Invasive hemodynamic monitoring in obstetrics
Hung N. Winn, Frank A. Chervenak, Roberto Romero in Clinical Maternal-Fetal Medicine Online, 2021
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).
Respiratory Failure after Surgery or Trauma
Stephen M. Cohn, Matthew O. Dolich in Complications in Surgery and Trauma, 2014
Judicious fluid management is an essential component of the management strategy for ARDS. The rationale for using a restrictive fluid strategy is to decrease the pulmonary vascular hydrostatic pressure, thereby limiting transudation across leaky capillaries. At the same time, however, adequate tissue perfusion must be maintained. Using a PAC may be helpful in achieving this fine balance. The pulmonary artery occlusion pressure is maintained at the lowest level that will result in adequate circulation volume and mean arterial pressures, and in cardiac output that meets the oxygen delivery needs of the tissues. For patients without PACs, surrogate markers include central venous pressure, urine output, and acid–base balance. Vasopressors may be used to maintain perfusion if fluid resuscitation is inadequate. There is, however, no role for their use in generating a supra-normal oxygen delivery. Adopting a restrictive fluid strategy with diuresis results in fewer days on mechanical ventilation and improved oxygenation, and is associated with better outcomes [42]. Great caution, however, should be taken in patients who have not yet achieved euvolemic states after injury. Restrictive fluid utilization policies or diuresis in patients with ongoing resuscitative needs is not advised.
Complications of Laparoscopic Adrenal Surgery
Kevin R. Loughlin in Complications of Urologic Surgery and Practice, 2007
Several intra-operative management details are important with these patients. An intraarterial catheter is used for blood pressure monitoring (12). Monitoring with a pulmonary artery catheter is useful for following cardiac output and systemic vascular resistance (2). Pulmonary artery occlusion pressures are monitored and crystaloid or colloid solutions are given to maintain a pulmonary artery occlusion pressure of between 10 and 12 mmHg in order to prevent any hypovolemia and its resultant hemodynamic effects after treatment with vasodilators. Also of note, pulmonary artery occlusion pressures can be artificially elevated during pneumoperitoneum because of increased intrapleural pressure. Ventilation is adjusted to keep the pulmonary end-tidal carbon dioxide between 32 and 38 mmHg (52).
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].
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.
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].
Related Knowledge Centers
- Acute Respiratory Distress Syndrome
- Pulmonary Circulation
- Atrium
- Pulmonary Edema
- Cardiac Output
- Pulmonary Artery Catheter
- Heart Failure