Study Design

Reduced Quality Factors

0 = no serious, - = serious,

- - = very serious

Positive Quality Factors

0 = none, + = one, ++ = multiple

Dichotomous Outcome Summary

Non-Dichotomous Outcome Summary

Brief description

Overall Quality

High, moderate, low,
very low, none

No of studies

Study Type

RoB

Indirectness

Imprecision

Inconsistency

Large Effect

Dose-Response

Confounder

# Intervention with Outcome

# Control with Outcome

RR (95% CI)

Outcome: Favorable neurologic outcome

1

Obs

0

- -

-

0

Very low

Outcome: Survival to discharge

1

Obs

0

- -

-

0

Very low

Outcome: ROSC

0

Outcome: Time to identify CPA

1

CT

0

- -

-

0

0

0

0

Very low

1

OB

0

- -

0

0

0

0

0

Very low

Outcome: Time to start CPR

1

CT

0

- -

-

0

Very low

Introduction

Blood pressure (BP) monitoring is frequently performed in veterinary and human hospitals. Serial BP measurements allow early recognition of clinical deterioration and provide the clinician with important patient care information that may ultimately affect the quality of care provided. This PICO question investigated the use of blood pressure monitoring in patients at risk of CPA to improve outcomes.

Consensus on science

Outcome 1: Favorable neurologic outcome

For the most critical outcome of favorable neurologic outcome, 1 observational study in people who achieved ROSC after OHCA was identified (very low quality of evidence, downgraded for very serious indirectness and imprecision).1 This study included 11,352 patients with OHCA that achieved ROSC and were admitted to the hospital. Of those, 7,706 had indirect systolic blood pressures measured in the pre-hospital setting. Both hypotension and hypertension were associated with decreased FNO in this cohort. Relative risks for poor neurologic outcome were 1.069 (95% CI = 1.033–1.105) for SBP of 80–99 mmHg, 1.203 (95% CI = 1.158–1.243) for SBP < 80 mmHg, 1.076 (95% CI = 1.043–1.110) for SBP 130–160mmHg, and 1.168 (95% CI =1.126–1.208) for SBP > 160 mmHg, all P < 0.001.

Outcome 2: Survival to discharge

For the next most critical outcome of survival to discharge, one observational study in people was identified that informed an answer to the PICO question (very low quality of evidence downgraded for very serious indirectness and imprecision).2 This retrospective registry study evaluated the association between systolic BP on arrival to the hospital and survival to discharge in 3620 adult people surviving OHCA. Among the subjects, 14% were hypotensive at hospital arrival. In the patients with an initial shockable rhythm, hypotension was associated with less frequent survival to discharge. In these patients, systolic BP < 90 mmHg was associated with significantly decreased adjusted odds ratio of survival to discharge: 80–89 mmHg AOR = 0.49 (95% CI: 0.24–0.95); <80 mmHg AOR = 0.24 (95% CI: 0.10–0.61); unrecordable AOR = 0.10 (95% CI: 0.04–0.30). However, in patients with initial non-shockable rhythms, systolic BP was not associated with survival to discharge.

Outcome 3: ROSC

For the next most critical outcome of ROSC, no relevant studies were identified to inform an answer to the PICO question.

Outcome 4: Time to identification of CPA

For the next important outcome of time to identification of CPA, 1 clinical trial of simulated anesthetic events in people (very low quality of evidence, downgraded for very serious indirectness and imprecision) and 1 observational study in people were identified (very low quality of evidence, downgraded for very serious indirectness).3,4 The clinical trial included 58 senior anesthesiology residents randomized to either invasive blood pressure monitoring or non-invasive blood pressure monitoring during a simulated cardiopulmonary arrest. The group with access to invasive blood pressure monitoring palpated for pulses in the patient 6.5 seconds sooner (P=0.047) and initiated chest compressions 17 seconds sooner (P=0.004) than the group with indirect blood pressure monitoring. The observational study evaluated 269,956 adults admitted to hospital wards, 422 of which developed CPA.4 The analysis showed that the lowest systolic and diastolic blood pressures measured in the four hours prior to CPA were lower than those measured in patients that did not experience CPA, but no specific blood pressure cutoffs were reported.

Outcome 5: Time to start CPR

For the outcome of time to start CPR, 1 clinical trial of simulated anesthetic events in people (very low quality of evidence, downgraded for very serious indirectness and imprecision) was found that addressed the PICO question.3 As described above, the group with access to invasive blood pressure monitoring initiated chest compressions 17 seconds sooner than the group with only indirect blood pressure monitoring (P=0.004).

Treatment recommendation

We recommend frequent or continuous blood pressure monitoring in patients at risk of CPA, including patients under anesthesia, in shock, and in the PCA period. (strong recommendation, very low quality of evidence)

We suggest the use of continuous, direct arterial blood pressure monitoring if feasible in patients at risk of CPA. (weak recommendation, very low quality of evidence)

Justification of treatment recommendation

The evidence reviewed supports the utility of blood pressure monitoring to diagnose CPA rapidly in high-risk patients. Direct, continuous arterial blood pressure monitoring has been shown to allow faster recognition of CPA and initiation of CPR, and so is preferred over intermittent non-invasive monitoring if feasible.3

A single veterinary study was evaluated in which the relationship between Doppler BP and survival or response to treatment in critically ill cats was investigated.5 This was a retrospective study of 83 cats and there was a significantly higher mortality frequency in hypotensive cats.5 In this study, hypotensive critically ill cats with an increase in Doppler BP of at least 20 mmHg during hospitalization were more likely to survive to discharge when compared to cats in which the difference in BP was <20 mmHg (survival rates 69% and 17%, respectively). No data was available in this study related to the relationship between severity of hypotension, frequency of monitoring, or incidence of CPA. But this study provides some additional justification for blood pressure monitoring in critically ill cats.

A retrospective observational study evaluated the association of blood pressure monitoring with adverse outcomes in people admitted to an emergency department.6 Worsening of clinical signs was associated with decreases in systolic and diastolic BP values; however, this association was not seen between BP and length of hospital stay, repeat admission to the hospital, or CPA.

Human studies have also used the Modified Early Warning Score (MEWS) to identify high-risk ward patients and trigger rapid response teams in cardiac arrest.4,7 The MEWS scoring system incorporates systolic BP measurements, as well as HR, RR, temperature, and level of consciousness to provide a warning score for clinical deterioration. Use of this scoring system has provided some evidence that patients with lower diastolic and systolic BP have a higher risk of CPA.4

Knowledge gaps

There have been no studies in dogs or cats examining the utility of blood pressure monitoring in patients that ultimately develop CPA. Given the minimal risk of blood pressure monitoring and the likelihood that early identification of hypotension in patients at risk of CPA is useful, the committee suggests that further studies of blood pressure monitoring in these patients is a low priority.