Relationship between arterial and venous bicarbonate values.

We determined the clinical efficacy of using the venous CO2 value, as obtained with routine "electrolytes", in acid-base management. Venipuncture samples for venous CO2 content and chloride concentrations were obtained in 336 patients with arterial blood pH, PaO2, PaCO2, and oxygen saturation determinations. The linear correlation between actual calculated arterial HCO3- and the measured venous CO2 was significant (P less than .001). Using venous CO2, chloride, and arterial pH values, we present various prediction equations for estimating arterial HCO3-. We determined the effects of time delay, exposure to air, and acute changes in arterial blood pH and PaCO2 on venous CO2 levels. Venous CO2 determinations should not be substituted for the arterial HCO3 value in the Henderson-Hasselbalch equation to calculate arterial blood pH or PaCO2. Clinically, the venous CO2 value has little direct use, but when venous CO2 content is abnormal, it should alert the clinician to the need for obtaining arterial blood gas and pH values.

Cooperative study of hospital frequency and character of transient ischemic attacks. VIII. Risk factors.

A total of 969 (73%) of 1,328 patients with cases of suspected transient ischemic attacks (TIAs) who came to six institutions during a 21-month period were followed up. Factors were identified and prospectively analyzed for risk for further TIAs, stroke, and deatn. A history of multiple carotid artery TIAs was significantly related to further TIAs. A single TIA placed the patient at greater risk for early infarction. Older age, male sex, and unreliability to take dangerous medication were risk factors for cerebral infarction. Anticoagulant therapy, older age, male sex, diabetes mellitus, heart disease, abnormal ECG, and poor surgical risk were factors for death. The increased mortality associated with anticoagulants was confined to the older age group. While white patients treated with antiplatelet-aggregating agents had a lower mortality than those treated otherwise, this was not true amont black patients.

Prevailing patterns and predictor variables in patients with acute tubular necrosis.

The courses of 276 acute tubular necrosis patients referred for dialysis were reviewed in search for prognostic indicators. Sixty-three percent survived. Of 28 possible predictor variables, a posttoxic cause and nonoliguria were favorable, whereas myocardial infarction and peritonitis affected survival unfavorably. Total pareneral nutrition influenced survival favorably only in those with multiple complications or peritonitis. No single variable or combination predicted a lethal outcome. Since survivors were frequently restored to complete health, we advocate an aggressive therapeutic approach even in the face of multiple complications.

Cooperative study of hospital frequency and character of transient ischemic attacks.

Information was collected among six participating medial centers on frequency of performance and the percentage of abnormality of 30 tests performed on patients with complaints suggesting transient ischemic attacks (TIAs). A number of these were commonly performed and commonly exhibited abnormalities. Although the diagnosis of TIA is made by history and physical examination, these tests were of value in aiding the physician to determine possible causes of TIA, to detect risk factors of associated conditions, to rule out alternative diagnoses, and to assess the patient's ability to tolerate different types of therapy.

Cooperative study of hospital frequency and character of transient ischemic attacks. VI. Patients examined during an attack.

Examination during an episode of transient ischemic attack (TIA) was performed on 121 of 1,307 patients suspected of having a single type of TIA. This examination supported the diagnosis of TIA in 79 patients and contributed to the establishment of a diagnosis other than TIA in 42. Although the examination increased diagnostic reliability, it did not always result in a definite diagnosis. The most common neurologic findings during a TIA were weakness of an arm or side of the face. Important findings not suggested by history included visual defects and blood pressure fluctuation. Also unexpected were the absence of findings such as sensory deficits in the presence of sensory complaints, retinal emboli, and cardiac abnormalities. Severe arteriosclerotic disease was less evident, the attacks were longer and more severe, and monocular blindness was rare.

Cooperative study of hospital frequency and character of transient ischemic attacks. V. Symptom analysis.

All patients (1,328) suspected of having transient ischemic attacks (TIA) who came to six institutions during a 21-month period were identified. Symptoms and symptom complexes were related to the clinical diagnoses by cross-tabulation, factor analysis, and discriminant analysis. The diagnoses obtained by the discriminant analysis program were comparable to those of reviewing clinical neurologists. Symptoms of importance in the vertebral-basilar system (VBS) were bilateral visual blurring, diplopia, ataxia, and dizziness; In either carotid system (CAS), ipsilateral monocular visual disturbance anc contralateral weakness or sensory complaints; in the left CAS, language disturbances; and in those whose ultimate diagnosis was not TIA, loss of consciousness, confusion, and bilateral leg weakness. Patients with VBS TIAs have symptoms common to conditions that are not TIA and have a greater variety of symptoms and more combinations of symptoms than CAS TIA.

Cooperative study of hospital frequency and character of transient ischemic attacks. IV. The reliability of diagnosis.

All patients (1,328) suspected of having transient ischemic attacks (TIA) who came to six institutions over a 21-months period were identified. Each case was reviewed by a neurological investigator, and a definite diagnosis of TIA was supported in 39% and ruled out in 30%. The reliability of the neurologist's review diagnosis was assessed by three methods, and close agreement (84% to 93%) was obtained. Factors demonstrated to effect the diagnosis were historical information, neurological training of the examiners, type of symptom complex, presence of carotid artery bruits, and examination during an attack.