Table 1 Baseline characteristics of included randomized controlled trials

Gutierrez and colleagues [15]

Inclusion criteria: medical and surgical patients consecutively admitted to ICUs with APACHE II scores of 15 to 25.

pHi guided: 65.98 (15.77)

pHi guided: 18.85 (2.93)

pHi guided: if the pHi was below 7.35 or had fallen by 0.10 units or more from the previous reading, normal saline, dobutamine was used according to a procedure in the study.

All patients received histamine-receptor-blocking agents throughout their ICU stay.

pHi guided: 135

ICU survival, hospital survival

Control: 63.22 (17.07)

Control: 19.10 (2.75)

Control: 125

Exclusion criteria: patients with esophageal varices or esophageal or nasopharyngeal obstructions.

Control: patients were treated according to the conventional practices of each participating ICU.

Ivatury and colleagues [17]

Inclusion criteria: any patient with trauma injury who had substantial and prolonged hypotension in the prehospital period, emergency department, or operating room, an Injury Severity Score >25, an initial base deficit >5 mol/l, or an initial blood lactate level >4 mmol/L.

pHi guided: 27 (11.1)

pHi guided: −

pHi guided: the oxygen delivery index (DO₂I) was increased progressively by crystalloid and blood infusion to a pulmonary capillary wedge pressure of 18 mmHg and a hematocrit of 35%. If pHi was not corrected, inotropic therapy with dobutamine hydrochloride (5 to 10 μg/kg/minute) was started.

All patients in both groups received a low-dose dopamine (2 to 5 μg/kg/minute) infusion as a renal vasodilator. A histamine H₂-receptor antagonist (cimetidine) was administered routinely to all the patients.

pHi guided: 30

Overall survival

Control: 27.8 (10.4)

Control: −

Control: 27

Control: the goal of therapy was to achieve and maintain a DO₂I of 600 ml/minute/m² or greater, or an oxygen consumption index of 150 ml/minute/m² or greater, or both.

Exclusion criteria: patients who died of exsanguinating hemorrhage within 24 hours of injury were excluded from the study.

Pargger and colleagues [20]

Inclusion criteria: patients scheduled for elective repair of infrarenal abdominal aortic aneurysms.

pHi guided: 64 (10)

pHi guided: 11 (4)

pHi guided: pHi values lower than 7.32 were treated by the attending physician according to a predefined treatment flow chart (Figure 1 [20]).

Starting on the day of surgery, each patient was given 40 mg omeprazole intravenously at 24-hour intervals.

pHi guided: 29

Hospital mortality, days on SICU, total days in hospital, days intubated.

Control: 67 (9)

Control: 12 (5)

Control: 26

Exclusion criteria: not mentioned.

Control: treatment was performed according to the usual clinical guidelines: hemodynamics were stabilized primarily by means of intravenous fluids (Hetastarch, Ringer’s lactate).

Gomersall and colleagues [16]

Inclusion criteria: a total of 210 adult patients, with a median APCAHE II score of 24 (range, 8 to 51).

pHi guided: 54 (17.5)

pHi guided: 24 (7.167)

pHi guided: after achieving the basic targets, if the pHi <7.35, patients were given additional colloid and then a dobutamine infusion at 5 and then 10 μg/kg/minute, titrated against pHi (Figures 2 and 3 [16]).

Specific therapy to treat the patients’ underlying disease and other forms of organ dysfunction were prescribed as indicated clinically according to standard ICU treatment protocols.

pHi guided: 104

ICU and hospital mortality, duration of ICU stay, duration of hospital stay.

Control: 56 (18.5)

Control: 24 (6.667)

Control: 106

Exclusion criteria: a primary admission diagnosis of cardiogenic pulmonary edema, asthma, isolated neurologic trauma, intracerebral hemorrhage, or active gastrointestinal bleeding or contraindications to the insertion of a nasogastric tube or to the use of dobutamine.

Control: achieve the basic targets. (Figure 2 [16]).

Hameed and colleagues [18]

Inclusion criteria: trauma patients admitted to the TICU met entry criteria for the study by definition.

pHi guided: −

pHi guided: −

pHi guided: if pHi was lower than 7.25, active interventions to treat hypoperfusion including infusion of crystalloids, colloids, blood products and pressors (Figure 1 [18]).

Immediately after randomization, subjects received 600 mg cimetidine intravenously. An additional 600 mg were administered every 12 hours.

pHi guided: 50

Ventilator days, ICU length of stay, hospital length of stay, mortality.

Control: −

Control: −

Control: 54

Exclusion criteria: patients arrived more than 12 hours post injury, were pronounced brain dead in the TICU, were pronounced dead in the resuscitation area or operating room, were burn patients, or they underwent gastroenterostomy.

Control: patients were resuscitated based on conventional physiologic parameters such as blood pressure, urine output, cardiac output, or systemic indicators of hypoperfusion such as lactate, base deficit, pH, or mixed venous oxygenation, crystalloid, colloid, blood products.

Palizas and colleagues [19]

Inclusion criteria: adult patients fulfilling criteria for septic shock according to the ACCP/SCCM Consensus Conference within 48 hours of ICU admission were considered and selected if they were in a 12-hour time window.

pHi guided: 59.9 (15.9)

pHi guided: 19.4 (5.6)

pHi guided: after achieving the basic goal, if the pHi was lower than 7.32, crystalloids/colloids, dobutamine were used to make the pHi >7.32 (Figure 1 [19]).

All patients received histamine H₂-receptor antagonists, and enteral feeding was avoided throughout the study period.

pHi guided: 64

Twenty-eight-day mortality, ICU length of stay.

Control: 57.4 (15.9)

Control: 18.5 (3.8)

Control: 66

Control: using the common hemodynamic protocol to reach the common physiological objectives, making the CI ≥ 3.4 l/minute/m² (Figure 1 [19]).

Exclusion criteria: terminal illness with the patient expected to die within 28 days, irreversible neurologic impairment, and contraindication for nasogastric tube placement.