Biomedical subjects

R C Mackersie

Publications and source records attributed to R C Mackersie.

44 records · Page 3Linked to original sources

PubMed1988

Base deficit as a guide to volume resuscitation.

The base deficit (BD), is a potentially useful indicator of volume deficit in trauma patients. To evaluate BD as an index for fluid resuscitation, the records of 209 trauma patients with serial arterial blood gases (ABG's) were reviewed. The patients were grouped according to initial BD: mild, 2 to -5; moderate, -6 to -14; and severe, less than -15. The volume of resuscitative fluid administered, change in BD, mean arterial pressure (MAP), and presence of ongoing hemorrhage were analyzed for differences between the BD groups. The MAP decreased significantly and the volume of fluid required for resuscitation increased with increasing severity of BD group. A BD that increased (became more negative) with resuscitation was associated with ongoing hemorrhage in 65%. The data suggest that the BD is a useful guide to volume replacement in the resuscitation of trauma patients.

Adolescent↗

PubMed1987

Impact of a trauma system on outcome of severely injured patients.

We examined the impact of a trauma system on the survival of patients with a Trauma Score of 8 or less. We compared the observed survival with that predicted using a method that calculates the probability of survival (Ps) based on age, physiologic score, and anatomic severity of injury. Of 3394 patients triaged to trauma centers in a 12-month period, 283 (8.3%) had a Trauma Score of 8 or less. Sufficient data were available in 189 patients with blunt trauma to make the survival comparison. The Ps was 18%; the observed survival was 29%. Of 60 patients with penetrating trauma and complete data, the Ps was 8%; the observed survival was 20%. We attribute the improved survival to the integration of prehospital and hospital care and expeditious surgery.

Adult↗

PubMed1987

The role of pulmonary lymphatics in the clearance of hydrostatic pulmonary edema.

Pulmonary lymphatics are believed to play a major role in preventing the formation of pulmonary edema, but their role in clearance of established edema has not been defined. To measure the lymphatic contribution to the clearance of acute hydrostatic pulmonary edema, a lung lymph fistula was established in 16 anesthetized sheep. Pulmonary edema was induced by a rapid volume infusion of Ringer's lactate (six animals) or homologous plasma (six animals). Four control animals received no fluid. Simultaneous measurements of lymph flow and extravascular lung water (EVLW) were made. Data were analyzed for the resolution phase of pulmonary edema. The contribution of the pulmonary lymphatics to resolution was expressed as a percentage of total lung water resolved. Resolution rates for crystalloid and plasma infusion groups were 3.8 +/- 2.4 cc/kg/hr and 2.7 +/- 1.0 cc/kg/hr, respectively. There was no statistically significant difference between the groups in terms of EVLW increases or resolution rates. Net measured pulmonary lymph flow during the resolution phase of pulmonary edema was 0.33 +/- 0.18 cc/kg/hr and 0.39 +/- 0.20 and accounted for only 8.8 and 14.6% of resolved pulmonary edema in these respective groups. These data suggest the pulmonary lymphatic drainage plays a very minor role in the clearance of acute hydrostatic edema. The lungs appear to be capable of resolving as much as 40% per hour of increased extravascular lung water produced under these circumstances.

Animals↗

PubMed1987

Continuous epidural fentanyl analgesia: ventilatory function improvement with routine use in treatment of blunt chest injury.

The safety and effectiveness of continuous epidural fentanyl analgesia (CEFA) in the treatment of blunt chest injury was evaluated by reviewing its use in 40 patients with multiple rib fractures or flail chest. Ventilatory function tests were performed before and after the institution of CEFA and mean changes calculated. The use of CEFA was associated with significant improvement in vital capacity and maximum inspiratory pressure (p less than 0.05). Minute ventilatory volumes and tidal volumes also showed slight improvement. There was no significant change in arterial CO2 tension with the institution of CEFA, and 85% of patients had good pain relief with CEFA. None of these patients required any other narcotic administration. Documented complications associated with CEFA included pruritus, urinary retention, and transient hypotension. There were no major associated complications. The results suggest that CEFA is a safe, effective method of pain control that acts to improve ventilatory function in patients with blunt chest trauma.

Adult↗

PubMed1986

Self-induced subcutaneous air mimicking a gas-forming infection.

We describe three cases of self-induced soft-tissue gas among inmates at a prison. This behavior was specifically designed to gain hospitalization and relied on the simulation of a necrotizing soft-tissue infection. Two cases were treated by surgical exploration only. The third case was treated non-surgically after the etiology was suspected. The possibility of self-induced injury or manufactured physical signs is high in the prison population, and the presence of isolated physical signs or symptoms should be cause for suspicion. The inmates in these cases used manufactured signs and professed symptoms to extract themselves successfully from a prison environment.

Adult↗

PubMed1984

The prehospital use of external counterpressure: does MAST make a difference?

Military anti-shock trousers (MAST) have achieved widespread civilian usage because of reported effectiveness in treating hypovolemic shock. The literature, however, consists of either case reports or series in which no controls were evaluated. No published reports exist which compare similar groups of patients treated with and without MAST in the pre-hospital setting. We reviewed the paramedic and emergency department records of 226 patients sustaining moderate to severe trauma who were transported to San Francisco General Hospital by paramedics over a 15 month period. MAST usage during this period was approximately random as a result of logistical and training constraints. For analysis, patients were divided into two groups: those in whom MAST was applied and inflated during transport and those in whom it was not used. Paramedic interventions other than MAST were similar in both groups. Trauma Scores (TS), and blood pressure index (greater than 90 = 4, 70-89 = 3, 50-69 = 2, 0-49 = 1, no pulse = 0), were calculated for initial field observations and initial emergency room evaluation after hospital arrival. Patients with isolated head injury were excluded. The average change in TS and BP index (E.R.--field value) was calculated for MAST and non-MAST groups of patients. Mortality and total field times were also evaluated. Average TS and BP index increased slightly in both groups. Use of MAST produced no significant improvement in trauma score, BP index, or mortality over non-MAST patients. There was no demonstrable field benefit of MAST in fully arrested patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗

PubMed1984

Morphologic and physiologic correlates of increased extravascular lung water.

The thermal-green dye indicator dilution method for measuring extravascular lung water (EVLW) has been extensively validated against gravimetric EVLW, but no reports to date have correlated in vivo EVLW with pulmonary physiologic parameters or postmortem lung morphologic findings. A predetermined level of hydrostatic edema was created in 12 swine by the variable inflation of a left atrial Foley balloon. EVLW, arterial and mixed venous blood gases, and mixed expired gases were before balloon inflation and periodically throughout the experiment. The animals were killed by rapid excision of the lungs, which were then reinflated and frozen in liquid nitrogen. Postmortem morphometrics were performed by photographing random sections of the lungs while still frozen. A blinded observer measured perivascular cuff width, interlobular septal width, and percent of alveoli flooded on each section. Perivascular cuff width:vessel diameter ratio correlated linearly with EVLW (r2 = 0.76; p less than 0.0001) and increased 25% for each 5 ml/kg of EVLW. Alveolar flooding did not begin until EVLW had doubled from normal to 11.4 ml/kg but then increased linearly with EVLW, reaching 60% flooding at 21 ml/kg. Increase in shunt fraction correlated linearly with increases in EVLW (r2 = 0.76; p less than 0.001) and increased approximately 10% for each EVLW increment of 5.0 ml/kg. We conclude that in vivo EVLW measurements correspond closely to more conventional morphologic and physiologic measurements and sensitively detect all levels of pulmonary edema from minimal perivascular cuffing to fulminant alveolar flooding.

Animals↗

PubMed1983

Pulmonary extravascular fluid accumulation following intracranial injury.

Previous investigations have reported an 11 to 71% incidence of pulmonary edema following CNS injury, based on post-mortem examinations. No premortem assessment to date has been made of the frequency and severity of in vivo pulmonary fluid accumulation following acute head injury. The thermal green dye technique was used to objectively determine extravascular lung water (EVLW) in 18 comatose patients with severe acute intracranial injuries resulting from trauma or spontaneous subarachnoid hemorrhage. Patients with aspiration, lung contusion, or pneumonia were excluded from the study. Control values for EVLW were obtained on admission from a group of 13 traumatized patients without head injury or evidence of pulmonary disease or injury. Intracranial injury patients who had EVLW values greater than two standard deviations above the control group mean were considered to have pulmonary edema. The incidence of pulmonary edema in this series was 50% (9/18). Extravascular lung water was determined post mortem in five patients using the gravimetric method of Pearce. The results suggest that pulmonary edema is a distinct clinical event occurring frequently after acute intracranial injury. Edema appears to be mediated by increased pulmonary microvascular permeability, and is not primarily dependent on postinjury changes in intracranial pressure or pulmonary vascular pressures.

Blood Pressure↗