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Invasive hemodynamic monitoring in obstetrics
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Luis D. Pacheco, Shannon Clark, Gary D. V. Hankins
The pulmonary artery catheter (PAC) allows one to measure multiple hemodynamic variables. The catheter is 110 cm long and contains a variable amount of ports. An infusion port is usually present. The proximal port connects to the proximal lumen, which is located 30 cm proximal to the distal end of the catheter. This port, when connected to a fluid-filled system and a pressure transducer, permits continuous measurement of the CVP. The distal port allows continuous measurements of pulmonary artery pressures. An additional port allows a syringe (with 1.5 mL of air) to be connected to it. By inflating this port, one inflates the balloon present in the distal part of the catheter. When this happens, blood flow after that point will be interrupted due to vascular occlusion secondary to the inflated balloon. The pressure immediately distal to the balloon, when inflated, is the pulmonary artery occlusion pressure (PAOP). PAOP is also measured at the end of expiration. This, theoretically, is a surrogate of the left ventricular filling pressure at the end of diastole since a “column” of blood will be present between the site of balloon inflation (in a branch of the pulmonary arterial system), the pulmonary venous system, the left atrium, the mitral valve, and, finally, the left ventricle (LV).
ARDS and ALI
Published in T.M. Craft, P.M. Upton, Key Topics In Anaesthesia, 2021
Acute respiratory distress syndrome (ARDS) is a syndrome of respiratory failure associated with severe hypoxia and low respiratory compliance. The characteristic radiological changes are of widespread pulmonary infiltrates. Pulmonary artery occlusion pressure (PAOP) measurements may be low or normal. The plasma oncotic pressure is usually normal. The reported annual incidence of ARDS is variable, 5:100 000 being quoted in the UK, but 75:100 000 in the USA. This reflects differing thresholds for diagnosis.
The management of major injuries
Published in Ashley W. Blom, David Warwick, Michael R. Whitehouse, Apley and Solomon’s System of Orthopaedics and Trauma, 2017
In pulmonary artery flotation catheterization (PAFC), a catheter is passed via a central vein through the right heart to rest within a branch of the pulmonary artery. Inflation of the distal balloon permits measurement of the pulmonary artery occlusion pressure (PAOP), which allows an estimate of left atrial pressure and hence (it is assumed) left ventricular preload. Many errors may, however, confound this measurement. The PAFC also allows measurement of cardiac output by way of thermodilution (either by cold injectate or by proximal heating coil, allowing semi-continuous data to be recorded). This is calculated from the area under a curve of distal temperature (recorded by a thermistor at the catheter tip) plotted against time. Cardiac output is inversely proportional to this area.
The acute respiratory distress syndrome
Published in Baylor University Medical Center Proceedings, 2020
Christopher Wood, Vivek Kataria, Ariel M. Modrykamien
Avoidance of fluid accumulation, especially in the thorax, is considered beneficial in critically ill patients. The FACTT trial evaluated fluid management in ARDS by using a strict fluid balance protocol guided by central line or pulmonary artery catheter data.45 The study included 1000 patients, randomized to one of four hemodynamic protocols for a week. The conservative fluid group aimed at a pulmonary artery occlusion pressure of <8 mm Hg or a central venous pressure of <4 mm Hg, whereas the liberal fluid group aimed at a central venous pressure of 10 to 14 mm Hg or a pulmonary artery occlusion pressure of 14 to 18 mm Hg. Upon analysis, the liberal fluid group presented a net positive fluid balance of 6992 ± 502 mL, while the conservative fluid group ended up with a negative fluid balance of 136 ± 491 mm Hg (P ≤ 0.001). Importantly, the conservative use of fluid was not associated with an increased need for dialysis or an incidence of shock in the first 60 days (19% vs 14%; P = 0.06). Also, a conservative fluid strategy showed an increase in ventilator-free days (14.6 ± 0.5 vs 12.1 ± 0.5; P ≤ 0.001). This pivotal trial remains the best supporting evidence for a conservative fluid strategy when managing patients with ARDS.
Current challenges in managing comorbid heart failure and COPD
Published in Expert Review of Cardiovascular Therapy, 2018
J. Alberto Neder, Alcides Rocha, Maria Clara N. Alencar, Flavio Arbex, Danilo C. Berton, Mayron F. Oliveira, Priscila A. Sperandio, Luiz E. Nery, Denis E. O’Donnell
Alleviation of lung congestion increases the inspiratory ‘ceiling’ (TLC) and reduces the work of breathing by improving lung stiffness and airway function (increasing mechanical time constants and lung emptying) [26,85]. By decreasing the LV filling pressures (pulmonary venous pressures), diuretics conceivably lessen the juxta-capillary receptors stimulation, an important source of high neural respiratory drive and dyspnea in HF [4]. In fact, pulmonary artery occlusion pressure and PaCO2 are inversely related in these patients [87]. Thus, lower respiratory stimuli are expected to increase the PaCO2 set point thereby decreasing the risk of ventilatory control instability, including exercise oscillatory ventilation [45]. The latter, in particular, accelerates the progression of critical mechanical constraints on exertion in HF–COPD [67]. Collectively, alleviation of lung congestion fights the two main determinants of dyspnea in HF–COPD: high respiratory neural drive and neuromechanical dissociation (Figure 3) [68].
Pre-anaesthetic ultrasonographic assessment of neck vessels as predictors of spinal anaesthesia induced hypotension in the elderly: A prospective observational study
Published in Egyptian Journal of Anaesthesia, 2022
Bassant M. Abdelhamid, Abeer Ahmed, Mai Ramzy, Ashraf Rady, Haitham Hassan
The IJV-CI simulates the respiratory variations in the CVP waveform, which increases in hypovolemia. Killu, K. et al.; demonstrated that increasing the IJV-CI by more than 39% predicts hypovolemia in ICU patients [24]. It was also reported that a significant negative correlation was found between compression IJV-CI (performed by manual compression of IJV) and both mean right atrial pressure (Spearman: – 0.43; p-value = 0.0002) and pulmonary artery occlusion pressure (Spearman: −0.35; p-value = 0.0027). Also, there was a negative correlation between the respiratory IJV-CI and mean right atrial pressure and pulmonary artery occlusion pressure, but it did not reach a statistical significance [25].