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Resumen: Las Interacciones Cardiopulmonares (ICP) corresponden al conjunto de interrelaciones entre el sis tema respiratorio y el cardiovascular, durante el ciclo respiratorio y cardíaco. Estas interacciones varían dependiendo de si el paciente se encuentra en ventilación espontánea o mecánica, afectando en distintos grados la precarga y postcarga, tanto del ventrículo derecho e izquierdo. El entender estas interacciones, resulta esencial al momento de manejar pacientes críticamente enfermos, en donde las manipulaciones de la precarga y postcarga, son de especial importancia al momento de optimizar el débito cardíaco y la entrega de oxígeno a los tejidos. En este artículo se presentan los principios fisiológicos que permiten entender las interacciones cardiopulmonares en ventilación espontánea y en ventilación mecánica, aplicadas a situaciones clínicas específicas, lo que nos ayudará a utilizarlas como herramientas en el manejo de los pacientes.
Abstract: Cardiopulmonary Interactions (CPI) refer to the interplay between the respiratory and cardiovascu lar systems during the respiratory and cardiac cycle. These interactions vary depending on whether the patient is in spontaneous or mechanical ventilation and affect the preload and afterload of both ventricles at different levels. Understanding CPI is essential to the management of critically ill pa tients, where preload and afterload manipulations are specialy important to optimize cardiac output and oxygen delivery to the periphery. The present article reviews the physiological principles required to understand CPI in patients both in spontaneous and mechanical ventilation using specific clinical scenarios to facilitate its use as part of day to day clinical practice.
Subject(s)
Humans , Respiration, Artificial , Respiratory Physiological Phenomena , Cardiovascular Physiological Phenomena , Critical Illness , Heart/physiology , Heart/physiopathology , Lung/physiology , Lung/physiopathologyABSTRACT
Objective To observe the effect of different airway pressure on ventilation, organ perfusion and return of spontaneous circulation (ROSC) of cardiac arrest (CA) pigs during cardiopulmonary resuscitation (CPR), and to explore the possible beneficial mechanism of positive airway pressure during CPR. Methods Twenty healthy landrace pigs of clean grade were divided into low airway pressure group (LP group, n = 10) and high airway pressure group (HP group, n = 10) with random number table. The model of ventricular fibrillation (VF) was reproduced by electrical stimulation, and mechanical chest compressions and mechanical ventilation (volume-controlled mode, tidal volume 7 mL/kg, frequency 10 times/min) were performed after 8 minutes of untreated VF. Positive end expiratory pressure (PEEP) in LP group and HP group was set to 0 cmH2O and 6 cmH2O (1 cmH2O = 0.098 kPa) respectively. Up to three times of 100 J biphasic defibrillation was delivered after 10 minutes of CPR. The ROSC of animals were observed, and the respiratory parameters, arterial and venous blood gas and hemodynamic parameters were recorded at baseline, 5 minutes and 10 minutes of CPR. Results The number of animals with ROSC in the HP group was significantly more than that in the LP group (8 vs. 3, P < 0.05). Intrathoracic pressure during chest compression relaxation was negative in the HP group, and its absolute value was significantly lower than that in LP group at the same time [intrathoracic negative pressure peak (cmH2O): -4.7±2.2 vs. -10.8±3.5 at 5 minutes, -3.9±2.8 vs. -6.5±3.4 at 10 minutes], however, there was significantly difference only at 5 minutes of CPR (P < 0.01). Intrathoracic pressure variation during CPR period in the HP group were significantly higher than those in the LP group (cmH2O: 22.5±7.9 vs. 14.2±4.4 at 5 minutes, 23.1±6.4 vs. 12.9±5.1 at 10 minutes, both P < 0.01). Compared to the LP group, arterial partial pressure of oxygen [PaO2 (mmHg, 1 mmHg = 0.133 kPa): 81.5±10.7 vs. 68.0±12.1], venous oxygen saturation (SvO2: 0.493±0.109 vs. 0.394±0.061) at 5 minutes of CPR, and PaO2 (mmHg: 77.5±13.4 vs. 63.3±10.5), arterial pH (7.28±0.09 vs 7.23±0.11), SvO2 (0.458±0.096 vs. 0.352±0.078), aortic blood pressure [AoP (mmHg): 39.7±9.5 vs. 34.0±6.9], coronary perfusion pressure [CPP (mmHg): 25.2±9.6 vs. 19.0±7.6], and carotid artery flow (mL/min:44±16 vs. 37±14) at 10 minutes of CPR in the HP group were significantly higher (all P < 0.05). Arterial partial pressure of carbon dioxide (PaCO2) in the HP group was significantly lower than that in the LP group at 10 minutes of CPR (mmHg: 60.1±9.7 vs. 67.8±8.6, P < 0.05). Conclusions Compared to low airway pressure, a certain degree of positive airway pressure can still maintain the negative intrathoracic pressure during relaxation of chest compressions of CPR, while increase the degree of intrathoracic pressure variation. Positive airway pressure can improve oxygenation and hemodynamics during CPR, and is helpful to ROSC.
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Objective To explore the mechanism of intrathoracic pressure(ITP) influncing cardiac function and facilitate noninvasive determination of ventricular pressure theoretically.Methods With Valsalva and Mueller maneuver,two-dimension images of standard long axis views and the cross-sectional views were recorded in 20 volunteers,aged from 18 to 45 years,at the specific ITP levels(including-20 mmHg、-10 mmHg、0 mmHg、+ 10 mmHg and + 20 mmHg).The subjects were instructed to mantain for at least 10 s,and three successive measurements were recorded and averaged.The stroke volume(SV) and radius of curvature(R) were obtained from further off-line analysis.Results With the ITP maintaining at -20 mmHg,-10 mmHg,0 mmHg(end expiration),+ 10 mmHg and + 20 mmHg respectively,the corresponding radiuses of curvature were (2.35 ±0.24)cm,(2.25 ± 0.23)cm,(2.14 ± 0.21)cm,(2.02 ± 0.21) cm,(1.93 ± 0.19) cm,there were statistically significances between two groups (P =0.006,0.031,0.005 and ＜0.001,respectively].When the ITP were at 0 mmHg(end expiration),+ 10 mmHg and + 20 mmHg,the stroke volume were (71.54±8.81)ml,(73.20±9.52)ml and (78.81± 14.61)ml (P =0.674,0.135).When the intrathoracic pressure decreased from 0 mmHg to-20 mmHg,the stroke volume were (78.81±14.61)ml,(68.28 ±9.28)ml and (59.69±7.52)ml(P =0.029,0.037).Conclusions The ITP has different effects on the two ventricles,and subsequently generates a pressure gradient across the IVS which can alter its shape and position at end-diastole.With the IVS shifting,the preload and filling function of left ventricle gets changed acorrding to the Frank Starling principle.
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Objective To study the changes of trans-diaphragmatic pressure (Ptra) and its correlation with esophageal pressure (Peso) through ARDS piglet model.Methods Five piglets were enrolled in the study.Peso,gastric pressure (Pgas) and intra-thoracic pressure (Pint) was monitored through balloon inserted.The data before ARDS serve as control.ARDS was produced in the piglets through saline lavage.The pressure were observed and the Ptra were calculated.The pressure changes and correlation between Ptra and Peso were analyzed as well.Linear regression with the coefficient of determination and t-test were used as appropriate.Significance was assumed for P ＜ 0.05.Results Peso,Pgas and Pint before ARDS were 7.3 ± 1.9,25.5 ± 2.4,- 1.23 ± 0.21 cmH2O,Ptra was 18.2 ± 1.6 cmH2O.While after ARDS,the data were 4.7 ± 1.4,31.1 ± 3.1 and - 1.79 ± 0.28 cmH2O,and Ptra was 26.4 ± 2.1 cmH2 O,and all these changes were obviously ( P ＜ 0.05 ).The correlation between Pint and Peso,Pint and Ptra (A) and Ptra ( B ) were 0.93 ± 0.025,0.88 ± 0.023 and 0.87 ± 0.37 before ARDS.After ARDS,the correlation changed to be 0.82 ±0.21,0.81 ±0.20 and 0.78 ±0.31.Although a bit decreased,the correlation was still positive (P ＜ 0.01 ).Conclusions There existed good correlations between Peso and Ptra as well as between Pint and Peso before or after ARDS.Ptra was increased obviously after ARDS,which could lead to respiratory muscle fatigue.
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Objective To investigate the effects of elasticity resistance (Ers) in respiratory system on oxygenation in patients with acute lung injury (ALI) after recruitment maneuvers (RM). Method Meta-analysis of data about the effects of recruitment maneuvers on oxygenation in ALI patients with different elasticity resistances in respiratory system carried out with pooling of study-oriented data stored in Pubmed, Embase, Web of Science databases from January 1999 to June 2010. Results A total of 281 articles were taken, and 20 of them included a sample size of 395 ALI patients. In patients treated with RM in different degrees of respiratory system elasticity resistance ( ≥33.3 cmH2O/L and ＜33.3 cmH2O/L), the effect of RM was better in patients with the high respiratory system elasticity resistance than that with the low one [(51.97 + 8.89) mmHg vs. (35.13 ± 10.33 ) mmHg], P ＜ 0. 01 ), but the high respiratory system elasticity resistance was potentially to lower blood pressure [(4. 33 ± 1.32 ) mmHg vs. (0.22 ± 1.03 ) mmHg],P ＜ 0.01 ). Conclusions This study suggests RM could improve oxygenation of ALI patients with high respiratory system elasticity resistance, and caution must be made to avoid hypotension during RM.
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BACKGROUND: The hemodynamic effects of increased intrathoracic pressure (ITP) have been the focus of many investigations. However, very little is known about the effects of elevated ITP on the occurrence of stroke. CASE REPORT: Four young patients with a cardioembolic source of stroke were examined. In all cases the stroke was preceded by an increase in ITP that occurred during coughing, vomiting, or sexual intercourse. CONCLUSIONS: We suggest that cardioembolic stroke is facilitated by situations in which ITP is elevated.