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Biomedical subjects

C Beattie

Publications and source records attributed to C Beattie.

65 records · Page 4Linked to original sources
PubMed1988

Evaluation of the Dinamap continuous blood pressure monitor.

The validity of the Dinamap automated oscillometric blood pressure monitor, an instrument frequently used for continuous monitoring in intensive care settings, was evaluated in comparison to two standard methods of blood pressure measurement. Oscillometric monitoring was compared to random-zero sphygmomanometry in 28 ambulatory subjects, using the instruments in a random order. The oscillometric monitor overestimated random-zero systolic pressure (mean difference = 5.7 mm Hg; P less than 0.001), but did not differ in diastolic pressure (difference = 1.3 mm Hg, P greater than 0.3). Correlation (r) between methods was 0.94 for systolic pressure and 0.83 for diastolic pressure. Repeatability of sequential measures did not differ between methods. To evaluate the oscillometric monitor in the intraoperative setting, it was used simultaneously with a radial artery catheter to measure blood pressure in 14 patients undergoing peripheral vascular or other major surgery. The oscillometric monitor underestimated intra-arterial systolic pressure (mean difference = -9.4 mm Hg; P less than 0.002), but overestimated intraarterial diastolic pressure (difference = 5.7 mm Hg; P less than 0.005). There was no difference in mean arterial pressure (P greater than 0.1). Correlation between methods was 0.88 for systolic, 0.71 for diastolic, and 0.79 for mean arterial pressure. The oscillometric instrument had a sensitivity of 63% and specificity of 97% in detecting intraarterial systolic pressures of 160 mm Hg or greater, and a sensitivity of 89% and specificity of 89% in detecting intraarterial systolic pressures of 100 mm Hg or less. These findings demonstrate differences between the oscillometric monitor and other standard methods of blood pressure measurement.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗
PubMed1988

Cyclic elevation of intrathoracic pressure can close the mitral valve during cardiac arrest in dogs.

Mitral valve closure during cardiopulmonary resuscitation may result from direct cardiac compression. An alternative hypothesis is that with a rise in intrathoracic pressure, mitral valve closure can occur but may be influenced by whether the lungs are inflated or deflated. To test this hypothesis, we placed a large-bore cannula into the thoraces of 11 dogs. Intrathoracic pressure was changed by inflating and deflating the thorax through the cannula while the airway was open, as well as by inflating and deflating the lungs with the thoracic cannula clamped. Mitral valve motion was observed with two-dimensional echocardiography from the right chest wall or esophagus in eight of the dogs. With a rise in intrathoracic pressure from thoracic inflation, all eight dogs showed closure of the mitral valve, while with thoracic deflation, all showed mitral valve opening. With lung inflation and deflation alone, however, the mitral valve remained open throughout the cycle. In seven dogs, with thoracic inflation, the peak gradient from the left ventricle to the left atrium was (mean +/- SEM) 18 +/- 4 mm Hg and the average gradient was 7 +/- 3 mm Hg, while with lung inflation alone, the average gradient was -1 +/- 1 mm Hg (p less than 0.01 vs. thoracic inflation). Thus, mitral valve closure, with concomitant retrograde pressure gradients, can be produced by intrathoracic pressure changes with accompanying lung deflation. With lung inflation alone, however, the mitral valve remains open, and there are no significant transmitral pressure gradients. We conclude that intrathoracic pressure changes can cause the mitral valve to close or to remain open, depending on how intrathoracic pressure is generated.

Animals↗
PubMed1988

Mesoatrial shunt hemodynamics.

Hemodynamic profiles were obtained for patients with portal hypertension secondary to the Budd-Chiari syndrome who underwent mesoatrial shunting procedures. In contrast to the well-known hyperdynamic, low-resistance state of chronic cirrhosis, patients with the Budd-Chiari syndrome had normal cardiac index and systemic vascular resistance values before anesthesia and surgery. Opening the mesoatrial shunt produced a 46% (p less than 0.01) increase in cardiac index and a 38% (p less than 0.01) decrease in overall systemic vascular resistance. Right atrial pressure and pulmonary capillary wedge pressures were sharply increased--by 5.3 mm Hg and 4.7 mm Hg, respectively (p less than 0.01). A mathematical model was developed to assess the cause of the observed changes in systemic vascular resistance. The model suggests that the hemodynamic changes seen with shunt opening are unlikely to be the result of shunt effects alone and that dilatation of peripheral vascular beds is probable. Thus shunting converts the normal systemic vascular resistance and cardiac index of patients with the Budd-Chiari syndrome to the high-output, low-resistance state seen in patients with chronic cirrhosis. Although the physiology is complex, we conclude that the data are consistent with release, by the shunting process, of a systemic vasodilator.

Adult↗
PubMedDate not supplied

Perioperative rate-related silent myocardial ischemia and postoperative death.

A case is presented that demonstrates heart rate (HR)--related silent myocardial ischemia occurring preoperatively, subsiding intraoperatively, then recurring and leading to a post-operative cardiac death in a patient undergoing peripheral vascular surgery. This case illustrates that patients may have an ischemic threshold for HR whereby recurrent depression of the ST segment may occur during increase of HR to rates as low as 80 to 85 beats per minute (bpm), even in the absence of acute blood pressure (BP) changes. Myocardial ischemia may be HR related; however, the authors are not aware of a case that demonstrates repeated episodes of rate-related ischemia occurring at HRs well below the 100 bpm traditional definition of tachycardia. The authors conclude that patients at risk for perioperative myocardial ischemia should be identified and the hemodynamic management of these patients should include control of HR. This implies control of the physiologic variables that influence HR, along with the use of beta-adrenergic blockers. This case also demonstrates the value of Holter monitoring for ischemia, which, when done preoperatively, can detect patients at risk for unfavorable cardiac outcomes. Ischemia monitoring also may be useful during the intraoperative and postoperative periods, a time when ischemia is often silent and undetected. The early recognition of ischemia would allow for anti-ischemic interventions, which could decrease the morbidity and mortality of patients at risk for perioperative cardiac complications.

Arrhythmias, Cardiac↗
PubMedDate not supplied

The difficult airway: mechanisms for effective dissemination of critical information.

The perioperative management and dissemination of critical information regarding a patient with an unexpected difficult intubation, including successful application of a difficult airway algorithm (Figure 1), are described. Documentation and dissemination of critical information include entry of patient data into an in-hospital computerized Difficult Airway/Intubation Registry, simultaneous application of a highly visible Difficult Airway/Intubation Patient Wrist Band (coded for access to computer registry), summary reports distributed to health care providers, and enrollment of the patient in the Medic Alert Foundation International's newly established category difficult airway/intubation for 24-hour access. We postulate that the widespread use of the procedures described in this report may reduce the contribution of unexpected difficult airway/intubation to anesthetic morbidity and mortality.

Algorithms↗
PubMedDate not supplied

Epidural morphine decreases postoperative hypertension by attenuating sympathetic nervous system hyperactivity.

Twenty-four adults who were undergoing operations on the abdominal aorta were enrolled in a randomized, double-blind, placebo-controlled study in which epidural morphine sulfate (6 mg) was employed to attenuate the sympathoadrenal response to surgery to evaluate the possible contribution of sympathetic nervous system hyperactivity to postoperative hypertension. Patients who received epidural morphine required less parenteral morphine in the 24 hours following surgery, had lower analogue pain scores, and had markedly lower plasma norepinephrine levels when compared with patients in the control group who received an identical volume of saline in the epidural space. Epidural morphine had no effect on plasma epinephrine or arginine vasopressin levels. Fewer patients in the morphine group (4 of 12 vs 9 of 12 patients in the saline group) required treatment for hypertension (mean arterial blood pressure, greater than or equal to 110 mm Hg) in the 24 hours following surgery. In addition, patients in the morphine group had lower blood pressures in the 24 hours following surgery. These data suggest that sympathetic nervous system activity and not adrenal epinephrine or pituitary secretion of arginine vasopressin is responsible for the development of hypertension following aortic surgery. Furthermore, epidural narcotics appear to provide a means of attenuating this response.

Adult↗
PubMedDate not supplied

Double-blind randomized evaluation of intercostal nerve blocks as an adjuvant to subarachnoid administered morphine for post-thoracotomy analgesia.

BACKGROUND AND OBJECTIVES: Thoracotomy is associated with pain and compromised pulmonary function. Intercostal nerve blocks (INB) and subarachnoid morphine (SM) act on different portions of the pain pathway. Each is effective for post-thoracotomy pain relief. The combination of these two modalities in relieving post-thoracotomy pain and improving postoperative pulmonary function has not been investigated. METHODS: In a double-blind study, 20 patients undergoing lateral thoracotomy for lung resection were randomized to receive 0.5 mg SM preoperatively and INB with bupivacaine (INB+) prior to wound closure or 0.5 mg SM with INB using saline (INB-). Visual analog scale pain scores at rest, with cough, and with movement of the ipsilateral arm, forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC) were measured at 4, 24, 48, and 72 hours after the operation. Opioid use was measured during the initial 24 hours after the operation. RESULTS: At 4 hours, the INB+ group demonstrated better FEV1 (56.6% vs. 40.4% of baseline, P < .05) and FVC values (54.6% vs. 39.6% of baseline, P < .05) and less resting and cough pain (P < .05). However, FEV1 continued to decline in the INB+ group at 24 hours to lower than the INB- group although pain scores were similar beyond 4 hours. Opioid usage during the first 24 hours was similar (INB-, 16.7 mg vs. INB+, 13.2 mg, P = .7). CONCLUSIONS: Although postoperative INB provided modest improvements in pain and pulmonary function when used as an adjuvant to 0.5 mg SM for post-thoracotomy analgesia, the benefits were transient. The authors do not recommend adding INB for patients undergoing lateral thoracotomy who receive 0.5 mg SM.

Aged↗