Optimal Ambulatory Vital Sign Targets in Pulmonary Hypertension Pregnant Women via Time-Dependent Survival Analysis
Background: Pulmonary hypertension (PH) can cause complications in pregnant women due to significant hemodynamic fluctuation or right heart failure as well as death during pregnancy and postpartum. Those in critical condition would be sent to the intensive care unit (ICU) for observation and treatment. However, evidence to suggest the safe target vital signs is limited and none specific to pregnancy with PH.Methods: This retrospective study of consecutive obstetric patients with PH admitted to
... CU of the First Affiliated Hospital of Air Force Military Medical University of China, from January 2011 to May 2020, consisted of 92 cases analyzed using time-dependent Cox regression to consider the dynamic features of vital signs. Results: 7/92 maternal deaths occurred. Most of these deaths occurred within the first three days of admission to the ICU. The vital signs for survival were stable and normal compared to death. Three vital signs were identified as risk factors in the maternal in-hospital mortality model via backward selection: SpO2(HR,0.93;95%CI,0.88-0.97;P=0.003), heart rate(HR,0.94;95%CI,0.90-0.99;P=0.027), and mean arterial pressure (MAP) (HR,1.09;95%CI,1.00-1.18;P=0.045). Log of relative hazard ratios of mortality is linearly negatively related to SpO2 value with a U-shaped correlation with heart rate and MAP (both lower and higher values were associated with high mortality). The optimal range of SpO2 <73%, MAP was 65–95 mmHg, and heart rate was 59–125 beats per minute (bpm). Further exploration showed that the cumulative and the longest consecutive time of abnormal vital signs also affect the outcome. For example, SpO2<73% accumulated for 5 h or continuously up to 2 h increases mortality.Conclusions: Pregnant women with PH who died in the hospital experienced long-term abnormal fluctuations in MAP, heart rate, and SpO2 during ICU stay. Maintaining SpO2>73%, MAP at 65–95mmHg, and heart rate at 59–125 bpm can significantly reduce in-hospital maternal mortality. The effects of the abnormal SpO2, heart rate, and MAP on in-hospital maternal mortality should be combined with the cumulative time and the longest duration.Trial Registry: ChiCTR2100046637.