Preoperative pulmonary blood flow and one-lung anaesthesia

Abstract

The distribution of pnlmonz~ry hlood fiow was measured in supine patients before surgery by meom of lung pe~usion scanning with 99'nTc-macroaggre gated albumin in an attempt to predict values of Pa02 during subsequen2 one-lung anaesthesia. The Pa02 values during one-lung anaesthesia were well correlated with the preoperative lung perfusion partition ratios (r = 0.84, p < 0.05). In 9 of4Opat&nts, Pa02 was < 80 mmHg during one.lung ventilation (FRO2 0.99). In these patients the lung perfusion ratios of the dependent lung were as low as 41.0-48.2 per cent. These results indicate that preoperative measurement of pulmonary, blood flow can predict values of Pa02 during one-lung anaesthesia. Severe hypoxaemia develops occasionally during onelung anaesthesia. Peltola ~ reported that during one-lung ventilation, 6 of 32 patients had PaO2 values less than 70mmHg, in spite of breathing 10t') per cent oxygen (lowest value 52.4mmHg). Katz etal. 2 reported that one-lung ventilation with an FmO: of 0.99 resulted in a PaO2 of less than 80 mmHg in 5 of 17 patients and in two patients PaO2 was less than 60mmHg. In this study, the distribution of preoperative pulmonary blood flow was measured by means of lung perfusion scanning with 99r~Tc-macroaggregated-alhumin (99mTc-MAA) in an attempt to predict values of PaO2 during subsequent one lung anaesthesia. Methods The investigation was perfon~led in 40 adult patients between the ages of 27 and 74 years undergoing elective thoracotomy, Surgery was for cancer of the lung in 26 patients, empyema in eight patients and pulmonary tuberculosis in six patients. Following intravenous injection of approximately

Gradient of bronchial end-tidal CO2 during two-lung ventilation in lateral decubitus position is predictive of oxygenation disorder during subsequent one-lung ventilation

“…The infl uence of positional laterality in our study is similar to the fi ndings of previous reports [6,15]. Nomoto [7] suggested the distribution of preoperative lung perfusion and the percentage of predicted vital capacity as predictors of hypoxemia. Slinger et al [15] indicated that the LP side, the preoperative percent forced expiratory volume in 1 s and the intraoperative Pa O 2 during TLV may be predictors of hypoxemia.…”

“…The reduction of Pa O 2 /FI O 2 during OLV would also be affected by the distribution of lung perfusion, especially by the amount of shunt fl ow in the nondependent lung. If the D-ETbr CO 2 represents the difference of pulmonary blood fl ow between the dependent and nondependent lungs, then our results are coincident with those of previous studies [5][6][7][8], in which the distribution of pulmonary blood fl ow was preoperatively determined by using a radioisotope. Clinically, the D-ETbr CO 2 can be obtained instantly and noninvasively by interposing a pair of measurement instruments in the respiratory circuit.…”

“…Because the end-tidal carbon dioxide pressure (ET CO 2 ) is mostly infl uenced by the pulmonary blood fl ow [3,4], each lung ETbr CO 2 refl ects the gross pulmonary blood distribution between the dependent and nondependent lungs. The preoperative state of perfusion in each lung was reported to be one of the predictors of hypoxemia in OLV [5][6][7][8]. The online determination of each lung ETbr CO 2 prior to starting OLV is easier, time-saving, and noninvasive compared with a visualizing examination of lung perfusion using a radioisotope.…”

Hypoxemia during One-lung Ventilation

“…Distribution of perfusion between the two lungs is another important factor that may be measured preoperatively and may help to predict hypoxemia during OLV 8 ( fig. 1A).…”

“…Because transpulmonary venous shunting depends on the percentage of cardiac output that is not oxygenated, the less the perfusion of the nonventilated lung is and the more the perfusion of the ventilated lung is, the higher the PaO 2 is during OLV. 2,5,4,8,9 Because a good number of patients presenting for major thoracic surgery may have perfusion scans in the workup for the operation, it is important that the anesthesiologist take the results of the scans into account.…”