of the women with a radiologically adequate pelvis, 61 achieved a vaginal delivery and 22 were delivered by caesarean section. All of the three cases of uterine rupture occurred in women with a radiologically adequate pelvis. This study suggests that x-ray pelvimetry is not a good predictor of the outcome of a trial of vaginal delivery. We conclude that the practice of routine postnatal pelvimetry should be abandoned.
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Severity of illness or injury should be the primary justification for aeromedical transport. To determine whether differences in patient severity were detectable in air transport programs, helicopter-transported patients were examined by three established physiologic scores: the Trauma Score, the Acute Physiology and Chronic Health Evaluation Score, and the Rapid Acute Physiology Score. These scores were obtained prospectively on 1,868 consecutive patient transfer requests from six air medical services for periods ranging from two to six months. A patient meeting strict physiologic criteria was considered critically ill. Overall, 42.6% of the patients (range, 34.8% to 53.3%) were considered critically ill. Patients transported from inpatient hospital units and patients with cardiac disease were less likely to be critically ill than those transported emergently from scenes of accident or from emergency departments. There were also significant differences between programs with regard to the percentage of critically ill patients transported. This study suggests that physiologic scoring may be useful in comparing air ambulance programs and that a majority of patients transported by these services may not be critically ill.
The purpose of this study was to measure the predictive power of Acute Physiology and Chronic Health Evaluation (APACHE II) with respect to mortality in a group of seriously injured patients and to compare this predictive power with that of the Trauma Score (TS) and the Injury Severity Score (ISS). Six hundred ninety-one helicopter-transported patients were studied. Individual logistic regressions demonstrated that all three scores had significant predictive power when considered individually (TS chi 2 = 136, p less than .0001; APACHE II chi 2 = 171, p less than .0001; ISS chi 2 = 109, p less than .0001). In addition, each severity score added significantly to the predictive power in a stepwise logistic regression (TS chi 2 = 15, p less than .0001; APACHE II chi 2 = 45, p less than .0001; ISS chi 2 = 15, p less than .0001). Areas under the receiver operating curves for the three scores were not significantly different (TS 0.8116, SD 0.0245; APACHE II 0.8515, SD 0.0204; ISS 0.7967; SD 0.0223). APACHE II is a good predictor of mortality, and its predictive power is complemented by TS and ISS.
A multi-institutional study was undertaken to define the predictive power for mortality of the Rapid Acute Physiology Score (RAPS) in a large and diverse group of transported patients. RAPS is a truncated version of the Acute Physiology and Chronic Health Evaluation (APACHE II) score that uses definitions and weighting consistent with APACHE II, but is modified to provide a consistent score just before transport, just after transport, and to use the most deranged (worst) physiologic values during the initial 4 h after arrival at the receiving hospital. During an 8-month period, 1,927 patients transported by six helicopter emergency medical service programs were studied. Over 97% (1,881) of the patients had RAPS obtained before and after transport to the receiving hospital and 92.6% (1,785) had APACHE II scoring completed after hospital admission. Receiver operating curves demonstrate similar predictive power for RAPS and APACHE II (both based on the most deranged physiologic values during the initial 24 h after admission). Before- and after-transport RAPS were also highly predictive of mortality. RAPS appears to be a reliable and highly predictive measure of patient severity/physiologic stability before and after transport to critical care.
A radial "high-performance" thin-layer chromatographic (HPTLC) method is described by which the percentages and ratios of phosphatidylinositol, sphingomyelin, lecithin, phosphatidylethanolamine, phosphatidylglycerol, and dimethyl phosphatidylethanolamine may be determined simultaneously. An additional method for radial HPTLC determination of saturated phosphatidylcholine is described. We report results of application of these methods to greater than 2000 specimens of amniotic fluid from both diabetic and nondiabetic cases.
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The purpose of this study was to determine the frequency of electrolyte abnormalities in emergency department patients, to assess the proportion of these abnormalities affecting patient outcome, and to develop a set of clinical criteria to allow selective ordering of serum electrolytes. The ordering physicians completed questionnaires describing the clinical presentations of 1,031 patients on whom electrolytes were requested. For every patient with abnormal electrolyte values, the chart was reviewed to ascertain whether this was a clinically significant electrolyte abnormality (CSEA). The clinicians' responses to the questionnaires were used to construct a clinical criteria set predictive of CSEAs. Five hundred forty-five patients (52.9%) had one or more abnormal electrolytes, but only 161 patients (15.6%) had CSEAs. A set of ten clinical criteria detected 159 of 161 CSEAs (98.8% sensitivity) and would have avoided the ordering of electrolytes in 262 cases (29.9% specificity). At a cost to the patient of $20 per set of electrolytes ordered, detection of 159 CSEAs using the clinical criteria would cost $96.73 per CSEA detected. Detection of the additional two CSEAs by ordering electrolytes on all patients in the series would cost an additional $5,240. If the accuracy of these clinical criteria is confirmed in other settings, they may be useful guidelines for reducing laboratory charges without compromising patient care.
This study tested the hypothesis that rapidly expanded random pattern skin flaps demonstrate enhanced resistance to bacterial invasion from intradermal injection of Staphylococcus aureus in a porcine model. Sites for a 6 X 12 cm expanded, a 6 X 9 cm sham-expanded, and a 6 X 6 cm acute random pattern skin flap were outlined, but not elevated, on the backs of 14 white pigs. A 450-cc tissue expander inserted beneath the panniculus carnosus at the site for expansion was sequentially filled to the limits of skin viability each day for 5 days. At the sham site a tissue expander was similarly inserted but left unexpanded; the acute flap site was left undisturbed. On day 8, flaps were elevated, immediately sutured in place, and 0.1 ml of saline solution containing 10(7) Staphylococcus aureus inoculated intradermally at four corresponding sites in each flap and at three sites in normal skin. In seven animals these sites were at the proximal base of the flaps; in seven others the sites were distal. The resulting areas of erythema and skin ulceration were measured on each of the next 3 days and the measurements compared. At corresponding proximal sites, the mean area of erythema and ulceration measured over the next 3 days in expanded flaps (31.2 mm2) and in sham-expanded flaps (33.8 mm2) was significantly less than in acute flaps and control skin (47.5 mm2, 43.4 mm2, p less than 0.05). Measurements in the rapidly expanded flaps were not significantly different than those in the sham-operated expanded flaps.(ABSTRACT TRUNCATED AT 250 WORDS)
The question of whether physicians are cost effective in helicopter emergency medical services (HEMS) transport remains an unresolved issue. During a four-month study period, all physician-specific contributions to medical care were recorded by means of a questionnaire that was completed by the flight physician and the flight nurse after each flight. In the judgment of the nurse, the flight physician made a unique and important contribution to the care of the patient in 38 of 174 flights (22%) completed during the study. Judgment, the most common contribution, was cited on 29 flights (17%). Both skill and judgment were contributed on seven additional flights (4%), and skill alone on only two flights (1%). Judgment was exercised most frequently in making diagnoses, initiating critical medical treatments, and determining destination. The cost to this program of providing physicians is approximately $85,000 per year, or 7% of an annual budget of approximately $1.2 million. Flight physicians make a substantial and important contribution to patient care in HEMS operations, exercising critical judgment regarding diagnosis, medical treatment, and disposition in 22% of transports. The benefits of this contribution far outweigh the 7% program cost.
Helicopter emergency medical services (HEMS), which are both expensive and resource intensive, lack objective measures for system evaluation. We computed the Therapeutic Intervention Scoring System (TISS) score for all patients during six consecutive months of service in a HEMS program to assess the value of this score for measuring the performance of the program. The TISS assigns values ranging from 1 to 4 for 57 medical and surgical interventions to measure the intensity of care during a 24-hour period. The TISS was recorded for 203 patients beginning at the time HEMS transport was requested. These flights also were classified as appropriate or inappropriate, given the information available, when HEMS care was initiated and days later when diagnostic evaluation was complete. Classification was done on the basis of whether the following criteria (potentially) ensure patient survival or improve outcome: speed of transport, presence of a medically skilled flight team, or the helicopter's ability to overcome hostile environmental conditions. The mean TISS score for all patients was 21.7. One hundred thirty-two of 203 flights (65%) were thought to be medically necessary, both at the time HEMS was requested and later (mean TISS, 28.1; analysis of variance, P less than .001). Thirty-four flights (17%) were thought to be appropriate using the information available at flight time, but not after the diagnostic workup was completed (mean TISS, 10.0). Thirty-six patients (18%) did not appear to require helicopter transport at any time, and had a mean TISS of 9.0. We conclude that TISS is a useful, objective measure of the performance of a HEMS program, and it should be tested in other HEMS programs.
We have quantitatively examined the effect of rapid sequential skin expansion on capillary blood flow in the porcine random flap model in order to determine the relation between the increased survivability of expanded random flaps and capillary blood flow. Three 6 X 20 cm random flaps were tattooed on the backs of six small (20-kg) pigs. One flap was not manipulated (control). A 450-ml expander was inserted at the base of the second flap and left in place (sham). At the base of the third flap a 450-ml expander was inserted and each day for 5 days sequentially filled to the limits of skin viability as determined by vital dye staining (expanded). Capillary blood flow was measured on day 8 by measurement of radioactivity after injection of 15-microns radiolabeled microspheres. Samples were taken at 4-cm intervals from the base of each flap. Rapid expansion led to significant increases in capillary blood flow in expanded skin and to enhanced preservation of capillary flow after elevation of random pattern flaps based on expanded skin compared to sham and to control tissues. This correlates with and explains at least in part our previous observation of improved length of survival of flaps raised on expanded skin.
Femoral neck fractures are uncommon but serious injuries in young adults, with high rates of nonunion and avascular necrosis reported. This study was undertaken to examine the relationship between the mechanism and severity of injury, anatomic site of fracture, health status, and method of therapy on the incidence of these complications in young adults. The hospital records of 32 skeletally mature patients between the ages of 15 and 50 years (mean, 33) treated for femoral neck fracture between 1975 and 1982 were reviewed, and data analyzed for the 25 patients with a minimum 2-year followup (mean, 61 months). Data pertaining to the cause of injury, fracture pattern, prior health status, overall injury severity, method of fracture treatment, and long-term outcome were analyzed. Nonunion of the fracture site was observed in five (20%); avascular necrosis in nine (36%). Of patients with subcapital fracture 83% developed nonunion or avascular necrosis, compared to 21% with true femoral neck fracture (p = 0.05). There was no difference in cause of injury, overall injury severity, degree of comminution, displacement, method of treatment, or prior health status between those with and without complications. In this study, high rates of nonunion and avascular necrosis were seen after all types of femoral neck fracture in young adults, but were more often associated with subcapital fracture. These complications of hip fracture appeared to be independent of health status, method of treatment, or mechanism or severity of injury.
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We studied the physiologic accommodation of tissues to 5-day expansion in a porcine random flap model to assess the time taken to expand skin to provide early coverage of traumatic defects. Three 6 X 20 cm random flaps were outlined but not elevated on the backs of 12 small (20-kg) pigs. One flap was not manipulated (control). A 450-ml expander was inserted at the base of the second flap and left in place (sham). At the base of the third flap a 450-ml expander was inserted and sequentially filled to the limits of skin viability each day for 5 days (expanded). Skin tension produced by the pressure of expansion and tissue oxygen (TpO2) in each flap were measured before and after each manipulation. Flaps were raised on day 8, and survival determined on day 15. Creation of the pocket reduced TpO2 to 55% of control values, expansion to 17.5% of control. Within 24 hours both sham and expanded had recovered to 80% of control values. After the second expansion, recovery from hypoxia was again almost complete after 24 hours. Recovery after subsequent expansions was less complete, but 3 days after the final expansion there was no statistical difference between TpO2 values in expanded, sham, and control groups. High pressures generated in the flap by expansion also returned to near normal within 24 hours. Flaps utilizing expanded skin survived to greater length (14.2 cm) than did sham (11.6 cm) or control (7.2 cm) flaps (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Long-term survivors with traumatic ruptures of the aorta that are not detected at the time of injury manifest pseudoaneurysms. We reviewed a ten-year experience with pseudoaneurysms of the thoracic aorta to correlate anatomic and roentgenographic findings in this unusual group of patients. Eleven patients, who were 28 to 65 years of age, had abnormal chest findings one to 36 years after their injuries. Nine patients had calcification that was visible on the plain chest film, and two patients had calcification that was visible on computed tomography. Nine of the 11 pseudoaneurysms, all of which were distal to the left subclavian artery, were saccular and involved only the medial aspect of the aortic wall. Anatomically, they appeared to have been confined in a space bordered by the mediastinal pleura, pulmonary artery, left mainstem bronchus, and normal aorta. Pseudoaneurysms that occur on the medial aortic wall at the level of the ligamentum arteriosum may be more stable because of anatomic confinement by stable adjacent structures.