Pulmonary hypertension in the critical care setting: classification, pathophysiology, diagnosis, and management

Pulmonary Hypertension an Independent Risk Factor for Death in Intensive Care Unit: Correlation of Hemodynamic Factors with Mortality

OBJECTIVE

Critically ill patients with pulmonary hypertension (PH) pose additional challenges due to the existence of right ventricular (RV) dysfunction. The purpose of this study was to assess the impact of hemodynamic factors on the outcome.

METHODS

We reviewed the records of patients with a diagnosis of PH admitted to the intensive care unit. In addition to evaluating traditional hemodynamic parameters, we defined severe PH as right atrial pressure >20 mmHg, mean pulmonary artery pressure >55 mmHg, or cardiac index (CI) <2 L/min/m². We also defined the RV functional index (RFI) as pulmonary artery systolic pressure (PASP) adjusted for CI as PASP/CI; increasing values reflect RV dysfunction.

RESULTS

Fifty-three patients (mean age 60 years, 72% women, 79% Blacks), were included in the study. Severe PH was present in 68% of patients who had higher Sequential Organ Failure Assessment (SOFA) score (6.8 ± 3.3 vs 3.8 ± 1.6; P = 0.001) and overall in-hospital mortality (36% vs 6%; P = 0.02) compared to nonsevere patients, although Acute Physiology and Chronic Health Evaluation (APACHE) II scores (19.9 ± 7.5 vs 18.5 ± 6.04; P = 0.52) were similar and sepsis was more frequent among nonsevere PH patients (31 vs 64%; P = 0.02). Severe PH (P = 0.04), lower mean arterial pressure (P = 0.04), and CI (P = 0.01); need for invasive ventilation (P = 0.02) and vasopressors (P = 0.03); and higher SOFA (P = 0.001), APACHE II (P = 0.03), pulmonary vascular resistance index (PVRI) (P = 0.01), and RFI (P = 0.004) were associated with increased mortality. In a multivariate model, SOFA [OR = 1.45, 95% confidence interval (C.I.) = 1.09–1.93; P = 0.01], PVRI (OR = 1.12, 95% C.I. = 1.02–1.24; P = 0.02), and increasing RFI (OR = 1.06, 95% C.I. = 1.01–1.11; P = 0.01) were independently associated with mortality.

CONCLUSION

PH is an independent risk factor for mortality in critically ill patients. Composite factors rather than individual hemodynamic parameters are better predictors of outcome. Monitoring of RV function using composite hemodynamic factors resulting in specific interventions is likely to improve survival and needs to be studied further.

Perioperative management of pulmonary hypertension during lung transplantation (a lesson for other anaesthesia settings)

Patients with pulmonary hypertension are some of the most challenging for an anaesthesiologist to manage. Pulmonary hypertension in patients undergoing surgical procedures is associated with high morbidity and mortality due to right ventricular failure, arrhythmias and ischaemia leading to haemodynamic instability. Lung transplantation is the only therapeutic option for end-stage lung disease. Patients undergoing lung transplantation present a variety of challenges for anaesthesia team, but pulmonary hypertension remains the most important. The purpose of this article is to review the anaesthetic management of pulmonary hypertension during lung transplantation, with particular emphasis on the choice of anaesthesia, pulmonary vasodilator therapy, inotropic and vasopressor therapy, and the most recent intraoperative monitoring recommendations to optimize patient care.

Intravenous clonidine administration and its ability to reduce pulmonary arterial pressure in patients undergoing heart surgery

OBJECTIVE

Evaluate the ability of clonidine to reduce pulmonary arterial pressure in patients with pulmonary hypertension undergoing heart surgery, either by reducing the pressure values from the direct measurement of pulmonary arterial pressure or by reducing or eliminating the need for intraoperative dobutamine and nitroprusside.

METHOD

Randomized, double-blind, placebo-controlled, comparative study conducted in 30 patients with pulmonary arterial hypertension type 2 undergoing cardiac surgery. Mean pulmonary arterial pressure and dosage of dobutamine and sodium nitroprusside were assessed four times: before intravenous administration of clonidine (2 μg/kg) or placebo (T0), 30 min after tested treatment and before cardiopulmonary bypass (T1), immediately after CPB (T2), 10 min after protamine injection (T3).

RESULTS

There were no significant differences regarding mean pulmonary arterial pressure at any time of evaluation. There was no significant difference between groups regarding other variables, such as mean systemic arterial pressure, heart rate, total dose of dobutamine, total dose of sodium nitroprusside, and need for fentanyl.

CONCLUSION

Data analysis from patients included in this study allows us to conclude that intravenous clonidine (2 μg/kg) was not able to reduce the mean pulmonary arterial pressure in patients with pulmonary hypertension in group 2 (pulmonary venous hypertension), undergoing heart surgery, or reduce or eliminate the need for intraoperative administration of dobutamine and sodium nitroprusside.

Diaphragm atrophy and contractile dysfunction in a murine model of pulmonary hypertension

Pulmonary hypertension (PH) causes loss of body weight and inspiratory (diaphragm) muscle dysfunction. A model of PH induced by drug (monocrotaline, MCT) has been extensively used in mice to examine the etiology of PH. However, it is unclear if PH induced by MCT in mice reproduces the loss of body weight and diaphragm muscle dysfunction seen in patients. This is a pre-requisite for widespread use of mice to examine mechanisms of cachexia and diaphragm abnormalities in PH. Thus, we measured body and soleus muscle weight, food intake, and diaphragm contractile properties in mice after 6-8 weeks of saline (control) or MCT (600 mg/kg) injections. Body weight progressively decreased in PH mice, while food intake was similar in both groups. PH decreased (P<0.05) diaphragm maximal isometric specific force, maximal shortening velocity, and peak power. Protein carbonyls in whole-diaphragm lysates and the abundance of select myofibrillar proteins were unchanged by PH. Our findings show diaphragm isometric and isotonic contractile abnormalities in a murine model of PH induced by MCT. Overall, the murine model of PH elicited by MCT mimics loss of body weight and diaphragm muscle weakness reported in PH patients.

Correlates of in-hospital deaths among hospitalizations with pulmonary embolism: findings from the 2001-2008 National Hospital Discharge Survey

BACKGROUND

Deep vein thrombosis and pulmonary embolism (PE) are responsible for substantial mortality, morbidity, and impaired health-related quality of life. The aim of this study was to evaluate the correlates of in-hospital deaths among hospitalizations with a diagnosis of PE in the United States.

METHODS

By using data from the 2001-2008 National Hospital Discharge Survey, we assessed the correlates of in-hospital deaths among 14,721 hospitalizations with a diagnosis of PE and among subgroups stratified by age, sex, race, days of hospital stay, type of admission, cancer, pneumonia, and fractures. We produced adjusted rate ratios (aRR) and 95% confidence intervals using log-linear multivariate regression models.

RESULTS

Regardless of the listing position of diagnostic codes, we observed an increased likelihood of in-hospital death in subgroups of hospitalizations with ages 50 years and older (aRR = 1.82-8.48), less than 7 days of hospital stay (aRR = 1.43-1.57), cancer (aRR = 2.10-2.28), pneumonia (aRR = 1.79-2.20), or fractures (aRR = 2.18) (except for first-listed PE), when compared to the reference groups with ages 1-49 years, 7 days or more of hospital stay, without cancer, pneumonia, or fractures while adjusting for covariates. In addition, we observed an increased likelihood of in-hospital death for first-listed PE in hospitalizations of women, when compared to those of men (aRR = 1.45).

CONCLUSIONS

The results of this study provide support for identifying, developing, and implementing effective, evidence-based clinical assessment and management strategies to reduce PE-related morbidity and mortality among hospitalized PE patients who may have concurrent health conditions including cancer, pneumonia, and fractures.

Reversible pulmonary hypertension in a cat

A 13-year-old, neutered female domestic shorthair cat was presented for sudden respiratory distress following palliative radiotherapy and the combined administration of a single dose of carboplatin for the treatment of recurrent fibrosarcoma. Clinical and radiographic findings were suggestive of pleural effusion. Echocardiography revealed marked right-sided cardiac enlargement associated with tricuspid regurgitation and Doppler evidence of pulmonary hypertension. After 25 days of treatment for congestive heart failure and suspected pulmonary thromboembolism, clinical signs and echocardiographic and Doppler evidence of right-sided cardiac enlargement and pulmonary hypertension had completely resolved. To the best of the authors' knowledge, this is the first report of reversible pulmonary hypertension, likely secondary to pulmonary thromboembolism, in a cat.

The impact of micro-embolism size on haemodynamic changes in the pulmonary micro-circulation

Embolus occlusion of pulmonary arteries can result in elevated pulmonary blood pressures, often resulting in pulmonary hypertension (PH). Experimental observations have shown that small emboli (diameter <170 μm) can have a disproportionate effect on pulmonary vascular resistance (PVR) compared with larger emboli for the same tissue occlusion. We present an anatomically based theoretical model of perfusion in the acinar blood vessels designed to investigate changes in PVR following occlusion of arteries <500 μm in diameter. The model predicts that emboli lodged near proximal capillary beds have a greater effect on PVR--regardless of their size--than emboli occluding 200 μm diameter arterioles, with PH occurring for 10% less tissue occlusion. Capillary blood pressures are predicted to exceed 24 mmHg (levels initiating capillary wall damage) in regions of the capillary bed at approximately the onset of PH. This study focuses on the effect of mechanical obstruction alone; however, we present simple models of vasoconstriction illustrating an increased impact on PVR.

Ongoing paradoxical particulate embolism during megaprosthesis placement

Pulmonary embolism (PE) by solid particles is an infrequent complication encountered during orthopedic procedures. A patent foramen ovale (PFO) allows embolic material into the left-sided circulation, potentially affecting several organs. A case of a 33-year-old woman undergoing total proximal femur resection with megaprosthesis reconstruction is presented. Towards the end of surgery, cement was injected to stabilize the prosthesis. Echodense particulate matter was first seen in the right atrium, subsequently in the right ventricle, and also in significant quantities in the left atrium and ventricle. This was accompanied by significant changes in partial pressure of arterial oxygen. Despite the aforementioned disturbances, hemodynamic stability was observed throughout the event. Postoperative follow-up showed persistent hypoxemia but no other abnormalities. This intriguing case of embolism via particulate material in a patient with PFO during hip replacement surgery allows review of the physiology and pathophysiology of PE phenomena.