Effects of PEEP on Respiratory Mechanics after Open Heart Surgery (2)

Methods and Materials
Ten patients who were admitted to the intensive care unit (ICU) of Kuopio (Finland) University Hospital after open heart surgery were included in the study. Their entry data are shown in Table 1. All patients were male. Two patients were current smokers and seven were ex-smokers. All patients had normal vital capacity and forced expiratory volume in 1 s as measured preoperatively and none of them had a history of lung disease. The operative procedure was coronary artery bypass in eight patients and aortic valve replacement in two. The protocol was approved by the institutional ethics committee and informed consent was obtained from each patient preoperatively.
During the operation, patients were anesthetized with high-dose Fentanyl (0.1 mg/kg) and halothane (up to 3 percent) if needed. Paralysis was achieved by the combination of alcuronium and pancuronium (0.25 mg/kg and 0.15 mg/kg, respectively). Toward the end of the operation, the lungs were inflated with several large tidal volumes and PEEP of 5 cm H20 was applied for the rest of the operation. After the operation, patients were immediately transported to the ICU where they were maintained in controlled mechanical ventilation.

Table 1—Entry Data of Ten Patients

Data Mean ± SE
Age, yr 57 ±3
Weight, kg 77 ±3
Height, cm 174 ±2
Tidal volume, L 0.64 ±0.03
f, breaths/min 12.2±0.1
PEEP, cm H20 5.1 ±0.1
Flo* 0.41 ±0.01
Pa02, mm Hg 152 ±14
(a/A) Po, 0.61 ±0.06