On pulsus paradoxus

An abnormal amount of pulsus paradoxus may be produced in normal volunteers, for teaching purposes, by having them inspire and expire against resistance.     

Measurement of pulsus paradoxus

Pulsus paradoxus is a valuable clinical sign when there is a greater than 10 mm Hg drop in peak systolic blood pressure during normal inspiration. Although the exact mechanism is not known, tense fluid accumulation within the pericardial sac impairs left ventricular filling during inspiration when right ventricular filling is increased. This causes an exaggerated reduction in systolic blood pressure during inspiration. Critical care nurses need to become familiar with the three methods of measuring pulsus paradoxus: palpation, cuff sphygmomanometry, and arterial wave formation. Nurses should practice and become skilled at measuring a greater than 10 mm Hg change.     

Continuous Noninvasive Determination of Pulsus Paradoxus: A Pilot Study

Objective: To evaluate two methods of continuous, noninvasive monitoring of pulsus paradoxus (PP). Methods: A single-subject, nonblind assessment was conducted of the ability of noninvasive monitoring techniques to measure experimentally induced PP. Variable degrees of PP were induced in a healthy adult breathing through a oneway valve to which a series of external airway resistances were added. Intra-arterial pressure (IAP), finger arterial blood pressure (FINAP), pulse oximeter pulse waveform, and chest wall motion were continuously recorded. For each resistance, PP was calculated from the IAP (PP_IAP) and the FINAP (PP_FINAP) recordings. PP was measured manually (PP_manual) in the opposite arm. The percentage pulse waveform decrease on inspiration (%PWD_pleth) was derived from the oximeter pulse waveform. These measurements were compared with the PP_IAP. Bias was assessed as the mean difference between PP measures. Results: PP_FINAP, was highly correlated with PP_IAP (r = 0.96; 95% CI 0.93 to 0.98; p < 0.0001). There was a weak correlation between PP_manual and PP_IAP (r = 0.27; 95% CI -0.05 to 0.55; p = 0.0963). The %PWD_pleth correlated with PP_IAP (r = 0.59, 95% CI 0.32 to 0.78; p = 0.0002). Bias was -1.515 ± 5.6 mm Hg between PP_IAP and PP_FINAP; and -4.508 ± 23.4 mm Hg between PP_IAP and PP_manual. Conclusion: An accurate and continuous PP can be measured noninvasively using a FINAP monitor. This method has much better agreement with IAP measurements than do manual measurements. The qualitative information provided by the oximeter pulse waveform is less accurate than that provided by the FINAP monitor, but is a potentially useful screening tool for detection of significant PP.     

Pulse oximetry for assessment of pulsus paradoxus: a clinical study in children

Objective: To evaluate the relationship between intraarterial measured pulsus paradoxus (PP) and photoplethysmographic wave changes. Setting: Tertiary pediatric intensive care unit. Patients: 62 nonintubated children with or without respiratory disorders. Design: Prospective, clinical study. Measurements and results: Simultaneous paper recordings of photoplethysmographic wave, arterial blood pressure, breathing cycle and electrocardiogram. The respiratory dependent changes of the plethysmographic respiratory wave (delta pleth, mm) were defined as the difference between the highest value of the upper peak of the wave (in expiration) and the lowest value of the upper peak (in inspiration). In each patient, ten consecutive breaths were averaged for analysis. Five recordings could not be evaluated (movement artifacts). In 57 children (median age 2.4 years, range 7 days to 17 years), the photoplethysmographic fluctuations (delta pleth, mm) correlated with PP (mm Hg): r = 0.85; 95 % confidence interval (CI), 0.76 to 0.91. The sensitivity to detect a PP of > 10 mm Hg with a plethysmographic fluctuation of > 8 mm was 89 % (95 % CI, 77 to 100 %) and the specificity was 90 % (95 % CI, 79 to 100 %). Conclusions: Pulse oximetry appears to be a rapid and easily performed, noninvasive method for the objective estimation of the degree of PP. Received: 15 July 1997 Accepted: 1 December 1997     

Mechanism of Pulsus Paradoxus in Clinical Shock

An inspiratory fall in systolic arterial pressure of more than 10 mm Hg (pulsus paradoxus) was noted in 30 of 61 patients with shock. Inspiratory right atrial pressures and total blood volumes were significantly lower in patients with pulsus paradoxus. Rapid infusion of dextran in 22 patients usually was effective in reversing the exaggerated inspiratory fall in systolic pressure. Total peripheral vascular resistance tended to be higher in the patients with pulsus paradoxus and administration of vasoconsrictor drugs often accentuated the respirator pressure variation.Respiratory effects on blood flow in the aorta, pulmonary artery, and venae cavae were studied in anesthetized, closed-chest dogs. In the control state, pulmonary arterial flow increased during inspiration but aortic flow remained nearly constant. After hemorrhage a sharp inspiratory fall in aortic flow was associated with decreased central blood volume and attenuation of the usual inspiratory increase in venae caval and pulmonary arterial flows. The respiratory changes in aortic flow after hemorrhage could be attributed both to depletion of the pulmonary reservoir and to alterations in pulmonary inflow related to changes in systemic venous return.These data indicate that blood volume depletion may precipitate pulsus paradoxus both in the anesthetized dog and in the critically ill patient. The occurrence of pulsus paradoxus may aid in the clinical recognition of the common syndrome of occult hypovolemia in patients with shock in the absence of signs of blood loss.     

Care management revisited: a follow-up study

This article describes a follow-up to a study of community nurse care managers, undertaken in 1993-1994, in the light of the community care policy of the time. The original research found care management to be a viable practice model for community nurses to adopt, given the contemporary context; however, its long-term future was debatable. The present study comprised a questionnaire sent to two groups of community nurse care managers and their managers, who had participated in the original research. Responses indicated that a large proportion remained in a care management role some 4-5 years later, with the mental health and learning disability specialties being better represented than district nursing. Once again, survival was found to be dependent on a number of related contextual variables, which are discussed. The study concluded that the philosophy and principles of care management are still relevant to today's community nursing practice, even though the actual title appears to be less in evidence and current policy changes may render it less viable for the future.     

"Menstrual" migraine: towards a definition

"Menstrual" migraine, a term misused by both patients and doctors, lacks precise definition. This dissertation critically reviews papers on the subject and examines the problem from a clinical perspective. A definition is proposed that the term "menstrual" migraine should be restricted to attacks exclusively starting on or between day l ± 2 days of the menstrual cycle; the woman should be free from attacks at all other times of the cycle. This definition, unlike many used previously, links to a specific mechanism; the timing is consistent with oestrogen withdrawal. If this is correct, "oestrogen withdrawal" migraine may be a better term. Future studies, necessary to support or refute these proposals, are suggested.     

Nursing diagnosis: the importance of a definition

Nursing as an evolving science entertains the usage of terminology that lacks clarity and the singular application of terms. The resulting semantic confusion leads to difficulty in operationalizing definitions for use in taxonomic efforts and in research. Examples of this confusion exist where the term nursing diagnosis is used as concept, category, process, and product. Four suggestions are made to alleviate these difficulties.